MODIFICATION OF THE TIME-EXPANDED STRATIGRAPHIC COLUMN OF NORTH EAST IRAQ DURING CRETACEOUS AND TERTIARY BY: Kamal Haji KarimPublished in: Petroleum Geology of Iraq (First Symposium, 21-22, April 2010, Baghdad, Abstract book, p.4.

AbstractThe time expanded stratigraphic (time-stratigraphic or chronostratigraphic) column of Iraq was established in the fifties of the last century by Oil Companies that were working in Iraq. During this long time the column remained without important changes. Therefore, the present study tries to update and modify the column according to recent sedimentoggical and stratigraphic studies of the northeastern Iraq. The main modifications include removing of all previous unconformity between the following formations: Qamchuqa with Dokan and Kometan, the later formation with both Dokan Golneri, Kometan with Shiranish, Qamchuqa with Bekhme, Tanjero with Kolosh formations. The contacts between the above formations are changed to conformable and their boundary assigned as gradational in the new chronostratigraphic column. The modifications also include lateral combining of the lower and upper parts of Red Bed Series with Kolosh and Gercus Formations respectively which are deposits of one large foreland basin. Moreover, during Eocene, the tectonic and geographic location of the Walash Naoperdan Series is indicated and correlated with Pila Spi Formation which is separated by paleo-high from the series. On the new chronostratigraphic column, locations of the stratigraphic units are indicated according to present tectonic zones (Low and High Folded, Imbricated and Thrust Zones) of Iraq instead of previous general geographic position. Another type of location which is followed, in the new column, is putting the formations in their historical position of deposition within foreland basin of Late Cretaceous and Tertiary. In the studied area, the coarse clastic units are put in the costal area near to source areas while the very fine ones (marl and Shale) put near to basin plain of the foreland basin. Between the two, the medium grain clastics and biogenetic limestones are deposited in intermediated depth (shelf and slope).

keywords: stratigraphic column of Kurdistan. oil in Kurdistan, Iraq stratigraphy,

تغير العمود الزمن الطباقي لشمال شرق العراق للعصر الكريتاسي و الثالثي

من قبل: كمال حاجي كريم

المخلص

اسست عمود الزمن الطباقي للعراق منذ خمسينيات القرن الماضي من قبل شركات النفط العملة في العراق و خالل هذه المدة الطويلة بقيت بدون تغير كبير. لذلك تحاولالدراسة الحلية الى تجديد و تغير العمود الزمن الطابقي للشمال الشرق العراق لكي يتضمن جميع التغيرات الحاصلة اعتماد على الدراسات الرسوبية و الطباقة الحديثة بحيث يتفق التغيرات مع تطورات العلمية الحديثة حول الجيولوجية المنطقة. ان تغيرات الرئسيسة عبارة عن ازالة عدم التوافقات السابقة بين التكاوين التالية: قمجوغة مع دوكان و كوميتان و بين هذا التكوين مع دوكان و كولنيري، كوميتان مع شيرانش وقمجوقة مع بخمة و تانجرو مع كولوش. ان حد التماس بين التكاوين السابقة تم تغيرها من عدم توافق الى توافقي و غيرت حدودهم التباقي الى تدرجيا في العمود الجديد. ويشمل التغير كذلك دمجا افقيا لجزء السفلي و العلوي للسلسلة الطبقات الحمراء مع تكوين كولوش و جركس بالتوالي و اعتبار كالهما ترسبات الحوض المقدمة القارة و باضافة الى ذالك تم تحديد الموقع التكتوني و الجغرافي للسلسلة واالش ناوبردان و مضاهاته زمنيا مع تكوين بالسبي حيث يفرق بينهما مرتفعا. حددت موقع الوحدات الطباقية طبقا لالنطقة التكتونية الحالية للمنطقة )انطقة الطيات الواطئة والعاليةو التراكب والزاحفة) بدال للموقع الجغرافي العام المتبع سابقا. نوع اخر متبع هو تحديد موقع حسب موقع تأريخ الترسيب كل وحدة ضمن حوض المقدمة القارة في العصر كريتاسي المتأخر و الرباعي في العمود الجديد. وضع الوحدات ذات الصخور الفتاتية الخشنة في النطقة الساحل الحوض الترسيبي لقريبة من الصخور المصدر. بينما وضع الصخور الناعمة كالصلصال و المارل قرب وسط الحوض الترسيبي. و يقع الصخور الفتاتية المتوسطة و الصخور الكلسية الحياتية في نطقة متوسطة بين الموقين السابقين (في .الرف و منحدر)

INTRODUCTION The time expanded stratigraphic column (time-rock or chronostratigraphic column) is that type of stratigraphic column on which many chronostratigraphic unit and the missing ages (the time is expanded) are shown and very useful for basin analysis and oil exploration. The missing ages are those age that have not representative lithology in the rock column due to erosion or non-deposition. In this type of column, the rock body is deformed (mainly expanded or exagurated according to time span of depostion) to fill the age in which it deposited (wheeler, 1953). In Iraq, most of the missed ages (unconformities) are indicated between the formations by Bellen et al (1959), Buday (1980) and Jassim and Goff (2006). According to North American Stratigraphic Code (1983), chronostratigraphic units are bodies of rocks established to serve as the material reference for all rocks formed during the same span of time. Each of its boundaries is synchronous. The body also serves as the basis for defining the specific interval of time, or geochronologic unit represented by the referent. In the mentioned Code, it is cited that the purpose of these units are to be used as a means of establishing the temporally sequential order of rock bodies. The same Code farther added that the principal purposes are to provide a framework for (1) temporal correlation of the rocks in one area with those in another, (2) placing the rocks of the Earth's crust in a systematic sequence and indicating their relative position and age with respect to earth history as a whole, and (3) constructing an internationally recognized Standard Global Chronostrati-graphic Scale.The present study tries to update and modify the column in order to include all the recent studies (they are indicated in the text and diagrams as “st”) and agree with new development of the tectonic setting of the area. The study mainly limited to the northeast Iraq where the most recent studies (that are relevant to the subject) are conducted (Fig.1). Even, in this area each part (Arbil and Sulaimanyia Governorate) need their specific chronostratigraphic column but now both are represented by one column until the adequate concerned sedimentologic and stratigraphic projected are conducted. The time expanded stratigraphic (time-stratigraphic) column of Iraq and Northeastern Iraq was established in the fifties of the last century by Bellen, et al (1958) (Fig.2 and 3). During this long time, the column remained nearly without main changes which are widely used for teaching, academic purposes in all Iraqi university and for practical implication by petroleum companies (Oil companies) and other economic businesses. These columns can be called wheeler diagram in honor to H. E. Wheeler (1953) who showed that these columns consist of two axes: time as vertical axes and horizontal one as geographic (spatial axis) extend. He clarified that the disadvantages of these columns are the deformations of rock bodies that deposited in certain time. He added that these deformations are not occurring in normal stratigraphic (lithologic) column in which erosion and no-deposition are shown as zero thickness.

Fig.1: Tectonic subdivision of North Iraq (Simplified Al-Kadhimi et al., 1996) showing the studied area. The Inner and outer platform terms are from S. F. Fuad: Personal communication

Fig.2: Tertiary Chronostratigraphic column of Iraq including Northestern Iraq (Bellen et al, 1959).

Fig.3: Cretaceous Chronostratigraphic column of Northeastern Iraq (Bellen et al, 1959)

DISCUSSIONIn the recent years many sedimentologic and stratigraphic papers are conducted on the studied area that make the present modifications are possible. These studies are shown by numbers and letters (st1, st2….) on the modified column and on the area where the modification are made (Fig.4). The recent relevant studies that are used for modification are: 1-The study of Karim(2004) (St1) and Karim and Surdashy(2006) in which the Wheeler column (diagram) is drawn for northeast Iraq in which 500m of conglomerate is correlated and combined ,in Chuarta-Mawat area (Imbricate and Thrust zones), with 400 of sandstone and shale in Dokan areas and South of Sulaimanyia City (High Folded Zones). In the column a gap of about 1million years (at proximal area near the coastal area) is shown within Tanjero Formation in the Chuarta-Mawat and become conformable in the south of Sulaimanyia and Dokan Area ( distal area: basin and slope areas). On the column, the gap is widening toward Coastal area and tightens

toward the basin (Fig.5).

Fig.4: New chronostratigraphic column of Northeast Iraq in which the stratigraphy of the Imbricated and Thrust Zones are shown and most of the previous unconformities in the High and Low Folded Zone are rejected (modified from Bellen et al, 1959 and Omeri and Sadiq, 1977).

2- The study of Al-Barzinjy (2005) (St2) which is concerned with Paleocene-Eocene and studied the Red Bed Series in Sulaimanyia governorate in the view of sedimentology, tectonics and sequence stratigraphy. Red Bed Series was remained mysterious units as concerned to its tectonic and lateral relation to other units. Previously no one has correlated (as concerned to basin and facies changes) this unit (in the Imbricated Zone) with other units of the same age in the High Folded Zone. But the in the st2 study, it combined basins of the lower part and upper part of Red Bed Series with Kolosh and Gercus formations respectively. It also put the basin of the Kolosh Formation and the series in one single basin (Paleocene Foreland Basin) and considered them as lateral facies of each other (Fig.6). It showed the possible gaps by Diagram of Wheeler (1953) (Fig.7) .In the previous studies such as Lawa (2004) and Jassim and Goff (2006), the basin of the two units are separated by paleohigh.3- The study of Karim, et al (2008) (St3) in which the unconformable contact between Kometan and Shiranish Formations is refused and changed to conformable one. In this study six sections are studied only in one, short sub-marine gap is observed. Later, Taha (2008) found fossils (nanofossils) of middle Campanian age in a section at northwest of Sulaimanyia city and ascertained the result of the study of Karim, et al (2008). Previously, this age (Middle Campanian) is assigned as a gap by Buday (1980) and Bellen et al (1959). 4-The study of Ameen and Karim (2008) (St4) in which the unconformity between Qamchuqa and Bekhme formations is changed to conformable one. Previously this unconformity is estimated to be about 18 million years between the two formations by Bellen et al (2008) Buday (1980) which extended from Cenomanian to Upper Campanian (Fig.3). The unconformity is previously based on occurrence of 20m conglomerate but in the all six sections that are studied by Ameen and Karim (op cit) it is not found. 5- The study of Ameen (2008) (St5) in which the unconformity between Qamchuqa and Kometan and Dokan is changed to conformable. In this study it is shown that the Dokan Formation is a transitional facies between shallow facies (Qamchuqa Formation) and deep one (Kometan Formation). 6-The study of Sharbazhery (2008) (St6) in which the unconformity between Tanjero and Kolosh formations is changed to conformable on the basis of the biozonation. In this study many species of planktonic formas (Fig.8) are found in the sediment of Danian that survived during this age. This age is previously assigned as a gap.7- The study of Baba Shekh (2006) (St7) and Ameen (2009) in which it is mentioned that the Oligocene rocks are occurring near Draband Bazian and in the southeast of Sangaw towns. The first study found Oligocene rocks between two conglomerates. These two studies are indicated on the modified column (Fig.4) by (St7).8-The study of Karim et al (2007)(St8) in which the possibility of concurrent deposition of the molasse and flysch sediments is discussed in same basin as lateral facies of each other during Late Cretaceous and Paleocene in Northeastern Iraq. By this work, the present author is able to modify the relation and distribution of Paleocene and Eocene units in Thrust, Imbicated and High Folded Zones (Fig.4). 9-The study of Taha (2008) and Taha and Karim(2009) (St9) in which it is shown that the unconformable upper and lower contact of Gulneri formation is changed to conformable one with Dokan and Kometan formations respectively. It is proved that the previously mentioned conglomerates are nothing except diagenetic ball-and pillow structures. In this two studies, the previous ideas are refused that the Gulneri and Dokan formations are deposits of small and euxinic basin that are bounded by unconformity from all sides as assigned by Bellen et al (1959) Fig.(3). Taha (2008) has shown that both formations deposited in large foredeep basin during post drowning and drowning phase of Arabian Platform (as represented by Qamchuqa and Gulneri formations) respectively. 10-The study of Karim (2007) (St10) in which the relation between Walash Naoperdan Series with both Pila Spi and Sinjar formations are discussed. It showed that during Middle Eocene the boundary between Imbricated and High Folded Zone was uplifted and divided the Zagros Foreland basin into two basins. In the northeastern and southwestern basins, Walash Naoperdan Series and Pila Spi Formation are deposited respectively (Fig.4 and 9).11-The study of Karim and Baziany (2007) (St11) in which the Qulqula Conglomerate Formation is combined with Red Bed Series and proposed to remove the formation in the stratigraphy of Iraq. Therefore, the formation is not shown in the modified column while the Qulqula Radiolarian Formation is shown as equivalent of Sarmord and Balambo formations (Fig.4).12- The study of Aghwan and Abdul Rahman (2008) (St12) ) in which, succession of Burdigalian stage (represented by Euphrates and Diban formations in the Northeastern Iraq(Kor Mor Oil Field) are found in the Low Folded Zone in the studied area. Due to this study, the author is able to insert the above formation in the new chronostratigraphic column of the Northeastern Iraq (Fig.4). 13- The study of Khanaqa et al (2009) (St13) in which, for the first time, the Oligocene rocks (represented by Anah and Ibrahim formations) are found in the High Folded Zone. In the previous studies the extent of the Oligocene rock not exceeded Low Folded Zone. Due to this study, the author is able to extend the distribution of the Kirkuk Group further toward northeast in the High Folded Zone in the chronostratigraphic column (Fig.4).

Fig.5: A) Topographic (geographic) cross section of Tanjero Formation. B) Time expanded (Wheeler) Diagram shows the unconformity at the lower part of Tanjero Formation which at X1 exists between Tanjero and Shiranish formations. The conglomerate of the lower sequence is also indicated (modified from Karim, 2004).

Fig.6: Simplified cross section of Chuarta and Sulaimanyia areas showing possible relation between Kolosh Formation and Red Bed Series during Paleocene (Al-Barzinjy, 2005).

Fig.7: Chronostratigraphic (Wheeler) diagram which shows two unconformities in the lower part of Red Bed Series (Al-Barzinjy, 2005).

METHOD OF MODIFICATIONThe modifications are not dependent competently on the aforementioned studies as the modification is aided by field studies of the author in the studied area for tens of years. This is including checking and evaluation of the result of the above studies (st). The paleontological results are inspected by the author for their compatibility with the tectonic and Sedimentology of the area. Another checking is to see if the modifications agree with the stratigraphy of neighboring regions in Iraq. For this, the boundary conditions of the modified contacts are checked between formations. The study of the boundary condition is aimed to fine equivalents or products of the previously mentioned unconformities. If an unconformity (erosion or non-deposition) exists in a place, the equivalent (sediments or paleosoil) of this unconformity must be present in other places around the claimed conglomerate. When an unconformity is assigned such as the previously mentioned gap between Qamchuqa and Bekhme formations (with 18 million years gap), the inspection of boundary condition is important for removal of doubt. The inspection includes search for the product of the 18milion years of erosion or non-deposition. The products (as clastic sediments or intense karstification or paleosoil) of this long time must be enormous and clearly observable in the surrounding areas in outcrop and wells. But if the products are not found, this means that the unconformity is suspicious. Therefore, many unconformities, preciously assigned, now they are changed to either conformable or to very short duration of a local submarine erosion which indicated by short zig zag lines with in the modified column (Fig.4).

In the modification, the principles of the sequence stratigraphy are considered in which the deposited rocks “how it is thick or thin” are inserted between the time lines between which the rocks are deposited. Therefore, the thick and rapidly (during short time) deposited rocks have thin vertical representation on the column while the thin and slowly (during long time) deposited rocks have shown as thick interval on the column. Therefore, the thickness of 500m conglomerate of Tanjero Formation may be thinner (on the column in the figure 4) than 6.5m of the Gulneri and Dokan formations.Previously, the unconformities in Iraq are assumed as regional such as that exist at Cretaceous- Tertiary boundary and that of Middle Campanian (between Shiranish and Kometan formations). Another example of such unconformities is that of Lower Cenomanian and Upper Campanian (Between Qamchuqa and Bekhme Formation). These unconformities, if true, they are local because till now no angular unconformities (which are mostly regional) are found in Iraq. Now, the sequence stratigraphic models of the marginal basins such as foreland basins of Iraq during Cretaceous and Tertiary can be applied. In Iraq, the tectonically active coastal areas of these basins are located mainly in the northeast Iraq near the border with Iran (Karim, 2004 and Barzinjy, 2005). As shown in the modified column (Fig.4), many unconformities elongate from coastal area and they become conformable toward the basin center. But some of these unconformities are located in the Thrust and Imbricated Zones which are not included in the column of Bellen et al (1959). Compound unconformities (Potter and Pettijohn, 1977), is characteristics of some of these unconformities which may spit into several smaller unconformities toward the deeper water. Karim (2004) has observed this phenomenon in the Tanjero Formation which is represented by spliting of single thick conglomerate succession (in the coastal area in Chuarta-Mawat-Qandil area) into several relatively thin beds of conglomerates (separated by thick bed of shale or sandstone) in the deeper water of the formation. In the column, these compound unconformities are not shown but the simplified ones are inserted (Table 1 and fig.10). In the modification the presence of index fossils for age determination and removal of unconformity is accepted as an undisputable fact. But the establishment of the unconformities on the basis of absence of index fossils is disputable and even danger. This is because the absence of index fossils does not mean that the sedimentation is stopped or erosion is happened. The absence of the fossils many be due to the following:1-The change of environment is important factor for absence of certain fossils such as those have short time duration. Previously some of the unconformities are indicated by absence of index fossils in the boundary between formations. Across the boundaries, the lithological change is due to environment changes. Therefore, disappearance of the certain fossils is attributed to environment changes not to erosion or non-deposition. The absence of fossils (when used for unconformities) must be aided by either terrigenous conglomerate and sandstone or karistfication and paleosol in nearby and surrounded areas.

Fig. 8: Planktonic Foramineral species as indicators of the continuous sedimentation at the Cretaceous/Tertiary boundary (Sharbazery, 2008).

Fig.9: The conclusions of present study as shown by conceptual models of paleogeography and tectonic evolution of the intermontane basin in Iraq. A: Middle Eocene, B: Lower Eocene, C: Upper Cretaceous and Paleocene.

2- The diagenesis has great role in removal of fossils in certain rock intervals. This is very clear in the Kolosh Formation which in certain areas such as Sartak Bamo (25 km) to the east of Darbandikhan town) contain abundant well preserved index planktonic forams (Khafoor and Karim, 2000). But in the south of the Sulaimani City, 600m of the same formation of the same lithology (marl) contain no any index fossils.3- The methods of the sampling and cooking may result in losing of the index fossils especially when the certain rocks contain scarce fossils.4- The patient of the worker is also important especially when the rocks contain abundant silt and sand-size grains which cause relative dilution of the number of the fossils in the sample. 5- The wave, current and bioturbation have more or less negative role in the dispersal and mixing of microfossil in certain beds. Now it is known that even very deep water sediments can be affected by deep marine erosion by deep marine currents.

Table (1) Stratigraphic position and geographic location of the dependent (in modification) conglomerates in the present this study.

Fig.10: Some of the pebble and boulder terriginous conglomerates at different geographic locations and stratigraphic positions. A and B) At the base of Pila Spi Formation, at 7km to the west of Shaqlawa town and 10km south of Qaradagh town respectively. C) Inside Gercus Formation 15 km south of Zarayeen town. D) In the lower part of the Red Bed Series 5km south of Chuwarta town.

CONCLUSION 1-A New chronostratigraphic column of Northeast Iraq is drawn2- In this column the relation between the stratigraphy of Imbricated and Thrust Zones with Low Folded Zone are shown.3- Most of the previous unconformities in the High and Low Folded Zones are rejected while many unconformity are introduced in the Imbricated and Thrusted Zones.4-The modification is compatible with new ideas of sequence stratigraphy, tectonic and sedimentology of the area.5-The previous unconformities are based on the absence of the index fossils but now it known that there are several factors other than erosion or non-deposition that cause absence of index fossil.

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thesis, University of Sulaimani University, 159p.Al-Kadhimi F., Sissakian V., and Duraid, 1996. Tectonic map of Iraq. GEOSURV , Baghdad.Al-Omari, F. S. and Sadiq, A., 1977. Geology of North Iraq. Mosul University Press, pp.197.Baba Shekh, S. M. R., 2001. Hydrogeochemisry of some Springs in Sangaw-Chamchamal area. Unpublished, M. Sc. Thesis, University of Baghdad, 150 pp. Bellen, R. C. Van, Dunnington, H. V., Wetzel, R. and Morton, D., 1959. Lexique Stratigraphique, Interntional. Asie, Iraq, Fasc, 10a, Paris,10a, 333 pp.Buday, T., 1980. Regional Geology of Iraq: Vol. 1, Stratigraphy: I.I.M Kassab and S.Z. Jassim (Eds) GEOSURV, Baghdad, 445pp.Buday, T. and Jassim, S.Z., 1987. The Regional geology of Iraq: Tectonism Magmatism, and Metamorphism. I.I. Kassab and M. J. Abbas and Jassim, S. Z (Eds), GEOSURV, Baghdad, Iraq, 445 pp.Ghafoor, I.M. and K.H. Karim, 2000: Biostratigraphy of Upper part of Kolosh Formation from Sartaq Bamo area, NE-Iraq. Scientific Journal of Dohuk University Vol.1, No.1.p.1-10 Karim, K. H., 2004. Basin analysis of Tanjero Formation in Sulaimaniya area, NE-Iraq. Unpublished Ph.D. thesis, University of Sulaimani University, 135pp.Krim, K H. and Baziany, M. M. 2007. Relationship between Qulqula Conglomerate Formation and Red Bed Series, at Qulqula area, NE-Iraq. Iraqi Journal of Earth Sciences, Vol.7, No.1. Karim, K.H. and Surdashy, A. M., 2006. Sequence stratigraphy of Upper Cretaceous Tanjero Formation in Sulanmaniya area , NE-Iraq. KAJ, Vol.4, No.1.p.19–43.Jassim, S.Z. and Goff, J. C., 2006. Geology of Iraq. Dolin, Prague and Moravian Museun, Berno. 341pp. Karim, K.H., Surdashy, A.M. and Al-Barzinjy, S.T., 2007.Concurrent and lateral deposition of flysch and molasse in the Foreland Basin of Upper Cretaceous and Paleocene from NE-Iraq, Kurdistan Region, GERMENA II, 2007, P.757-769.Karim, K. H., Al-Barzinjy S. T. and Ameen, B., M., 2008. History and geological Setting of Intermontane in in the Zagros Fold-Thrust Belt, Kurdistan Region, NE-Iraq. Iraqi Bulletin of Geology and Mining , GEOSURV, Vol.4. No.1. pp.12-33.Karim, K. H., Ismail, K. M. and Ameen, B.M., 2008. lithostratigraphic study of the contact between Kometan and Shiranish Formations (Cretaceous) from Sulaimaniyah Governorate, Kurdistan Region, NE- Iraq. Iraqi Bulletin of Geology and Mining, Vol.4, No.2, p.16 -27.Polla A.Khanaqa, Sahira A. Karim, Varoujan K. Sissakian and Kamal H. Karim. 2009.Lithostratigraphic study of a Late Oligocene – Early Miocene Succession, south of Sulaimaniyah, NE Iraq. Iraqi Bulletin of Geology and Mining Vol.5, No.2, p 41− 57.North American Commission on Stratigraphic Nomenclature, 1983. North American Stratigraphic Code. AAPG, vol.67, no.5, pp. 841-875.Sharbazery, K. I., 2008. Biostratigraphy and paleoecology of the Cretaceous-Tertiary boundary in the Sulaimanyia area, Kurdistan region, NE- Iraq. Unpublished Ph. D. thesis, University of Sulaimani University, 185pp.Taha, Z.A.2008. Sedimentology of Late Cretaceous Formation from Kurdistan Region, NE−Iraq, Unpublished, M.Sc thesis, University of Suilaimani, pp.150.Taha, Z. A. and Karim K. H.2009. New ideas about Gulneri Shale Formation (Early Turonian) in Dokan area, Kurdistan Region, NE Iraq Iraqi Bulletin of Geology and Mining, Vol.5, No.2, p29-39.Wheeler, H., 1953. Time Stratigraphy. Bulletin of the American Association of Petroleum Geologists, Vol. 42, No. 5, p.1047-1063.

STRATIGRAPHY AND BASIN ANALYSIS OF RED BED SERIES AT NORTHEASTERN IRAQ / KURDISTAN REGION

A THESISSUBMITTED TO THE COLLEGE OF SCIENCE, UNIVERSITY OF SULAIMANI, IN PARTIAL FULFILLMENT OF THE REQUIRMENTS

FOR DEGREE OF DOCTORATE OF PHILOSOPHY IN GEOLOGY

BY: Sherzad Tofiq Mohamad Al BarzinjyM. Sc. IN GEOLOGY/1989

Supervised by: Dr. Ali Mahmood Surdashy Assistant Professor

MARCH 2005 A.D NAOROZ 2704 KU

ACKNOWLEDGEMENTS I am deeply indebted to Dr. Ali Mahmood Surdashy for his undertaking the task of supervising this thesis and for offering many suggestions and corrections during all stages of the work. My best thanks to the Dean of the College of Science (Dr. Parykhan Mohamad Abdulrahman) and also the head of the Department of Geology for their generous help and assistance throughout this work especially offering the available facilities. I would like to express my gratitude to the university presidency for providing the financial support for transportation (during fieldwork) and printing the draft and final copy of this work. My sincere thank to my friends (Dr. Kamal Haji Karim and Khalid Mahmood Ismail) from the Department of Geology, University of Sulaimani for helping in fieldwork and photographing many features in this thesis. I would like to thank my friends (Yousif Mahmood Osman), reporter of the Department for providing me with suitable computer software for the program used in this study, and (Mr. Serwan Hama Ahmed). I also express my gratitude to (Salahaddin Saeed Ali), the Dean Assistant, for reading the original manuscript and suggesting many corrections. Finally, I would like to express my special appreciation for my wife, Zheyan, for her patience during the preparation of this work. Sherzad March,2005

Abstract The Red Bed Series is a Paleocene- Eocene unit, which crops out mainly within the Imbricated Zone and partially within Thrust Zone in Northeastern Iraq. It stretches as narrow northwest-southeast belt near and parallel to the Iranian border. The series mainly consists of alternation of thick beds of clastic rocks of red claystone, sandstone and conglomerate. On the basis of stratigraphy and lithology the series is divided, in Chwarta-Mawat area, into six units. Unit One is composed of red fine clastics (red claystone and bluish white marl), while change to sandstone in eastern end of Qandil Mountain toe. Unit two consists of about 17m of chert and limestone conglomerate with prevalence of red color. Unit three consists of more than 500m of thick-bedded gray sandstone with interlayers of claystone. This unit contains many sedimentary structures such as cross bedding; ripple mark, flute cast, plant debris and lamination. Unit four consists of alternation of red layers of claystone, sandstone with lenses of conglomerate. Unit five is most obvious and thickest unit of the series in all area except the western part of Qandil area, which change to claystone and sandstone. It consists of chert; limestone, igneous and metamorphic gravel in Chwarta-Mawat area, while in eastern part of Qandil mountain toes, near Suwais village, it includes only chert and limestone pebbles and boulders. But the western part of the mountain is similar to that of Chwarta-Mawat area as concerned to the type of gravel. This unit contain obvious imbricate pebbles and large scale cross bedding. The upper most part (unit six) consists of marl, claystone with some sandstone and a layer of fossiliferous limestone at the base of the unit. These units are correlated across five different sections, which are representing the available outcrops in Sulaimaniya and Arbil Governorates. The correlation is based on lithology and stratigraphic position of the units. In sequence stratigraphy, the rock body of the series is divided into three depostional sequences, (lower, middle and upper depostional sequences). Each of these is further analyzed into their systems tracts. The systems tracts of the units are lowstand, highstand, and transgressive systems tract. The most obvious one is lowstand systems tract and consists of Lowstand wedge about 1000m of boulder and block polymictic conglomerate. During lowstand many incised valleys scoured in the sediment of the previous highstand which is filled by coarse conglomerate. Great variations, in different areas, in lithofacies of each systems tract is detected, that is due to the shallowness of the environment. The correlation of systems tracts of the Red Bed Series at Chwarta, Mawat and Qandil mountain areas, at the Imbricated Zone, with the equivalent parts of the Kolosh and Gercus Formations at distal area (High Folded Zone) was the important part of sequence stratigraphy work. This correlation is the first one done for the different sections of the Red Bed Series in one side and with Kolosh, Gercus Formations in other side. By this correlation, the previous age of the Red Bed Series also changed from Paleocene–Miocene age to Paleocene - Eocene age only. Another result of the correlation is that the series and the formations sharing the same depostional basin and they represent lateral facies changes of each other. In this basin, the Red Bed Series is deposited in rapidly subsiding coastal area of the Early Foreland basin while the Kolosh Formation is deposited in deeper part of the basin. The environment of the series is highly variable; mainly consist of high gradient braided streams which transfer coarse and fine sediment to alluvial fan which merge into lowstand fan delta when reaches the main water body of the foreland basin. As concerning with the depth, it ranges from continental to shallow marine environment while the salinity ranges from dominant fresh river water to brackish and possible of invading of normal marine water occasionally. Water turbidity changed from highly turbid water in the incised valleys and in front of alluvial fans to normal marine water. Petrographic analysis revealed that the source area of each one was different. Even the source area of each section was different in different times. The clasts were dominantly derived from the Qulqula Radiolarian Formation at the area of eastern part of the Qandil mountain toe while that of Chwarta-Mawat are derived from the Qulqula Radiolarian and ophiolite source rocks in adition to Walash Naoperdan group . The source area is consisted of overthrusted sheets of frontal part of Iranian plate. In this study many sedimentary structures are found in the series such as, cross bedding, ripple marks, imbricated pebbles, laminations, and plant debris. Most of these structures are found in the unit three (sandstone unit) and few ones found in the upper conglomerate. The paleocurrent analyses, as revealed by these structures, are presented as rose diagrams show south and southwest directions.

CHAPTER ONE

1.1- Preface The Red Bed basin, as a part of the Neotethys, was strongly deformed by the Alpine Orogeny and was active from Jurassic till Miocene where a huge thickness of sediments was accumulated. These sediments now exposed on the surface as different types of stratigraphic units such as the Balambo, Kometan, Shiranish and Tanjero Formations, in addition to the Red Bed Series and Naoperdan Shaly Group.

The basin has a complicated history of development and tectonics, this history was demonstrated by different characteristics of these stratigraphic units. Among these units and in the present study, the tectonic framework and sedimentation (basin analysis) of the Red Bed Series was studied. Basin analysis involves the interpretation of the growth, evolution, building, and fill of a sedimentary basin by examining different geologic variables associated with the basin. The geologic variables include all branches of geology, but in the present study, the emphasis was put on traditional and sequence stratigraphic analysis based on detail study of exposed sections throughout the studied area. The detailed field and lab studies directed towards paleoenvironmental interpretation to interpret basin fill architecture and tectonics of the basin, in addition to the correlation and subdivision of the Red Bed Series. Observations during the last few years showed the probability of achieving more accurate study than that was done before.The most important duty is to establish relations between the Red Bed Series located in the Imbricated Zone (proximal area) with Kolosh and other Formations in the High and Low Folded Zones (distal area). In the present study there are attempt to answer many of the questions rasied since 1980 by Buday about subdivisions, age, paleogeographic reconstruction, and correlation of the Red Bed Series.

1.2-Location and Geomorphology The studied area is located within Sulaimaniya and Arbil Governorates in northeastern Iraq. It stretches as narrow belt from Nalparez, southeast, to Qandil mountain toe and Roste valley near Haji Omaran at the northwest (Fig1.1). The main outcrop of the studies series is located at Chwarta and Mawat area. This area is located between latitudes 35o 35-12= and 36o 40¬23= to the north and longitudes 45o 55-33=and 44o 40- 20= to the east. The studied area now covered by high mountains trending northwest –southeast. In the same direction and between these mountains there is narrow or wide subsequent (strike) valleys. The mountains and valleys are dissected by, at least, two large consequent valleys and tens of smaller ones. The large valleys are those in which the Little Zab and Diala Rivers flow. The outcrops of the series consist mainly of alternation of thick beds of red claystone, sandstone and conglomerate. In the upper part (in some areas) the formation contains interbeds of biogenic limestone (Al–Mehaidi, 1975).

1.3-Geological Setting The studied area is located at the southern boundary (in front) of the Zagros Thrust Belt, which is developed from the basin fill of the Neo-Tethys and colliding of the Iranian and Arabian plates. Structurally, the series is located within two different zones. The outcrops of Chwarta – Mawat areas and Roste Valley are located in the Imbricated Zone while that of Penjween and Qandil Mountain toe are located exactly on the boundary between the Imbricated and Thrust Zone of Buday and Jassim (1987) (Fig.1.1 and 1.2). Because of intense imbrication, the area is characterized by obscured anticlines and synclines which have been stacked together as very thick and tight packages which was overturned toward southwest. This imbrication includes the Red Bed Series and other units such as Qulqula, Balambo and Kometan Formations. Buday (1980), Buday and Jassim (1987) and Lawa et al., (1998) called the two tectonic zones of distribution of the Series, miogeosyncline and Euogeosyncline respectively. The Tanjero Formation underlies directly the Series; Karim (2004) regarded the basin of latter formation and Kolosh Formations as Zagros Early Foreland Basin. In the Chwarta and Mawat area the Series is underlain and overlain by Tanjero Formation and Naoperdan Group respectively. The contact of the series with the group is not clear but previously mentioned to be tectonic Al-Mehaidi (1975), Buday (1980) Surdashy (2001). While the contact with the Tanjero Formation is gradation (Lawa et al., 1998), Karim (2004) mentioned to be gradation in some places and unconformable in others. The tectonic setting of the series during Paleocene and Eocene will be discussed in Chapter Six. The tectonic setting of the present time as can be seen in the field is extremely complicated by commutative deformations from Eocene till the present. In Chwarta–Mawat area, now, the ophiolite (Photo1.1) rests on the Red Bed Series. Particularly as in Grdasha Mountain, near Taza De, Barda Zard and Ganka villages. In other places the Qulqula can be seen in contact and above the Red Bed Series, such as those along Kanarow Valley and along line connecting Tazade and Sinjale villages. In Qandil area same relation can be seen. In Penjween area the Red Bed Series rests on Qulqula Formation, especially around Milakawa Mountain at south of Penjween Town.

1.4- Studied Sections For detailed study of the formation, six sections are selected (Fig1.2 and.1.5). The stratigraphic and structural condition of these sections are shown either by photos or diagrams, these are:

1- Iran Section; it is located within Iran near the border with Iraq on the right bank of Du Awan (extreme upstream of Dokan Lake) 4 km west of Iraqi Awa Kurte village (Photo2.6A). 2-Khewata section; is directly located to the east of Khewata Bridge along the right bank of Khewata stream (Photo 2.4) and (Fig.2.1).

Fig.(1.1) Paleocene-Eocene facies map of the Middle East( Buday,1980) with location map of the studied area (lower left).

3-Tagaran Section at 350 39-48.3= and longitude 45 29-52.5=, the base of the section is directly located to the northwest of Tagaran village while its top located directly to the east of Chwarta Town at 20 km to the northwest of Sulaimaniya city (Photo2.1)

4-Type Section (Suwais village section) at the intersection of latitude 350 59¬00.2= and longitude 450 35-16=. It is located directly to the northwest of Suwais village at the toe of Qandil Mountain 20km to the northwest of Qaladiza town, (Photo 2.10A) and (Fig.1.3 and fig.2.2). 5-Kometan village section in Naudasht valley at the latitude: 36o 24-26= longitude: 44o 57-38=. It is located at the toe of Qandil Mountain at 1.5 km north of Kometan Village (Photo2.7) and (Fig.2.7) 6-Roste Valley section, located inside Roste valley at the area between Haji Omaran and Soran Valley (Photo2.9) and (Fig.2.3). It worthy to mention that the Penjween outcrops mostly covered by alluvium and serpentinite, therefore no section is taken.

Photo (1.1) Kanarw valley at 300m south of Kanarw town in which the Ophiolite and Qulqula Formation and Red Bed Series cropping out together

Fig.(1.2) geological map of the studied area, modified from Sissakian ( 2000)

1.5- Aims of the study The main aims of this work are to study the basin development of the Paleocene-Eocene successions, known as Red Bed Series in the Sulaimaniya, Arbil areas, which mainly appear on the Tanjero Formation.

This is based on the available and the inferred evidence and the study include the following: 1. New divisions of the series, taken into considerations, all the exposed outcrops by examining the outcrops in the field, to record all the vertical and lateral changes. 2.Descriptions and analyzing the different lithofacies in order to establish the depostional environment, this includes the study of sedimentary structures and paleocurrent analysis to interpret different depositional processes. 3.Sequence stratigraphic analysis in order to interpret the effect of sea level changes and subsidence on the development of third and fourth order cycles and determines the controlling components (eustasy and tectonic subsidence). 4.To interpret the tectonic framework of sedimentation and paleogeography of the Red Bed Series. 5. To establish the relations between the Red Bed Series and contemporaneous formations in the High and Low folded Zones such as Kolosh and Gercus Formations.

Fig.(1.3) Location of the type section of Red Bed Series around Suwais village

1. 6- Methodology 1-Study of all outcrops in detail as well as petrographic study of more than 100 thin sections. Then point counting to calculate the percentage of different 2-The conglomerates were studied in the field for constituent minerals of the andstones. lithology, structures, and directions. The percentage of the conglomerate is calculated by measuring the percentage of clasts by using the charts prepared by Folk et al., (1970) and Tucker (1989) for visual estimation percentage of the rock constituents by comparison. 3-Correlation between the different units of the series in the Imbricate Zone and equivalent successions at the High and Low Folded Zones. This is done by using the geologic map of the area where all lithologic changes in addition to sedimentary structures were recorded. 4- Point counting for conglomerates in order to determine the percentage of the main components. 5- Cooking of some samples of marl and red claystone for extraction of fossil content for inferring environment and age determination. 6- Using the Rock Ware program for plotting the directional sedimentary structures (uni-and bi-directional structures) on stereonet and plotting rose diagrams. The same program is used for plotting the sandstones and conglomerates on the Ternary compositional diagrams. Then, using the Photoshop program for drawing tetrahedrons combines the triangles.

1.7-Previous studies The Series was first described by Bolton (1958d) as a Suwais Red Beds (the name comes from Suwais village) in the Imbricate Zone bout 20km to the North of Sangasar town to the north of the Ranyia Town. It is not clear why did Bolton named the series “Suwais Beds “while the type section is near Bra De village which is located at about 15 km to the west of the Suwais village (Fig.1.3) even the lithology of the series near the latter village is exceptionally different from that of the type section. He divided it into four units (parts), they are as follows from bottom to top of the outcrop section: 1-Unit 1, Consists of different type of limestone beds (fossiliferous, detrital and conglomeratic limestone) 1. Unit 2, this unit overlying the previous one and consists of fine clastics (ferruginous red shale and blue siltstone) with some interlayers of limestone conglomerate. The thickness of this unit is about 300m. 2. Unit 3, Polymictic conglomerate containing boulder and blocks of limestones, chert, igneous and metamorphic rock fragments. 3.Unit 4, Composed of marly shale and sandstone with some conglomerate.

At Chwarta area and in the same manner Al-Mehaidi (1975), divided the Series into four parts (Fig.1.4). But his division did not include the first unit of Bolton (1958d). Instead, he separated the second unit of Bolton into two parts he named them unit one and unit two from the bottom to the top. The other units of the two authors are nearly coinciding. Karim (1975) studied the Series paleontologically and clamed that the age of the series is Miocene. Buday (1980) reviews the earlier studies about the series with citation of regional distribution and interpretation of different lithologies. Al-Ameri et al. (1990) studied the palynology of the Unit one of Suwais Red Beds in Chwarta Area; they concluded that this unit is deposited during Santonian. Lawa et al. (1998) recorded gradational contact between Red Bed Series and Tanjero Formation in Chwarta area; While Karim (2004) recorded both gradational and unconformable contact in different localities in Chwarta and Qandil area. Al-Qayim (2000) studied sedimentation and tectonic environment of the Suwais Red Beds from northeast margin of the Arabian plate. He concluded that the unit indicates flysch type sequence of variable facies. Lawa (2004,p.222,224 and 231) showed by sketch that the Red Bed Series is deposited during Paleocene and in an intermountain basin above the sea level in which the Kolosh formation located to the southwest of that of the series. He separated both basins from each other by mountain ranges.

Fig.(1.4) Stratigraphic column of Chwarta area (by Mehadi, 1975)

Fig.(1.5) studied sections of the Red Bed Series

CHapter Two, Stratigraphy and lithology, Red Bed Series

CHAPTER TWO

STRATIGRAPHY AND LITHOLOGY

2.1-Preface In this chapter, a detailed study of the exposed sections of the Red Bed Series and extensive fieldwork at different settings is presented towards a reasonable and meaningful subdivision of the studied successions as well as correlation with equivalents in other areas.

2.2- Divisions of the Red Bed Series

2.2.1-Bolton division

The first definition and division of the series was made by Bolton (1958d), he divided it to four units as follows: 1-Unit 1, Consists, at the lowermost beds, of different type of limestone beds (fossiliferous, detrital and conglomeratic limestone) interbedded with red ferruginous shale at upper part. Their thicknesses range between 50-100m. They contain many indigenous Cretaceous fossils such as rudists; large forams etc., and were considered to be of Late Maastrichtian age. 2- Unit 2, this unit overlies the previous one and consists of fine clastics (ferruginous red shale and blue siltstone) with some interlayers of limestone conglomerate. The thickness of this unit is about 300m and according to Buday (1980), the age of this unit is Paleocene – Lower Eocene. He had regarded this unit as flysch type sediments.

3- Unit 3, Polymictic conglomerates containing boulder and blocks of limestone, chert, and igneous and metamorphic rocks fragments. The chert clasts were derived from the Qulqula Formation. The thickness of this unit reaches 400m in Chwarta area and 200m at the type area. This unit represents talus sediments. In the present study this conglomerate is called Chwarta Conglomerate. 4- Unit 4, Composed of marly shale and sandstone with some conglomerate and layers of reddish or gray nummulitic limestone. The thickness of this unit reachs 800m in the type area.

2.2.1.1-Discussion of the Bolton division Field observations showed that this division is not applicable for the Red Bed Series because unit one of Bolton (1958d) is proved, in this study, to be belonging to the upper most part of Tanjero Formation. This is because of the following: A-Bellen et al. (1959), Buday (1980) attributed these beds to Aqra tongue while Lawa et al. (1998), in Chwarta area, studied similar beds and proved that they belong to the interfingering of Aqra Formation with Tanjero Formation. B- Very recently Karim (2004) proved that these fossiliferous limestone beds with shale and red claystone are belonging to Tanjero Formation. He called the alternations of these layers “Mixed carbonate-siliciclastic succession”. Moreover, he found the equivalent of these beds in Dokan area at the upper part of the formation. C- In some places such as right bank of Khewata stream. The alternation of red claystone and shale with fossiliferous limestone represent the gradational contact between the Red Bed Series and the Tanjero Formation. The limestone contains Upper Cretaceous fossils such as large forams, echinoderms, and rudist.

2.2.2- Divisions of Al- Mehaidi (1975) At Chwarta area, Al-Mehaidi (1975) suggested another division, which is different from that of Bolton mentioned above. Field study showed that the division of Al-Mehaidi is more accurate than that of Bolton. He didn’t include Unit one of Bolton from his division. Instead, it appears that he subdivided the Unit Two of Bolton into two units. He named these two units as Unit One and Unit Two from the bottom to the top (Fig.1.4). The divisions of Al-Mehaidi (1975) are as follows

2.2.2.1-The Lower Red Bed Unit The thickness of this unit ranges between (0-400m) and consists of interbedded red and grey silty shale and claystone, radiolarian chert, arenite, lithic arenite, gray detrital limestone (calcarenite) and thin beds of conglomerate.

2.2.2.2-The Sandstone Unit It is rest on the Lower Red Beds and has a thickness of (0-500m). This unit, to the southeast of Chwarta town, is directly overlying The Tanjero Formation. Thin beds of conglomerate, which indicate unconformity between the two units, mark the contact with lower Red Beds Unit, in most of the area.

2.2.2. 3- The Conglomerate Unit This Unit forms a thick lens (0-900m) of poorly sorted polymictic conglomerate. The rock fragments range from pebble to boulder and mostly consist of limestone, igneous and metamorphic rock fragments. In the present study it is called Chwarta Conglomerate.

2.2.2. 4-The Upper Red Bed Unit This unit consists of grey, red and greenish calcareous lithic arenite, silty shale and marl, polymictic conglomerates and thin beds of coralline limestones. This unit is overlies the conglomerate unit and represents a shallow marine environment.

2.2.3 -New division of the Red Bed Series in the present studyAs generally agreed that the depositional environment of the series is shallow, mainly continental, therefore, a unified division for all areas might not be suitable. Instead a new division of each area would be more convenient to achieve and finally to correlate the divisions in different areas together.

2.2.3.1-Chwarta - Mawat area In the present study, detailed fieldwork showed that the series is well developed in Chwarta-Mawat area and the maximum units can be distinguished in this area. So this area is suggested to be standard for comparing and dividing for other areas. The Red Bed Series is divided into the following units from the bottom to the top of outcrop sections:

Unit One (Lower Fine Red Clastics)Unit Two (Lower Conglomerate Unit) Unit Three (Sandstone Unit) Unit Four (Mixed fine and coarse clastic unit)Unit Five (Upper conglomerate or Chwarta Conglomerate) Unit Six (Upper fine clastics)

The description of these units is as follows:

2.2.3.1.1- Unit One (Lower red fine clastics) This unit represents the lower 200m of the sections of Red Bed Series that located directly above the Tanjero Formation. It consists of red claystone and siltstone with interbed of sandstone and rare lenses of conglomerate. At the Southeast of Chwarta and at 1km to the northeast of Tagaran village, this unit comprised of rhythmic alternation of red and bluish white claystone and sandstone (Photo2.1, 2.3A and 2.4). Toward Mawat (to the west) the percentage of conglomerate increases and the bluish white layers become thinner and coarser in grain size. Inside Iran this unit is about 60m thick and contain a bed of bluish white marl about 10m.thick. The cooked samples of this bed yield no any fossils to indicate the age or environments. In many places, as 600m west of Kani Sard and west of Shams Awa villages, there is a layer of white clay (soil). This layer covers the unit, which has the thickness of 0.5 -4m. This clay is studied by Mohyaidin and Merza (2004), they concluded that they are composed of calcareous materials and generated by weathering of recent alluviums derived from the Kometan and Balambo Formations. Field study shows that their conclusion is correct.

Fig.(2.1) Schematic geological cross section Khewata area

2.2.3.1.2- Unit Two (Lower Conglomerate Unit) This unit is located above Unit one and has a thickness of 16m (Photo2.1) and (fig. 2.1 and 2.4). It is well outcropped at the east of Tagaran villages and has a predominant red or brown color. Texturally the clasts consist of pebble and boulder with some blocks, while the matrix consists mainly of coarse sandstones. Compositionally, different types of limestones and cherts are the only constituents of the clasts and matrix. This type of conglomerate is called oligomictic conglomerate by Pettijohn (1975) and Selley (1988). Texturally, it is badly sorted and sub-rounded. In Mawat area, in contrary to Chwarta area, this unit, contains igneous and metamorphic clasts. This is clear at the east of the Suraqallat village where the thickness of the unit changes to 9m.

Photo (2.1) Unit one, two and three as can be seen in Tagaran section.

Photo (2.2) Unit four of the Tagaran section, composed of mixed fine and coarse clastics

2.2.3.1.3- Unit Three (Sandstone Unit) This unit is very distinctive and very thick (about 500) in the Chwarta area (Photo2.1 and 2.3B). In this area, this unit consists of alternation of thick, succession of coarse and gray sandstone (arenite). These sandstone beds alternate with thick beds of brown claystone and siltstone. The sandstone beds can be traced laterally for more than 10kilometers and make many geomorphological features such as Questas and Hogbacks in the area. The prominent feature a long the outcrops of this unit is the resting of tens of blocks of sandstone on the scarp slope of the Questas and hogbacks, which are detached from their original place by toppling and sliding (Photo 2.3A). At the south and southwest of Mawat town the thickness of this unit decreases and become less than 70m. In all areas this unit contains many sedimentary structures such as cross bedding, lamination, ripple marks, plant debris, flute casts and tool marks; it is possible that these sedimentary structures are the transitional features between the Red Bed Series and Kolosh Formation (see chapter three). The thin section study of this unit showed that the sandstone composed of carbonate (52%) chert and quartz (40%) and Igneous rock fragments (8%), (Fig.2.10). Texturally and genetically the sandstone of this unit can be classified as lithic arenite. This is because the matrix is less than 25% (when the division of Dott (1964) and Pettijohn et al. (1987) is used). The cement material is not much clear but some of them have calcite cement. It has a moderate sorting and subrounded texture which indicate a relatively rapid deposition.

Photo (2.3) A) unit one, Lower clastic unit, at the west of Kani Sard village. It consists of red and bluish white claystone and siltstone. B) Unit three (sandtone unit) at East of Tagaran village

2.2.3.1.4- Unit Four (Middle coarse and fine clastic unit) This unit is located on the Sandstones unit and characterized by its red color and contains red claystone, sandstone and conglomerate with predominance of fine clastics (Photo2.2 and 2.4). The claystone of this unit is similar to that of unit one (lower fine clastics) but without the bluish white layers, while the sandstone layers nearly contain the same constituent of unit three (sandstone unit). The conglomerate of this unit, as compared to that of unit two, has more sorting and roundness and contains igneous and metamorphic clasts. The thickness of this unit reachs 150m. (Fig.2.4).

2.2.3.1.5- Unit Five (Upper conglomerate or Chwarta Conglomerate) At Chwarta-Mawat area, this unit consists of thick successions of conglomerate (about 1000m thick) which contains different types of clasts such as limestone, chert, igneous and metamorphic rock fragments (Fig.2.4). At the area around Suwais village, it contains only limestone and chert clasts. The grain size of this unit ranges from granules to blocks (Photo 3.3 and 3.4). The blocks mainly belong to black or gray limestone of Qulqula Formation with block of serpentinite (altered peridotite).

Bolton (1958) and Al- Mehaidi (1975) called this unit “Unit Three “. Generally the sediments of the unit are subangular and badly sorted suggesting near source area and steep gradient of the transport surface. We have seen flat large blocks (weighted 50kg) in Chwarta Mawat area. The flatness of these blocks is such that they transported only by sliding not rolling. The texture reveals that transportation is not by debris flow because the blocks are found in orthoconglomerate (grain supported conglomerate).

The field point counting by using comparison chart showed that most grains are derived from Qulqula Radiolarian Formation (chert and limestone) and few ones have the source of Ophiolite and limestones of Walash-Nauperdan Series. The percentage of these grains is 55%, 30 and 15 respectively. At Suwais village the conglomerate has coarser texture and compositionally contains clasts of chert and limestone derived from Qulqula Formation. Field and laboratory studies showed that stratigraphic position of this unit is uncertain; this is because of the following: A)In Chwarta area, this unit contains boulders, blocks (Photo3.6A) and pebbles of gray and milky Nummulite and Alveolina bearing limestones

Photo(2.4) Khewata section, as shown by composite photo . To complete the panoramic sense, the upper and lower ones must be jointed at A-B and A- -B-

(Photo4.1 and 4.2). These fossils also reported by Omari and Sadiq (1977) in Chwarta area. The age of these fossils is Lower to Middle Eocene. These clasts are derived from source area of Walash-Naoperdan Series. This proves that the age of unit five (unit three of Bolton) is younger than the Walash-Naoperdan Series. This means that this unit has no stratigraphic relation with the units one, two, three, four and six. B) Surveying the Sarsir Mountain especially it’s northern and southern side, the absence of any exposure of this unit was noted, while there is thick succession of this unit on the southern side of the mountain. As the paleocurrent in this unit is towards south, it should be thicker and coarser at the northern side of the mountain. This observation prove that the unit is deposited as an alluvial fan (or as a Talus) Buday (1980) on the regional paleoslope of Eocene which now partly represented by Chwarta-Mawat area for more evidence see section (4.2.1 and 6.5). During Eocene, other units of series (with Walash- Naoperdan Series) are exposed along the regional paleoslope. The sudden uplift activated erosion of the existed outcrops in relatively arid climate. C) At the southern side, the dip of the layers of the conglomerate is less than the dip of the other units of Red Bed Series. The dip of the layers is nearly 20 degrees while the dip of other units reaches 30 degrees. This means that the conglomerate deposited on the slope of the terrestrial lands, which were surrounding the basin of the Red Bed Series during late Eocene. The deposition occurred in an onlapping manner, which causes decrease of the slope. As a result of this fact the stratigraphy and division of the Red Bed Series must change totally and unit five must be separated from other units and put at the top of the Walash –Nauperdan Series not at the middle of Red Bed Series. Therefore its name and position must be change, from unit three in previous studies, to new name or even may be designated as a new formation. To simplify and to avoid repetition of Unit Five, the present study named it Chwarta conglomerate. For more detail see Chapter Five,(Sequence Stratigraphy). One can see on the outcrop sporadic blocks on surface outcrop of this unit in Chwarta-Mawat and Qandil area some block weighted more than 300kg (Photo2.5). Omari and Sadiq (1977) mentioned that this unit contains fossiliferous pebbles and boulders belong to Naoperdan Group so he assigned the age to be younger than the Eocene.

Photo(2.5) Surface of the unit five showing blocks of limestone of Qulqula Formation at southwest of Chwarta town

Photo(2.6)A) Iran section showing unit one, two, three and four inside Iran.B) unit two int the mouth of Siramerg Valley at 2kms west of Qala Chuallan Town. The concave black line is Channel lag deposit

2.2.3.1.6-Unit Six (Upper fine clastics) It is composed of calcareous shale, brown claystone, marl and sandstone with some conglomerate. The lower part of this unit contains interval of fossiliferous limestone. The fossils include coral (Photo4.3), green algae, pelecypods and oysters. Buday (1980) mentioned the presence of nummulitic in the same unit in Chwarta area. But in the present study it has not found. The thickness of this unit reachs 800m in the type area, but in Chwarta-Mawat area, the thickness of this unit reachs 100m.(Fig.2.4). In most areas this unit is covered by soil and sediment or it cannot separate from Walash-Naoperdan Series. In Rosty valley and west of Dina town it partially covered by ophiolite in tectonic relationship.

2.2.3.2 -Divisions of Suwais Village section (Southeastern end of Qandil mountain toe) This section is located at the southeastern end of Qandil Mountain at 30km to the northeast of Ranyia Town directly to the north of Suwais Village (type locality of the series) near the border of Iran. Field study showed that the description of the series does not belong to one single section but it has taken from the combinations of two sections at two nearby localities. These localities are Suwais village and Pshtashan Village to the north (Fig.1.3). Therefor the best outcrop to be taken as type section is the section of Tagaran. The Red Bed Series around Suwais village is more sandstone and conglomerate rich and its units are not well developed as compares to Tagaran section (Fig.2.6). The units are as following:

2.2.3.2.1 - Unit One (Lower Fine Red Clastics) This unit is located directly on the Tanjero Formation. It consists mainly of sandstone rich with gray color and has the thickness of 90m. (Fig 2.6). The red color, which is noticeable in Tagaran section, does not exist in this area. Thin section studies revealed that sandstone consists mainly of limestone and chert clasts, which are derived from Qulqula Formation provenance with some igneous rock fragments of Ophiolite origin.

.2.2.3.2.2 -Unit Two (Lower Conglomerate Unit) This unit consists of two beds of conglomerate exclusively composed of limestone and chert fragment. This unit has the thickness of 15m but the red color cannot be seen, which is very observable in the Chwarta-Mawat area. The grain size is finer than that of Tagaran section, which contains no boulders and blocks (Fig.2.6).

Fig.(2.2) Schematic geological cross section of Shahidan valley near Kometan Village

2.2.3.2.3 - Unit Three (Sandstone Unit) This unit is nearly similar to Unit Three (Sandstone Unit) in color and lithology of the Tagaran section with a thickness of nearly 60m. The main difference is that in the latter area the sandstone contains more grains of chert, limestone and lesser amount of igneous and metamorphic rock fragments as compared to Chwarta – Mawat and Qandil foothill area (photo 2.10).

2.2.3.2.4 - Unit Four (Mixed Fine and Coarse Clastic Unit) This unit is nearly similar to that of Chwarta-Mawat area, which consists of alternation of coarse and fine clastics (Red claystone, sandstone and conglomerate). The color is the same as that of Tagran section, while in this area, it contains no clasts of igneous and metamorphic rocks, and the thickness is about 75m (Fig.2.6).

2.2.3.2.5 - Unit Five (Chwarta Conglomerate) This unit is similar to that of Chwarta-Mawat area in color (grey). But the section differs in the absence of Igneous and metamorphic clasts (Fig.2.6). Moreover the limestone clasts are larger and more abundant than the chert ones. Some of the limestone clasts consist of blocks which may reach in weight 200kgs. The percentage of limestone and chert clasts is 72 and 38 respectively. The field and thin section inspection of the pebbles, boulders and blocks revealed that they derived from Qulqula Formation. While the same unit in Chawrta-Mawat area derived from more than one source rocks including the Qulqula Formation, Ophiolite and metamorphic rocks in addition to Walash-Naoperdan Series. The thickness of this unit cannot be measured as it shows possible imbrication of the blocks on each others so that the thickness is doubled. However the apparent thickness is about (800 m). 2.2.3.2.6 – Unit Six (Upper fine clastics) The top of the Suwais section is covered by soil and alluvium so that we are not able to study it (Photo2.10A). The thickness is about 800m.

Photo(2.7) Kometan section at northwest of Kometan village at Qandil mountain foot

2.2.3.3-Devisions at Qandil mountain toe and Roste valleyMost units at these areas either not exist or not developed well (Photo2.9). For example, at the north of Kometan village, units one and two are well developed while unit three is thin and contain several bed of conglomerate (Fig.2.7). Units four, five and six all make thick successions of fine clastic with some lenses of conglomerate. In this area it is obvious that the upper conglomerate (unit five of this study) is not present. It seems that the latter two units were deposited as a thick aggradational pile of fine clastics in a relatively low energy environment. These sediments are similar to that of unit six. The conglomerates, in this area, are rare and contain lesser amount of igneous and metamorphic rock fragments as compared to Chwarta Mawat area. At Roste valley all the representative lithologies of the Red Bed Series are fine clastics (red claystone with some sandstone). At these areas coarse units are not present especially unit five (unit three of Bolton).

Fig.(2.3)Schematic geological cross section of Rose valley

The problem is that one did not know whether the units are not deposited during their respective time or they are deposited as fine clastic because of persistence of relatively calm environment. At the base of Red bed series, in this valley, there are 15m thick alternations of fossiliferous limestone (in situ) and conglomerate beds. Thin section study revealed that limestone beds were deposited in their original place (not reworked) while the conglomerate bed seems to be intraformational (Fig2.3).

2.3-Origin of red color in the Red Bed Series Field study in the source area of Red Bed Series at the north and northeast of the studied area showed that Qulqula Formation contain many thick successions of red color (Photo2.8). These successions consist of red shale, brown siliceous shale, red and brown cherts. They are seen clearly to the north of Kanarw town ( Chwarta area), especially near Dere , Basine, , Bewre, Mirana, and Kani Showan villages, in addition to the east of Nalparez Town in Penjween area. In later area and in some place, the red shale changes to highly deformed brown jasper. The red intervals, in the Qulqula Formation, constitute more than half of the total thickness of the formation. Karim (2003a) observed similar lithologies in the formation in the area that is located between Chwarta and Said Sadiq Towns. As mentioned before Qulqula Formation is the main source area of the Red Bed Series. Therefore the origin of the red color is mainly attributed to the erosion of the observed red and brown successions in the Qulqula Formations. Previously, the red color of the red beds was attributed to the oxidation of iron in the continental environment during deposition (Blatt et el. 1980 and Potter et al. 1980). According to Al-Qayim (2000), the red color of the Red Bed Series is most likely originated from thermodynamic alteration due to thrusting of the Iranian blocks over the flysch trough of Arab plate margin during late phase of Alpine Orogeny. But the homogeneity of the red colors in the claystones and some conglomerate refuse these ideas, at least for the series in the studied area. This is because the oxidation, as diagenetic processes, cannot generate homogenous red or brown color in the thick bed. It can generate spotted or amalgamated color. In this connection( Harmann, 1963, in Turner, 1979) mentioned that diagenetic color of continental red beds is characterized by the occurrence of grey and green zones or white mottled zones within predominantly red successions that cut across the depositional boundaries. Eren (2001) mentioned that after reviewing of Turner (1980), Pye (1983), Friedman et al. (1992), Einsele (1992), there are two hypothesis which show the staining of sediments (the red color). The first hypotheses suggest that hematite is detritally derived from lateritic soils. The second hypotheses suggest that hematite forms authigenitically after deposition and by alteration of iron bearing detrital grains. Another evidence for affecting of the source area on red color is the regular alternation of red and bluish white layers of claystone and sandstone in some places (Photo2.3A). Among these places we mention, the east of Tagaran and south of Kani Sard villages. Moreover, the contacts between both layers are sharp and not gradational. The red and white layers are derived from sources with the respective colors (i.e. Red shale and bluish white marl of Qulqula Formation). Gavrilov (2002) mentioned that in some cases, (Fe) might penetrate into underlying and overlying sediments as the stage of diagenetic compaction changing primarily white sediments to a red color. Irregularity in staining caused the spot appearance of deposits. In the Red Bed Series the red color is existed in narrow strip controlled during deposition by the limit of the costal area where there is no reduction environment, but the red interval of Qulqula may be 100km wide and 100m thick. As the bluish white layers are not affected by the red color so the diagenetic or oxidation is excluded for main source of red color of Red Bed Series. We do not refuse the enhancement of the red color by oxidation but the main color is due to the source area, which is homogenized during transport by the rivers. The oxidation is happened during exposure of the red intervals of the Qulqula Formation, the same thing may also happen during transportation of these sediments. The dissolved oxygen may be incorporated with the existed (Fe) ions in the sediment of the Qulqula Formation. Many other authors argued that red color is attributed to pigmentary hematite which is derived from either weathering of source area or sediments previously deposited in a parallic oxidizing environments (Lajoie and Chagnon, 1973, in Turner, 1979). The detritus of Kolosh and Tanjero Formations are believed to be partly derived from Qulqula Formation, but their colors are green and buff, this is because these formations have deep deposits and with organic matter shows dark color, but when one sees the shallow facies their color become light or brown which appear in Qallachwalan area.

2.4-Classification of the Red Bed Series sandstone Classification of sandstone and conglomerate have many restrictions which include wide variations of lithic clasts and mineralogical constituents of the sandstones of the Red Bed Series from one unit to others. Even same unit show large lithologic change laterally. For example, unit one, in the south of Chwarta town contains no igneous clasts but they increase laterally toward Mawat area. Another restrictions is that, traditional (common) method of classification of Folk (1974) and Pettijohn (1975) by equilateral triangle can not be used (Fig. 2.5A and B). This is because the sandstones of the Red Bed Series is generally contain no feldspars or contain very little amount. So the triangle of the above author can not be used more successfully. While that of Al-Rawi (1982) is the most suitable than the others but it gives no convincing result (Fig.2.5C). This is because he did not put an apex for chert, which is common in the sandstone of the Red Bed Series.

Photo (2.8) Thick interval, mainly consisted of red ferrogenous shale of Qulqula Formation, at 10kms to the northeast of Chwarta town. It possibly responsible for red color of Red Bed Series

Another classification adopted in this study in which the apexes of the equilateral triangle are assigned to represent limestone, chert +quartz and igneous rock clasts (grains). The igneous rock clasts consist of altered peridotite and gabbros clasts. The chert clasts include all type of cherts such as red (jasper), black (bituminous), clayey chert, limey chert and others in addition to quartz. This classification can also be applied to the conglomerate of the Red Bed Series. For this classification the thin sections of the sandstones are studied under polarizer microscope and point counting is achieved for the calculation of the constituents. The constituents of conglomerates are estimated by using comparison chart of Folk et al. (1970) and Tucker (1988). The comparison is done visually in the field, and the result is arranged in the tables (2.1, 2.2, 2.3, 2.4, and 2.5) and plotted on the compositional triangle (Fig 2.8 and 2.9). Quartz grains are not plotted on the triangle, because most of them were grown as secondary grains and derived from Qulqula Formation before erosion ( many large secondary crystals was found in the Qulqula Formation).

Photo (2.9)

Photo (2.10)

Photo (2.11)

Photo(2.12)

Fig.(2.4 )

Fig.(2.5) classification of sandsytone of Red Bed Series according to , A)Pettijohn,1975, B)Folk,1974, C)Al-rawi,1982

Table (2.1) constituent of unit three at Khewata section

Table (2.2) Constituent of unit two at Tagaran section

Table (2.3) Constituent of unit two at Khewata section

Table (2.4) Constituent of unit five at Qalachwalan section

Table (2.5) Constituent of unit two at Suwais section

Fig.(2.6) Stratigraphic column of the outcrop section of Red Bed Series at northwest of Suwais village ( type section) toe . Not to scale

Fig.(2.7) Stratigraphic column of the outcrop section of Red Bed Series at Qandil mountain toe , near Kometan village. Not to scale

Fig.(2.8 ) A) lithologic constituents of the unit five (chwarta conglomerate) at Swais village area.B) lithologic constituents of the unit five (chwarta conglomerate) at chwarta aera.

Fig.(2.9 ) top) lithologic constituents of the unit three (Sandstone unit) at Swais village area.Below) lithologic constituents of the unit two (lower conglomerate unit).

CHAPTER FOUR

LITHOFACIES AND DEPOSITIONAL ENVIRONMENTS

4.1-Preface The environment of the Red Bed Series was swinging during the total time span of Paleocene and Eocene in response to the eustatic sea level changes, tectonic subsidence, uplift, and sediment fill in addition to the possibility of the effect of climate. Accordingly, in the basin, the environment was changing both in time and space mainly as a result of relative sea level changes. The variations of environment are demonstrated by lateral and vertical lithological changes, so that the shoreline was shifting continuously, especially during TST and LST. The depostional environments were mainly continental, ranging from proximal alluvial fan to fan delta environment. During Paleocene these environments were located in the coastal area of the deep marine basin in which the Kolosh Formation was deposited (Fig.4.8). During Eocene the deep environment of the Kolosh Formation is changed to shallow one either by sediment fill or by uplift of the area of coverage. In the position of Kolosh Formation, shallow environment Sinjar Formation and continental Gercus Formation are deposited while their counter part (Red Bed Series) was continued in deposition in more contrasted environments ranged between alluvial fan to marine coastal area. During Paleocene the coastal area was located in the Imbricated Zone (as now a days called), Buday, 1973 in Omari and Sadiq, 1977, while the deep basin (Kolosh Formation) was located at the present high folded zone which were located to the north - northeast and were changed to continental one. During Eocene this continental areas extends from Imbricated Zone to the boundary between Low and High Folded Zone.

4.2-Lithofacies of the Red Bed Series As the environment was highly variable (lateral changes) many different lithofacies were deposited. Seven major lithofacies were recognized in the studied area, they are as the following:

4.2.1- Grain-supported Boulder Conglomerate Lithofacies( A ) This lithofacies makes up both unit five (Chwarta conglomerate) and unit two. This facies mainly consisting of gravel, boulder and block conglomerate. It has gray or red color and the matrix consists of medium or nearly coarse sand. It is characterized by pebble orientation (imbrication) and large-scale cross bedding. The texture is mainly clast supported with the presence of minor amount of matrix–supported conglomerates. According to Einsele (2000) the clast supported conglomerate were deposited in river channel as bedload deposits in steep gradient alluvial fan or fan delta while Shao et al. (2003) attributed the matrix-supported conglomerate to the debris–flow deposit. Conglomerate deposited by debris flow is rare in Red Bed Series, it may exist in Units One and Four as a small lenses. Pettijohn (1975) and Selley (1988) named the former and the latter conglomerates as orthoconglomerate and paraconglomerate respectively. It is obvious from the size of clasts, thickness, amalgamated form (no stratification), and large scale cross bedding and erosional hole, that it was deposited in a braided stream with high discharge feeding alluvial fan. Then alluvial fan reaches the sea water of Paleocene- Eocene basin and forming a fan delta (or lowstand fan delta). The alluvial fan was deposited in wide incised valleys during a major sea level fall (lowstand system tract). The successive channel lag deposits are so closely stacked that there are no intervening sandstone and claystone deposits. The matrix of these conglomerates is composed of coarse and medium sand. The deposition of sand with gravel is described by Rust and Koster (1984, p.54), they attributed the grains-supported gravel to the deposition from bedload sediments by energetic aquaeous flow. They added that the sand remains in suspension (which transported to deeper water), but when the flow velocity decrease the sand infiltrates into the space between the frameworks of the particles. This is possible to occure in alluvial fan and marine environment. Einsele (2000, p.41) mentioned that interstices of gravels are later filled with sand during low water period. The coarsest sediments (block and boulder) represent channel lag deposits while the rare sandstone was deposited as longitudinal bar and sieve sediments (Fig.4.1). Some clasts have the size of blocks and weighted more than 200kg. From these, it is evident that the source area was a recently elevated terrain in that time and most probably deposited in fault-bounded alluvial fan with rapidly subsiding area of deposition. This lithofacies is characteristic of unit two and five; more detail is given about lithology and geographic distribution (in chapter two). In unit five (Chwarta conglomerate), this facies has aggradation stacking pattern with a thickness of 200-1000m while that of unit two has the thickness of less than 15meters.

Photo (4.1) two species of nummmulite which are found in the Chwarta conglomerate (unit five) at the south of chwarta town. They are most probably belonging to Walash- Naoperdan Series.

Fig.(4.1) a part of section at Khewata area showing lithofacies A and B.

Photo(4.1a) colony of coral in the base of the unit six .cropped out at 3km to the west of Chwarta Town which proves gradation of alluvial (fan delta) environment to shelf one. The related bed found by joined group of geologists from Geological survey of Baghdad and Sulaimanyia

Fig.(4.2) a part of section at Khewata area showing lithofacies C

4.2.2- Massive (or well bedded) cross bedded pebbly sandstone Lithofacies (B)This facies exist in units three and four. It also exists rarely at the base of unit one in Khewata section. It may represent the middle reach bar or point bar of braided rivers (Fig.4.1). This facies is clearer in unit two at the Qandil mountain toe near the Kometan Village. At this locality, it is associated with facies C and A.

4.2.3-Matrix-supported Conglomerate Lenses Lithofacies (C) This facies exists as lenses inside red claystones. When one observes this facies across certain traverse it alternates with red claystone or sandstone. But when it is seen from considerable distance, it appears as a multistory pattern (Fig.4.2). The distance between one story and the other ranges between one to five meters. The conglomerate is mainly matrix -supported and has lighter color than the surrounding claystone. In some cases the color of conglomerate lenses are gray as could be seen in the area between Chwarta and Mawat Towns. In rare cases, with this lithofacies and associated red claystone, one can find thin beds of white carbonate laterally disappear at the distance of 50 meters at the west of Sura Qalat and in thin section it is appeared as clayey limestone and show motling. The environment of this facies with the surrounding terrigenous claystone belongs to deposits of meandering river, which controlled by structure. The conglomerate represents the channel lag deposits while the red claystone belongs to flood plain deposits. The sandstone is deposited from crevasse splay or low energy point bars. As a result of vertical aggradation and lateral migration, the conglomerate appears as multistory building in vertical outcrop section.

Photo (4.2)

4.2.4- Laminated, Cross-Bedded Sandstone Lithofacies (D) This facies exists only in unit three of the present division (unit two of the previous divisions). It locally consists of thick bedded grey sandstone locally laminated and cross bedded with claystone and siltstone (Photo3.2A and B). It has coarse-grained texture and may be pebbly at the base of the beds. This facies is thicker and coarser in the Qandil mountain area, where it contains lenses of conglomerate. The lamination in this facies is so developed that they resemble the pages of an open book; therefore it is called papery sandstone (3.8A). On the surface of the sandstone sheets, one can see parting lineation (photo3.1.3). According to Selley (1988, p.93), laminated sandstone is usually formed by the upper flow regime (laminar flow). He added that, it occurs in diverse sedimentary environments ranging from fluvial channels to beaches and delta fronts. Another characteristic feature of this facies is the erossive base, which is associated with striation, drag cast (groove cast), flute cast and small channel (Phot3.7). In rare cases, the sandstone is gravely at the base. The environment of this facies is probably of fluvial environment of sand-dominated distal braided river. According to Mial (1985), this type of river is located at the distal area of alluvial fan, which characterized by wide channel and linguoid sand bar. The claystone that associated with this facies is attributed, in this study, to over bank fine distal braided plain and delta front environment (Fig.4.3). Einsele (2000) mentioned that low gradient; low relief channels and bars characterize this type of rivers. He added that the main sediment types are massive, laminated and cross-laminated sandy silt. This type of environment can be applied to Units One and three in the Chwarta-Mawat, which are mainly, consist of sandstone, red claystone and silt stone. The continuity of the sandstone beds to several kilometers attributed to lateral migration with little contemporaneous subsidence during deposition of this facies (Fig.4.4)

Fig.(4.3) a part of section at Shahedan area showing lithofacies D .

Fig.(4.4) Block diagram showing deposition of the Unit three (The sandstone unit) by channel fill and lateral channel migration with some subsidence.

4.2.5-Red-brown Mudstone Lithofacies (E)

This facies consists of massive or thick beds red or brown claystone and siltstone with sandstones and rare lenses of conglomerates. It is occasionally laminated and is the most common lithology of units One and Six. It also exists in other units, except Units Five and Two, in more or less proportion. This facies has different depositional environment. In unit one, it is most probable, that this facies is deposited on the floodplain of the meandering and braided rivers (Fig.4.5), while in units such as, Three and Six; they may belongs to the delta front and delta plain deposits at the distal area of the alluvial fan where the fan reaching the marine water. On other side this facies may represent the transition from alluvial fan to marine deposit of the Kolosh Formation. In this connection, Mial (1992, p.138), recorded such type of transition and called it “interfingering of alluvial succession with marine deposits”. He added that in some basins, the wedge of fluvial sediments, up to hundred meters thick, are interbedded with marine shoreface deposits. In this study, the exact position of interbedding of alluvial and shelf deposits is located at the present position of Azmir, Goizha, Sara anticlines, but unfortunately the sediment of these areas were removed by erosion.

Fig.(4.5) a part of section at Khewata area showing lithofacies D and E.

4.2.6-Thin-bedded carbonate lithofacies (F) This lithofacies exist inside Unit One which consists of several thin beds of carbonate materials inside red claystone and sandstone. Under polarizer it appears as fine-grained and clayey limestone (crystalline argillaceous). They can be seen for only a distance of 400m and laterally change to red claystone. They exist in Chwarta-Mawat, and Qandil area (Photo 2.9B). It is probable that this facies is deposited either in oxbow lakes or in the lakes on the delta plains.

4.2.7- Fossiliferous Carbonate Lithofacies (G)

This lithofacies is very unusual in the Red Bed Series as it contain clear coral colony (Photo4.3), large gastropods and oysters. It is originally found by a team of geologist from Directorate of Geological Survey of Baghdad and Sulaimanyia at the 3km west of Chwarta town at the base of Unit Six. The coral colonies exists as separate blocks (patches) in the most highly deformed bioclastic and fossiliferous background limestone materials. This is returned to competent coral colonies blocks as compared to incompetent background limestone. This facies is also associated with bioclastic limestones and underlain by green marl. In other sections, this facies is not found. The existence of this facies, as indicator of marine environment, may be due to the formation of in land bay in Chwarta area, where shallow marine conditions existed. This bay may represent the extension of a valley land ward in North-South trend where corals grown on its hard base (fluvial deposits of previous incised valley). Karim (2004) found the same growth of the corals on the conglomerate of the incised valley within the Tanjero Formation.

4.3- Depositional Model and Climate It can be inferred from the above discussed facies and sedimentary structures that the best depostional model for the Red Bed Series is alluvial environment model in arid climate. According to Pettijohn et al. (1987) this environment is subdivided into fan, alluvial plain and delta. He added that sand is the component of all three but, in the fan, it may be subordinate as compared to coarser debris and to fine silts and clays in the delta. Bloom (1998, p.247) mentioned that alluvial fan and delta are two depostional landforms that form from abrupt loss of competences in the stream. He added that delta are mostly subaqueous form while the alluvial fan are subaerial forms deposited when stream channel loss water by infiltration, decrease its gradient, or widen abruptly. Moreover, he confirmed that both alluvial fan and delta may merge (join) and many deltas may cap by low gradient alluvial fan. Field study and facies analysis showed that the above facts about alluvial fans and delta are applied for the Red Bed Series. This is because more evidence of sedimentology and lateral facies changes exists which proved that Units One and Six are deposited in delta depositional environment and Units Two and Five deposited in alluvial fan environment while Units Three and Four deposited in braided delta environment, where the base level of the river too much lowered by the uplift of the source area and the alluvial fan prograde seaward and combined with sea water, in this case it is called lowstand fan delta, which formed during seal level fall and associated with valley incision. This type of environment prevailed during deposition of Units Two and Five. The environments are bordered from north and northeast by thrust fault on which the overthrusted sheets of Iranian plate advanced towards the southwest (Fig.6.6 and 6.7). The fluctuation of sea level fall caused rise and fall of the existed base level of rivers. In response to this the process is changed from erosion to deposition and grain sized also changed from boulder to sand and clays in different environment. The change of environment was occurred in repeated cyclic manner, which is manifested by coarsening upward stacking of sediments. The lithology of all cycles of eustatic sea level change and tectonic phases are not represented now in the area. This is due to the erosion by which most of the fine sediments (claystone and siltstone) were removed. The environment of the Red Bed Series grades to that of the Kolosh Formation via transitional environment, by possibly terregenous dominated shelf. When the sediment of the Red Bed Series accumulated at the delta front and on delta plain, they reworked into deeper part of the Paleocene foreland basin through submarine channels. The reworking was resulted from generation of turbidity current by slump, slide and wave and currents mixing sediments. Recently, Zelilidis et al. (2002) Studied similar occurrence of gradation environment, from alluvial fan into deep marine turbidite. In his study of Mesohellenic Basin evolution of Greece (Miocene–Oligocene), he showed that the basins (such as that of Iraqi Paleocene) is divided into several formations. The proximal area (near shore), shelf and basin consisted of conglomerate (Fan delta conglomerate), sandstone and deep sandstone and shale respectively. In the same way Emery and Myers (1996, p.128) mentioned that lateral change of fluvial architecture reflects the reduced fluvial gradient from the hinterland to the margin of the marine basin. Therefore, this arrangement of the sediment and environment as studied from Greece by Zelilidis (op.cit) is similar to our discovery of combining both Red Bed Series with Kolosh and Gercus Formations in the studied area. If we suppose that the environment, in certain location and time in the studied area, was proximal braided river (alluvial fan apex), this environment was changing with time. The change is from alluvial plain (braided plain) to delta plain (paralic environments) and delta front occasionally (Fig.4.7 and 4.8). This is due to high tectonic activity of the studied area, which was probably aided by eustatic sea level change.

Fig.(4.6) Depositional environment and system of Red Bed series , (a) Gravel dominated braided river as a feeder of alluvial fan at proximal area.(d) Sand dominated braided at distal area with iguanid sand bar. (b,c,e,f) litho logic column of the environment during deposition of several cycles . Modified from Einsele (2000) and applied on Red Bed Series.

Fig. (4.7) The most close model ( in literature) to the Red Bed Series and Kolosh Formation . The fan delta-alluvial fun and slope-basin areas can be representative for Red Bed Series and Kolosh Formations respectively . While the shelf represent the transition between the two units . Drawn by Link et al., 1976, in : Pettijohn et al.(1987)

Fig.(4.8A) Position of Kolosh Formation and Red Bed Series in the Foreland basin of Paleocene

Fig.(4.8B ) depositional model of Red Bed Series during Paleocene (A) and Eocene

Fig.(4.9) Lithology and environment of the one cycle of the unit three

CHAPTER FIVE

SEQUENCE STRATIGRAPHY

5.1-PREFACE Sequence stratigraphy is a new tool for more accurate basin analysis than the traditional stratigraphy. This is because traditional stratigraphy divides the outcrop section of certain area in term of similar lithologies while sequence stratigraphy divides the sections according to equivalent lithologies and equivalent times intervals. Therefore sequence stratigraphy is not concerned so much with the lithology as do the traditional stratigraphy. Emery and Myers (1996) defined sequence stratigraphy as “subdivision of sedimentary basin fill into genetic packages (depositional sequence) bounded by unconformity and their correlative conformities”. Previously no one has studied sequence stratigraphy of the Red Bed Series. Karim (2004) has studied the sequence stratigraphy of the underlying Tanjero Formation in the same studied area. He cited that the rock of the most upper part of the Tanjero Formation represent shelf margin system tract (SMST). For the division of the rock body of the series, into depositional sequences, the method of Vail et al. (1977) is used, the method of Galloway (1989) (Genetic sequence) is not used because the Red Bed Series is mainly deposited in the continental environments, so no condensed sections can be found easily and they have very limited outcrops. That’s why Galloway method (1989) could not be used in this study. Before the study of the sequence stratigraphy of the series the following points should be considered: 1-Only one narrow strip of outcrop is available for the study. This prevents wide and accurate sequence stratigraphy study of the series. 2- Although the lower boundary of the series is clear, which is indicated by Karim (2004) as unconformable in some places (as in Qandil mountain toe) and conformable in others (as in Chwarta area) but the upper boundary with Naoperdan shaly Group is not clear. Previously this contact mentioned to be tectonic by Al-Mehaidi (1975), Buday (1980) and Surdashy (2001). 3. It is agreed that the series has shallow environment (mainly continental), therefor the lithology and facies change dramatically both laterally and vertically. This makes study of sequence stratigraphy of the series difficult. Moreover, this environment may cause erosion of some of the systems tract especially those, which have fine grain lithology such as transgressive systems tracts. Extensive lateral fieldwork is achieved to find all sedimentary facies deposited in response to relative sea level change. Finally, these facies are organized in system tracts (LST, TST, and HST) and the associated sequence boundaries are identified. The systems and boundaries rarely can be seen in one continuous surface section.

5.2-Contact between the Red Bed series and the Tanjero Formation The contact was cited previously to be gradational by Lawa et al. (1998) while Karim (2004) recorded both gradational and unconformable contact at Chwarta-Mawat area. Moreover, the latter author mentioned that the contact is totally unconformable at the Qandil mountain toe. So he concluded that the upper most part of the Tanjero Formation represent shelf margin system tract (SMST) in Chwarta-Mawat area and underlain by SB2, while in Qandil area the upper part of Tanjero Formation underlain by SB1.In the present study this conclusion is assigned as a starting point for the discussion of the sequence development of the Red Bed Series.

5.3- Relation of the series with the other formations The basin analysis of the Red Bed Series could not be completed without sequence stratigraphy study. For accurate analysis of the basin, the series must be correlated with other units (formation). For this the study of the Red Bed Series is expanded from proximal area (area of the series outcrop at Chwarta, Mawat and Qandil areas) to the distal area (Dokan area and Sharazoor plain, at south of Sulaimaniya City). Field study and literature review showed that the closest and synchronous (time equivalent) unit is the Kolosh Formation. According to our assumption both Red Bed Series, and Kolosh Formation are deposited in one single basin as a time lateral equivalents (Fig.5.2). This relation is approved for lower and middle parts of the Red Bed Series with Kolosh Formation according to the following recorded facts: 1.The ages of the Kolosh Formation, as given by Bellen, et al. (1959) and Buday (1980), was Paleocene-Lower Eocene while that of the Red Bed Series is highly doubtful but roughly assigned to be Paleocene to Miocene. This shows that some parts of the series are time equivalent to the Kolosh Formation. 2.The pebbles and boulders of Naoperdan, as mentioned by Omari and Sadiq (1977), are ascertained in this study and found in the Red Bed Series so there is a direct evidence to prove that some part of the series is younger than Eocene.3.Karim, (2004) found that 500m conglomerate of the Tanjero Formation at proximal area (same area of the series) has equivalence of nearly 400m of sandstone with some interbed of conglomerate at distal area (Dokan area and Sharazoor plain). When this fact applied to the Red Bed Series, the equivalent of all units of the Red Bed Series in the distal area must be found too.The fieldworks were successful, for finding this fact in the area of exposing of the Red Bed Series and the Kolosh Formation. It was found that at the base of the Kolosh Formation in Dokan area, there are many intervals of brown calcareous shale (or brown calcareous red claystone). These intervals have deep environment (pelagic) and contain Paleocene planktonic forams and exist above the conglomerate between Kolosh and Tanjero Formations. These intervals can be correlated easily with Unit One of the Red Bed Series in Chwarta- Mawat area, which has generally a fine-grained and red color lithology. That unit of the series is equivalent to the Unit Two of Bolton (1958) and Mehaidi (1977). Hoy and Ridyaway, (2003) mentioned that lateral changes in depositional systems are related to variation in tectonic subsidence at different parts of the basin. Even the equivalent of bluish white layers of sandstone and siltstone in the unit one of the series (Photo2.3A) can be distinguished in the lower part of the Kolosh Formation as bluish white marl and marly limestone.Another interval of Kolosh Formation, which can be correlated with the Red Bed Series, is its middle part. This part of Kolosh Formation can be correlated with the conglomerate of Unit Two of the Red Bed Series on the bases of lithology, paleocurrent and stratigraphic position, as concerned to lithology, both have the same constituent of clasts (limestone, chert, igneous and metamorphic rock fragments). While the measured paleocurrent in both units is toward southwest (about S70W) and both contain same sedimentary structures. In the correlated parts of both the Red Bed Series and Kolosh Formation same type of flute cast and same direction of arrangement were found (photo 3.7, 5.1, and 5.3). Unit Two of the Red Bed Series, in Chwarta area, consists of chert and limestone pebbles only, while in Mawat area consists of chert, limestone, igneous and metamorphic pebbles, therefore it is the most possible that lithology of the middle part of the Kolosh Formation is derived from that conglomerate of Mawat area, especially during early lowstand, in which huge amount of gravels and sands transported southwestwards and deposited as Kolosh Formation. The sandstone reached the present position of the Kolosh Formation at the south of Dokan area (distal area of Paleocene basin), while the gravels deposited, most probably, at the intermediate area between Mawat and Dokan area, but these deposits now cannot be seen because of erosion. For establishing a relation between lower parts of the Red Bed Series and the Kolosh Formation and according to the above facts, a sketch is drawn. It shows the lateral change of lithology down the basin paleoslope of the Paleocene. In traditional stratigraphy this lateral change of lithology, from coastal area to center of the basin, is assigned now as the Red Bed Series and Kolosh Formation (Fig. 5.2). The discovery of reefal limestone (photo4.3) in upper part of the Red Bed Series is evidence of gradation of fluvial environment of the Red Bed Series with normal marine one of the Kolosh Formation. As mentioned in the section (2.2.3.1.5), unit five is younger than the Eocene which contain boulder of the Naoperdan Series.Fieldwork, depending on the lithology, thickness and stratigraphic position, proved that this unit is equivalent to the Gercus Formation. This is based on the extensive survey in the area at the boundary between Low and High Folded Zones (area of exposure of the Gercus Formation). These areas include east, north and west of Darbandikhan town

in addition to Bazian and Haibat Sultan Mountain. At these areas all the conglomerates are studied lithologically and stratigraphically. The closest one is that of Gercus Formation which in some places have a thickness of 60m, and it is located at the top of the formation (Photo 5.2). The grain size range from pebbles to granules and the grains has more roundness and sphericity than its equivalent at proximal area (unit five or Chwarta Conglomerate) from which they derived. The conglomerates of the Gercus Formation contain similar types of cherts and limestones gravels as that Unit Five of the Red Bed Series of The conglomerate of the Gercus Formation contains grey or milky gravels, which resemble that of Walash-Naoperdan Series. The thickest exposure of conglomerate of the Gercus Formation is located at 10km north of Darbandikhan town. At this locality the conglomerate form a mountain called Barda Asin Mountain (Photo5.2). The same conglomerate is recorded by Karim (1999 in press) in Sartak-Bamo area, which has thickness of 70m and interbedded with sandstone. As will be seen later this conglomerate with Chwarta conglomerate represents sediment of incised valley during Eocene. Field study failed to find positive relation between this conglomerate and the conglomerate of the Lower Fars and Pila Spi Formations. This is because the gray limestone (as gravel) of Naoperdan is not observed in all areas of occurrence such as Darbandikhan, Darbandi Bazian and Haibat Sultan Mountain. In this conglomerate, the carbonate gravels are totally composed of porcelaneous white limestones, which are belonging to Avanah Formation. This conglomerate is studied in detail by Ameen (2002 in press). He called it Lower Fars Formation basal conglomerate. Karim (1999) recorded the existence of the Avanah Formation above the Pila Spi Formation at the area east of Darbandikhan Town.

Photo (5.1)

Photo (5.2)

Photo (5.3)

Fig.( 5.1 )

5.4- Depositional sequences and systems tracts of the Red Bed Series In this study, the whole rock body of the Red Bed Series except unit five (Chwarta Conglomerate) is divided into three main depositional sequences. But the latter conglomerate will be discussed separately. Beside the main sequences, this study does not exclude existence of other minor depostional sequence within the main ones but the study of these minors make the Red Bed Series more complex to be understandable and to be conclusive. The main sequences are as follows:

5.4.1- Lower depositional sequence

5.4.1.1- Highstand systems tract (unit one) According to Karim (2004), the upper most part of Tanjero Formation is shelf margin systems tract (SMST). Therefore, Unit One, which is directly overlying this part of Tanjero Formation, can be identified as high stand systems tract (HST). This unit consists of red claystone and sandstone. In some localities it consists of alternation of red claystone and bluish white siltstone (or sandstone). This systems tract has aggradational pattern of deposition. Toward northwest (toward Mawat and Qandil Mountain), the lithology of this system tract changes from claystone and siltstone to claystone with lenses of conglomerate. The transgressive systems tract of the lower depositional system is not found in the Red Bed Series. It is possible that the underlying dark shale beds which are located on the top of the Tanjero Formation (which is not mentioned by Karim, 2004) may represent a Maximum Flooding Surface (MFS).

5.4.2- Middle depositional sequence 5.4.2.1- Lowstand systems tract (unit two) This systems tract is consisting of the red colored conglomerate between unit one and unit three. In Chwarta area, these conglomerates consist of exclusively of chert and limestone clasts (boulder and pebble). While towards west the shares of igneous and metamorphic clasts gradually increase. The underlying surface is sharp and undulated, therefore it is erosional and type two sequence boundaries (SB2) which formed during early LST according to the following: A-This conglomerate is regarded as orthoconglomerate, as it has grain supported texture and contains clasts range from pebble to boulder, it even contains sporadic blocks. B-In Chwarta area and Qandil Mountain, the conglomerate can be traced laterally for several kilometers. C-The conglomerate bed represents incised valley fills. In these valleys the conglomerate fills the channel floor (as lag deposits) deposited during sea level fall. D- Before the deposition of this conglomerate, it was possible that huge quantity of fine red clastics of the previous highstand systems tract may be eroded and transported to the basin (distal) area (location of Kolosh Formation). This extensive erosion is probably responsible for the brown and red interval at the base of Kolosh formation. This conglomerate, in distal area and inside Kolosh Formation, has only fine grain equivalents.

5.4.2.2- Transgressive systems tract The rock body of this systems tract is represented by thick succession (500m) of thick-bedded gray sandstone interbedded with light color claystone. The thickness of each bed ranges between 1m.to 6m. The succession has a clear aggradational pattern. This shows neither shallowing nor deepening. The sandstone unit (unit three) is assigned as transgressive system tracts because of the following: 1. It directly overlies the conglomerate of unit two. According to Emery and Myers (1996), this change from coarse sediments to fine one is evidence of transgressive system tract. Posamentier (2002) mentioned that transgressive system tracts are commonly sand prone and tend to be encased in shelf mudstone. He added that the area about 20km long and may be 17m thick. These characteristics are nearly coinciding with that of the Red Bed Series at Chwarta-Mawat area. 2-It contains many observed sedimentary structures such as cross bedding, ripple marks and laminations that prove it is deposited in less turbulent environment than the conglomerate. Other observed features are the continuity of the sandstone bedding for several kilometers.The environment of this facies is indicated as delta (Fig.4.8) and it is possible that occasionally flooded by marine water during short sea level rise.

5.4.2.3- High stand systems tract This system tract is composed of thick alternation of sandstone, conglomerate and claystone with prominent red or brown color. The lithology of this system tract belongs to that of unit four which has thickness of about 150m. Smith and Jacobi (2001, p.22) have found several shallowing-upward parasequence which they grouped them into aggradational or progradational parasequences. In Red Bed Series, the alternation of several successions of sandstone, conglomerate and claystone can be compared with shallowing parasequences of the above authors. The existence of conglomerate may be attributed to unusual large storm or may be returned to braided delta (Fig.6.4). Because of contrasting lithologies (competent and incompetent beds), the area of the outcrop of this systems tract is densely dissected by streams and forming badlands. In Roste valley this systems tract does not exist at all, instead its position is either covered or occupied by fine grain clastics. The red claystone, sandstone and conglomerate, can be deposited in delta front, delta mouth and delta feeder - channel respectively. The red claystone, sandstone and conglomerate, are belonging to deposits of river systems, which has intermediate characteristics between braided and meandering streams.

Fig.(5.2) possible relation between Gercus Formation and Red Bed Series during deposition of the unit five (Chwarta Conglomerate)

Fig.(5.3) Final Stratigraphic column of the Red Bed Series at Chwarta Area when the result of the present is encountered. The conglomerate has erosional relation with other units

5.4.3- Upper depositional sequence This system tract is not ordinary in out crop and field stratigraphic succession. In the field, this systems tract is started with low stand systems tract of 1000 m conglomerate (Chwarta conglomerate). But originally the conglomerate is not related to the Red Bed Series, as it contains fossils of Walash–Naoperdan Series. So, in this study, the upper depositional sequence is supposed to be covered by Chwarta conglomerate. This depositional sequence consists of unit six (unit five is excluded from the Red Bed Series).

5.4.3.1- Transgressive and highstand systems tract The fine clastic (claystone, marl and sandstone) with lensoidal beds of reefal limestone is the clear evidence for the transgressive or high stand system tract. But, because of the covering by Chwarta conglomerate and soil, the two systems tracts cannot be separated. The only sign for the transgressive systems tract (at the base of unit six) is the local existence of green marl, fossiliferous reefal limestone at the north of Shams Awa Village in Chwarta-Mawat area. The rest of the fine clastic, with conglomerate at the top, represent high stand systems tract. The low stand systems tract is not clear; it may be incorporated with the Chwarta conglomerate. While the Walash-Naoperdan can be regarded as the high stand systems tract.

5.4.4- Unknown Lowstand systems tract In Chwarta-Mawat and some part of Qandil mountain area, this systems tract is very well developed which is represented by more than 1000m of pebble and boulder conglomerate (Chwarta Conglomerate). It contains all types of gravels such as igneous, metamorphic, chert and limestone clasts. The most important fact about this conglomerate is that it contains fossiliferous limestone pebbles and boulders of Naoperdan Series (Photo4.3). This means that this conglomerate is younger than this latter Series (Fig.5.3) and overlying all the Red Bed Series and Naoperdan Series erosionally (unconformity). So in this study this unit is excluded from the Red Bed series, and

in some places this unit inters bedded with other units of the Red Bed Series, which may be due to the tectonic imbrication with other units. The position of this conglomerate in the stratigraphy of the area and its systems tracts are unknown. At the distal area (South of Sulaimaniya and Dokan area) great efforts were exhausted to find the equivalent of this conglomerate. This is because the thickness of this conglomerate is so high (about 1000m.) that must have equivalent in other areas towards the basin center of the Eocene. The lithologic correlation showed that the Gercus Formation is more close to this system tract. Although same fossils are not found in the conglomerate of Gercus Formation but many types of gravels were found which have the same type of lithology i.e. grey or milky limestone. The absence of the Alveolina and nummulite forams in the conglomerate of the Gercus Formation may be attributed to the diagenetic processes, which attacked more easily, the smaller gravel of Gercus Formation than the larger one of the Chwarta Conglomerate. Another reason is the longer distance of transportation (25km) of the latter gravels, which is mechanically deformed during rolling. The continuous rolling, during transport, homogenizes the texture of the gravels. Chwarta conglomerate is underlain by a clear erosional surface, which stand for type one sequence boundary (SB1). The shape of the conglomerate is lensoidal, representing an incised valley fill during sea level fall. In this connection Haq (1991) mentioned that during low stand systems tract when the relative sea level begins to raise slowly the stream incision is stopped and the existed incised valley may begin to be filled with coarser braided stream sediments. Shao et al. (2003), have found conglomerate of braided stream which nearly the same as that of the Red Bed Series as concerned to thickness, sedimentary structures and associated lithofacies. Einsele (1998, p.338 and 339) mentioned that during late lowstand the lowermost portion of incised valley is filled with coarse fluvial sediment (gravel in case of Red Bed Series) of braided stream. This conglomerate also exists at the eastern part of Qandil mountain toe at north of Suwais village while at the western part of the mountain it change to fine clastic which is more representative of high stand systems tract than lowstand systems tract.

5.4.5-Erosional surfaces and unconformities below and inside the wedges Field study showed that erosional surfaces exist below the conglomerates of units two and five. These surfaces are formed due to either sea level fall or uplift of the coastal area (Mawat and Chwarta areas). During exposure the rejuvenation and incision of river occurred by lowering of the base level. The river erosion of the previous coastal area scored incised valleys. The erosional surface is coinciding with the valley floor. The largest and most obvious valley is that, which extend from Chwarta to the north of Darbandikhan town. This valley is filled with 1000m and 60m of conglomerate at the two places respectively. These erosional surfaces, as unconformities, change to several unconformities towards south and southwest downdip. This occurred during successive flooding of the rivers, each ones carried huge quantity of gravel, sand and mud (clays). Most of the mud and sand carried to the deep parts of the basins and deposited as either Kolosh Formation during Paleocene at distal area of the basin or as Gercus Formation during Eocene. While conglomerate, sandstone and claystone were deposited as river and alluvial fan in near coastal area (proximal area). Emery (2002) mentioned that the low stand systems tract (sea level fall) must have time equivalent subaerial unconformity at the proximal area. This citation can be applied to the Red Bed Series (Unit Two and Five) and sandstone and conglomerate of Gercus and Kolosh Formations. The lithology of Units Two and Five as discussed previously imply that they are deposited in continental environment so the erosional surfaces are subaerial unconformities. In addition to the underlying erosional surface (unconformity), Unit Five (Chwarta conglomerate) contains many erosional surfaces between the stacked lenses of conglomerate. On these surfaces the sand and other materials are transported to the basin. So it is supposed, that each sandstone or conglomerate bed of the Gercus Formation is time equivalent to one of the erosional surfaces. Along down dip extension of these surfaces in the Eocene basin from Imbricated Zone to the south of High Folded Zone each surface splits into several smaller surfaces. In the literature, similar types of unconformities are cited by Potter and Pettijohn (1977, p.295), in basin margins, they called them “compound unconformity”. In some places of the distal area the surfaces become correlative conformity.

5.4.6-Incised valleys and their sediment fill The conglomerates of Unit Two and Five belong to sediments of incised valley fill. This can be proved by observing the clear imbricated pebbles (Photo 3.4 and 3.6) and large scale cross bedding in addition to their general lensoidal form (Photo 3.3 and 3.5A). Blatt et al. (1980, p.640) mentioned that in braided stream deposits imbrications of pebbles are well developed. During sea level fall the shelf of the basin (or coastal area) of the Red Bed Series is exposed to subaerial erosion and fluvial incision. This is initiated when the stream base level was lowered. The base level change is shown by Stephen and Dlrymple (2002) schematically for alluvial systems during LST, TST and HST (Fig.5.5). The number of these valleys cannot be indicated because of lateral coalesce of these valleys and their sediment. Therefore, thick pile of conglomerate can be traced laterally for tens of kilometers. It is possible that the sand of the Red Bed Series, Kolosh and Gercus Formations are supplied from these valleys. The sediment transferred from source by braided stream and when these valleys reach the main body of the sea, they form lowstand fan delta (Fig.6.4). The incised valleys, now can be identified by their sediment fills, which have lensoidal form of conglomerate and underlain by relatively soft sediments, such as those of Units One and Four.The coarse sediments ( gravel and boulders) are laid on the braided delta as bed load deposits while the sand fractions were farther transported to the distal area and deposited in the deeper part of the basin as the Kolosh Formation (as turbidite) during Paleocene, while during Eocene they are deposited as the Gercus Formation. This type of deposition of sand and gravel is well documented by Bhattacharaya and Willis (2001) during the study of lowstand delta in the Frontier Formation in USA.The width of these valleys is larger than those, found by Karim (2004) in the Tanjero Formation, and that of latter Formation is about 2km. in width while that of the series reaches 4km. Mial (2002) found incised valleys, which have a width of 4km in Malay Basin in Southeast Asia. While Samuel et al. (2003) found incised valley of 6km width in front of Nile Delta which belongs to Pliocene age and eroded during sea level fall on the shelf and upper slope. The high width of the valleys found in the Red Bed Series is due to the low relief, which associates with possible lateral migration of braided streams (Surdashy personal communication). According to Einsele (2000), the valley fill mainly consists of coarse-grained (pebble size) fluvial deposits. He adds, that, these sediments overlain by sediments of brackish and estuarine water. According to Emery and Myers, (1996, p.140) as a result of river rejuvenation, incised valleys commonly contain the coarsest sediment available locally. They believed (p. 137), if the new river tracks were steeper than equilibrium river profile, the river would firstly straighten course and then incise to form a valley. Furthermore, they mentioned that these valleys are important because they represent unequivocal evidence of a sequence boundary and they can form stratigraphic traps for hydrocarbons. The conglomerate of the Red Bed Series is deposited during late lowstand systems tract. In this connection, Haq (1991) mentioned that during lowstand systems tract, when the relative sea level begins to climb slowly, the stream incision is stopped and the existed incised valley may begin to be filled with coarser braided stream sediments (coarse conglomerate in case of the Red Bed Series).

Fig.(5.4) Stratigraphic column of the Red Bed Series at type section(near Suwais Village) ( tectonically corrected)

Fig.(5.5) Alluvial architecture as related to simple cycle of base level fluctuation( Stephen and Dalrymple,2002)

5.4.7-Sediment of the incised valleys during TST When one looks at the sediment above the conglomerate of the lowstand systems tract he realizes that their sediments mainly consist of claystone, sandstone without conglomerate. But that of lowstand systems tract contain abundant conglomerate. This is agreed with the observation of Vincent et al. (1998, p.335) that the coarse braided fluvial facies are more prevalent in lowstand and early transgressive systems tract while fine grain meandering fluvial facies are developed in the late transgressive and highstand system tract. It was observed in this study that, in most cases, both sediments of transgressive and highstand systems tracts have red color and contain some beds of conglomerate. It is well known that conglomerate is mainly deposited during sea level fall (Lowstand systems tract). But in case of the Red Bed Series they exist as a miner component of Transgressive and Highstand systems tract. This is attributed to general continental environment of the Red Bed Series. The sea level fall, during deposition of the Red Bed Series, is probably due to the phases of tectonic uplift of the source area and subsidence of the basin. But the shallowness of the sediments of the highstand systems tract supposed to be due to tectonic uplift and sediment fill. The sediment fill caused decrease in basin depth by more than 500meters from the top of conglomerate of unit two to the top of sediment of transgressive systems tract (unit three).The braided deposit during lowstand systems tract is changed (more or less) to meandering fluvial deposits. In this type of deposit and according to Eiensele, (2000) it may include coarse sediments (conglomerate) and fine ones at the point bars.

5.4.8- Condensed section Condensed sections as thin marine stratigraphic horizons are composed of pelagic and hemipelagic sediments characterized by very slow sedimentation rate (Loutit et al. 1988). Within depostional sequence, the condensed section occurs partly at the top of transgressive system tract and partly within high stand system tract. They represent the maximum landward extent of marine condition. Marine condensed sections are created by sediment starvation and thus, characterized by apparent hiatus, thin zones of burrowed and somewhat lithified beds (Haq, 1991). In the Red Bed Series one cannot find any condensed sections, but when the whole basin is specified, they can be found inside the Kolosh Formation. They exist as thin pelagic and hemipelagic thin layers at the lower part of the formation (Fig.5.7). The interval that contains condensed section is time equivalent to the transgressive or highstand systems tract (unit one and three) of the lower and middle sequence (Photo 2.1 and 2.3). The green marl at the top of Unit Four and the reefal limestone at the base of Unit Six may be reported as equivalent to the condensed section. The reefal limestone at the base of Unit Six may be correlated with the Sinjar Formation. This is because in the section (5.3), the relation between the Red Bed Series and the Kolosh Formation is stated. Moreover than that Unit Four can be correlated with the conglomerate and sandstone that exit, at some places, between Kolosh and Sinjar Formations.

5.4.9- Forced regression The main succession of the Red Bed Series is sandwiched between a forced regression and normal regression from the base and the top

respectively as follows: Posamentier et al., (1992) defined forced regression as basinward movement of the shoreline, caused by relative sea-level fall and independent sediment supply. While Ainworth and Crowley (1994) defined it as progradational of the shoreline in response to relative sea-level fall in which the rate of sediment supply exceeds the rate accommodation space added. Gayara and Al-Ubaidi (2000) found sediments, which are attributed by them to the deposition by forced regression and they concluded that it was deposited during sea level fall, which exceeded the rate of subsidence. This is recorded in Amij siliciclastic –carbonated succession from western Iraq. The most important evidence of the forced regression in the Red Bed Series, during certain time interval, is rapid coarsening upward, i.e. the resting of 1000m of boulder and block conglomerate, in case of unit five, on the finer sediments of other units and 16m. in case of unit two. In this study, unit five is separated from other units of the Red Bed Series and positioned at the top of Walash–Naoperdan Series in unconformable relationship. As a result of the forced regression, the thick pile of lowstand systems tract is deposited unconformably over highstand system tract. This forced regression is affected by tectonic uplift of the source area and enhanced by eustatic sea level fall and may be enhanced by sediment fill, for example150m. Sediments of unit one and about 700m. of deposits ( unit three, four, and six) below unit five. The erosional surface below unit two and five represent the most intense tectonic periods coinciding with syntectonic deformation of the area (uplift of the source area). These surfaces are overlying unconformably units one of the Red Bed Series and Walash-Naoperdan Series respectively. The lithology of the Red Bed Series revealed that the source area (hinterland) was mainly comprised of accretionary prism of Qulqula Radiolarian Formation and the ophiolite (Fig.6.6 and 6.7). Unit two of the Red Bed Series represents low amplitude of sea level change as compared with unit five, and bounded below by type two-sequence boundary (SB.2), which formed during the early lowstand systems tract and no fluvial deposits were appeared.

Fig.(5.6) Correlation of different units of the Red Bed Series in the studied area ( not to scale). The legend is shown in the Stratigraphic column in the chapter one

5.5-Sea level fluctuations and Wheeler diagram Wheeler diagram is time expanded lithological column, which shows the time span of systems tracts and gaps (non-deposition or erosion) between systems tracts (Fig. 5.7). The lower part of the Red Bed Series (Unit One) is represent HST bounded below by a maximum flooding surface MFS, this surface is represented by a thin dark shale bed at the top of underlying Tanjero Formation in Tagaran area while in Mawat it is represented by both fossiliferous limestone and shale. This parasequence consists of an aggradational succession of red claystones and sandstones of the floodplain deposited during sea level highstand with moderate rate of subsidence. The lithology changes mainly into sandstone mainly at the eastern part of Qandil Mountain. The subsequent sea level fall with a relatively low rate of subsidence reflected in valley incision, channel clustering and sediment by pass. Unit Two was deposited during this episode of lowstand and bounded below by a type two sequence boundary (SB2) Fig (5.8), which was formed during the early LST where fluvial deposition occurred, then, followed by the deposition of relatively thin red conglomerates of Unit Two during the late LST. This parasequence (LST) was the result of forced regression, a process that is a direct result of relative sea level fall, and may be enhanced relatively by the effect of the sediment influx (Posamentier et al., 1992). The lithology of the next relative sea level rise TST is well demonstrated by thick deposition of retrogradational succession of fluvial deposits of Unit Three (Fig.5.7 and 5.8). This gradual sea level rise accompanied by gradual subsidence led to the deposition of this thick parasequence of sandstone and red claystone. Unit Four was deposited during relative sea level stillstand with continued moderate rate of subsidence and relative sea level fall (one cycle). This parasequence HST is represented by lithology of sandstone conglomerate and shale, which shows a progradational succession of fluvial facies. Unit Six on the other hand, was deposited during a relatively rapid sea level rise, where thin shallow marine facies TST retrogrades on Unit Four. The coaral and limestone bed (facies) may represent equivalent to condensed section. This was followed by a progradational delta front or delta plain facies deposited as HST. This parasequence is bounded at the top by a type one sequence boundary (SB1) separating the Red Bed Series from the overlying thick boulder conglomerate (Unit Five of traditional stratigraphy). Rapid sea level falls, which greatly enhanced by tectonic instability. This instability is, accompanied with high rate of subsidence and high sediment influx resulted in the formation of such huge thickness.

Fig.(5.7) Time expandedd stratigraphic collumn (wheeler diagram) of the Red Bed Series ( unit five is not shown)

Fig.(5.8 ) The 4rth order sea level curve, showing the timing of Red Bed Series units and nature magnitude and amplitude) during the deposition of each units.

5.6 -Base level transfer cycle Several fourth order cycles can be recognized within different units of the Red Bed Series. These cycles reflect a generally asymmetrical base level transfer cycles (BLTC), they also reflect fourth order relative S.L. fluctuation, as well as the imbalance between the accommodation space and sediment influx. Unit one which represents a third order HST can be divided into several base level transfer cycle (BLTC). The difference between the Early and Late HST is very clear (Fig 5.9). The Early HST consists of a relatively thin fourth order (BLTC) due to the reduced accommodation rate in an area of moderate subsidence , whereas the Late HST consists of thicker cycles due to increased accommodation at the start of S.L. fall, this has reflected in the formation of thick aggradational to progradational floodplain facies. Unit three (TST) can also be divided into several fourth order base level transfer cycle (BLTC), they reflect minor fluctuation within the rising sea level curve (Fig 5.10). In this case successive sea level rises and stillstands are reflected by a succession of floodplain (TST) and channel sand (HST) facies stacking pattern. A minor S.L. fall is represented by a minor valley incision and deposition of the conglomerate facies.

Fig.(5.9) Sequence Stratigraphic subdivisions of the unit one, showing 4th order BLTC within 3rd h order HST of Khewata section

Fig.(5.10) Sequence Stratigraphic subdivisions of the unit three, showing 3rd order BLTC within 4rth order HST of Khewata section

CHAPTER SIX

TECTONIC AND DEPOSITIONAL HISTORY OF RED BED SERIES

6.1-Preface The distribution of the Red Bed Series sediments from Penjween to Haji Omran as a narrow belt infers that the setting of the basin is as elongate lake that filled with terrestrial (terrigenous) sediments. The model is drawn previously show apparently this type of setting which shows that basin of Red Bed Series bounded by high paleohighs (Fig.6.1and 6.3). But the actual basin of the Red Bed Series, as inferred in the present study, was neither lake nor narrow sea, but it was large, wide and deep basin. Therefore one cannot establish tectonic setting and history of the Red Bed Series if does not consider its basin as single one, in which the known lithologies (conglomerate, sandstone and red claystone) of the Red Bed Series deposited. This is proved sedimentologically in field and in sequence stratigraphy (see Chapter Five) in which the basin of Red Bed Series is combined with the basin of the Kolosh and Gercus Formations. There are some evidences for the joining basin of the series and the formations. The first one is the incompatibility of accumulation of 1000m of conglomerate in front of proposed paleohighs in Chwarta-Mawat area. This paleohigh has put between the Red Bed Series and Kolosh Formation by the previous studies. This paleohighs is assigned by Buday (1980), Al-Hashimi and Amer (1985). The position of the paleohigh coincide with Azmir, Goizha, Daban and Sara anticlines. Very recently this paleohigh was also confirmed by Lawa (2004, p.174) who mentioned that the “”Red Bed Series of Suwais Group separated from the Kolosh foredeep and Early Paleocene deposit of the Kolosh Formation””. The observed incompatibility is demonstrated by occurrence of (1000m) of block and boulder conglomerate at short distance behind the paleohighs (Fig. 6.1B and D). This distance is not more than 6km from the summit of Goizha, Azmir and Daban, anticlines. The sedimentogical principle does not aid the existence of paleohigh in front of 1000m conglomerates. This is because of the followings: 1- Huge quantity of sandstones and claystone must be derived from 1000m of conglomerate (Chwarta conglomerate) and from the source area. Now this huge quantity is not present if we do not connect basin of the Red Bed Series with that of the Kolosh and Gercus Formations. When this connection is done the shale, sandstone and siltstone of these latter formations can be correlated with the conglomerate of Red Bed Series. When the complete connection between basin of the Red Bed Series with the Kolosh and Gercus Formations is done, all the sediments finer than conglomerate were transported to the deep basin of the later formations and deposited as sandstone, shale and marl (Fig.6.4). Therefore, the tectonic basin reconstruction of the Red Bed Series is based on the absence of the above anticlines at most times. In this basin, the Red Bed Series was deposited in a coastal area that was covering Chwarta –Mawat area while the central area of the basin located at Sharazoor – Piramagroon plain in addition to present location of the anticlines. 2- Karim (2004), in the same area, cited that 500m conglomerate of Tanjero Formation in Chwarta- Mawat area has equivalent of 400m sandstone in Sharazoor-Piramagroon plain. He correlated both conglomerate and sandstone in the two areas and proved that both were time and lithologic equivalent. He measured the distance between the conglomerate and sandstone, after the removal of effect of folding, to about 25km. Therefore when the same principle is applied for the Kolosh Formation, it is obvious that the Kolosh and Gercus Formations are time equivalent to the Red Bed Series (or to some parts of the series).

Fig.( 6.1)

Fig.(6.2 )

3-The extensive fieldwork (in this study) failed to find the sediment of coastal area of Kolosh Formation. According to principle of sedimentology huge thickness of conglomerate must be deposited in coastal area of these two formations. As the Red Bed Series with Kolosh and Gercus Formations have nearly same age so the best coastal area, which fit with the basin of the Kolosh and Gercus Formations, is the depositional area of the Red Bed Series. It is worthy to mention that the previous studies have mentioned nothing about the coastal area of the Kolosh Formation. 4- The paleocurrent direction of Units Two, Three and Four of sediments of the Red Bed Series is toward southwest (Fig.3.2) while that of Unit Five (Chwarta conglomerate) point toward the south. The maximum development of the Kolosh formation exists at the same directions. In other side, the sediment of the Red Bed Series is deposited by rivers and alluvial fans, therefore, the paleohigh cannot be put in front of the river, which transport sediments south of the Red Bed Series. 5-The measured paleocurrent of the Kolosh Formation in Dokan area at 500m to the west of Qulka village is same as that of the Red Bed Series at the 100m. West of Diralla Village, at Chwarta area. This paleocurrent is measured by Flute cast and channel in both units (Photo5.1). This also refuses the presence of paleohigh during deposition of most parts of the Red Bed Series. 6-The lithologic study of both units proved that both have same source areas. These source areas consisted of Qulqula Radiolarian Group and ophiolite complex. In addition to the above source areas, the upper part of the Red Bed Series (Chwarta Conglomerate) have a source area consisted of Walash – Naoperdan Series. 7-No clasts of Kometan, Shiranish and Tanjero Formations are found in the sediment of Red Bed Series; this proves that there was no prominent paleohigh to a scale shown by Al-Hashimi and Amer (1985), and Surdashy (1998) (Fig.6.1). If the paleohigh existed between the Red Bed Series and the Kolosh Formation, the paleohigh must have neen suffered from erosion and supplied sediments to the basin of the Red Bed Series. According to the above points, the sediments of the Red Bed Series, Kolosh and Gercus Formations are deposited in single basin (in most time) and nearly under the same tectonic effects and eustatic see level change. In other side, the series is deposited under effect of tectonic of Paleocene and Eocene only and not extending to Miocene as mentioned before. This is because, there is no evidence to show

that the basin of the Red Bed Series is extended, in age, from Paleocene to Miocene as mentioned by Buday (1980), and Al-Mehaidi (1975, p. 36). But this does not means that in some time intervals there was no paleohigh. During deposition of Sinjar Formation and Naoperdan Series, the possibility of a submerged paleohigh must not be excluded. This paleohigh in the basin decreased the accommodation for clastic sediment to accumulate in high thickness and relatively wide distribution. This is because the paleohigh generate barrier in front of sediment transport and decreases the kinetic energy of the sediment and turbidity current obtain during free transport from source area and when the obstacles (paleo-highs) were not grown up. During existence of this paleohigh, only little fine clastics are deposited which were eroded later during sea level fall or reefal limestone had grown on them because of clastic decrease. 8- Red Bed Series can be correlated with the Kolosh Formation on the basis of lithology and paleocurrent as follows: A- The red interval of lithology of the series is located near the base (Unit One and Two). The equivalent of the interval exists also at the base of Kolosh Formation at Dokan area at right bank of Qashqully stream, which consist of fine brown shale. The brown interval is more obvious at south Jally Village near the Gorge of Smaqully (North of Koyia town). B- Karim (2004), found a para-and polymictic conglomerate, that exist at the top of the Tanjero Formation in Chwarta-Mawat area (He named it “Tagaran Conglomerate”). This conglomerate also exists at Dokan area and has same lithology as that of Chwarta area, and in both areas composed of rounded pebbles of igneous, metamorphic and sedimentary rocks. C- The middle part of the Kolosh Formation, lithologically and stratigraphically is most probably equivalent to the conglomerate of Unit Two. Especially the sandstone of the Kolosh Formation is similar in their constituent to the conglomerate of Unit Two at Mawat and Qandil Mountain toe (Photo2.11).

Fig.(6.3) different stages of the development of Red Bed Series as related to plate tectonics (Numan,1997).

6.2-Changing of the previous time expanded stratigraphic column of Tertiary When one looks at the time expanded stratigraphic column of Tertiary drawn by (Jassim et al.,1984 in: Al-Rawi, 1977) (Fig.6.5A), he realizes that no position is indicated for Red Bed Series. Later all other authors worked on Tertiary of Iraq applied the same column without any changes (among these authors Buday, 1980, Buday and Jassim (1987). In the present study, as a result of lithologic correlation and sequence stratigraphic study, new relation with Kolosh and Gercus Formations is established and new expanded stratigraphic column of Tertiary is drawn (Fig. 6.5A and B) which shows that distribution of time and locality of Red Bed Series is located at the northeast of that of Kolosh and Gercus Formations with lateral possible interfingering relationship (Fig.5.2). Now the location of this interfingering is eroded and coincides with the position of Goezha, Azmir, Daban, Piramagroon, Sara and Kosrat anticlines.

6.3-One foreland basin for Kolosh Formation and Red Bed Series together The term foreland basin is introduced by Dickenson (1974) on the principles that, mountain belt is associated with uplift of rock materials to several kilometers in height. Regions of subsidence, called foreland sedimentary basin, border the uplifted belts. These basins are

“wedge shaped “in cross-section with depth that gradually decrease from the mountain belt towards the adjacent craton. He proposed two broad types of foreland basins: 1-Peripheral foreland basins, which are related to continent-continent collision. 2-Retro-arc foreland basins, which are related to the subsidence of oceanic lithosphere. The basin and provenance of the Red Bed Series belong to type one in the above division. According to Einsele (2000) and Walker (1992), the thickest alluvial deposit occurs in several tectonic related basins, one of which is foreland basin. The thick accumulation (in some case reach 2500m) of conglomerate sandstone and red claystone in the basin of Red Bed Series (including basin of Kolosh Formation) is the evidence for foreland basin. Especially Karim (2004) proved that Tanjero Formation is deposited in an early foreland basin (He called it Early Zagros Foreland Basin). According to this tectonic setting, both Tanjero Formation and Shiranish Formations are deposited in one early foreland basin. So according to his suggestion the foreland basin started from upper Campanian. Al-Qayim (2000, p.112) is the first who showed that Kolosh Formation is deposited in foreland basin. The same type of basin is reported and showed by diagrams by Lawa (2004) for Kolosh Formation (Fig.6.2). Dole et al., (2001, p.111) mentioned that the sediments of the foreland basin are characterized by heterogeneous gravels, sands, and mud derived from orogenic belt. When the relation and correlation of the Red Bed Series and the Kolosh Formation is considered, it is obvious that both deposited in single foreland basin in coastal areas and off-shore respectively. The relation and correlation of both formations are discussed in Chapter Two and Three. This foreland basin developed after colliding of Continental part of Arabian and Iranian Plate at Upper Cretaceous. This is associated with uplift of Qulqula Group and ophiolite complex with shedding huge quantity of sediments into the foreland basin during tertiary, which are deposited as the Red Bed Series, Kolosh and Gercus Formations. From Tertiary till now the continuous southwest advance of the frontal part of the plate, most probably, made some units of the Red Bed Series to be imbricated and the thickness appeared to be doubled. This phenomenon is not so clear in the field to be ascertained. But at least at one locality (near Suwais village) some sign of the imbrication can be seen in the unit five (Chwarta conglomerate). Buday (1980,p. 217) mentioned that the basin of the Kolosh Formation, in the unstable shelf, is separated from Red Bed Series in miogeosyncline. This tectonic separation of the two basins is based on the classic tectonic classification of the basins into many types of geosyncline. Numan (1997) separated tectonically and topographically Red Bed Series from Kolosh Formation. In the present study, it is proved, in most time and in the studied area the basins of Red Bed Series and Kolosh Formation were combined during Paleocene and Eocene and cannot be separated tectonically and physiographically.

Fig.(6.4)

Fig.(6.5) time expanded Stratigraphic column of the late Cretaceous and Tertiary (Jassim et al,1984 in Al-Rawi,1988) obvious that the position and relation of Red Bed Series with Kolosh Formation and Gercus Formation are not indicated

Fig.(6.5a) time expanded Stratigraphic column of the late Cretaceous and Tertiary (upper one) the position and relation of Red Bed Series with Kolosh Formation and Gercus Formation are indicated as a result of this study.

6.4-Alluvial fan development Alluvial fans that progrades directly into standing body of water are termed fan delta or coastal alluvial fan. Alluvial fan and fan delta is sedimentary responses to flow expansion at basin margin, and so the identification of fan deposits in the ancient record may be a useful indicator of sharp basin–margin relief, commonly fault controlled (Mial, 1990). According to Burner and Smosa (2000) the fan delta in Spain during Carboniferous are formed in direct response to tectonic uplift along a nearby thrust-fault. Einsele (2000) observed coarsening upward alluvial fan (as seen in Red Bed Series from Unit One to Unit Five) that reflects growth during continuous faulting. Walker (1992) mentioned that alluvial deposits are sensitive indicators of allogenic processes, such as tectonism and base-level change. He also cited that the drainage (paleocurrent direction) and the orientation of proximal-distal facies change are basically perpendicular to basin margin (coastal area). He included foreland basin in this type of basin. Selley (1988, p.169) referred to the Alluvial fans as piedmont (mountain foot) fanglomerates, which are characterized by extremelycoarse grain and poor sorting, by massive and sub-horizontal bedding and absence of fossils. He also attributed the great thickness of fanglomerates to repeated syn-sedimentary movement along fault scarp. The repeated fault scarp rejuvenation generates upward coarsening conglomerate cycles as fan prograding toward the basin depocenter. The same results are cited by Blatt et al. (1980) and showed by diagram how a thick pile of alluvial fan is deposited in front of faults in a rapidly subsiding basin. Nearly all above mentioned characteristics (as mentioned by the authors) are more or less can be seen in the sediments of Red Bed Series which is deposited in front of advancing head of the Iranian plate. Unit Two, and Five all have the prerequisites for alluvial fan (low stand fan delta when reach water body) cited by above authors.

6.5- Provenance of Red Bed Series It is clear from paleocurrent measurements that source area is located, directly, at the northern and northeastern of area of the present location of outcrops of the series. The lithology of the series showed that the most of the clasts are those that derived from Qulqula Formation, while those of ophiolite and Walash-Naoperdan Series are less and least common respectively. This arrangement of commonness of clasts is reversed in case of the closeness of source area. This is because the closest source area to the basin is the rocks of Walash-Naoperdan Series comes after it Qulqula and Ophiolite respectively. As a whole, the source areas are relatively close to the basin of deposition of the Red Bed Series. The closeness is demonstrated by subangularity of nearly all the clasts and the largeness of the clasts within the conglomerate. One can find blocks weighted more than 200kgm at Qandil mountain toe and 100kgm at Chwarta area (Photo3.6A). In the studied area, the source area changes from unit to others; even the same unit has different source areas for different localities. These changes are as the following: 1-At Chwarta and Mawat area, Unit One is completely derived from Qulqula Group, which is composed of limestone and chert pebbles and boulders. The limestone clasts are radiolarian fossil rich and grey or black in color. 2-At the same area, the source area of unit five

(Chwarta conglomerate) changes to Qulqula Group, metamorphic rocks, ophiolite rocks and Naoperdan group. This mixture of many types of rocks may be attributed to: A) Interconnection of more than two drainage basins in the source area so that each one responsible for influx of one type of rock clasts to the basin together or alone. When the lithology of rocks including one source area and change in other places, it attributed to abrupt change of provenance from local to more distant ones Ryu ( 2003). It is obvious from the lithology of Red Bed Series, that the valley streams through which the sediment transported were large and possessing high gradient as reflected by large transported clasts (block s). B) The co-existence of three different clasts of different source areas are possibly attributed to deep dissecting of the source area by a large stream which caused consecutive exposing of several rock types along both sides of the valley. C) Tectonic mixing during deformation of source area and during development of accretionary prism by continuous advancing of the thrust sheet towards southwest. 3- At Qandil mountain toe more than 70% of the clasts of Unit Five are limestone of Qulqula Group and the others are chert clasts. 4- The provenance of claystone and its red colors of Red Bed Series are attributed to the source area, which is rich in red jasper; brown shale and red siliceous shale of Qulqula Group (see section two for more details).

6.6- Relation between the Red Bed Series and Walash –Naoperdan Series The most problematic issue in the tectonic and stratigraphy of the Imbricated and Thrust Zones is the uncertainty of the relationship between Walash – Naoperdan Series and other units in the two zones. Bellen, (1959) and Buday (1980) and Buday and Jassim (1987) have not mentioned any things about the relation between the two series. Numan (1997) put each series in two different basins. He put Red Bed Series and Walash-Naoperdan Series in diverging basin and converging basins respectively (Fig.6.2). Al-Hashimi (1985) positioned the two series in two different local basin separated by emerged paleohigh (Fig.6.1B). In his model the former series located in southwestern basin while the latter is located in northeastern one. Al-Mehaidi (1975) and Surdashy (2001) indicated a tectonic boundary between Walash-Naoperdan and the Red Bed Series. Previously Walash–Naoperdan Series was thought to be deposited at the extreme northern border of Iraq or even inside Iranian border. The field and sedimentological study do not aid this assumption and the existence of two different basins, which separated by emerged paleohigh. This is because type and amount of sediments are such that one can observe the continuous and high supply of coarse terrigenous clastics from north and northeast during nearly all time spans of Paleocene and Eocene. This huge quantity of sediment does not aid the existence of small source area or island between the two basins. Another reason is that, the reefal and pure limestone generally grows in the clear water, away from terrigenous clastic influx and tectonic activity. Therefore, we cannot put Walash –Naoperdan Series in the extreme northern boundary where is more clastic influx and tectonic activity than the the basin of the Red Bed Series. It is more convenient to put both series in the same basin. In this model (setting), Walash-Naoperdan Series is deposited during basin calm, and relative subsidence of the basin and source area). The most previous convenient model is that of Surdashy (1998), which positioned the two series in two basins, which separated by submerged paleohigh. But even this suggestion does not agree completely with field and sedimentological observations, which show existence of some stratigraphical relation between the two series. According to the most previous models (see page 112), several parallel paleohighs extend in northwest-southeast direction, the first one located near the Iranian border while the second at 5km north to Sulaimaniya. The latter one coincides with Goizha, Sara, Daban and Kosrat anticlines. The sedimentological and structural evidences do not aid presence of these parallel-emerged paleohighs during Paleocene and Eocene. The thick accumulation of coarse sediments and southwestern paleocurrent direction refuse existence of the paleohighs because accommodation cannot be created in narrow basin and to be continuous for long time during Paleocene and Eocene. As concerned to the structure, the present dip of the strata is not so steep to be accumulative of the dip angles from Paleocene to present. In the present study, it is inferred that Unit Five (Chwarta Conglomerate) is not related to the Red Bed Series but it has different stratigraphic and tectonic setting which are not certain. Field study showed that this unit is younger than the Red Bed Series and the Naoperdan Series. This is because it contains reworked pebbles and boulders of the latter Series. The position of Chwarta Conglomerate between Units Four and Six may be attributed to the one of the following tectonic possibilities: A- It is most possible that Chwarta conglomerate was representing alluvial fan, that were eroded from source area consisted of Qulqula Group, ophiolite and Walash–Naoperdan Series. The erosion is occurred at middle Eocene after deposition and uplift of the series. The Alluvial Fan is deposited unconformably on rocks of Paleocene and Lower Eocene (Fig.5.3 and 5.4 after tectonic corrections). The deposition occurred as alluvial fan at the base of mountain range (on mountain toe) that surrounded the basin of Eocene. More specifically, the Chwarta conglomerate is deposited on the mountain slope bordering the coastal area of the Gercus Formation and Naopurdan Series, while the Gercus Formation itself deposited in the deltaic environment. It is possible that the climate was semi-arid one and during the seasonal storm deep erosion scored deep incised valleys during sea level fall. The Valleys later filled with boulder and block conglomerate forming alluvial fan. The paleocurrent direction of Unit Five is towards south while other units have southwest direction. The valleys were descending from north toward south due to the effect of tectonic stress and stream dissection now unit five appears as a depostional unit of the Red Bed Series.B- It is possible that the present position of unit five is stratigraphically in the right position (Fig.2.4 and 2.6 before tectonic correction). According to this, the nummulite in the pebbles and boulders may be belonging to an age (upper Paleocene) younger than Walash-Naoperdan. During this age, nummulite-bearing layers are deposited and then eroded during early Eocene. For this assumption it is necessary to conduct precise boistratigraphic study for both Walash-Naoperdan series, and the pebbles and boulders in the Red Bed Series to prove the exact relation between the two units.

Fig.(6.6) Tectonic development of Red Bed Series during late Maastrichtian and Paleocene.

Fig.(6.7) Tectonic development of Red Bed Series in the foreland basin

6.7-Paleo- Shoreline of Paleocene Foreland Basin Nearly, all previous studies as mentioned before have not indicated the paleoshore line of Paleocene–Eocene basin. This is because they all separated the basin of the Red Bed Series from that of the Kolosh Formation. These studies are regarded the present position of Goezha, Azmir, Daban and Kosrat mountains (or anticline) as the paleohigh which was separated the two basins. Recently Lawa, (2004) indicated the shoreline of Paleocene foreland basin as a straight line passing through Dokan town from the northwest and coinciding nearly with the Tanjero River from southeast. But in the present study the shore line of the basin is indicated at the south of Mawat-Chwarta and Khurmal town, which nearly coincide with the maximum deposition of the Red Bed Series during HST (Fig 6.8). This indication is base on the combining of the two basins of the Red Bed Series and the Kolosh Formation in a single one. The combination of the two basins is achieved by detail field study of the lithology, facies, and sedimentary structures.

Fig.(6.8A) Extent of the foreland basin during Paleocene in which Kolosh Fn and Red Bed Series are deposited

Fig.(6.8B) Extent of the foreland basin during Eocene in which Gercus Fn and Red Bed Series are deposited

Fig.( 6.9 ) Stratigraphic ( time expanded ) column of North Alpine foreland basin, complied by Sinclair et al, in Allen and Allen, 1990. The lithology, tectonic and environment of the area are nearly similar to that of Chwarta area. The comparison with unit of Red Bed Series are shown on the right and upper margin

CONCLUSIONS FOR SIX CHAPTERS This thesis has the following conclusions: 1- On the basis of stratigraphy and lithology the series is divided in Chwarta-Mawat area, into six units in contrast to the previous studies, which divided the series into three units. 2-Unit One (at the base of the series) is composed of red fine clastics (red claystone and bluish white marl), while change to the sandstone in the area around Suwais Village. This unit represents deposits of HST and included in depostional sequence (lower sequence), which exist at the top of Tanjero Formation. It is possible that this unit deposited in either delta plain or in delta slope. The existence of the white thin bed clayey limestone is attributed to deposition in ponds in the delta plain. 3- Unit two consists of about 16m of chert and limestone conglomerate with prevalence of red color at Chwarta and Mawat area while the share of Igneous increases towards west. This unit deposited during sea level fall (regression or LST). The erosional base of this unit represents the starting point of the second sequence (middle sequence). The coarseness and badly sorting of this unit denote deposition in alluvial fan as channel lag deposits. 4-Unit three consists of more than 500m of thick-bedded gray sandstone with interlayers of grey to brown claystone. The sediment of this unit is overlying the LST and its deposits belong to TST of the middle sequence. Compositionally the sandstone consists of lithicarente with abundant content of limestone and chert clasts in addition to minor amount of quartz. The quartz grains are mainly derived from plutonic igneous rocks. The grains content of this sandstone is plotted on compositional triangle of Folk (1974), Pettijohn (1975) and Al-Rawi (1982). 5-Unit four consists of alternation of red layers of claystone, sandstone with lenses of conglomerate, which returned to episode of HST which the area suffered from slight base level uplift because of the sediment fill. The lithology of sandstone and conglomerate consisted of sedimentary, igneous and metamorphic clasts. Units one and two are correlated with the Kolosh Formation on the bases of lithology and stratigraphic position. 6-Unit five is the most obvious and thickest unit of the series in all areas except the western part of Qandil area (Naudasht valley), which change to claystone and sandstone. It consists of chert; limestone, igneous and metamorphic pebbles and boulders in Chwarta-Mawat area, while in eastern part of Qandil mountain toe, near Suwais village, it contains only chert and limestone pebbles and boulders. This unit, as low stand wedge, was deposited by forced regression during main sea level fall (LST) and has identified equivalent low stand sandstone wedge inside Gercus Formation. This unit represents obvious alluvial fan deposits, in which many braided bars observed during the field study. These bars shows large scale cross bedding , irregularities at their erosional base, holes and channels. 7-On the basis of fossils content it was proved, in this study, that unit five has no stratigraphic relation with the Red Bed Series. This is because this unit contains alveolina and nummulite, large forams, of Walash- Naoperdan Series. 8-In sequence stratigraphy, the rock body of the series is divided into three depostional sequences (lower, middle and upper depostional sequences). Each of these is further analyzed into their systems tracts. The systems tracts of the units are lowstand, highstand and transgressive systems tract. The most obvious systems tract is lowstand systems tract, which consist of Lowstand wedge about 1000m of boulder and block polymictic conglomerate. During lowstand many incised valleys scored in the sediment of the previous highstand which filled by coarse conglomerate. The closest (probably equivalent) formation to this unit in distal area is Gercus Formation. This is inferred on the basis of lithologic study of both units. 9-It was observed that, because of shallowness (mostly continental) of the environment the lithofacies of each systems tract is highly variable in different areas. The most important work in sequence stratigraphy

is the correlation of systems tracts of the Red Bed Series at Chwarta, Mawat and Qandil Mountain area, at Imbricated Zone, with the equivalent parts of the Kolosh and Gercus Formations at distal area (High Folded Zone). This correlation is the first one done for the different sections of the Red Bed Series in one side and with the Kolosh Gercus Formations in other side. 10- By above correlation, the previous age of the Red Bed Series changed from Paleocene –Miocene age to Paleocene - Eocene age only. 11- Another very important result of this thesis is proving that the Red Bed Series and the Kolosh Formation sharing the same depostional basin and having the same tectonic setting, moreover, both representing lateral facies change of each other. This is also true for the relation of unit five (Chwarta conglomerate) with the Gercus Formation. 12-In this basin, the Red Bed Series is deposited in rapidly subsiding coastal area of the Early Foreland basin while the Kolosh Formation deposited in deeper part of the basin. The basin existed in front of the southwest advancing tectonic nape. 13-The environment of the series is highly variable; mainly consists of high gradient braided streams which transfer coarse and fine sediment to alluvial fan which merge into lowstand fan delta when reachs the main water body of foreland basin. The delta plain and front environments are not excluded. As concerning depth it ranges from continental to shallow marine environment while the salinity ranges from dominate fresh river water to brackish and possible invading of normal marine water occasionally inside the incised valleys. Water turbidity is changed from highly turbid water in the incised valleys and in front of alluvial fans. 14-The petrology of the sections showed that the source area of each one was different. Even the source area of each section was different in different times. The clasts are dominantly derived from the Qulqula Radiolarian Formation at the area of eastern part of Qandil mountain toe while that of Chwarta-Mawat area are derived from both Qulqula Radiolarian and ophiolite source rocks with share of Walash–Naoperdan series as less important source area. The source area was consisted of overthrusted sheets of frontal part of Iranian plate. 15-In this study many sedimentary structures are found in the series such as, flute cast, small and large scale cross bedding, ripple marks, parting lineation, imbricated pebbles, lamination, truncated layers and plant debris. Most of these structures are found in unit three (sandstone unit) and few ones are found in the upper conglomerate. 16-The paleocurrent analyses, as revealed by above structures, are presented on rose and stereonet diagrams shows southwest direction for units two, three and four while unit five shows clear southward paleocurrent direction. 17- The origin of the red color in the Red Bed Series is discussed and attributed to the derivation from source area (Qulqula Formation). 18-The tectonic setup of the series and the neighboring formations are discussed in detail. Tectonically, they all deposited in a foreland basin. This foreland basin was covering both the present days Imbricated and High Folded zones without existence of paleohigh (most times) in the basin of foreland basin. Both Red Bed Series and Kolosh Formation are affected by the same tectonic setting during Paleocene. During Eocene the tectonic activity was more intensified, which caused uplift both the basin and source area. This is manifested by a very thick accumulation (1000m) of polymictic conglomerate. In the distal area, instead of Kolosh Formation, Gercus Formation is deposited which is correlated with that 1000m. of polymictic conglomerate. 19-The time expanded stratigraphic column of the Tertiary is changed to agree with the result of this study. Red Bed Series is shown on this column as lateral gradation with both Kolosh Formation and Gercus Formation.

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FACIES ANALYSIS OF AQRA FORMATION IN CHWARTA-MAWAT AREA FROM KURDISTAN REGION, NE−IRAQ

A THESISSUBMITTED TO THE COLLEGE OF SCIENCE, UNIVERSITY OF SULAIMANI, IN PARTIAL FULFILLMENT OF THE REQUIREMENTS

FOR DEGREE OF MASTER OF SCIENCE

IN GEOLOGY

BYDeeren Mohammad Sadiq

B.Sc. in Geology, Sulaimani University, 1999

Supervision by:Dr. Sherzad Tofiq Mohamad

Assistant Professor

September 2009 A. D 2709 Kurdish

Supervisor CertificationI certify that this thesis has been prepared under my supervision in the Department of Geology of the University of Sulaimani, in fulfillment of the requirement for the degree of M.Sc. in Geology.

Signature:Name: Dr. Sherzad Tofeeq MohammadTitle: Assistant professorAddress: University of SulaimaniCollege of Science Department of Geology Date: / /

The Certification of the Chairman of the Committee of Higher Student. According to the recommendation submitted by the supervision, I nominate this thesis for discussion.

Signature:Name: Dr. Kamal Haji KarimTitle: Assistant professor Address: University of SulaimaniCollege of Science Department of Geology Date: / /

We, the examining committee, her by certify that we have read this thesis and examined the student in its contents and whatever relevant to it and, in our opinion; it is adequate with " ” standing for the Degree of master of Science in Geology/Sedimentology. Signature: Signature:Name: Name:Title: Title:Address: Address:Date: / / Date: / /(Chairman) (Member)

Signature: Signature:Name: Dr. Name:Title: Assistant professor Title:Address: University of Sulaimani Address:Date: / / Date: / /(Supervisor and Member) (Member)

Approved by the Council of the College of Science

Signature:Name: Dr. Parekhan M. Abdul-RahmanTitle: Assistant professorDate: / /

ACKNOWLEDGMENTS

I am deeply indebted to Dr. Sherza Tofiq Mohamad for undertaking the task of supervising this thesis and for offering many suggestions

and corrections during the stages of the work in the field and lab. My best regards to the presidency of university, the dean of the College of Science and head of the of Department of Geology for their generous support including equipments facilities that offered to this work.I would like to express my gratitude to the Dr. Kamal Haji Karim and Zardasht Ahmad Taha of Geological Department for their field support. My sincere thanks to my friends in Geological Department, University of Sulaimani for their laboratory help. The effort of Dr.Khalid Mahmood Ismail in identifying some of the fossils of this study is highly appreciated. Finally, I would like to express my gratitude and appreciation for my parents, for their continuous support and encouragement, and I would like to extend my thanks to all who helped me during my study.

Dereen Mohammad Sadiq

ABSTRACT

The present study is concerned with facies analysis of the Late Cretaceous outcrops of Aqra Formation (Aqra lens) in Chwarta-Mawat area, Sulaimanyia Governorate, northeastern Iraq. This area is located within Imbricated Zone which includes Chwarta and Mawat towns. The microfacies and lithofacies of the formation are studied in addition to stratigraphy in three selected outcrop sections. The study also includes the inspection of its boundary conditions in the surrounding areas.Aqra Formation (Late Maastrichtian) area mainly consists, in Chwarta-Mawat, of biogenic and detrital limestones. These rocks appear as thick succession of light grey and well bedded or massive beds which can be seen along both sides of the existed streams and gorges. The boundaries with both underlying Tanjero Formation and overlying Red Bed Series are gradational and the contact is conformable. The fossil contents are rich and belongs mainly to foramol association which includes large forams (Loftusia, Omphalocyclus and Orbitoids) with mollusks (Gastropod and Pelecypods, including Rudist) in addition to echinoderm and rare ammonites and solitary corals. The main facies are floatstone, mixstone, rudstone, packstone, and Bafflestone. The allochems of these facies consist of the skeletons of one or more of the above fossils or their bioclasts. The lithofacies such as terrigeneous conglomerate, marlstone and red clastics of Tanjero Formation and Red Bed Series exist at the underlying and overlying boundaries the important for tectonic and environment reconstruction of the formation. Most of the litho and microfacies can be identified by eyes or hand lens due to large size of the fossils the matrix is consist mainly of sand or silt sized bioclasts with more or less micrite. These facies are deposited in shallow and high energy platform (basin) of mid-latitude temperate climate with high rate of sedimentation. The basin is supplied by terrigenous clastics from source area and appeared in some place as bed or lens of sandstone interbedded with the biogenic limestones. The initial growth of the reefal and biogenic limestones were depended on the low stand fan sediments (accumulation of graves and boulders) which acted as hard substrate for stabilization reefal growth (biostromes and bioherms) and decreasing turbidly. This does not mean that there was no turbidity as there were many streams in Chwarta-Mawat area during late Maastrichtian. These streams were small and low energy which were reaching the foreland basin and supplying the sediments and nutrients to the basin. The roles of the coarse sediments are very clear from two field observations. The first is that the thickness of the conglomerate is high the thickness of the Aqra Formation is high too as can be seen in the Kato and Kele sections with 100 and 80metter thickness. The second is that at the base of the both sections the conglomerate alternate with biogenic limestone as discussed in the conglomerate lithofacies.Facies analysis appears that the energy was high during the deposition of the formation and during Late Maastrichtian. But it was higher in the lower part than upper part this is clear from reworked Loftusia and broken skeleton debris that can be seen more frequently in the lower part. Because of this, even the floatstone of rudist and large pelecypod contain bioclasts and lithoclasts. The low occurrence of the grainstone is attributed to high rate of deposition and influx of terrigenous clay from outside of the basin. .

Chapter: One (Introduction)

1.1- Introduction:Aqra Formation is a reefal limestone; which was first studied from Aqra area, Kurdistan Region- Iraq. Aqra formation was defined by Bennett (in1945) from the Aqra anticline of the High Folded Zone (Bellen et al., 1959). According to same author, at the type section, it is consisting of massive detrital bituminous partially siliceous reefal limestone. The limestone is reefal and progressed to fore reef and withdraws to shoal limestone. The equivalent formation of Aqra Formation is Bekhme Formation. Some time it is not easy to make distinguishing between both Formations. On the base of the available index fossils, it confirmed that age of the Aqra Formation is Maastrichtian. The overlying Formation in the type area is Kolosh-Khurmala Formations; the contact is unconformable since there is conglomeratic bed at the base of Aqra Limestone (Buday, 1980). In the studied area the formation is regarded as lens inside the Tanjero Formation by Karim (2004), as there are a grey clastic intervals above the Aqra lens and between former formation and Red Bed Series, but it is assigned as interfinguring with Tanjero Formation by Lawa, et al 1998. According to Buday, (1980) the underlying formation (lower boundary) is probably not seen in the type section, while in the studied area it is considered to be Tanjero Formation and the citation of (Karim, 2004) is ascertained (being it appears as a lens in the Tanjero Formation). Field study showed that Tanjero formation, in the studied area, is not connected with the Aqra Formation. This means that in this area Aqra Formation surrounded by Tanjero Formation from all sides.Aqra Formation was deposited in a reef environment ranges from back reef to fore reef, it known from the relatively shallow-water paleoenvironment located in the outer parts of the Late Cretaceous Tethyan platforms. This Formation is cropping out around Aqra Town, Gali sheikh Abdul Aziz, Gara Mountain, Zinta Gorge, Bekhme, Dar-e- Tesu, Diza, Gundi-i- Shikavt, Zibar, Chalki, Ser Amadia, Hadiena, Rowanduz and Chwarta-Mawat area. The equivalents of Aqra Formation are Bekhme Formation from Kurdistan, but its equivalents from southern Iraq are called Hartha and Tayarat Formations.

1.2- Location and geomorphologyThe area of the study is located in the Zagros Mountain belt near the border between Iran and Iraq, at 30km to the north and northeast of Sulaimani city (Fig. 1.3 and 1.4). The area includes famous Chwarta, Mawat and Basini towns at its eastern, western and northern boundaries respectively (Fig.1.3 and 1.4). The area consists of large valley (Chwarta-Mawat valley) which is surrounded by several mountains from east, northeast and north by Kato, Sarsir, Gimo, Pyr Mohammad and Gawraqul mountains. From southeast, south and southwest it surrounded by Goizha, Azmir and Jafayati Mountain respectively (Fig 1.6). This large valley compartmentalized by three large perennial streams such as Goga Sur (Kele or Mokaba), Tagaran and Sywail (Fig.1.5 and 1.7). From catchment area, these large streams flow toward southwest and finally meet near Mokaba village forming larger stream known as Mawat stream. Near this latter village, the stream diverts toward north till meet with Do Awan stream (up stream of Little Zab River) where again divert toward southwest. The Aqra Formation is exposed along the valley sides and gorges that are related to the above streams.

1.3- Geological and Structural SettingThe geology of the area has structural and stratigraphic complexity as it is partly located in the Thrust and partly in Imbricated Zones of

Buday, (1980), Buday and Jassim (1987) and Jassim and Goff (2006) (Fig.1.1 and 1.2) . The area represents the northeastern margin of the Arabian plate where the continental part of Iranian and Arabian plates occurred during Eocene (Numan, 1997 and Surdashy, 1997) or during Upper Cretaceous (Karim, 2004 and Karim and Surdashy 2006).The northern part of the area is occupied by Ophiolite and Naoperdan Series thrust sheets while the northeastern part one covered by Qulqula Formation. In the south and southwest of the Cretaceous rocks are exposing (Fig. 1.3, 1.4, 1.5 and 1.6).According to Karim (2006), the area consist of large graben which formed by two transverse normal faults. These faults have the direction of northwest southeast north and one of them located two the southeast of Chwarta town while the other one located to the northwest of Mawat town (Fig.1.7). Muhammad (2004) studied the geochemistry of the Mawat ophiolite and he assigned that the area has suffered from extension during Eocene. The outcrops of these rocks form a tongue, which elongates from the north (from Iranian border) towards the south and ends near Chwarta Town. Its central part consists of ophiolite and metamorphic rocks surrounded by the outcrops of Red Bed Series and Nauprdan Series. This tongue is called Mawat Nappe by Al-Mehaidi (1975) who studied that this Nappe which is thrusted over Red Bed Series and Cretaceous rocks. Tectonically, the area is located in the Zagros Thrust-Belt and include two different zones which are Thrust and Imbricated Zones (Sissakian et al, 1996). According to (Jassim and Goff, 2006), the studied area located inside the Balambo-Tanjero Zone (Fig.1.1).The field study in the northeastern Iraq revealed that the thrust has the attitude of 10 o −35 o /35 o. The low dip angles (10 o –20 o) is exist in the low lands such as Mawat-Chuarta area while the high angle ( 20 o −35 o) exist where the thrust climbs the elevated anticlines in the Avroman–Surren and Kaolos–Chuarta areas, in the latter cases the thrust can be called reverse fault ( Karim, et al, 2007). Due to imbrication, the anticlines and syncline cannot be distinguished and all the strata are dipping about 20 degrees toward northeast.

Fig.(1.1) Tectonic classification of the north Iraq (Jassim and Goff, 2006) showing the studied area.

Fig. (1.2) Boundaries of the tectonic subdivision of the Western Zagros in Iraq (modified from Buday and Jassim, 1987).

Fig (1.3) Northeastern Iraq map (from site of Iraq Map) shows the location of the studied area.

Fig (1.4) Location and geological map of the studied area (modified from Sissakian, 2000)

Fig.(1.5) Geologic cross section passing through Piramagroon and Gimo mountain in addition to Mokaba stream showing the stratigraphic and geomorphologic position of the Aqra lens.(Karim et. al., 2007)

Fig.(1.6) Geologic cross section passing through Kato, Goizha and Baranan mountains showing the stratigraphic and geomorphologic position of the Aqra lens.(Karim, 2004)

Fig.(1.7) geologic longitudinal section of the Chwarta-Mawat area showing the two normal fault and the Aqra lens( Karim,2006).

1.4- Studied sectionsGeographically, studied area located at Northwest of Sulaimani city; between Chwarta-Mawat districts, Northeast limb of Azmr Mountain (fig 1.3and1.4) three sections were selected for this study, these sections are:

1.4.1- Kato section: This section is located about 6 kilometers to the east of Chwarta town, at the toe of Kato Mountain (lower part of northwestern side of the mountain). The base of this section is located at the intersection of Latitude (N: 35 39 24. 36) and longitude (E: 45 35 25. 55), while the top is located in intersection of Latitude (N: 35 39 31.87) and longitude (E: 45 35 17. 88). The section runs along a meandering stream at 2km to the southeast of Harmin village. The strata are dipping 25 degrees toward the northwest (Fig1.8).

Fig.(1.8) Limestone succession of Aqra Formation in Kato section (sampled)

1.4.2- Sura Qalat section: This section is located about 10 kilometers to the Southeast of Mawat town. The base of the section is located at the intersection of Latitude (N: 47 35 48.05) and longitude (E: 45 26 24.27), while the top is located in intersection of Latitude (N: 46 35 55.56) and longitude (E: 45 26 26.13). It located along the northeastern valley side of the Mokaba (or Qalachuallan) stream (Fig1.9).The strata are dipping 16 degrees toward northeast and are highly deformed which appear as faulting and fracturing.

Fig (1.9): Location map of the Kele and Sura Qalat section, as viewed from west, Satellite Image (from Google, 2007).

1.4.3- Kele section: This section is located at 7kilometer to the southeast of Mawat town. The base of this section is located at the intersection of Latitude (N: 35 48 42.83) and longitude (E: 45 25 56.52.), while the top is located in intersection of Latitude (N: 35 48 57.32) and longitude (E: 45 26 31.27). The section runs along the sides of the Dolbeshk or (Mawat) stream and consists of high erosional cliff (Fig, 1.10 and 1.11). A part (about 30m) of the section is located on the right side of the stream while the rest is located on the left side. The strata are thick and occasionally massive which dipping 20 degrees toward northeast.

Fig.(1.10) Part of Kele section as exposed along the Dolbesk Gorge (lower and upper contact are not appeared).

1.5 - Aims of the studyThe main aim of the current study is to analyze the microfacies and lithofaces of Aqra limestone Formation from the Chwarta-Mawat

regions, and to reconstruct the paleogeographic and depositional environment aspect of the basin. In addition to that, the study also includes the study of lithology and stratigraphy and characteristics and comparison with that of the type locality to establish a complete configuration of the basin during the deposition of the formation.

Fig (1.11) Representation of the Kele section, as viewed from western side of Dolbeshk stream which flow across Dolbeshk Gorge (Karim et al, 2007)

1.6- Methods of Study:

1.6.1- Sampling and Field trips:This study is achieved through field trips and laboratory works. During field survey, nearly ten field trips (reconnaissance and detail survey) were performed at the studied area; it included observations and searches for the exposed and conspicuous outcrops around the area during which three sections are selected for sampling and description.Field trips included lithology description, measuring thickness, vertical and lateral lithology changes. For the current study, about two hundred rock samples have been collected from Kato, Sura Qalat and Kele sections. From these samples 100 thin sections are made for the petrographic studies under the microscope. Sample collection depended on the variation in lithology; that is rock samples have taken according to the lithological characteristics and change in the stratigraphic column of the studied area. Detailed field study of the outcrops done to get a general view of the distribution of the lithological changes in addition to vertical (stratigraphic) and (geographic) lateral lithofacial variations and indication of most suitable sections for sampling.

1.6.2- Laboratory works To achieve the aims of this study, the following works are conducted:1- Study of about 100 thin sections of the collected samples of all outcrops of area and description of the sections.

2-Thin section studies under binocular and polarizer microscopes for differentiation of the constituents and photographing the most useful samples. 3-Calculating percentage of the constituents (for identification of facies and rock types) by using point counter. The method of( Flugel, 2004, in: Betzer, et al., 2005) is used for point counting in which void with in particles were counted as constituent of the particles. The slides and samples that contain few allochems the visual estimation by using the charts prepared by Folk et al., (1970) and Tucker (1989).

Fig.(1.12) Kele section in which Aqra Formation is underlain by conglomerate of Tanjero Formation with about 300m. high.

1.7- Previous Study:Aqra Limestone Formation was first described by the two Germany researchers (Kuhn and Kumel, in Lawa, 1983). They said that the formation, in the type locatlity, is formed from calcareous rocks and is saturated by bituminous materials. Depending on some Foraminifera, Echinoderms, Brayozoa and Brachiopoda; they indicated the age of the Formation is Upper Campanian-Maastrichtian. Wetzel (1947. In Bellen et al 1959) described the formation and he said that the formation is calcareous and saturated with bituminous materials, it is partially dolomitized, siliceous and containing Loftusia. He mentioned that the upper part contain quartz bearing bands which composed of yellow calcareous rocks containing geode of Quartz alternating with marl layers. The latter author added that the thickness of the formation in the Gali Sheikh Abdul Aziz is about 813m. Andre,1949 in Lawa (1983) in his study pointed to many sections of Aqra Formation like Asmawa, Gali Sheikh Abdul Aziz, Gali Zinta …etc. all of these sections are composed of dolomitized calcareous rocks containing bitumen, he recorded some fossils like: Rudist, Corals, Gastropoda and Pelecepoda. Henson (1950) assigned the Aqra Formation as one of the Middle East reefal formation with Upper Cretaceous age. In his report about Aqra Formation, Dunnington (1953), mentioned many different Benthonic and Planktonic Foraminifera and he recorded the presence of Encrusting Algae and calcareous green algae.Bellen et al. (1959) mentioned that Aqra Formation composed of calcareous reefal rocks with shallow reef of rudist and calcareous fore reef rocks and is partially dolomitized and siliceous, which contains bitumen in some layers. They indicated that the Upper surface of the Formation is Unconformable with Kolosh and Khurmala Formations and the age is Maastrichtian.Kureshy (1969) referred possibility of the existing age correlation between the rock successions of Pilsner Formation in Aqra area . Lawa et al (1998) concluded that the Aqra Formation, in the Chwarta-Mawat area is interfingering with Tanjero Formation and connected with rock of the type area. Al-Amery and Lawa, (1986) studied paleontological model (Fig.1.13) and funal interaction in Aqra Limestone Formation in the type section in Dohuk area. They recorded seven biofacies which are: type one, two, three, four …. … and type seven which are all consisted of packstone or grainstone.Karim (2004) concluded that it consists only a lens that has no lateral continuity with that of the type area. He assigned the rock of the lens as the sediments of high stand systems tract which deposited in proximal area of a foreland basin. Al-Kubaisy (2008) studied Biostratigraphy of Aqra Formations in Chwarta area found three zone of large foraminiferas and proved that the age of the formation is Late Maastrichtian.The recorded zones are:1-Lepidorbitoides Range Zone2-Omphalocyclus-Orbitoides medius-Siderolite Calcitrapoides Assemblage Zone3-Loftusia morgani Range Zone.

Fig.1.13 Paleogeographical model of Maastrichtian (Al-Ameri and Lawa, 1986)

Abid and Al-Kubaysi (2009) studied microfacies and depositional environment of the Aqra Formation in Chwarta area. They recorded four microfacies as follows:

1- Pelagic Lime Wackestone Facies2- Foraminiferal Lime Wackestone Facies3- Larger Foraminiferal Lime Wackestone Facies4- Larger Foraminiferal Lime Packstone Facies

Depending on the high diversity in the species of different groups of foraminiferal assemblage, they concluded that the depositional environment of Aqra Formation which suggested by application of the environment triangle, showed that the depositional environment extends from near pelagic area to the toe of slope area and its continuation to the shallow water area, and the rudist reef body, although the counting of the fossils content of the foraminiferal species showed that Aqra Formation (in Zarda Bee section) was deposited in deeper environment.

Chapter Two: ( Lithology and Stratigraphy) Dereen Mohamad Sadiq, MSc thesis

2.1-P reface

This chapter deals with the detailed study of lithology and stratigraphy of the Aqra Formation which mainly consists of biogenic and detrital limestones. The lithology and stratigraphy is necessary for facies analysis of Aqra Formation to indicate constituents of each interval and their stratigraphic position.According to Westphal and Munnecke (2003), the distribution of carbonate deposits is dependent on paleoenvironmental conditions such as temperature, salinity, and nutrient levels. The vertical (time) and lateral (geographic) relationships between different parts of the formation in one side and with underlying and overlying formations are deciphered by field and laboratory studies.These relations as the boundary condition are extremely necessary for tectonic, environmental and paleogeographic modeling. The study of the contacts let the geologist to put the formation and neighboring units either in a one basin or in several basins by applying Walther Law as cited in Blatt et al., (1980).This is also useful for tectonic consideration of the formation, and it’s depositional basin during Late Cretaceous.. 2.2-Carbonate constituents (allochems)Carbonates, unlike siliciclastics, are "born, not made" in the depositional setting (Goldhammer et al., 1990) which means considerable information can be obtained about their generation from the sediment character (allochems). This is because specific carbonates accumulate in specific settings which means that carbonate production, in a certain conditions, must have been met and maintained certain condition in order to sustain a particular character. Thus the depositional environment must have been just in proper condition for the production of particular carbonate, meaning that the sea may not have been too warm, or not been too cold; not been too shallow, or not been too deep; not been too fresh, nor been too saline; had not too many nutrients; while the sea floor had not too fast a subsidence, was not too stable; and there was not too rapid sea rise or fall; (Goldhammer et al. 1990).In Aqra Formation, the allochems are mainly consisting of either fossils skeletons or their bioclasts and lithoclasts with lesser amount of terrigenus (extraclasts)ones. The fossil shells are large which range between 0.1-150 mm and extraclast and intraclasts are range from clay to gravel size. The most abundant skeletons are those of benthonic large forams such as Loftusia, Omphalocyclus and Orbitoids. The next one in abundancy is mollusk of which the extinct genus Rudist is the most common and next comes Pelecypods and Gastropods. The shells of Echinoderms can be observed frequently while the Ammonites are very rare and can be observed in the deeper part of the basin. The main facies are floatstone, mixstone, rudstone, grainstone, packstone and bufflestone (Pillarstone). Each of these facies consists of the skeleton of one or more than one of the above fossils or their bioclasts. These fossils are useful for environment and age determination such as foraminiferas, which is used as index fossils for the age determination because of short age. In this connection, Al-Kubaisy (2008) studied biostratigraphy of Aqra Formation in Chwarta area and found three zones of large foraminiferas and proved that the age of the formation is Late Maastrichtian. The recorded zones are:1-Lepidorbitoides Range Zone2-Omphalocyclus-Orbitoides medius-Siderolite Calcitrapoides Assemblage Zone3-Loftusia morgani Range Zone.Rudist is very sensitive for the environment depth and it lives above 50m depth.Bellen et al (1959) recorded the following fossils from Aqra Formation in the type area (From the top to the bottom). They are:(Top): plagioptychus sp, cf. Biradiolites sp.; arcopegia cf. numismalis (d,Orbigny); Bournonia aff. Judacia var. Lavies Blankenhorni; Praerdiolites saemmani Bayle; Rhyncopygus cf. thebensis de Loriol; R. sp.; Ampullosprira incerta Forbes; Solarium; cardita sp; Cyclolites sp., Elphidella multiscissurata Smout; Loftusia persica Brady; Omphalocyclus macropora (La Marck); ? Chrysalidina sp.; Cymopolia tibetica Morellet; Cymopolia sp. Nov. Elliot MS… (Base): plagioptychus sp Bournoni cf. excavata (d,Orbigny); Sauvagesia sp.; cf. Radiolites sp.; Sphaerulites sp.; Acteonella sp., Praerdiolites haydeni (Douville); Vanikora cf. asiatica (Blankenhorn); Tylostoma cf. rachaiti (d,Orbigny); Omphalocyclus macropora (La Marck); Monolepidorbis sp.; Orbitoides media (d, Archiac); Discocylina Schlumbergeri Munier-Chalmas; Cunneolina cylindrica Henson; Dicycloconella complanata Henson; Elphidiella truncana stuarti (de Lappaarent); Cymopolia tibetica Morellet; cymopolia sp. Nov. Elliot MS.

2.2.1-Loftusia Loftusia is benthic foraminifera of Maastrichtian age and it known from outer platform facies of the Tethys Ocean. The genus Loftusia is characterized by planispiral fusiform test which has non-lammilar agglutinated with calcareous cement, calcitic wall structure. The shell has labyrinthic wall with Irregular septa and chamberlets (Fig.2.1 and 2.3).

Fig.(2.1) General view of fusiform test of loftusia (a), equatorial section(b) and cross section of wall(c) (Bracier,1980)

The genus is abundant in Arabo Iranian platforms and rare in eastern Mediterranean and totally absent in western Mediterranean (Zambetakis et al, 2004).This genus with larger benthonic genera with complex chamber wall that are represented by several species confining mostly to Maastrichitian and are reported from Middle East, Eastern Turkey, Iran, Iraq, Qatar and Oman in the Tethys and no record further in the east (Meric and Mojob, 1977). The restricted distribution of this Late Cretaceous taxon is suggesting small dispersal potential possibly due to ecological constraints (Govindan, 2008).Al-Omari and Sadek (1976) investigated microscopically and statistically specimens of Loftusia from the Maastrichtian of Northern Iraq (Aqra Formation). They noticed that during this period the genus exhibited a gradual increase in size (length and diameter). Thus, they recognized an evolutionary line for the development of Loftusia considering the forms of the early stages of the genus’ development. In addition they recorded a tendency for tighter forms during the transition from Mid to Late Maastrichtian (Zambetakis et al, 2004).Systematic classification of Loftusia:Order: Foraminiferida EICHWALD 1830Suborder: Textulariina DELAGE & HEROUARD 1896Super family: Loftusiacea BRADY 1884Family: Loftusiidae BRADY 1884Genus: Loftusia BRADY (in Carpenter & Brady 1870).Sartorio and Venturini (1988) during their study of Southern Tethys Biofacies recorded these fossils from Maastrichtian time such as: Loftusia, Omphalocyclus macroporus, Rotaliidae and Miliolidae from Maastrichtian age of parnezam, Zagros, Iran. In addition to that they also recorded Rotalia skourensis, Orbitoididae and Loftusia from Maastrichtian age of Ras Shrawayn of Yemen. They also claimed Orbitoides from Maastrichtian age of Gianna 2 well, Adriatic Sea. And Orbitoides, Siderolites calcitrapoides and Omphalocyclus macroporus from (LAMARCK) and rudist fragments from Maastrichtian of Emilio 5 well, Adriatic Sea also figured out by them.They recorded Lepidorbitoides, Orbitoides, Siderolites calcitrapoides (LAMARCK) Pseudedomia and Rotaliidae from Maastrichtian age of Fartaq of Yemen and Rhapydionina Iiburnica (STACHE), Miliolidae and Montcharmontia from Maastrichtian age of Vremski Brilot, Yugoslavia. They concluded that Loftusia is very common in the Middle East, the genus Rotalia already present in the Early Cenomanian shows a marked differentiation during the Maastrichtian and Orbitoides is very common during and at the end of the Maastrichtian. Zambetakis et al (2004) claimed that in Greece it has so far been reported from two sites: 1. On Kassidiaris mount as debris in bioclastic upper Cretaceous limestones of the internal zones (Ferrière, 1982), and on mounts Valtou in an occasionally bioclastic conglomerate which is limited by faults that prohibit us from observing its relation with the surrounding formations (Fleury et al., 1990). 2.In the area of Boeotia, on mount Ptoon, a horizon rich in Loftusia cf. anatolica has been found in an undisturbed sequence of Upper

Cretaceous limestones up to Paleocene flysch of the Eastern Greece zone. This recovery is considered very important for the paleogeography of the Tethys Ocean during late Cretaceous.Őzcan (2008) studied the Latest Cretaceous benthic foraminiferal on the Arabian platform, Southern Turkey, he suggested that diversified foraminiferal assemblages including genera such as Orbitoides, Siderolites, Omphalocyclus, Loftusia, Lepidorbitoides, Sirtina and other benthic taxa suggesting a Maastrichtian age.Akyazi and Ardem (2003) studied Ődemis Formation–Turkey. He showed that the formation was deposited in neritic environments, and it consists of conglomerate, nodular limestone, sandy limestone and claystone, interbedded with volcanic. The sandy limestone contains the benthic foraminifera Orbitoides aff. medius (d,Archiac), O. aff. Apiculatus Schlumberger, Sirelina orduensis Meriç and Inan, Omphalocyclus macroporous (Lamarck), Sirtina orbitoidiformis Brönnimann and Wirtz, Praestorrsella roestae (Visser), Laffitteina bibensis Maria, Laffitteina boluensis Dizer, Laffitteina aff. Marsicana Farinacci, Smoutina aff. Cruysi Drooger, Siderolites Calcitrapoides Lamarck, and Selimina spinalis Inan, Praestorsella roestae (Visser) was abundant. This foraminiferal assemblage indicates an upper Maastrichtian age.

2.2.2-Omphalocyclus Omphalocyclus is orbitoidal benthic foraminifera, known from the relatively shallow-water paleoenvironment located in the outer parts of the Late Cretaceous Tethyan platforms. The mineralogy of this type of the forams is calcitic by which the shell microstructure is well preserved which similar to orbitoid but with larger and discoidal shape (Fig.2.2 ana 2.3) Instead of fusiform. It is a relatively common taxon with a geographic distribution from Europe to North Africa, India and as far as Indonesia in the east, and to Caribbean in the west.Apart from its debatable diagnosis only in the (late) Maastrichtian of western Tethys, the genus has been discovered in Turkey in further much older beds in association with Orbitoides and Lepidorbitoides having rather primitive developmental stages (Özcan, 2006). He also suggested that the morphometric analysis of A-forms in successive assemblages (based on seventeen populations in seven sections located in Sakarya, Eurasian and Arabian plates), ranging in age from (late) Campanian to terminal Maastrichtian, enables the documentation of phylogenetic changes for the first time. Since these horizons contain a rather rich assemblage of accompanying specimens of Orbitoides and Lepidorbitoides, a correlation of the phylogenetic changes of the genus to that of Orbitoides and Lepidorbitoides, rather well-known in Europe, can also be made.The systematic classification of Omphalocyclus is as follows:Suborder: ROTALINA Delage and Herouard, 1896Super family: ORBITOIDACEA Schwager, 1876Family: ORBITOIDiDAE Schwager, 1876Subfamily: OMPHALOCYCLUS Vaughan, 1928 Genus: OMPHALOCYCLUS Bronn, 1853The most conspicuous phylogenetic change in the equatorial layer of Omphalocyclus is found to be the general increase in the size of embryon, which on average doubles by the end of the Maastrichtian. This trend is followed by the increase in the number of epi-embryonic chamber lets, which is however not as significant as the former parameter.Omphalocyclus in the stratigraphically lowermost populations has mainly three to four primary epiembryonic and no accessory epi-embryonic chamber lets. With the introduction of radial stolons which seems to have taken place in horizons referable to the Gansserina Gansseri Zone, only several accessory epi-embryonic chamberlets arise from the tritoconch. Instead, epi-embryonic chamberlets become rather larger in size and also they cover a wider portion of embryon along its thick outer wall. Considering the suitable changes in embryon size, and also some other morphologic features in successive populations, two new species, O.anatoliensis sp. nov. and O. cideensis sp. nov. have been erected in late Campanian and late Campanian-early Maastrichtian populations, respectively.

Fig. (2.2). Left) Cross section of Omphalocyclus macropora, Aqra Fn., Kato section, 20X slide No.KA3.Right) Longitudinal section of Omphalocyclus minor, the central area is white due to thinner shell at center which not cut by the section, Aqra Fn., Kato section, 20X slide No.KA10.

Fig.(2.3) current accumulated shells of Omphalocyclus and Loftusias of a bed 30cm thick (near Homaragh village) .

2.2.3-Rudist According to their life habit, rudist morphotypes are classified as 'elevators', 'clingers' or 'recumbents', each morphotype being adapted to specific environmental conditions (type of sediment, sedimentation rate, current regime) (Skelton 1991, and Steuber and Loser,2000).According to Flugel (2004), the rudists are sessile gregarious bivalves characterized by lower attached and an upper opercular valves of different sizes. The group appeared in the late Jurassic and disappeared at the end of the Cretaceous. Rudists were common throughout the Cretaceous and diversity dropped during the Early Aptian and the Latest Cenomanian and increased significantly in the Early Maastrichtian.He added those major subgroups are differentiated by shell morphology, the number and position of the teeth, accessory cavities, canal, pores and pillars. Thin sections exhibit characteristic microstrucutre patterns. The shells consist of an inner and middle aragonitic layer (nearly always recrystalized and replaced by blocky calcite) and an outer Low-Mg calcite layer with compact and \or cellular microstructures. The shells of the hippuritid rudists exist as densely packed biostromes which are characterized by pillars with in shell wall (Fig. 2.4 and 2.5B). The radiolitids rudist shells exhibit reticulate pattern cased by the calcitic cellular prismatic outer layer, and a compact inner layer (Fig2.5A 2.6b and 2.7).

Fig.(2.4) Outer and inner layers of the hippuritid rudist shell. The inner layer is replaced by secondary calcite.

Fig. (2.5 ). A) longitudinal section of the shell of radiolitid rudist in life position showing outer reticulate layer( o) cased (covered from inside) by the calcitic cellular prismatic, and a compact inner layer(i) s.n.14, Kele section. B) Cross sections of hippuritid rudists characterized by pillars within shell wall (small black spots indicated by letter p and teeth (t). s.n.24, Kele section.

Fig.(2.6 ) A) Fragment of pelecypod, Aqra Fn., Kato section, 20X slide No.KA1B) Reticulate shell of radiolitid rudist Aqra Fn., Kato section, and 20 X slide No.KA4.

Rudists are anomalous bivalves which developed massive sessile shells, often with two valves showing strong asymmetry (Dechaseeaux et al, 1969) and were adapted to filter feeding. Many forms show the strong development of the attached valve and the subsequent reduction of the free valve. In general forms, rudists resemble corals and it has been suggested that rudists displaced corals from reefs during Cretaceous (Kauffman and Shol, 1974: Johnson and Kauffman, 1996) in Mitchell, 1999).Gilbert et al, (2008) claimed that Maastrichtian strata from the Pachino area (SE Sicily) provide a model of association between rudist-coral framework and submarine volcanic activity. Rudist buildups are probably the result of two interrelated factors: the contemporaneous growth of major structures in the Mesopotamian Basin due to the upward migration of the Infracambrian Hormuz salt, and the geometry of the shelf at that particular time. The effect of salt penetration structures on the nature of the carbonate sediments, particularly during the Cretaceous Period, has been discussed by Sadooni (1993) and Sadooni and Aqrawi (2000). Gaddo (1971) noticed that rudist buildups were formed where the developing structures were accompanied by regional uplift. Videtich et al. (1988) found an association between the movement of the Infracambrian Hormuz salt and the buildups within the Mishrif Formation in the Fateh Field, Dubai.They suggested that the rising salt led to the doming of the Fateh structure and at the same time triggered subsidence in the surrounding area of salt withdrawal.The rudist buildups developed on the flanks of these subsided areas, which were then filled with fore-reef debris.The common occurrence of these buildups in the crestal wells of southern Iraq (Fuloria, 1976; Sadooni, 1993; Sadooni and Aqrawi, 2000), however, contradicts this model. If rudist buildups commenced on the flanks of the intervening basins between structures, we would expect the opposite result, viz. rudist buildups in the flanking wells.Schafhauser et al (2003) studied the upper Cretaceous Cardenas Formation (Central Mexico), they showed that swallowing- upward sequences defined by a Hippuritid- acteonellid- coral/rudist facies transition. This cyclic sedimentation pattern is obscured by an episodic input of classic sediments derived from the uplifting Sierra Madre Oriental, which in turn triggered either the development or decline of reefs.Sadooni, 2005 during his study of the nature and origin of Upper Cretaceous basin-margin rudist buildups of the Mesopotamian Basin, southern Iraq suggested that in the absence of seismic sections it is difficult to comment on details of the geometry and distribution of the rudist buildups within the Cretaceous subsurface carbonates of the Mesopotamian Basin, including those of the Mishrif Formation. However, examination of the geological data collected from the limited scattered outcrops of the M’sad facies (of the Mishrif Formation) in the Western Desert, and the nature of the rock materials (cores and cuttings) from some subsurface wells in the Mesopotamian Basin, yield some insights on the nature and distribution of these buildups. In the Western Desert, outcrops of the M’sad facies of the Mishrif Formation are composed of shelf limestones, reef limestones, shell breccias, micro detrital limestones, chalky limestones of whitish color with pinkish marls and sands, and a thin sandstone tongue near the base (Bellen et al., 1959). The rudist Eoradiolites liratus Conrad and Caprinula sp. were recovered from these outcrops. It has been predicted that the same species will occur in the subsurface of the equivalent strata of the Mishrif Formation to the west (Bellen et al., 1959; Buday, 1980; Sadooni and Aqrawi, 2000).

Fig. (2.7) top view of the lower valve of the radiolitid rudist with an echinoderm shell. S.n.1, upper part of the Kele section. The white piece of paper is 25cm long.

Fig.( 2.8) Structure of different types of rudist shells in cross sections (Flugel, 2004). 1-Caprinid rudist showing polygonal canal (c)2-Hippuritid rudist showing outer (CL) and inner (AL) layers in addition to two pillars (teeth).3-Radiolitid rudist showing outer folded cellular network cased by the calcitic layer 4-Radiolitid rudist showing outer cased by the calcitic layer.

Steuber at al., (2002) studied the limestone beds of Jamaica and they proposed that species- rich rudist- coral associations persisted into the Latest Maastrichtian (66-65 Ma). Abdelghany (2003) studied Campanian- Maastrichtian rock strata in the jabal El Aqabah, Jabal El Rawadh and Jabal Malaqet sections, Oman, Emirate, the rock beds (openmarine environment passed laterally into shallower marine conditions) are characterized by larger foraminiferal species including Loftusia morgani, Orbitoides Media, O. apiculata, Omphalocyclus macropora, Lepiorbitoides minor, Sulcoperculina dickersoni, and Sedirolites calcitrapoides.

2.2.4-OrbitoideThe genus Orbitoides was established by d.Orbigny (1848). The test of Orbitoides is lenticular with a circular outline, and can reach a diameter of up to 5 cm (Loeblich and Tappan, 1988). The test is biconvex, often with one side more elevated. The surface is ornamented with small knobs. The juvenarium consists of three or four chambers and is usually embraced by a thick wall. An equatorial layer is distinct. The mineralogy of the shell of this type of forams is calcite by which the ornamentation of shell preserved and clears under microscopes (Fig. 2.9). The systematic classification of Orbitoides is as follow:Suborder: ROTALIINA Delage and Herouard, 1896Super family: ORBITOIDACEA Schwager, 1876Family: ORBITOIDiDAE Schwager, 1876Subfamily: ORBITOIDIINAE Schwager, 1876Genus: ORBITOIDES d.Orbigny 1848The genus Orbitoides displays some of the widest latitudinal and longitudinal extensions among the larger Upper Cretaceous foraminifera. The particularly wide distribution over the circumtropical warm water belt of the Cretaceous ocean is comparable to the distribution of modern amphisteginids (Langer and Hottinger, 2000) and thus particularly valuable tracer in indicating of circumglobal warm water surface currents and the heat transfer towards higher latitude.

Fig.(2.9 ) A) Orbitoides, Aqra Fn., Kato section, 20X slide No.KA3B) Orbitoides, Aqra Fn., Kato section, 20X slide No.KA6.

2.2.5-Actaeonellid gastropodsActaeonellids and other gastropods commonly have aragonitic shell which may suffer from two processes. The first one is removal of shell by solution and filling by micrite or secondary calcite. In this case only the mold (general form) remained and microstructure is obscured. The second is replacement by calcite through volume per volume dissolution of aragonite and precipitation of calcite and it is possible that some microstructure is preserved espiciaaly the outer organic rich layer. (Tucker, 1991 and Flugel, 2004). The observed gastropods in the selected samples are suffered from the first process (Fig.2.10 and 2.11).

Fig. (2.10) Cross section of Actaeonellid gastropods which consist of one aragonitic layer, middle of the Kele section, s.n.17.

Fig.(2.11 ) Actaeonella shells in the lower part of Kele section, S.N.32

2.2.6-EchinodermEchinoderms are marine invertebrates with a multi-plate calcareous internal skeleton embedded in the skin, a marked five-rayed symmetry and a water vascular system through which the water is circulated in the body. Echinderm fragment are present in limestones formed in shallow –marine as well as in deep-marine environment (Flugel, 2004).The Echinoid and crinoids skeletons are calcitic and their fragment is easily identified since they are composed of large single calcite crystals and each grain shows straight extinction and the spary calcite grow around the grain syntaxially. But the echinoderm grain is distinguished from the sparite by its dusty appearance (Tuker, 1991).In the study area, many intervals of Aqra Formation contains frequent echinoderm which have good preserved with micro and macrostructures( Fig2.12 ). But the echinoderm grains (fragments) are rare due widespread of forams and other fragments such as rudist.

Fig.(2.12 ) Echinoderm shell showing the arms, lower part of Kato section, S.N.42.3-StratigraphyAccording to Bellen et al (1959) the Aqra Formation is defined by Bennet in 1945 as Aqra Formation in the Aqra area and the section runs along Gali Sheikh Abdul Aziz. According to Bellen et al (op cit) the thickness of Aqra Formation in the area is about 793 meters and the overlying formation is Kolosh Formation which is very thin in the area. The underlying formation is not seen in the type section but they mentioned that it may be continuous with the Bekhme Limestone. They added that the contact with the Kolosh formation is unconformable which is transgressive over eroded Aqra Formation. According to Jassim and Goff (2006), the Upper contact of the Aqra Limestone, in some areas, are marked by an erosional break at the Cretaceous- Tertiary boundary while in other areas trangressively overlies the Tanjero Formation.At Dar-e- Tesu, and other locations, the Aqra Limestone is developed as isolated tongues and lentils of neritic rudist bearing Limestone, at the top of or within the Tanjero clastic Formation, a variable thickness of Tanjero clastic Formation and or Shiranish Formation intervening between the base of the Aqra Formation and the top of the Bekhme Limestone. Where the Aqra Limestone is superimposed directly up on the Bekhme Limestone, without intervention of Shiranish or Tanjero Formations, the composite name Aqra/ Bekhme Limestone may be used (Bellen et al, 1959).From the above discussion and according to the field description it appears that Aqra Formation exist as lenses either inside Shiranish

Formation (at Aqra area) or inside Tanjero Formation (at Chwarta-Mawat area) (Fig.2.17) .

2.3.1-Lower boundary at the proximal areaAs the Aqra Formation, in Chwarta-Mawat area, located in the Imbricated Zone, therefore the inspection and determination of the nature of the boundary is difficult. This is because the boundary is the zone of combining of two different lithologies; in most cases one of them competent and the other is incompetent. Therefore, the boundary is a zone of different mechanical properties. Thus the boundaries may be zone of faulting, imbrications and even thrusting. However, some ideas are given about the lower and upper boundaries of the Aqra Formation depending on the field observation. In the studied area as a rule and in the proximal area, the lower boundary is showing signs of gradational and conformable as shown below:1-Gradational boundary (the conformable contact) with red clastics of Tanjero Formation. The red claystone and sandstone changes upwards to marly limestone and then changes to biogenetic limestone as can be seen at the northwest of Kani Sard village (Fig. 2.13) and near Yalanqoz. 2- Kele and Kato sections show some marine erosion at the lower boundary with the conglomerate of Tanjero Formation (Fig.2.14 and 2.15). In some place, in this section, the biogenic limestone alternate with conglomerate or sandstone but this alternation indicate more or less conformability unconformity.

Fig. (2.13) shows the lower boundary of the Aqra Formation at the northwestern side of Kato mountain which appears gradational.

Fig.(2.14) Lower boundary of Aqra Formation with Tanjero Formation at Kele section showing sharp contact between limestone and conglomerate..

2.3.2- The lower boundary at the distal areaAccording to paleocurrent analysis of Tanjero Formation (including Aqra lens), the distal area (deeper area of the basin) is located toward southwest (Karim, 2004 and Karim and Surdashy, 2005). This area is relatively far from the source area and tectonic force of the Iranian and Arabian plates. Therefore, this area is less affected by post and syn-depositional tectonic force than the proximal area. Therefore, the realization of the nature of the boundary is easier than the proximal one. About 200m to the southeast of the Zarda Bee the Aqra Formation succession can be seen in a position, which overlying Tanjero Formation.At this place the Tanjero Formation change upward to marl and marly limestone with some lenses of sandstone and conglomerate. Then, at the contact the lithology changes to thin beds of marly limestone, toward more upward it changes to the laminated, cross bedded and burrowed bioclastic limestone and contain bioclasts of rudist and whole shell of orbitoids (Fig2.15 , 2.16 and 2.17). The present study did not found any sign of unconformity such as conglomerate beds or paleosoil or karstification. Therefore, in the present study it is assigned that the boundary is gradational and the contact is conformable. The conglomerate lenses occur inside Tanjero Formation several meters below the contact and is deposited by reworking transporting from shallow marine to deeper one due to submarine current and don’t indicate any sign of subearial erosion. In the area around the Homaragh and Qshlagh villages the condition is the same as that of the Zarda Bee village but without recording of the conglomerate lenses.In the Sura Qalat section, the gradational boundary is very clear without conglomerate or erosional surfaces. In this section, the upper part of Tanjero Formation is composed bluish grey marl and upwards changes to marly limestone in the transition zone and then fossiliferous limestone in the Aqra Formation (Fig.2.15 and 2.16 and 2.17). From the above discussion and according to the type of the boundaries, the stratigraphic column of the three sections are drawn (Fig. 2.19, 2. 20, 2.21, 2.22 and 2.23). The column of the Kele and Suraqlqat section is drawn in two page dueto high thickness.

Fig.(2.15 ) Lower boundary of Aqra Formation with Tanjero Formation at distal area to the northwest of Habasa Gulla village showing gradational boundary and conformable contact..

Fig.(2.16 ) Lower boundary of Aqra Formation with Tanjero Formation at distal area, Sura Qalat section showing gradational boundary and conformable contact

Fig.(2.17) Time expanded stratigraphic column of the Late Cretaceous (Bellen, et al., 1959) showing Aqra Formation as lenses either inside Shiranish Formation (at Aqra area) or inside Tanjero Formation ( at Chwarta-Mawat area).

Fig.(2.18 ) legend of the symbols used in the stratigraphic columns

Fig. (2.19) Stratigraphic column of the sampled Kato section (not to scale)

Fig.(2.20 ) Stratigraphic column of Upper part of Kele section,( not to scale) (continued in the next page)

Fig.( 2.21) Stratigraphic column of Lower part of Kele section (not to scale)

Fig.( 2.22) Stratigraphic column of Upper part of Sura Qalat section (not to scale) (continued in the next page)

Fig.( 2.23) Stratigraphic column of Lower part of Sura Qalat section (not to scale)

CHAPTER FOUR (DEPOSITIONAL ENVIRONMENT AND TECTONICS)

4.1- PrefaceThere are two facts that make the present study important for the formation in the studied area. The first is that, it is the first detailed one for the formation in the Chwarta-Mawat area. The second one is that all previous ones are conducted on the distal area of the basin (outer shelf). Among the new papers that dealt with this formation in the distal areas are that of Lawa et el (1998) and Kubaysi (2008) which treated the lithology and fossil content in addition to age determination in the Mokaba and Zarda Bee sections. The present study has taken three different sections which are previously not studied. Two of these sections are located in the proximal area of the basin (mid-shelf) where the thickness of the formation is maximum. Due to these facts, the present study have conducted detailed facies analysis and reconstructed both paleogeography and paleo-environment in manner to be realistic.

4.2- Depositional environment According to (Tucker, 1991), benthic foraminiferas are common in warm, shallow seas, living within and on the sediment and encrusting hard substrate.It is agreed that Aqra Formation in the type area is deposited in the reef and fore reef environment (Jassim and Goff, 2006). Henson (1950), recorded that in Aqra Formation in northern Iraq, the compact reefal rudistic limestones pass into shallow facies of the reefal margin with Loftusia, Omphalocyclus, and Orbitoides.According to Karim (2004), the Aqra Formation (or Aqra lens), in the Chwarta area, is deposited during sea level rise (high stand systems tract). While he assigned the conglomerate and sandstone of the Tanjero Formation (below Aqra lens) as deposit of low stand systems tract in the shape of low stand fan delta. He also mentioned that in Chwarta-Mawat area several large fans were deposited which consist of boulder and gravel conglomerate. The deposits of these fans are about 500m thick. He further added that this area was consisted of coastal area of a large foreland basin.According to Liu (2006), during Middle to Late Maastrichtian eustatic sea-level fall, the open marine condition was restricted to the basin centeral areas. He mentioned that a prominent hiatus developed on the NW flank, and platform carbonates were deposited as late highstand systems set on the SE flank of the Mesopotamian Basin.Sadooni (1996) claimed that shallow-marine carbonates were deposited in Central Iraq during the Late Campanian-Maastrichtian. These carbonates consist of foraminiferal-shoal and bryozoans-algal-rudist, bank deposits, separated by argillaceous, oligosteginal wackstone and mudstones. The build-ups are believed to have developed on block-faulted topographic highs, while marly limestones were deposited in the intervening basinal low areas.According to Cameil, (2005) the upper beds of the Qahlah Formation at Jabal Huwayyah, United Arab Emerates, is composed of massive conglomerates with subordinate sandstones. The sandstones increase upward and contain clasts of red mudstone and chert. Overlying this lower sequence of conglomerate and sandstone a highly fossiliferous silty limestone beds containing most of the fauna found in the Qahlah dominated by rudists were interpreted by Smith et al. (1995) as having been deposited on stable shoals above active wave base. This stratigraphic relation between conglomerates (with sandstone) is similar to Aqra Formation in the studied area (Fig.4.1).

Fig.(4.1) stratigraphic relation between Qahlan(conglomerate) and Simsima Formations (biogenic limestone: packstone) of Jabal El Rawdah, Cameil, (2005). This relation is similar to relation between Tanjero and Aqra Formation in the studied area.

Although rudists are sometimes considered as characteristic 'reef-builders' of the Cretaceous, several important differences exist between typical coral-algal-hydrozoan reefs and rudist formations. Rudist formations are typically of low relief and form more or less tabular bodies. Bound, wave-resistant fabrics were uncommon, and elevator morphotypes were supported by sediment which accumulated during their vertical shell growth. Consequently, growth fabrics of rudist associations were constratal, in contrast to superstratal fabrics of modern coral reefs (Steuber and Loser,2000).Alsharan et al. (2000) described these beds as representing a transgressive phase during the deposition of the formation. They attributed their deposition to an open shallow shelf environment, below wave base without or with very rare terrigenous influx. Their interpretation is based on the gradual upward decrease of algae and the gradual upward increase of planktonic forams. The hippuritid thickets, at the top together with the shallow water echinoid Codiopsis, indicate near shore conditions. Shallow water carbonate shoals form the remainder of the succession (Smith et al., 1995).Orbitoides usually occurs together with specimens of the genera Omphalocyclus, Siderolites, Lepiorbitoides and Sulcoperculina. Late Cretaceous Orbitoides is interpreted to be lived in deeper environments (Hohenegger, 1999) and in the Upper photic zone at the depths of about 40-80m. (Hottinger, 1997). The environment is mostly interpreted as being open marine with some terrigenous input (Caus, 1988; Caus et al, 2002). The morphology (thick lenticular test, presence of lateral chambers) indicates a habitat in high energetic environments, which is supported by the presence of siderolites. The model of Al-Ameri and Lawa, (1986) in the type locality shows the Aqra Formation as isolated platform in the deep basin. This is appear from their model (fig.1-13) and Aqra Formation is surrounded from all sides by deep basin as indicated by deposition of marl. The above ideas are very important for new environmental and paleogeographic reconstruction of the Aqra Formation in the studied area. This is because these ideas give us pre- Aqra environment and the base (substrate) on which the Aqra reef or biogenic carbonates are began to grow. According to Facies analysis and above ideas, the pre- Aqra environment was coastal area which was covered by gravels and boulders (Conglomerate lithofacies). The pre-Aqra topography that is formed by these sediments was hilly-like coastal area that was shaped by fan delta (alluvial fan discharged into the sea) (Fig.4.2).

Fig.(4.2) A model for the basin of the Tanjero Formation (slightly before deposition Aqra Formation) shows the conglomerate is acted as substrate for deposition of carbonate of the formation (Modified from Karim, 2004).

The coastal area of the Lower Maastrichtian was subsided and more or less deepened (depend on the nearness to the coast). After this deepening, the deposition of the transgression system tract began and then followed by high stand system tracts (Karim and Surdashy, 2005c). The sediments of the transgression system tract were marl (marl lithofacies at the base of Suraqalat section) in the distal area and red claystone at the proximal area. These sediments are not deposited or eroded during progradation of sea and the conglomerate remained clean for growth of biogenetic limestone.Another effect of the Deepening (TST and HST) was ceases or decreased of the influx of the turbidity due to retreat of the coastal area toward source area (toward NE). This is forced the existed streams to lose their gradient and their power to transport the sediments. When the alluvial fan is shaped due to very large flood, it deposits coarsest and most resistive sediments. This nature of sediments is other factor that stopped the turbidity from the source area due to resistance of the sediments of the alluvial fan (gravel and boulder). These coarse sediments has positive role in the diverting of the streams and putting turbidity away from previous routes. Therefore the next smaller flood takes other routes away from the previous place. Therefore, the growth of the reefal and biogenic limestones was depended on the low stand fan sediments (accumulation of gravels and boulders) for substrate and for decreasing turbidly. This don’t means that there was no stream in the area of Chwarta-Mawat area. In the area many small and low energy streams were reaching the foreland basin and supplying the nutrients to the basin as evident from prolific growth of organisms and from sporadic quartz, igneous and chert grains that can be seen in several beds (in the rudstone facies). Near Zarda Bee village terrigenous sandstone beds and lenses are alternating with biogenic or reworked limestone ones.

The high rate of the sedimentation is clear from the morphology of the rudest (shape of the body on the substrate). Most of the rudists have the elevator shape which stands vertical to the substrate and the growth is normal to the bedding plains (Fig. 4.3 and 4.4). According to Steuber and Loser (2000) elevator rudist requires a certain amount of background sedimentation to stabilize vertical growth shell. They added that all hippuritids and most radiolitids rudist lived as elevator while clinger cannot survive in high sedimentation rate.

Fig.(4.3) type of rudists shape on the substrate (Steuber and Loser,2000).

Fig.(4.4) Elevator rudists in the lower part of Kele section ( s.n.9)

The growth of the biogenetic limestone on hard substrate like conglomerate (Fig.4.1 ) is similar to the lower sequence of the Qahlah Formation at Jabal Huwayyah, Unite Arab Emerate as appear from the below paragraph by Cameil (2005).According to Flugel (2004, p.530) the Actaeonellid gastropod are common in brackish-influenced Cretaceous sediments. Therefore, it is possible that the basin was influenced by fresh water influx. In the studied area several bed at the lower and upper part of the section contain terrigenous clastic sediment that are supplied to the basin by fresh water influx.The roles of the coarse sediments are very clear from two field observations. The first is that where the thickness of the conglomerate is high the thickness of the Aqra Formation is high too as can be seen in the Kato and Kele sections with 100 and 80metter thickness . The second is that at the base of the both sections the conglomerate alternate with biogenic limestone as discussed in the conglomerate lithofacies (see chapter two).From discussion of all facies, it appears that the energy was high during the deposition and during whole span of the deposition of the formation, during upper Maastrichtian as evidence from mixstone. But it was higher in the lower part than upper part, which is clear from reworked loftusia and broken skeleton debris that can be seen in the lower part. Because of this, even the floatstone of rudist and large pelecypod contain bioclast and lithoclasts. The low occurrence of the grainstone is attributed to high rate of deposition.The temperature can be known crudely from the grain association which is defined by Flugel (2004), as assemblage of dominating skeletal and non-skeletal grains that are coexist in certain basin or formation. When the classification of Ensiele (2000) about grain association and their environments are applied for the formation, in the studied area, the foramol is only association that fit the formation (Fig.4.5).According to Flugel (2004) the framol (fra: Foraminifera and mol: mollusk) association is introduced for non-tropical carbonates that are consisting predominating of foraminifera and mollusks. This association is applicable because contain only foraminifera (loftusia, omphalocyclus and orbitoids) and mollusks (pelecypod (including rudists and gastropods). In the formation, no coral (except very rare solitary corals), algae and bryozoans are found. Therefore, the environment is deposited in temperate of mid-latitude (30-34degres of latitude) (fig. 4.5).According to Al-Ameri and Lawa (1986), the depositional location (paleogeographic location) of the Aqra Formation, at type locality, is situated at 0-10 degrees of latitude. This means that the formation was deposited in the equatorial environment and transported tectonically for about 3600km to the present position from Maastrichtian to present. But in present study Aqra Formation is deposited in 30-34degres of north latitude and not transported more than 1400km from Maastrichtian to present. This is because, today the Arabian Plate is moving north-east at rates now estimated from GPS measurements to be 25 mm/year for Oman or 15.7 mm/year for the southern Red Sea (Edgell, 2006).

Fig.(4.5) A) Grain associations and their latitude in addition to temperature (Ensiele, 2000) on which the latitude of the Aqra Formation is indicated by solid black line. B) Paleogeographic section showing environment of Aqra and Tanjero Formations in the studied area

4.3- Termination of the environmentIn the literature, the termination of the reefal limestone (or carbonate factory) on the platform is attributed to the drowning of carbonate which according to Schlager (1991), Kendall and Schlager (1981), the drowning may be resulted from decrease of nutrient supply and oxygenation and from increase of Salinity, predation and siliciclastic input. Platform drowning may occur in various tectonic settings: foreland basins (Robertson 1995; Galewsky 1989), extensional basins (Bice and Stewart 1990). According to (Tucker, 1991), drowned platforms are ones which is relatively rapid sea-level rise, so that deeper water facies are deposited over shallow water facies and many pelagic limestones were deposited in these situation. (Mutti et al., 2005) have mentioned that platform drowning can be controlled by many factors, including rapid eustatic sea-level raise, crustal subsidence, ecological stress, water temperature, upwelling of cold deep water and the rate of sediment production and removal.According to Catunenue (2006), the drowning represents the final stage in the evolution of a carbonate platform, prior to the return to a clastic dominated environment. Once the platform is drowned below the photic limit, filling of the available accommodation during subsequent highstand normal regression may only be achieved by means of siliciclastic progradation. Most of the above ideas are not applicable for Aqra Formation in the studied area as the termination does not relate to drowning. But the citations of Mutti et al., (2005) and Catunenue (2006), about ecologic stress and siliciclastic progradation, are valid. This is because, field study of the contact with Red Bed Series shows gradational boundary which shows shallowing not deepening as required for drowning. Due to tectonic uplift of the area, the siliciclastic progradation is increased and the carbonate deposits are ceased due to ecologic stress by influx of turbidity as red claystone and sandstone (red clastic lithofacies) in addition to conglomerate. These clastics as Red Bed Series are studied by Al-Barzinjy (2005) who showed that conformably overly Tanjero Formation (including Aqra Lens).The turbidity decreased the oxygen and light penetration which prevent algae and bacterial growth that are necessary of rudist and foraminifera. The problem of covering and termination of the Aqra Formation at the stuied area by Kolosh Formation is solved by the study of the Al-Barzinjy (2005) who concluded that Lower part (unit one and two) of Red Bed Series is equivalent to Kolosh Formation. Therefore, it is possible that in the type section, the basin is deepened and the processes of drowning are happened due to local subsidence below the photic limit. Other possibility is that mentioned by Bellen et al. (1959) that Aqra Limestone Formation, in the type section, has an unconformable upper surface with Kolosh and Khurmala formations. In this case and for unconformable contact, Walther Law (cited in Blatt et al (1980) cannot be used and the environmental relation cannot be established. The problem that arises against this tectonic discussion is the fact that in Chwarta-Mawat area, the basin of the Aqra Formation is uplifted while in the type section the formation is subsided or drowned. To minimize the effect of this problem, the author clarifies in the following two points. The first is that according to Karim and Surdashy (2005a) the depositional axis(e.g.: proximal area), during Late Cretaceous, was deviated (diverted) more toward north as compared to trend of present anticlines. The diversion of depositional axis is clear along their elongation from Arabian Gulf to Turkish border. This axis is indicated by the above authors by connecting same lithology and thickness in certain time.The depositional axis, was depended on the tectonic front (or deformational front) of Iranian Plate along its advance toward southwest during Late Cretaceous (Karim and Surdashy, 2005b, Ameen, 2008). Therefore, the type section was consisted of distal area and had the tectonic position of Sulaimani area where Kolosh Formation deposited due to subsidence.The second is that Chwarta-Mawat area was consisted (during late Maastrichtian) of part of source area (or coastal area) therefore, the source area was uplifted while the basin was subsided. This type of relation between source area and the depositional basin is shown by

Catunenue (2006) in the diagram which shows that the uplift (red or grey arrow) in the coastal area is associated with subsidence in the basin (black arrow), (Fig. 4.7)

4.4-Carbonate profile (or carbonate marine topography)According to Read (1985) marine carbonate can deposit on several profiles such as ramps and rimmed shelves. The ramp can be homoclinal and distally steepened. In literature, Jassim and Goff (2006) and Bellen et al (1958), mentioned that the Aqra-Bekhme Formation has ramp profile or deposited on ramp topography. They added that this ramp contained reefal, fore reef and shoal limestones in type section.A type of topography or profile that Aqra Formation had during deposition in the studied area is not exactly known and difficult. This is because, the outcrop is limited and only elongated along the depositional strike along the belt no more than 10km wide. Another factor of difficulty is that previously, this issue is not treated.Karim (2004) studded the underlying Tanjero Formation and mentioned that it has shelf topography rather than ramp. He depended on the existence of the thick lowstand wedge of sandstone (about 400m thick) at the area of Chaqchaq and Shadalla valley in addition to northern boundary of Piramagroon -Sharazoor plains. He supposed (and as cited in other literates) that this wedge is deposited on the slope. He further added that the shelf break is located to the northeast of this wedge at the present position of Goizha, Azmir, Daban and Qarasard Mountain (or anticlines). Another evidence is that he depended on the existence of incised valleys fill (Kato conglomerate) at the Mawat and Chuarta area, prove that this area northeast to these towns were forming the shelf during lower (former) HST and coastal area during upper (next) HST.Another evidence for shelf-slope profile (as cited by above author) is the high thickness of the LST, which is in some place more than 500m. For this, Haq, (1991) and Emery and Myers (1996) mentioned that low stand wedge in ramp setting is relatively thin. He added that the shelf of the lower sequence is developed by high sedimentation (such as deposition of 500m conglomerate) on the front advancing of Iranian plate and coalesces of several coarse sediment low stand alluvial fans. The rapid deposit and burial of coarse sediment prevented part of them from reworking into deeper water, thus a clastic dominated platform (or fan delta front) is developed which was modified (flattened) by wave as shelf (Fig.4.6).The result of the present study of the facies analysis showed that the profile is more or less changed to distally steepened ramp as compared to that of Tanjero Formation which was shelf as cited by Karim, (2004). Before assignment of the profile, it is better to clarify the following facts:

1-No signs of lagoon are found such as pelletal limestone, mudstone, dolomite, stromatolite and miliolids.

2-The buildup facies such as algal framestone is not fond and bafflestone constitute only less than 10 percent of the total thickness of the sections.

3-the presence of lenses or beds of terrigenous clastic sediments is the indicative of attached platfom model (Fig.4.6) (depositional and paleogeographic model).

4-the deposition of about more than 400m of sandstone and conglomerate of Tanjero Formation in the basin may decreased sudden brake in paleo-slope and changed the shelf-slope profile to ramp.

5- The high tectonic during Tanjero Formation (as evidence from deposition of 500m of conglomerate or conglomerate lithofacies) is more suitable for shelf-slope profile than ramp. This is because the huge thickness of sandstone and conglomerate is evidence of high gradient for shelf-slope profile not low gradient as required for ramp (according to Ahr, 1973, slope less than 1 degrees).6- In literature, the best case that can be compatible with Tanjero Formation and Aqra Formation is that mentioned by Read (1980). He cited that distally steeped ramps develop where earlier rimmed shelves undergo widespread drowning (transgressive and high stand system tract of Karim and Surdashy, 2005c, prior to deposition of Aqra Formation).He added that ramp also develop on rimmed shelves that are prograded by clastics (Tanjero Formation) prior to renewed carbonate deposition. 7-Abdelghany (2003) found Loftusia morgani near the base of the Simsima Formation in shallow-water facies. From this specimen, ophiolite particles have recovered within its agglutinated test. He mentioned that these particles were probably derived from the underlying ophiolite that supplied shallow-water clastics of the Qahlah Formation with grains. A similar conclusion was reached by Meric¸ et al. (2001), who found Middle–Upper Maastrichtian Loftusia species in Turkey with tiny ophiolitic rock particles adhering to their tests. They concluded that the shallow-water ophiolite platforms formed during Late Maastrichtian movements, which culminated in the closure of the Tethyan Ocean. In the studied area and in all thin sections no ophiolite particles were observed in the shells of the Loftusia, but the tectonic setting of the studied area is slightly similar to that of Qahlah Formation (Oman). Carbonate ramps dominate much of today's modern carbonate shelves and were equally widespread in ancient systems. Models for carbonate ramp shelves have come from tropical settings in the Yucatan, Persian Gulf, west Florida Shelf, and subtropical to cool-water shelves surrounding the south and northwestern margins of Australia (Read, 1985).

Fig. (4.6) A depositional and paleogeographic model (distally steepened ramp) for the basin of the Aqra Formation which shows that the maximum thickness of the Aqra Formation was deposited on the conglomerate of the Tanjero Formation (see fig. 4-2).

Fig.(4.7 ) Tectonic relation between source area and the depositional basin (Catunenue, 2006)

Fig (4.8) rimmed shelf topography and environment (After Tucker and Wright 1990) on which the environment of the Aqra Formation are indicated by the arrow. The dotted line is represent the paleogeographic cross section of the Aqra Formation in the studied area.

4.5-TECTONIC OF THE BASINAccording to many authors and on a global scale, Maastrichtian was a period of widespread marine regression (Buday, 1980, Fischer & Germann, 1987; Haq et al., 1988, Jassim and Goff, 2006). The upward deepening transgression in the Oman Mountains is unusual and it seems that this transgression resulted from local subsidence at a rate exceeding the supply of sediments (Alsharhan and Nasir, 1996).According to Karim and Ameen, (2008) after the deposition of Kometan Formation, the two continental parts of the Iranian and Arabian Plates were collided. Slightly before collision, the trench was filled with scraped off sediments (radiolarites) and ophiolites. These materials are uplifted and thrown onto the subsided continental part of the Arabian Plate. The uplifted and over–thrown materials have formed positive land in the suture zone of the two plates. According to Karim (2004), Karim and Surdashy (2005b and 2006), due to this colliding, the studied area was transformed from passive margin to active Early Zagros Foreland Basin. According to these authors, Shiranish, Tanjero, Aqra, and Kolosh Formations are deposited in this foreland basin. They added that the collision changed the accretionary prism to source areas (orogenic belt) for Late Cretaceous sediments such as Shiranish and Tanjero Formations. This collision is manifested by about 500m of gravel and boulder conglomerate (conglomerate lithofacies) that can be seen at Chwarta, Mawat and Qandil areas. Field relations and vertical facies changes show that Aqra Formation is deposited on this conglomerate as reefal facies in the inner, mid and outer shelf as foramol association.

When the uplifts and relaxation phases of Ameen (2009) is considered that deposition of the Aqra Formation (in the studied area) occurred in the end of the relaxation phase of the Middle-Late Maastrichtian. According to this author, the uplift signal consists of very thick successions of the sandstone-shales (flysch facies) and conglomerates-red claystone (molasse facies) at basin plain and marginal areas (proximal area) of the foreland basin respectively. The representing lithologies of the relaxation phases consist of thick succession of marl (hemipelagite) and shale at the proximal area and distal part of the basin respectively (Fig.4.9).The thickness of some of these above successions is more than four hundred meters thick. During Maastrichtian and Paleocene, the contrasts of the tectonic signals (sediments) are obvious and high but those of the post Paleocene are weak and not clear. He added that this attributed to concentration and release of stress along narrow strip near the Iraq-Iran Border while during post Paleocene time, the stress distributed and releases through wide and extended from Sanandij Serjan to the south of Sulaimani City. This is attributed to migration of the stress along low depth decollement thrusts toward southwest. Karim and Surdashy (2005) concluded that Aqra Formation (or Aqra lens) is deposited during deepening (transgression and high stand system tracts). While conglomeratic lithofacies is deposited during shallowing (low stand system tracts).These system tracts are equivalent to the relaxation and uplift of Ameen (2009). Numan (1997) in his study for the tectonic and paleogeographic position of Aqra Formation and Tanjero Formation assumed that Tanjero Formation (including Aqra Formation) is deposited in a trench before closure of the Neo-Tethys on the northeast sloping Continental Arabian margin (Fig. 4.10). Alavi (2004) discussed the ophiolite obduction (colliding of ophiolite with continental part of the Arabian Plate) but the stratigraphic position of Aqra Formation cannot be indicated on the models.In the present study, the tectonic model is totally changed depending on the facies analysis and study of Karim, (2004) and Ameen (2008) and Taha, (2009) Fig. (4.11B). They assumed that it deposited on the southwestern sloping foreland basin .This foreland basin is bordered from northeast by source area which was supplying the basin with terrigenous sediment. This influx was rapid and high during deposition of Tanjero Formation and was continuous during deposition of Aqra Formation. The effect of this influx was obvious in the distal area for the basin of Aqra Formation especially near Zarda Bee and Homaragh villages. Because of this clastic sediments, Karim (2004) named Aqra Formation, at distal area, as carbonate-siliciclastic succession. According to latter author, the constituents of this succession are alternation of biogenic limestone and calcareous shale with minor amount of sandstone and conglomerate. This influx is associated with nutrient influx too for organism growth.The present model (Fig.4-6) is made use of the models of Bosence (2005) about genetic classification of carbonate platforms based on their basinal and tectonic settings in the Cenozoic. In these models (eight models), three of them is used for construction of the present model. The three models are more or less related to the tectonic and paleogeographic models of the studied area. The three models are: 1-Thrust-top platform (Fig. 4.12 A). 2- Delta-top platform (Fig. 4.12 B). 3-Forland margin platform (Fig. 4.12 C). The first one (model A), is related to the studied area as this area is assigned zone of ophiolite obduction since the Late Cretaceous by Alavi (2004), Jassim and Goff (2006). The same obduction is suggested by Ibrahim (2009) (Fig.13).While according to Karim (2004) this area was zone of continental colliding of Iranian and Arabian plate which was occurred during Maastrichtian. So the studied area was affected by local tectonic front or thrust. The second model (B), is one which has the closest relation to the studied area because Karim and Surdashy (2005c and 2005a) found several Low stand fans that are discharged into (or connected with) the basin of Tanjero Formation in the studied area. As discussed in the section of environment, at least part of the Aqra Formation is deposited on these fans which consisted of boulder and gravels.The third (model C), is related to the studied area as this area is assigned as northeastern margin of Arabian platform (Buday,1980). Therefore, the present model (Fig.4.6) contain more or less some idea of the above models but the main dependent facts are obtained from facies analysis and field work.

Fig.(4.9) The four tectonic phases of uplift and relaxation of Zagros Fold–Thrust belt during Maastrichtian and Paleocene with lithological representation as shown by stratigraphic column the two ages of each phase (Ameen, 2009).

Fig. (4.10) The tectonic model of Numan (1997) in which the position of Tanjero Formation is indicated in a trench sloping toward northwest.

Fig.(4.11) Combination of tectonic, depositional history of Early and Late Cretaceous basin as considered in this study. A) From Karim and Surdashy (2005b), B) Taha (2009).

Fig.(4.12) Three models of Bosence (2005) about genetic classification of carbonate platforms based on their basinal and tectonic settings in the Cenozoic. From these models, a tectonical and depositional model of Aqra formation (in the studied areas) can be constructed.

Fig. (4.13) ophiolite obduction on Arabian platform (colliding of Oceanic floor of Iranian plate with continental part of Arabian plate (Alavi, 2004).

4.6-CONCLUSIONSThis study concluded the following:1- Aqra Formation (Late Maastrichtian) in Chwarta-Mawat area mainly consists of Biogenic and detrital limestones which appear as thick well bedded or massive succession along both sides of the existed streams and gorges. The boundary with both underlying Tanjero Formation and overlying Red Bed Series are gradational and the contact is conformable. 2- The field study showed that the formation, in the studied area, is not connected with the Aqra Formation at type section and surrounded by Tanjero Formation from all sides.3- The fossil content is rich, but with low diversity and belongs mainly to Foramol association which includes large forams (Loftusia, Omphalocyclus and Orbitoids) with mollusks (Gastropod and Pelecypods (including rudist) in addition to echinoderm and rare ammonites.4-The lithology is mainly consisting of biogeneic and detrital limetones.5- The main facies are floatstone, mixstone, Rudstone, grainstone, and bafflestone of the skeleton of one or more than one of the above fossils or their bioclasts. 6-The lithofacies such as terrigeneous conglomerate, marlstone and red clastic of Tanjero Formation and Red Bed Series are appeared very important for tectonic and environment reconstruction of the formation. 7-It is inferred that the highest thickness exists where the substrate is consisted of the thick conglomerate of the Tanjero Formation. 8-Most of these facies can be identified by eyes or hand lens due to large size of the fossils the matrix is consist mainly of sand or silt sized bioclasts with more or less micrite.9- These facies are deposited in shallow and high energy platform (basin) of mid-latitude temperate climate with high rate of sedimentation. The basin was supplied intermittently by terrigenous clastics from source area which appear in some place as bed or lens of sandstone interbedded with the biogenic limestones. These clastics are supplied by many small and low energy streams which were reaching the foreland basin and supplying the nutrients to the basin.10-The energy was higher in the lower part than upper part this is clear from reworked loftusia and broken skeleton debris that can be seen in the lower part.

11-The low occurrence of the grainstone is attributed to high rate of deposition in influx of terrigenous fine sediments.12-The growth of the reefal and biogenic limestones were depended on the low stand fan sediments (accumulation of gravels and boulders) for substrate and for decreasing turbidly. 13-In the present study, the tectonic model is totally changed depending on the facies analysis. It assumed that it deposited on the southwestern sloping foreland basin. This foreland basin is bordered from northeast by source area which was supplying the basin with terrigenous sediment.14-The Aqra Formation in the Chwarta-Mawat area cannot be correlated with type area in Dohuk Governorate due to high difference geological and stratigraphic setting of the both localities.

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HISTORICAL DEVELOPMENT OF THE PRESENT DAY LINEAMENTS OF THE WESTERN ZAGROS FOLD-THRUST BELT: A CASE STUDY FROM NORTHEASTERN IRAQ, KURDISTAN REGION

Kamal H. Karim, Amanj Ibrahim Fatagh, Azad Ibrahim and Hemin Koyi

Published in: Iraqi journal of Earth Sciences, Vol.9, No.1, pp.55-70, 2009

ABSTRACTThe part of the Zagros within the Iraqi border occupies an area less than quarter of the country. It includes three tectonic zones which can be clearly identified in the field. These are the Low and High Folded, Imbricated and Thrusted Zones. The main lineaments are the axes of the anticlines; transverse and longitudinal faults; lines of distribution of ophiolite and metamorphic rocks; drainage direction discharge and line of distribution of conglomerates. The direction of axes of the anticlines , as main structures of Kurdistan, are trending nearly N38W which normal to the direction of the imposed stress by the Iranian plate front. Due to differences in thicknesses and physical properties of the sedimentary rocks, the axes of these anticlines are not continuous they plunge more or less in an echelon pattern and in some cases are bend. The lengths of most of these anticlines are around 10-30km. The first appearance of the anticlines in the High Folded Zone possibly started at the Eocene while those of the Thrust Zone initiated at Maastrichtian. Some of these anticlines are cut by transverse faults whose ages are not known. These faults are trending nearly normal to the axis of anticlines. Other kinds of lineaments are the distribution of ophiolites and metamorphic rocks. Historically the first appearance of trace of ophiolites (as pebbles in sedimentary rocks) has an age of Lower Maastrichtian.The direction of drainage discharge is nearly towards the south and southwest, which is inherited from that of the Upper Cretaceous and Tertiary paleocurrent directions (sediment transport direction). This direction is related to uplift of the extreme northwestern part of the studied area during Maastrichtian. Evidence for these suggestions is the occurrence of thicknesses of 500m of conglomerates as valley fillings during Late Cretaceous. The depositional axes of the successions was migrated for about 40kms during Cretaceous and Tertiary and becomes younger from northeast towards the southwest as recorded by four narrow belts. The line of migration is nearly coinciding with both direction of present regional slope and the Cretaceous sediment transport.

Keywords: structures of Kurdistan, lineament of Kurdistan, faults in Kurdistan, Lineaments of Kurdistan, tectonics of Kurdistan

INTRODUCTIONThe present study deals with the Western Zagros Mountain Belt that is located in Iraq and is elongated parallel to Iran-Iraq border (Fig.1 and 2). On the regional scale the Western Zagros mountain belt consists of relatively straight and continuous series of high mountains that runs from southeast of Arabian Gulf to the eastern part of Anatolia at the northwest. The series has the elongation trend of northwest-southeast. The tectonic zones (Thrust, Imbricated, High and Low Folded Zones, fig.2) of Buday (1980) and Buday and Jassim (1987) have more or less local disturbances in the directions of elongation. When the ideas of Turrini, et al. (2001), Schreuer, et al. (2001) and Marshak (2004) are considered, these disturbances could be attributed to the difference of mechanical properties of stratigraphic units. According to the same authors, the local difference of the compressional stress in the orogenic wedge (the southwest thrusting of Iranian plate front) and local structures have affected on these disturbances (Fig.1 and 2). The field study showed that the belt contains clear large lineaments which have great importance in the studying of the depositional and tectonic history of the area where the sedimentary, igneous and metamorphic rocks and deformational lineaments are all combined mutually with the paleocurrent directions. Therefore the present study deals with the location, types and historical development of these lineaments. In literature, many studies, as a part of a structural geology, have been conducted for lineament analyses (without their historical developments) of the northeastern and northern Iraq such as Omer (2006) and Al-Brifkani(2008).

LINEAMENTSNortheastern Iraq which is part of Western Zagros Mountain series shows well developed large lineaments which could be seen in the field and by aerial photography and satellite images. These lineaments generally reflect the effect and direction of the thrusting front of Iranian plate which has the general direction of S38W and may have local variations of plus or minus 10 degrees. These lineaments are as follows:

1- Axes of the anticlinesThe main and wide spread lineaments are the axes of the anticlines which have the general direction of Zagros Fold-Thrust Belt (Fig.1). The trends of theses axes are nearly normal to the direction of the imposed stress (S38W). Due to differences in the thicknesses and mechanical stratigraphy of the sedimentary rocks, the axes of these anticlines are not continuous but plunge in an en echelon pattern. This can be seen in Dokan area where Piramagroon, Sara and Kosrat anticlines are arranged in this pattern from southeast to northwest. The same thing is true for the area between Arbat and Said Sadiq town where this pattern can be seen to the north of the road where many anticlines plunge under the Sharazoor plain in en echelon pattern. The lengths of most of these anticlines are around 10-30km. Some of these anticlines are cut by transverse faults.

Fig.1: Tectonic map of Northeastern Iraq (Al-Kadhimi et al, 1996) shows location of some of the prominent lineaments of the studied area.

The historical development of these anticlines is still controversial and is related to the collision of the Iranian and Arabian Plates, and the migration of the tectonic deformation towards the southwest inside Iraq. According to, Buday (1980), Buday and Jassim (1987), Numan (1997, 2000, and 2002) and Al-Qayim (2000) the collision of the continental parts occurred in the Eocene. Recently, Karim, (2004) Karim and Surdashy (2005a and 2005b) inferred from sedimentologically evidences that, the collision of the continental parts occurred in the Campanian. According to these the main thrust fault developed at the Campanian and a foreland basin was generated directly to the southwest (Fig.3A and B).

Fig. (2) Boundaries of the tectonic subdivision of the Western Zagros in Iraq (modified from Buday and Jassim, 1987.

Fig.3: A) Tectonic model of the studied area during early Cretaceous showing accumulation of the radiolarites as accretionary prism and forming foreland forebulge. B) Development of foreland basin and southwestern drainage discharge (sediment transport) by uplift of radiolarite due to collision of Arabian and Iranian plates. C) Shelair phyllite formed by the stress of the two plates.

Therefore, the first folding, in Iraq, in the present Thrust Zone occurred during the Campanian. Among the anticlines that most possibly related to that time is Avroman Anticline in the Thrust Zone. Later on, the tectonic front migrated towards the foreland interior (towards the southwest) and reached the High Folded Zone during Middle Eocene. A positive land was generated during this age in the present position of the Shinarwe, Goizha, Kewa Rash Mountains in the high Folded Zones (Karim et al, 2008). This positive land, as possible anticlines, separated the early Foreland basin into two minor basins. Towards Late Miocene the tectonic deformation (folding) migrated southwestward and reached the Low Folded Zone (Karim et al, (Karim et al, 2008).

2- Distribution of Igneous and Metamorphic rocks The igneous rocks, as ophiolite complexes, are distributed along a more or less straight line near the borders with Iran which studied by Jassim and Al-Hassan (1977) and Buday and Jassim (1987), Aswad et al (1991) Aswad (1999). This lineament has the black or dark violet color on satellite images and its direction coincides nearly with the Zagros Suture Zone and the schistosity of metamorphic Rocks (slate, phyllite that are exposed around Garmik and Penjween towns) (Fig.3c) with attitude of 320o, 70o as arranged according to right hand rule. The distribution of igneous rocks is not continuous but has occurred as separate spots or blocks (Fig.1). Some blocks are dislocated from the straight line; an example of such blocks is the Mawat ophiolite complex which has been thrusted further towards southward than the other blocks. Karim (2005) attributed this dislocation to the existence of graben in the area which acted as privileged direction for thrusting. When these blocks are connected by a line they give clear and large lineament which is nearly parallel to the axes of the anticlines.

3-First appearance of ophiolite The age appearance of this lineament is not exactly known exactly, but Aswad and Elias (1988) stated that it appeared in the Albian-Cenomanian. Karim (2004, 2006b) found gravels and boulders of gabbro and peridotite in the conglomerate of the Tanjero Formation (Fig.4A). The age of this conglomerate is Early Maastrichtian determined by planktonic foraminifera zonation of hemiplagite by Abdel Kareem (1986b). Karim (2004) showed that the interbedded marl and sandstone of the distal area is equivalent to the conglomerate at proximal (coastal) area. The appearance of these clasts is important as it indicates that the emplacement of ophiolite in the suture zone of Zagros belt started at the Maastrichtian. Another importance of these clasts is the possible indication of dissection of newly uplifted Upper Cretaceous positive land (foreland) by deep valleys causing the emplaced igneous bodies to be exposed to erosion processes. In this connection Karim and Surdashy (2006) found four incised valleys in the sediments of Tanjero Formation during Maastrichtian (fig.5B).

Fig.4:A) Conglomerate bed of Tanjero Formation that contain first appearance of boulders and gavels of Gabbro in history of Iraq, West of Shekhan village, Qandil mountain towards the at east of Kometan village. B) Four ancient valleys (Maastrichtian) that drain the surface runoff of the hinterland into the foreland basin (Modified from Karim and Surdashy, 2006).

Fig.5: (A) Division of the studied area (thrust and imbricate zones) into several blocks transversally by normal faults. (B) Position of the two normal faults that bound Mawat graben.

4- Transverse faultsIn addition to the main thrust faults, there are many transverse normal faults that cut across (nearly normal to) the axes of the anticlines and main Zagros Thrust Fault. These faults divide the area into many uplifted and subsided blocks (Fig.5A).These blocks make horsts and grabens which are bounded by normal faults and their traces, on the surface, die out towards the southwest and obscured towards northeast by the southeast thrusting of the front of Iranian plate. The erosion is highly modified the topography of these faults but they could be identified in the field. They are difficult to be identified from satellite images and could be indirectly inferred from the large elevation and depressions that bound these faults (Fig.5A).The most important feature that is associated with blocks is, the Zagros Thrust Fault which makes a reverse faults with horst (light grey blocks of the fig. 5A) and low angle with the grabens (dark blocks of the same figure 5A). The thrust can be seen in several areas such as the Chuwarta-Mawat and Said Sadiq areas, while the reverse fault could be seen in the two areas between Chuwarta-Sadiq and Halabja areas. In these areas the Qulqula Radiolarian Formation (as a thrust front) climbs over Balambo Formation (or Jurassic Rocks) with an angle nearly equal to about 40 degrees. The age of these transverse faults is not known but they appear, from stratigraphy, that most of them are younger than Eocene. The evidence of the two of these faults is discussed in detail by Karim (2005a) (Fig.5B).

5-Drainage discharge direction (sediments transport direction)Another kind of lineament is the direction of the drainage discharge (direction of sediments transport) which trending now from northeast to northwest. This trend has close relation to the geologic, geomorphologic and tectonic history of the studied area. The first uplift in the extreme northeast of Iraq and its migration towards southwest is the main factor for shaping of this lineament. The chronology of this uplift is controversial and according to many studies it occurred during Eocene (Numan,1997 and Al-Qayim, 2000). Other studies mentioned the occurrence of uplift at the Campanian, among these (Karim 2004b, Karim and Surdashy, 2005b). According to the last study and that of Al-Barzinjy, 2005) and Karim et al (2008) the paleoslope and drainage directions were nearly in the same direction from Campanian to Eocene (Fig.6). The first uplift of the northeastern part of the studied area started near the Iran-Iraq border. Al-Barzinjy, (2005) and Karim et al (2008) indicated that paleocurrent was towards the south and southwest during Upper Cretaceous, Paleocene and Eocene. The measurements of the paleocurrent of Upper Bakhtiary by imbricated pebbles, in the present study, reveal nearly the same direction of that in the Tanjero Formation and Red Beds Series. The data of paleocurrent as collected from cross bedding and imbricated pebbles are well documented in Karim (2004) and Al-Barzinjy (2005) (for the last two units.) As concerned to sediments transport and drainage discharge, Karim and Surdashy (2006) found four large incised valleys in the sediments of the Maastrichtian filled with boulder and pebble conglomerates (Fig.4).They mentioned that each valley was associated with low stand delta, submarine fan and channels. During the above mentioned ages the studied area was occupied by large foreland basin which was located in front of the advancing head of the Zagros thrust fault (Fig.6). Therefore the discharge direction, in the past and present, is closely related to the tectonic uplift of the area now called Zagros Fold-Thrust belt and foreland basin in front of it. It is generally accepted, that the main streams such as Dilla, Little and Great Zab Rivers are flowing on the large transverse faults that cut both the basement and sedimentary strata. Therefore, the drainage discharge is an important type of lineaments which is related to uplifting and fracturing developed by collision of the Arabian and Iranian plates.

Fig.6: Tectonic and paleogeographic models for the sediment transport. It shows the location of the shoreline (Location of deposition of the studied conglomerates) as respected to present location of Iran- Iraq border (During Maastrichtian, the shoreline was nearly coinciding with the present border).

6-Direction of the maximum facies changeOther types of the lineaments are the direction of the maximum facies change that can be detected from facies maps and satellite images as well as from field observation across the strike of strata. In the field, the coarse grain clastic sediments (facies) of Upper Cretaceous, Tertiary to Recent change to fine grain ones towards southwest. The sedimentary facies are arranged in down lapped fashion on each other towards the southwest from shallow to deep facies. Karim (2004) described facies changes of Maastrichtian from boulder conglomerates to marly limestone passing through sandstone and shale. The trend of the facies change is toward southwest beginning from conglomerate, from extreme northwest (near Chuwarta and Mawat), to marly limestone at the southwest (near Chamchamal town).This type of facies change was continuous and migrate towards the southwest and can be seen from satellite image across the limps of anticlines. The facies change can be applied to metamorphic facies also. They show variations from schist to slate passing through phyllite from inside Iran to Iraq then changes to fresh sedimentary rocks at 20km inside Iraq. The metamorphic facies are related to depth of metamorphism and dynamic of the plate collision.

RECORDED CONGLOMERATE IN THE STUDIED AREAThe facies change is clearer in the case of clastics dominating successions that start from conglomerate in the coastal area and ends up by shale or limestone in the offshore or (distal area) (Pettijhon, 1975, Blatt et al 1980 and Tucker, 1990). These two end members pass through intermediate facies such as sandstones and siltstones. The change of position of the conglomerates with time is a direct reflection of the tectonic activities in the studied area and is represented by juxtaposition of fine clastics by conglomerate in the foreland basin toward southwest. This is attributed to rejuvenated erosion by continuous uplift and advance of Iranian plate towards the southwest. Many thick conglomerate successions are found by the present authors and other workers (Al-Barzinjy, 2005, Karim, 2004) which have the depositional axes parallel to the axis of main Zagros thrust fault (Fig.6). Each conglomerate successions could be assigned to a certain age and location. The paleocurrent and tectonic migration directions are indicated by Imbricated pebbles and cross bedding. The migration has resulted either from migration of the thrust front or southwest moving of the folding or deformation front. This southwest migration of the conglomerate depocenter shows more than 60km of movement from the Upper Cretaceous to Pliocene time (Fig.5 and 6). These conglomerates are as follows, arranged from older to younger:

1-Lower Maastrichtian conglomerateThis is a very abundant conglomerate and located at the base of the Tanjero Formation The maximum thickness is 500m and exposed at Chuarta, Mawat, and Qandil areas near the border of Iran and was studied by Karim (2004) and Karim and Surdashy (2005). These workers put this conglomerate at the lower part of Tanjero Formation by correlation (stratigraphically and lithologically) with 400m of sandstone and shale beds south of Sulaimanyia City and Dokan area (Fig.8). The conglomerate thickness is at maximum in the location of the paleo-incised valleys. It is possible that this conglomerate is an indicator of the first appearance of some of the present lineaments such as the ophoilite and thrust fault.

2-Upper Maastrichtian-Eocene conglomerate The strata of Late Maastrichtian to Eocene contain several lensoidal conglomerate beds and successions. They include the upper part of Tanjero Formation, Kolosh Formation and Red Bed Series in addition to Sinjar and Gercus formations. Their thicknesses are variable and change from proximal to distal areas and range from 20cm to 1000m. Geographically these conglomerates are not found in all places as they appear in some places and disappear in others. In north of Darbandikan town, they reach about(60m) and belong to Gercus Formation while toward Haibat Sultan Mountain they are intermittently exposed as thin lenses. Al-Barzinjy (2005) correlated this conglomerate (in Darbandikan area) with the unit three (1000m thick) of the Red Bed Series and indicated the southwest paleocurrent direction (fig.9 and 10A). Some of these conglomerates are deposited in the coastal area of the foreland basin while others are transported to distal area by debris flow. These conglomerates are discussed in detail by Buday (1980), Karim (2004) and Al-Barzinjy (2005).

Fig.7: Present location of the maximum thickness of the recorded conglomerate succession in the studied area from Lower Maastrichtian to Pliocene

3-Lower Oligocene conglomerateThis conglomerate consists of (2-10m) of well developed conglomerate and located between Pila Spi and Fatha Formation at the boundary between Low and High Folded Zones. It is indicates as (conglomerate) no.3 on the map (Fig.7) and on the stratigraphic column (Fig.8).

4-Upper Miocene- Pliocene conglomerateThis conglomerate succession is the conglomerate of no.4 in the (fig.7), consists of very thick pile of pebbles, pebbly sandstone and interbedded with red claystone and erosional surfaces. This pile includes Mukdadyia and Bai Hassan (Lower and Upper Bakhtiary) Formations and studied by Bellen et al (1959) and Buday (1980). The thickness of this conglomerate is more than 1500m and is located mainly in the Low folded Zones. The paleocurrent of this conglomerate is towards southwest (Fig.10B).

Fig. 8: Stratigraphic column of the exposed units of the studied area showing the position of the studied conglomerates.

COMPUTOR PLOTTING OF THE DATA Paleocurrent indication is important for knowing the paleoshore line, sediment transport direction, direction of the elongation of the submarine fans, incised valleys and direction of the facies changes. Therefore imbricated pebble analysis is important for the history and elongation of the lineaments. In the present study, the outcrops of the conglomerate of Gercus and Upper Bakhtiary formations have

been surveyed (for Tanjero Formation and Red Bed Series see Karim, 2004 and Al-Barzinjy, 2005). For rose diagram plotting, the azimuth of the direction of the plunging of the pebbles are taken by compass and tabulated. The plunging direction is reversed 180 degrees to change the plunge to the direction of the imbrication (direction of paleocurrent as seen in table1). The data of each station are entered to the Rockwork software as one column. Then the unidirectional option is activated in the program when the activated rose diagram gives the paleocurrent direction as shown in the figure 11.

Fig. 9: A)Under side of a thick pebbly sandstone bed (1.5m wide) of the unit one of Red Bed Series showing paleocurrent direction toward southwest during the Paleocene. Flute casts (1, 2, and 3), small and large groove casts (4, 5) and striation casts (6, 7). B) Small eroded channel (30cm wide) showing groove cast in the red claystone of the same unit in the same bed (Al-Barzinjy, 2005).

Fig.10: (A) Eocene (Gercus Formation) conglomerate about 60m thick forming a mountain clalled “Barda Asin” at northwest of Darbandikhan town, southwest of Zarayen town. B) Upper Bakhtiary Formation (Pliocene) conglomerate shows southwest paleocurrent direction. The arrows indicate paleocurrent direction and bedding surfaces while small inclined lines indicate directions of pebble imbrications.

Table1: Direction of the imbrication of gravels and boulders in the conglomerate of Formation and Upper Bakhtiary Formations.

LINEAMENT OF THE NORTHERN IRAQIt is possible that the same or most of the lineaments occurring in the northern Iraq, including North Thrust Zone, have nearly same the historical development but with different direction and all are diverted anticlockwise by about 40 degrees as compared to the northeastern Iraq (Zagros Fold-Thrust belt). The anticlines and thrust front are trending nearly east-west. It is possible that the drainage, facies migration direction was towards south instead of the southwest. The main factor for diversion of the trend of the lineament is the collision of Arabian and Turkish plate which generated the Tauros mountain belt. Al-Brifkani (2008) has mentioned that most lineaments, in this area, are trending towards north–south and east-west.

Fig.11: Rose diagrams show paleocurrent direction (sediment transport direction) as indicated by imbricated pebbles of conglomerate of Eocene and Pliocene.

CONCLUSIONThis paper has the following conclusions:1-The most important main lineaments are axes of anticlines; transverse faults; line of distribution of ophiolites; drainage discharge direction and maximum thickness of conglomerates.2- It is found that the trends and history of these lineaments are closely related to the development of the Zagros Fold -Thrust Belt.3- The first appearance of ophiolites (as gravel and boulder in clastic sediment) was at Lower Maastrichtian.4- The first appearance of anticlines is Campanian age, but it is Eocene and Upper Miocene in the Thrust, High and Low Folded Zones respectively. 5- The first appearance of southwest direction of drainage (sediment transport) is aged Upper Cretaceous as indicated by incised valleys and imbricated pebbles.6-The trends and positions of conglomerates could be considered as a lineament with a southwest trend of migration for about 50km from Upper Cretaceous till the Pliocene.

AcknowledgmentsThe authors express their best thanks to the Swedish International Development Cooperation Agency (sida) for their financial supports covering the fieldworks of this paper.

REFERENCESAbdel-Kireem, M. R. 1986. Planktonic Foraminifera and stratigraphy of the Tanjero Formation (Maastrichtian), northeastern Iraq. Micropaleontology, vol. 32, no.3, pp.215-231.Al-Barzinjy, S. T. M., 2005. Stratigraphy and basin analysis of Red Bed Series from northeastern Iraq-Kurdistan Region. Unpublished Ph.D. thesis, University of Sulaimani University, 159p.Al-Brifkani, M.J. N.2008. structural and tectonic analysis of the Northern Thrust Zone (East Khabour River). Unpublished Ph.D. Thesis, University of Mosul, 160P.Al-Kadhimi F., Sissakian V., and Duraid, 1996. Tectonic map of Iraq. GEOSURV , Baghdad.Al-Mehaidi, H.M., 1975. Tertiary nappe in Mawat Range, N.E Iraq, Jour. Geol. Soc. Iraq, Vol. 8, pp31-44.Al-Qayim, B. 2000. Sedimentation and tectonic environment of the Suwais Red Beds, NE-Margin of the Arabian plate-5th international on the geology of the Arab world, Egypt. Abstract book, p.112.Aswad, K. J (1999) Arc-continental collision in Northern Iraq as evidenced by the Mawat and Penjween Ophiolite Complexes. Raf. Jour. Sci. Vol.10. No. 1., pp.51-61Bolton, C.M.G., 1958.The Geology of Ranya area. Site Inv. Co. Unpubl. Report, SOM Library, Baghdad . Aswad, K. J. and Elias, E.M.1988. Petrogenesis and geochemistry and metamorphism of spilitized subvolcanic rocks, Mawat Ophiolite Complexes. NE-Iraq. Ofioliti, 13,: 95-109. Buday, T. 1980. Regional Geology of Iraq, vol. 1 Stratigraphy, I.I.M Kassab and S.Z. Jassim (Eds) D. G. Geol. Surv. Min. Invest. Publ. 445p. Buday, T., and Jassim, S. Z., 1987. The Regional geology of Iraq: Tectonism Magmatism, and Metamorphism . I.I. Kassab and M.J. Abbas ( Eds ) , Baghdad, 445 p.Bellen, R. C. Van., Dunnington, H. V., Wetzel R. and Morton, D., 1959. Lexique Stratigraphique, Interntional. Asie, Iraq. vol. 3,c. 10a, 333 pp. Dunnington, H. V. 1958. Generation, migration and dissipation of oil in Northern Iraq. In : Arabian Gulf, Geology and productivity. AAPG Foreign Reprint Series No. 2. Jassim, S. Z. and Al-Hassan, 1977. Petrography and Origin of the Mawat and Penjwin igneous complexes. Jour Geol Soc. Iraq. Special Issue on 4th Iraqi Geological Conferences, Baghdad, 1976.Karim, K. H. 2004a. Some sedimentary and structural evidence of possible graben in Chuarta-Mawat area, Sulaimanyia area, NE-Iraq. Journal of Iraqi Science, Vol. 5, No.2, pp.9-18.Karim, K. H., 2004b. Basin analysis of Tanjero Formation in Sulaimaniya area, NE-Iraq. Unpublished Ph.D. thesis, University of Sulaimani University, 135p.Karim, K. H. and Surdashy, A. M., 2005a. Paleocurrent analysis of Upper Cretaceous Foreland basin: a case study for Tanjero Formation in Sulaimanyia area, NE-Iraq, Journal of Iraqi Science, Mosul University, Vol. 5, No.1, pp.30-44.

Karim, K. H. and Surdashy, A. M., 2005b. Tectonic and depositional history of Upper Cretaceous Tanjero Formation in Sulaimaniya area NE-Iraq. JZS, Vol.8, No.1.Karim, K. H. and Surdashy, A. M., 2006. Sequence stratigraphy of Upper Cretaceous Tanjero Formation in Sulaimanyia area, NE-Iraq. KAJ, Vol.4. No.1.Karim, K. H., Al-Barzinjy S. T. and Ameen, B , M.2008. History and geological Setting of Intermontane in in the Zagros Fold-Thrust Belt, Kurdistan Region, NE-Iraq. Iraqi Bulletin of Geology and Mining , GEOSURV, Vol.4. No.1. pp.12-33.Lawa, F. A. 2004. Sequence stratigraphic analysis of the middle Paleocene –Middle Eocene in the Sulaimani District (Kurdistan Region). Unpublished Ph. D. thesis, University of Sulaimani. Numan, N.M.S., 1997. A plate tectonic scenario for the Phanerozoic succession in Iraq. Iraqi Geological Journal, vol. 30, no. 2, pp.85-110.Numan, N. M. S. 2000. Discussion of “dextral transpression in the Late Cretaceous continental collision, Sanandaj–Sirjan Zone, Western Iraq”. Journal of Structural Geology, Vol.22, No.8. p.1125–1139.Numan, N. M. S. and Al-Azzawi, N.K. 2002. Progressive versus paroxysmal Alpine folding in Sinjar Anticline, Northwestern Iraq. Iraqi Jour. Earth of Sci., 2(2), p.59-69.Omar, A. A. 2006. An Integrated Structural and Tectonic Study of the Bina Bawi-Safin-Bradost Region. Unpublished Ph. D. Thesis, University of Salahaddin, 230pTurrini, C. Ravaglia, A. and Perotti, C. R., 2001. Compressional structures in a multilayered mechanical stratigraphy: Insight from sandbox modeling with three–dimentioinal variations in the basal geometry and friction. In: Tectonic Modeling by H. A. Koyi and N. L. Mancktelow. (Editor) Geological society of America Memoir 193 p. Schreurs, G. Hanni, R. and Vock , P., 2001. Four-dimensional analysis of analog model: Experts on transfer zones in fold and thrust belts. In: Tectonic Modeling by H. A. Koyi and N. L. Mancktelow.(Editor)Geological society of America Memoir 193p. Marshak, S., 2004. Salients, recesses, arcs, oroclines, and syntaxes—A review of ideas concerning the formation of map-view curves in fold-thrust belts, in K. R. Mc Clay, ed., Thrust tectonics and hydrocarbon systems: AAPG Memoir 82, p. 131 – 156.

HISTORY AND GEOLOGICAL SETTING OF INTERMONTANE BASIN IN THE ZAGROS FOLD-THRUST BELT, KURDISTAN REGION, NE-IRA

KAMAL H. KARIM , SHERZAD TOFIQ AL-BARZINJY AND BAKHTIAR, M. AMEEN

Published in: Iraqi Bulletin of Geology and Mining, Vo.4, No.1, 2008, p21-33

ABSTRACTIt is mentioned previously that the intermontane basins, in northeastern Iraq, are developed in the Early Paleocene. In present study, the timing, geographic location and geological setting of these intermontane basins are studied from Iraqi Zagros Fold-Thrust Belt during Tertiary. The study achieved in view of literature and recent sedimentological studies. The terrigenous clastic cutoff and facies comparison with their distribution is used as evidence for spatial and temporal development of intermontane basin. The study concluded that the first intermontane basin is developed during the Middle Eocene. It is observed that the present position of Thrust and Imbricated Zones of Iraq was area of subsidence and generation of the intermontane basin during Middle Eocene. Concurrently with this subsidence and directly to the southwest of the latter zone a narrow paleohigh is developed which separated subsidence from the main basin. The present position of the paleohigh coincides with of the boundary High and Imbricated Zones. In these intermountain basin the flysch facies (sandstone and shale of Walash Nauperdan Group) are deposited at the beginning while later molasses facies (conglomerate of upper part of the Red Bed Series) are dominated. Concurrently, in the area of present Low Folded and Mesopotamian Zones (main water body of the main foreland basin) thick succession of pure carbonate (Pila Spi Formation) was deposited signalize the total cutoff of clastic sediments from the latter zones In contrary, during the Early Paleocene till Middle Eocene clastic (conglomerate and sandstone) influx was continued from source area into Early Zagros foreland basin and mixed (occasionally) with carbonate of Sinjar Formation in many places. During these latter ages, intermontane basin is not generated as cited in previous studies to trap transferred sediments from source area except some basin irregularities on which reefal limestones of Sinjar Formation are deposited. The separation of Early Zagros Foreland basin into two smaller basins (Main foreland basin and intermontane basin) decreased the current circulation and wave activity therefore lagoonal dolomitic limestone of Pila Spi Formation was deposited.

INTRODUCTIONThe studied area is located in the Kurdistan Region, Northeast Iraq near the with Irani− Iranian border (Fig.1). This area forms the three main (present days) tectonic zones of Iraq (High, Imbricated and Thrust Zones) of Buday and Jassim (1987) ( Fig.2).The area is part of the Western Zagros Fold-thrust Belt, which is developed from colliding of Arabian and Iranian Plates and sedimentary fills of Neotethys basin (Alavi, 2004). The aim of this study is to record a new historical development and geological setting of intermontane basin in the Iraqi part of the Zagros Fold-thrust Belt. The study achieved in the through re-interpretation of the sedimentologic (sedimentary facies) and stratigraphic works of Bellen, et al (1959), Buday, (1980) and Al-Barzinjy, (2005) about the area during Tertiary.Intermontane basins are commonly elongate, narrow and evolved during late orogenesis and are associated within volcanism (Einsele, 2000). Small superficial, extensional intermontane basin exists in the present Andes Mountain is due to warping during subduction (Mail, 1990). Clevis et al (2004) has mentioned basins on the thrust- sheets under the name of “top thrust-sheet basin” , which are formed due to detachment faults. They assumed them as common features in foreland basin. Allen and Allen (1990) referred to generation of intermontane basins on the megasuture blow thrust sheets. These basins resemble the intermontane basin of Iraq where the oldest intermontane basins are those mentioned by Buday and Jassim (1987) in which molasses are deposited during Paleogene and located in the Tanjero-Balambo Zone. However, , maps are published maps by Buday (1980); Jassim and Goff (2006) (Fig.3) showed that these basins have started from Paleocene and continued till Middle Miocene and located in the present position of Thrust and Imbricates Zones.

Al-Hashmi and Amer (1985) separated Red Bed Series from Khurmal Formation (time equivalent of Sinjar Formation) by positive land (Fig. 4A, B, C). Surdashy (1989) has also separated the Red Bed Series as intermontane basin from the basin of Kolosh Formation during Paleocene and Eocene (Fig.4D). In the Tectonic Scenario of Iraq, Numan (1997) separated the Red Bed Series from the main basin of Iraq during Paleocene. He indicated the Red Bed Series in a basin between Kata Rash and Walash volcanic arcs, which resembles more or less the intermontane basin, since it is separated by positive land (Fig.5A). Lawa (2004) mentioned and showed (by sketch) that piggyback (intermontane basin) started in the early Paleocene which was filled with molasse deposit (Fig.5 B, C). According to the above studies, at the Early Paleocene, the narrow strip of Halabja, Said Sadiq, Sulaimanyia City, Ranyia and Rawandoz waslocation of a paleohigh (positive land), which separated the area that are located to the north and south of these towns. The southern and northern areas are called (previously) Mio and Eu-geosynclines, respectively, while in the present study they are called Main and Sub-Foreland Basins. The Main Foreland Basin occupies (as assumed in this study) the Low and High Folded Zones while the Sub-Foreland Basin occupies a southern part of the Thrust Zone and whole Imbricated Zones. But, during Campanian till Middle Eocene one large basin existed, which is called Early (proto) Zagros Foreland Basin (Fig. 6C and 7C).

Fig.1: Simplified geological map of the studied area (modified from Sissakian, 2000) showing location of intermontane basin during Middle Eocene.

Fig. (2) A: Location map of the studied area.

Fig.(3) A and B: Early Eocene and Oligocene paleogeography of the Iraq, showing intermontane basin in the northeastern Iraq ( after Jassim and Goff, 2006).

GEOLOGICAL SETTINGThe recent sedimentological and stratigraphical studies amended the geology of the studied area through simplifications of the tectonics. Due to this geographic position and history of the development of the intermontane basins can be realized with the type of separation from main water body. Among the studies that are indirectly related to this idea are the study of Karim and Surdashy (2005a and 2005b) which changed the tectonic setting of Tanjero Formation from subduction trench to early Zagros Foreland basin during Maastrichtian. They combined both Mio and Eogeosyncline in one single basin. Another study is that of Al-Barzinjy (2005), which concerned mainly with relation between Red Bed Series and Kolosh Formation. He concluded that both them (Red Bed Series and Kolosh Formation) are deposited in a single basin and there was no any paleohigh between the two units during Paleocene and Early Eocene. According to the Al-Barzinjy (2005), the Red Bed Series was deposited in the present position of the Imbricated Zone as coastal facies, while at the same time; Kolosh Formation is deposited in the basin plain, in the location of the present day High Folded Zone.

Fig.4: Different ideas about timing, tectonic setting and geographic location of the intermontane basin by different authors. A, B and C: By Al-Hashmi and Amer (1985). D: By Surdashy (1989).

Fig.5: A): Tectonic position of Red Bed Series between Kata Rash and Walash Volcanics, by Numam (1997). (B, C) Model and cross section of Early and Middle Paleocene paleogeography and tectonic setting of piggy back (intermontane) basin (Lawa, 2004).

Fig.6: The conclusions of present study as shown by conceptual models of paleogeography and tectonic evolution of the intermontane basin in Iraq. A: Middle Eocene, B: Lower Eocene, C: Upper Cretaceous and Paleocene.

Fig.7: Cross sections of the same ages and models that are shown in the fig. (6) showing generation of intermontine basin during Middle Eocene as inferred from present work.

FIRST APPEARANCE OF INTERMONTANE BASINThe first appearance time of the intermontane basin could be known only through a sedimentological study of a studied area. This includes the study of the types, calibers and distribution of the terrigenous sediments in both Imbricated and High Folded Zones. During the study of these sediments the hydrodynamic and lithology (mineralogy) are taken into consideration. The first and the prominent terrigenous sediments cutoff occurred during Middle Eocene. This cutoff is demonstrated by extensive deposition of nearly pure lagoonal carbonates of Pila Spi Formation. This deposition was relatively sudden and covered most part of the northern Iraq especially the High and Low Folded Zones (Main Foreland Basin). These carbonates lack clastic interbeds, which indicate the separation of the Sub-Foreland (Intermontane) Basin from the main foreland basin by a narrow paleohigh (Fig.6A and 7A). The present position of the paleohigh nearly coincides with of the boundary High and Imbricated Zones. The cutoff of the clastic sediments and deposition of carbonates is well

documented by Dunnington (1958) by isopach facies map (Fig.8). On the map, he assumed the Imbricated and Thrust Zones as source area and showed that the carbonate deposition is located to the south of boundary between High Fold and Imbricated Zones.

Fig.8:Isopach facies map of Middle–Upper Eocene showing extensive carbonate deposition (After Dunnington, 1958).

INTERPRETATION OF CLASTIC SEDIMENTS CUTOFFThe clastic cutoff and deposition of carbonates are clear evidences for separation of the source area (present days Iraqi Thrust Zone and Sanandij-Serjan Zone of Iran) from the main body of the water that was covering the rest of Iraqi territory. The deposition carbonates (Pila Spi Formation) started during Middle Eocene (Bellen, et al. 1958; Buday, 1980) therefore, at this time a paleohigh was developed that was led to the total cutoff the clastics and an intermontane basin was formed to the north of the paleohigh and concurrently the area that now covered by Imbricated and Thrust Zones are subsided (Fig.6A and 7A). But the paleoghigh was too narrow to supply sufficient clastics to main foreland basin to be detected. Instead of transportation of sediments to the south and southwest, the clastics were trapped in the post Middle Eocene intermontane basins (areas of the subsidence) and deposited as Walash Naoperdan Group. The generation of these basin associated with retreat of the source area, northeastwards to a position which may coincide with the present position of Sanandij-Sirjan Zone, inside Iran. The paleohigh was too small and tight to perform as new source areas. Other consequences of the separation of the Early Zagros Foreland Basin into Main Foreland Basin and intermontane basin was restriction of current circulation and wave activities in addition to cease of fresh water influx. Due to this, semi-restricted lagoonal sediments (dolomite and limestone) are deposited which were isolated from sediments and fresh water influx from northeastern source areas. The most important characteristics of the generated intermontane basin is the fineness of the clastic sediments as compared to the that deposited in the coastal area of the early (proto) Foreland Basin before separation. Karim and Surdashy (2005a and b), Al-Barzinjy (2005) concluded that during Upper Cretaceous and till Middle Miocene the area of the sub-Foreland basin (previous Eugeosyncline) was deposition locus of the thick pile of conglomerates and sandstone (Tanjero Formation and unit one and two of the Red Bed Series ). This position was coastal area for the Early Foreland basin during Late Cretaceous and till the Middle Eocene.In contrary to the Main Foreland Basin, in the intermontane (Sub-Foreland) Basin, the conglomerates are missing and fine clastics are deposited. These fine clastics coincide with the principle of sedimentation and with the deposition of carbonates (Pila Spi Formation) in the main water body. The fineness of clastic are attributed to three reasons, the first is retreating of source area into Iranian land, due to subsidence of the previous coastal area. The second is generation of a barrier (the paleohigh) in front of the paleocurrent direction, which led to a decrease of dynamic energy of the transportation and sedimentation. The third is that the intermontane basin is formed in the frontal part of the foreland fold-thrust belt, which decreased the accommodated space for submarine turbidity currents. The fine clastics are represented by Walash Naoperdan Group (flysch facies), which consist mainly of shale, sandstone limestone and igneous rocks (Fig. 6A and 7A) that deposited at early stage and later, changed to molasse facies (upper part of the Red Bed Series) when the basin filled with sediment. During the deposition of flysch facies, it is possible that the biogenenic carbonates (Naoperdan Limestone) were deposited in the shallow areas where there are no turbidite.

POSSIBLE PALEOCENE INTERMONTANE BASIN During Late Paleocene Sinjar and Khurmala Formations, were deposited at the boundary between High and Low Folded Zones, inside main foreland basin (inside previously so called miogeosyncline).These formations consist of reefal facies. They have limited distribution as compared to Pila Spi Formation which, occurs as, northwest-southeast strip about 15km wide along the above mentioned boundary. The Sinjar Formation is supposed to be deposited in submerged high as reefal facies by (Al-Hasmi and Amer, 1985 and Surdashy, 1989) (Fig.4B and D). About this paleohigh and possibility of Paleocene intermontane basin, it deserves to clarify two points in this study. The first is that the Sinjar Formation was deposited at the top of Kolosh Formation which consists of flysch facies (basinal sandstone and calcareous shale). The top of this unit represents the shallowing episode due to filling and tectonic uplift, during which Sinjar Formation was deposited. While in Sub-Foreland (Intermontane) Basin the clastics (sandstone) of the Red Bed Series (part one and two) were deposited, in Chuarta, Mawat, and Qandil areas (Al-Barzinjy, 2005).The second is that unlike to Pila Spi Formation, Sinjar and Khurmala Formations, in most places, contains coarse clastic interbeds. At Sartak Bamo valley, Baranan Mountain (Fig.8 A and B), Barda Asin (east of Zarain town) and Sagram anticlines and Darbandikhan dam site (Fig.10), Sinjar Formation contains terrigenous conglomerates. According to Al-Banna, et al (2007), at Dohuk area the equivalent of Sinjar Formation (Khurmala Formation) contains conglomerates, sandstones, shales and marls (Fig.11). These authors showed that the limestones beds are sandy also. This means that the Sinjar and Khurmala Formation were not separated by positive paleohigh from the source area and the intermontane basin was not formed yet. The Sinjar Formation is possibly separated partially and intermittently, in some places, by irregularities (submerged high) that prevented high influx of clastics and turbidity current to the basin of Sinjar

Formation (Main Foreland Basin). In these places, Sinjar Formation is composed of pure limestone and without conglomerate interbeds. These areas such as Glazarda and Bazian, where there are more or less occurrences of pure reefal limestone of the formation (Fig.6B). Therefore, the map and tectonic setting of the Middle Eocene is shown in the figure (12), which indicates position of the paleohigh and location of the deposition of Pila Spi Formation and Walash -Naopewrdan Group.

Fig. 9: A) Sections of western side of Sartaq Bamo valley ( east of Darbandikhan dam) showing main exposed units, the pure carbonate of Pila Spi Formation( 200m thick) can seen at top of a section is 450m thick. In many places Sinjar Formation contain conglomerate and terrigenous clasts.B) The photo shows pebbly limestone of Sinjar Formation at Baranan (Glazarda Homocline) mountain south of Sulaimanyia city.

Fig. 10: A) Outcrop section of Pila Spi, Gercus and Sinjar formations in the main Foreland Basin(previous Miogeosyncline). Sinjar Formation contains interbed of conglomerate and sandstone, while Pila Spi Formation is exclusively limestone. B) Polished slab (4cm wide) of the latter formation contains algae.

Fig.11: Eastern part of Dohuk dam valley showing thick outcrop of Pila Spi Formation and clastics of pre –Middle Eocene. The Khurmala Formation is less than 10m thick. The clastic influx cutoff is very clear with deposition onset of Pila Spi Formation.

Fig.12: Lithofacies map during Middle Eocene and geologic block diagram of the same age showing intermontane basin as inferred from the present work.

CONCLUSION•The previous Early Paleocene as starting point fore evolving of the intermontane basins is changed to Middle Eocene.•The Pila Spi Formation and Walash Naoperdan group are connected with this development as sediments of the main basin and intermontane basin respectively.•The reason for this new age is total terrigenous clastic cutoff influx from source areas to the previous clastic dominated basin.•The study solved the problem of great uncertainty that associated with history and tectonic of Walash-Naoperdan Group.

REFERENCESAl-Banna, Y.N, Al-Mutawali and M. M., Al-Ghrear, J. S. , 2007. Facies depositional environments of Khurmala Formation in Bekhair anticline-Dohuk area, North Iraq. Iraqi Jour, Earth Sci. Vol.6, No.2, p.13-22Al-Barzinjy, S. T. M., 2005. Stratigraphy and basin analysis of Red Bed Series from NE-Iraq, Kurdistan Region. Unpublished Ph.D. thesis, University of Sulaimani, 159pp.Al-Hashimi, H., J. and Amer R., M., 1985. Tertiary Microfacies of Iraq. GEOSURV Baghdad. 56pp.Alavi, M., 2004. Regional stratigraphy of the Zagros fold-thrust belt of Iran and its proforeland evolution. American Journal of Science, Vol.304, pp.1-20.Allen, P.A. and Allen, J.R. , 1990. Basin Analysis: Principle and Application, Balckwell, London, 451p. Bellen, R. C. Van, Dunnington, H. V. Wetzel, R. and Morton, D., 1959. Lexique Stratigraphique, Interntional. Asia, Iraq, Vol. 3c. 10a, 333 pp. Buday, T., 1980. Regional Geology of Iraq: Vol. 1, Stratigraphy: I.I.M Kassab and S.Z. Jassim (Eds) GEOSURV. Pub. 445pp.Buday, T. and Jassim, S.Z., 1987. The Regional geology of Iraq: Vol. 2, Tectonics Magmatism, and Metamorphism. I.I. Kassab and M.J. Abbas (Eds), Baghdad, 445 pp.Clevis, Q., de Jager G., Nijman, W. and . de Boer P. , 2004. Stratigraphic signatures of translation of thrust-sheet top basins over low-angle detachment faults. Basin Research, vol. 16, p.145–163. Dunnington, H. V. ,1958. Generation, migration and dissipation of oil in Northern Iraq. In : Arabian Gulf, Geology and productivity. AAPG Foreign Reprint Series No. 2.Einsele, G. , 2000. Sedimentary Basin: Evolution, Facies and Sediment Budget. 2nd ed. Springer, Verlage Berlin 792pp.Jassim, S.Z. and Goff, J.C., 2006. Geology of Iraq. Dolin, Prague Museun, Berno. 341pp.Karim, K.H. and Surdashy, A. M., 2005a. Paleocurrent analysis of Upper Cretaceous Foreland basin: a case study for Tanjero Formation, NE-Iraq, Journal of Iraqi Science, Vol. 5, No.1, pp.30-44. Karim, K.H. and Surdashy, A. M., 2005b. Tectonic and depositional history of Upper Cretaceous Tanjero Formation, NE-Iraq. JZS (Journal Sulaimaniya University), Vol. 8, No.1, p.47-62. Lawa, F.A., 2004. Sequence stratigraphic analysis of the middle Paleocene –Middle Eocene in the Sulaimani District( Kurdistan Region). Unpublished Ph.D. thesis, University of Sulaimani. Mial, A. D., 1990. Principles of Sedimentary Basin Analysis, 2ed Edi., Springer Verlag. 668p. Numan, N.M.S., 1997. A plate tectonic scenario for the Phanerozoic Succession in Iraq. Iraqi Geol. Jour. Vol.30, No. 2, p 85–110. Sissakian, V. K., 2000. Geological map of Iraq. Sheets No.1, Scale 1:1000000, State Establishment of Geological Survey and Mining. GEOSURV, Baghdad, Iraq.Surdashy, A. M. ,1889.Microfacies and depositional environment of Sinjar Formation in selected section from Sulaimanyia area, NE-Iraq. unpublished Ms thesis, University of Salahaddin, 140p.

Tectonic and depositional history ofUpper Cretaceous Tanjero Formation in Sulaimaniya Area, NE-IraqKamal Haji Karim*1 and Ali Mahmood Surdashy*2

*1: University of Sulaimani, Geological department*2: University University of Koyia, College of Oil and Minerals

Published in: (JZS) Journal of Zankoy Sulaimani, 2005, Vol.8. No.1 Part A , p.47-61.

AbstractThe basin of (Upper Cretaceous) Tanjero Formation is combined (tectonically) with that of the underlying Shiranish Formation and named Upper Cretaceous Zagros Early Foreland Basin instead of previous miogeosyncline and trench. In this basin Tanjero Formation is deposited in the near shore area in front of southwest advancing positive land of Iranian plate. This near shore area is called Upper Cretaceous Depocenter, whereas, the underlying Shiranish Formation a summed to be deposited in the deeper central part of the basin, which is called Upper Cretaceous Basin Center. The advancing of the hinterland (Iranian plate front) is very clear from southwest position changing of the shelf for about 20km. The shelf of lower sequence was near the Iranian border during Upper Campanian while it migrated to the area around Chuarta and Mawat Towns during middle Maastrichtian. It was inferred that most part of the formation is deposited by forced regression during collision of Iranian and Arabian plate. During this regression both flysch and molasses facies are deposited.

Introduction Tanjero Formation is an Upper Cretaceous (Campanian-Maastrichtian) unit, which crops out within the Imbricated and High Folded Zones in Northeastern Iraq Buday (1980) [1] and Buday and Jassim (1987)[2]. It stretches as narrow northwest-southeast belt near and parallel to the Iranian border (Fig. 1). The formation mainly consists of alternation of sandstone, marl and calcareous shale with occurrence of very thick conglomerate and biogenic limestones (Bellen et al. 1959)[3]. On the basis of main lithological distribution, it is divided the formation into three parts (lower, middle and upper parts Karim (2004)[4]). These parts are correlated across eight different sections (Fig. 2). The correlation is based on lithology and stratigraphic position of distinctive conglomerate and its derivative Sandstones, which are discussed in detail n different geo graphical localities in the paper. The lower part (lower regressive part) is mainly composed, on the lower slope and basin, of thick succession of sandstone (100-400m), whereas on the shelf it is dominated by 500m thick succession of conglomerate (in this study, called Kato conglomerate). The middle part is composed of 100-300m of bluish white marl and marly limestone on the slope and basin whereas it changes to calcareous shale on the shelf and to 20-50m thick of red claystone inside incised valleys. The upper regressive part consists chiefly of 50-200m thick mixed carbonate-siliciclastic successions (in this study, named Kato Mixed Carbonate-Siliciclastic Successions).The constituents of this succession are alternation of biogenic limestone and calcareous shale with miner amount of sandstone and conglomerate. He also found both flysch and molasse facies in the lower part of the formation in the distal and proximal area of the basin respectively.

Tectonic history It can be inferred from the facies distribution maps given by Buday, (1980) [1] that the basins paleoslope direction (depositional dip) was toward northeast during Lower Cretaceous till Middle Turonian. During later ages (Coniacian and Santonian) the general basin paleoslope direction was reversed 180 degree toward southwest during Upper Cretaceous. This reversal case is associated with colliding of continental parts of Arabian and Iranian Plate after deposition of Qamchuqa and Balambo Formation in the studied area. This colliding occurred after the oceanic crust is exhausted and then the two related continents are collided. Before this, the studied area was passive continental margin (carbonate platform) and bordered from the north by subduction trench (active continental margin). The collision finally changed the area of subduction to positive land and studied area to foreland basin (Fig 5B and 7). According to Karim (2003a)[5],during this process, the previously deposited Qulqula Formation compressed, as accretionary prism, between two plates and uplifted forming positive land and source area.According to Buday (1980, p.402) [1] the miogeosyncline was separated from unstable shelf by a ridge. He mentioned that the continuation of this ridge is not clear enough in the area southeast of Ranyia Town (part of the studied area). In the present study, the absence of this ridge is proved in the Sulaimaniya Governorate. It is observed that the present position of Azmir, Goizha, Piramagroon, Sara, Qarasard and Kosrat anticlines (Fig. 1 and 3) was part of the slope of the Tanjero basin, while the present position of Haibat Sultan, Tasluja and Baranan homocline most possibly comprised part of the basin plain of the formation. The deposition, bypassing and erosion of sediment occurred extensively during deposition of Tanjero Formation on the position of former anticlines (Azmir, Goizha, Sara and Kosrat). So there were not any major irregularities (submerged paleohigh or geoflexture) in the basin of Tanjero Formation, in the studied area, during deposition.

The possible tectonic activities are observed as following:At the beginning of the deposition of the lower sequence (proved to include Kometan, Shiranish and part of Tanjero Formation, the studied area suffered from clear deepening. This is proved from field work which is demonstrated by deposition of deep pelagic Kometan Formation over shallow marine reefal Qamchuqa Formation. This transgression may be reflection of prominent subsidence due to tectonic loading of the existed platform. The over loading is happened by colliding of Iranian and Arabian plate by which the former plate thrusted over the latter and advanced toward position of Tanjero basin. The thrust has uplifted the area the area that located to the north and northwest of the studied area and source area.

This is probably started from Campanian and continues till the beginning of Tertiary and forming active continental margin. Uplifting created a southwest advancing positive tectonic front (frontal part of Iranian plate). The continuous erosion of this front shed large quantity of clastic sediment into the Tanjero basin. It is possible that later in the early Tertiary, the position of the slope was acted as geoflexture for the existing present anticlines. The sequence stratigraphy proved that the facies of the Tanjero Formation have migrated to south and southwest in such way that the position of the shelf, slope and basin plain changed during lower and upper sequences, mostly by forced regression. This regression is due to eustatic sea level change with the aid of tectonic uplift of source area and possibly part of the basin. The high thickness and coarseness of the Kato conglomerate is evidence for above-mentioned facts. The high tectonic and elevated source area is opposed in the basin by slight subsidence and general gradual shallowing, which is in some time, demonstrated by incised valleys (see Karim 2004) [4]. In some cases, they have scoured the shelf down into the Shiranish Formation such as the Iran and Qandil sections (Fig.2). At Iranian section the thickness of formation consists only of Kato conglomerate and typical lithology of Tanjero Formation is absent.

Previous ideas about tectonics of the basinPrevious workers have published the following ideas on tectonic and depositional history of Tanjero Formation:

Miogeosyncline ideaAccording to these ideas, the formation is deposited in miogeosyncline realms (deep marine trough) in which flysch sediments are deposited by turbidity currents (Buday, 1980[1]; Buday and Jassim 1987[2], Kettaneh and Sadik, 1989[7] and Lawa et al., 1998) [8]. But in the present study, both Tanjero and Shiranish Formations are considered as lateral and vertical facies change of each other and the

differences between the two formations are only attributed to nearness to the shore and source rocks not to tectonism. Now these types of facies can be clearly explained by relative sea level change in sequence stratigraphy. In the present study both Shiranish (and Shiranish-like lithology) and Tanjero Formation are combined in single depositional sequence and even in single system tract (when distal and proximal lithologies of HST and TST is considered). In all ancient and recent basins, it is normal to see the near shore (proximal area) to more uplifting and sedimentological activities than the central part of the basin. This fact is interpreted previously, as regarded to Tanjero Formation, deposited during abnormal tectonic activity.

Tanjero Formation: Transgressive sediment Previously Tanjero Formation was considered as transgressive sediments Buday (1980, p.402) [1] and Minas (1997) [9]. Other authors mentioned intense subsidence of the Upper Cretaceous basin (Marouf, 1999) [10]. But in the present study it is proved that nearly all the typical lithology of the formation is deposited during major forced regression (LST), which is discussed in detail below.

Present ideas The following ideas of the present study are based on fieldwork, recent new sedimentological and stratigraphic principles which are applied on the studied area.

Same tectonic setting of Shiranish and Tanjero Formations: While the tectonic of Tanjero Formation is exaggerated in the above-published ideas, nothing is mentioned about tectonic of Shiranish Formation. In the present study, Tanjero Formation is neither sedimentologically nor tectonically separated from basin of Shiranish Formation. Also the unstable shelf and previous miogeosyncline is united in single basin named Upper Cretaceous Early Foreland Basin, all these are deduced from the following: The contact between the two formations is gradational and they laterally interfingering Bellen et al. (1959) [3] and Buday, 1980) [1]. This was also observed in the field by the present author. The same above authors mentioned that Shiranish basin extends to unstable shelf (to near central Iraq) (Fig.6 and 7). Therefore, according to traditional and sequence stratigraphy, both formations form one sequence, one depositional basin, and affected by one cycle of sea level changes. Therefore both formations must be put in one single basin of same tectonic setting. In all areas of distribution of both formations, the extent of Shiranish Formation is more than Tanjero Formation. Therefore the former formation acts as a carpet for the latter one. We called this relation between the two formations “a sleeping man on a carpet” which means that Tanjero is the man and Shiranish Formation is the” carpet”.

The paleocurrent direction (see Karim 2004) [4] indicates the general direction of south and southwest, which shows no any separation of the region called “miogeosyncline” and “unstable shelf” from each other during Upper Cretaceous. Previously these two zones were assigned for sedimentation of Tanjero and Shiranish Formations respectively. In the present study the miogeosyncline basin (previously assigned as basin for Tanjero Formation) is changed to upper Cretaceous depocenter and unstable shelf to Upper Cretaceous basin center (Fig.7). Both basin center and depo-centers combined to form a broad southwest sloping Zagros initial foreland basin. This basin was bordered, from northeast, by recently uplifted (or over-thrusted) positive land, which was migrating continually. Karim( 2004)[4] found both land plant and 500m of boulder conglomerate which are direct evidence for positive land mountain belt). This terrestrial land drained by initial drainage pattern which most possibly of parallel type. This pattern is formed at the front of the thrust sheet (or reverse fault) formed a scarp. This pattern included many deep valleys through which water and sediments of many small watersheds (possibly less than 400km2 for each drainage basin) were delivered (drained) to the basin (Fig. 7). During relative sea level fall (LST) these valleys, more and more advanced towards the basin by scoring of the delta plain and shelf sediments of previous HST. During this sea level fall, the coarse sediments are deposited as alluvial fans in the coastal area of the basin and part of these fans were built in to the main body of the sea forming fan delta (Fig.7). The valleys mentioned above are called incised valleys; three of these valleys are ascertained and mapped in the field. These valleys are filled with Kato conglomerate on the shelf and with both alternation of sandstone and conglomerate on the Upper slope and sandstone and shale at lower slope and basin floor. In North America Bhattacharya and Willis (2001) [11] described, in detail, a lowstand system tract in foreland basin during Cenomanian. The content of the lowstand is much similar to that of lower part of Tanjero Formation in the view of lithology, trace fossil (cruziana and skolithos) and sedimentary structures (HCS, Cross bedding)(see Karim 2004) [4]. Although Kolosh Formation has nearly same lithology as the Tanjero Formation, it is tectonically separated from miogeosyncline and regarded as a unit of unstable shelf by above authors. In the present study, the three formations (Shiranish, Tanjero and Kolosh) have given same rank of tectonics (early foreland basin or syn -collision active margin). The only difference is the possible depocenter migration toward southwest for about 25 km (estimated only) as regarded to position Tanjero Formation. Even Aqra-Bekhme Formation is included in the basin as reefal facies on local submerged paleohighs. Recording of abundant plant debris is good evidence for existing of lands that surround the basin. For this and other evidence cited above the basin is called foreland basin.

Initial (early) foreland basin Bate and Jackson (1980) [12] defined foreland basin as:A stable area marginal to an orogenic belt, toward which the rocks of the orogenic belt were thrust or over folded. Generally, the foreland is a continental part of the crust and is the edge of craton or platform area. In this study the Tanjero basin is considered to be initial foreland basin so the above definition can be applied to this basin when considerable amount of activity is given to the basin because of its early development. The applicability of the definition is attributed to the following:The basin of Tanjero formation was relatively stable as compared to thrust sheets and over-folded source area of the formation which located in the Iran Territory. Another reason for relative stability of the basin is the basin shows no igneous activities. In other side, more active area is the source area of the Formation which includes Qulqula Formation, Ophiolite Complex and Qandil Group. All these represent the orogenic belt of the above definition.As seen in sequence stratigraphy sea level fall and rise of the formation is nearly coinciding with the 3rd order eustatic sea level change. This is meaning that the tectonic was not so intense to obscure the effect of eustatic sea level change. The final reason for relative stability of the basin is the fact that the basin of Tanjero Formation is characterized by growth of the thickest and best reefal limestone. These limestones include both Aqra-Bekhme Formation and Kato Mixed Carbonate-Siliciclastic Succession. Both the formation and the succession are consisting of thick rudist and large foram bearing limestone which proves the relative stability of the basin with constant subsidence as all other basins. All these prove that the Tanjero basin was not tectonically so active such as estimated previously. This is true also for depth which was shallower than that assigned before. Einsele (2000, p.606) [13] called

this type of initial foreland basin “remnant basin” which is more active and deeper than the foreland basin. According to him it is largely filled with deep-water flysch sediments and confined with, on one side, by pre-existing passive continental margin (platform) (western desert in case of Iraq) with wedge of older clastics and carbonate sediments. On the other side, an approaching thrust belt confines the formation.Qulqula Radiolarian Formation (accretionary prism) represented the thrust belt (in case of Tanjero basin) (Fig.5B). This prism (after erosion) is shedding relatively large volume of various clastics in the form of turbidites and mass flow deposits into the basin. The actual position of Tanjero Formation may be located in transition zone between foreland and remnant basin. Balambo and Qamchuqa Formations were forming the platform during Lower Cretaceous and Tanjero Formation started deposition on top of these formations after rapid subsidence. This rapid subsidence led to the deposition of Kometan Formation. Later, when the source area was uplifted and sea level was lowered (during most times) Tanjero formation was deposited. In foreland basins, sediment shallows up from deep water to shallow marine and then continental sedimentation (Mail, 1995) [14]. This type of shallowing is exactly applicable for Tanjero Formation and Red Bed Series, which have gradation contact (in some place) in the area of the study. In this connection Doyle et al. (2001, p.111) [15] mentioned that the sediments of foreland basin deposited in mostly river and deltaic environment and consist of heterogeneous gravel, sands and muds derived from orogenic belt.

Syn -collision ideaIn contrary to pre-collision model, the present study assigned to the setting (tectonic model) of the Tanjero basin to syn-collision of the Arabian and Iranian plates (collision of their continental parts). The birth of Tanjero Formation started when Qulqula Formation (as an accretionary prism) was uplifted after the collision of the two plates. The relatively sudden start of the clastic influx and gradual increase of grain size to coarse conglomerate indicated uplift of the Qulqula Formation by thrusting or block faulting. When an oceanic basin completely closed with the total elimination of oceanic crust by subduction, the two continental margins had been converged. Where two continental plates converge subduction does not occur because the thick, low-density continental lithosphere is too light to be subducted. In between these plates Qulqula Radiolarian Formation, as the softest rocks in the collision zone, is deformed and uplifted forming orogenic belt. This belt might be developed by collision of the plates, which involved a thickening of the lithosphere. As the crust thickens it undergoes deformation with occurrence of metamorphism in the lower part of the crust (e.g. Shalair Phyllite) and faulting with folding at shallower levels in the mountain belt. Finally the uplifted land may thrust and form thrust belt. The material of belt is moved outwards, away the center of the orogenic belt. This caused the Tanjero and Kolosh Formation to be deposited by dislocation of depocenter toward southwest as the gradual moving or uplifting of source area (Fig.6 and 7).

Migration of depocenterDuring fieldwork at the studied area, two depocenter of Tanjero deposits were found. These depocenters belong to two different successive depostional sequences. The distance of migration is about 25km, which measures the distance between two identical lithologies in the two sequences. These two sequences are as follows:

Campanian-Lower Maastrichtian Sequence This sequence can be identified easily in the Chuarta area. This sequence is partially eroded by overlying (SB1). These situations are very clear at Kato Mountain where this sequence is located under Kato conglomerate and the coarsest existed lithology consists of package of 30 m thick medium grain sandstone. This package represents sediment of LST.Similar package of the upper sequence is outcropped at south of Sulaimaniya City. The distance to the Kato Mountain and this latter locality is a bout 25km when the folding shortening is considered. The identification of this sequence is very difficult in the distal area. This is because it either changes to Shiranish Formation

or it is interfingering, as fine sand, with marl of Shiranish Formation forming transitional zone between the two formations. The age of the two sequences is based on age of the formation at Dokan area, which is indicated by Abdul-Kareem (1986b)[16]. One realizes why the formation has high thickness and compositionally different lithologies.In this study, the above two characteristics are attributed, partly, to the following:The source area (Qulqula Formation) is composed of 30% variegated marl, calcareous shale; 40% thin bedded chert and 20% of limestones. These sediments

are easily weathered and eroded during Upper Cretaceous stormy climate.The source area, hinterland and foreland, was steep sloping and highly deformed during the collision of the Arabian and Iranian plates (continental –continental colliding phase). It is likely that at that time the brittle bedded chert and soft marls are so intensely jointed and fractured that helped rapid weathering, the erosion and creation of deep valleys.The bedded cherts, although brittle, they shaped into hard and sharp edged boulder and gravel (with some blocks) by jointing. During transport in streams, these act as millstone for grinding and breaking up the clasts and the underlying rock too. All these helped enormous amount of material to be available for transporting andarea, which is indicated by Abdul-Kireem (1986b) [16].

Middle –Upper Maastrichtian SequenceThis is the main sequence comprising more than 90% of previously known lithology of the formation. This sequence is discussed in detail in the paragraph on sequence stratigraphy. The 25 km migration of the depocenter is attributed to sea level change and basin fill which are both well enhanced by progressive southeast advancement of thrust sheet of Iranian plate.

Sediments: as an apparent indication of high tectonicAs mentioned before both Tanjero and Shiranish Formations were sharing same basin and exchanging position laterally and vertically (Fig.6 and 7) The Tanjero Formation basin was active and relatively high tectonic but when compared to Shiranish Formation, its tectonic is highly exaggerated this is due to the high thickness and alternation of coarse and fine sediments. This gives, apparently not really, the exceptionally high tectonics during deposition. But when one studies the nature and lithology of the source area, one realizes why the formation has high thickness and compositionally different lithologies. In this study, the above two characteristics are attributed, partly, to the following:The source area (Qulqula Formation) is composed of 30% variegated marl, calcareous shale; 40% thin bedded chert and 20% of limestones. These sediments are easily weathered and eroded during Upper Cretaceous stormy climate. The source area, hinterland and foreland, was steep sloping and highly deformed during the collision of the Arabian and Iranian plates (continental –continental colliding phase). It is likely that at that time the brittle bedded chert and soft marls are so intensely jointed and fractured that helped rapid weathering, the erosion and creation of deep valleys. The bedded cherts, although brittle, they shaped into hard and sharp edged boulder and gravel (with some blocks) by jointing. During transport in streams, these act as millstone for grinding and breaking up the clasts and the underlying rock too. All these helped enormous amount of material to be available for transporting and deposition in the basin of Tanjero Formation. It is worthy to mention that villagers, in the northeastern Iraq villages, use Kato conglomerate as a millstone after shaping into large circular disk then used for grinding the wheat into flour by water-powered mills.The uplift of the source area is partly due to presence of the soft rocks mentioned above. These rocks sandwiched between the two plates as accretionary prism and uplifted by imbrications or forcefully emplaced upward by flowage like salt domes or tooth past (see Costa and Venderville, 2001 for principle of diapirism in convergent setting, p.123-151) [17). The softness of these rocks also led the ophiolite to rest in the core or boundary of the prism and later outcropped during erosion of the source area. This is can be ascertained by the fact that the lower part (e.g., Kato conglomerate) of the Tanjero Formation does not contain any type of igneous boulders and gravels while the upper part contains these rocks. The high thickness may be partly returned to climate of Upper Cretaceous, which was stormy and wet. In this connection Haq (1991 p. 34) [18] mentioned that increased albedo during lowstand favors extreme climate, and this, in turn lead to enhanced thermal contrast of land and sea, between surface and bottom of seawater. He also added that the extreme climate increase weathering and erosion on land.

Types of regressions The main succession of the Tanjero Formation is sandwiched between a forced regression and normal regression from the base and the top respectively as follows:

Forced regression in Tanjero Formation Posamentier et al. (1992) [19], has defined forced regression as basinward movement of the shoreline, caused by relative sea-level fall and independent sediment supply. While Ainworth and Crowley (1994) [20] defined it as progradation of the shoreline in response to relative sea-level fall in which the rate of sediment supply exceeds the rate accommodation space added. The most important evidence of the forced regression is rapid coarsening upward, i.e. the resting of coarse sediments on fine ones with erosional contact between the two (Einsele, 2000) [13]. In Tanjero this arrangement of sediment is very clear in Kato Mountain (Plate 5.1.2 and 5.2) where coarse conglomerate (coastal sediments) rests on shale of shelf of the lower sequence. Moreover in Iranian section and Kometan section (Fig.2) Kato conglomerate rest on the pelagic marl of Shiranish Formation. As a result of the forced regression, the thick pile of lowstand system tract is deposited. This forced regression is affected by eustatic sea level change and most possibly enhanced by tectonic uplift of the source area. The uplift is also accompanied by progressive horizontal advancing (closing) of the source area.The lithology of the Tanjero Formation revealed that the source area (hinterland) was mainly comprised of accretionary prism of Qulqula Formation and minor amount of ophiolite (exposed only during deposition of upper part), which was pushed southwestward toward early foreland basin (Shiranish and Tanjero basins). The grain size and roundness (fine grain size and rounded clasts) of the igneous pebbles showing that the outcrops of the ophiolite are located more remote distance than the chert ones.

Normal Regression In contrast to forced regression at lower part of the formation, the upper part suffered from normal regression, which happened during the end of highstand system tract. According to Einsele (2000) [13] this type of regression also occurs during stable sea level and occurs as a result of sediment fill of the basin and not as a result of relative sea level fall. The arrangement of sediments is coarsening upward which shows no omission of any member of gradation facies succession. In Tanjero Formation, this type of regression is occurred during deposition of the upper part in which the sediment supply exceeded the available accommo-dation space so that shallow bioclast and biogenic limestone, as a part of upper part, is deposited. These limestones contain abundant large forams and pepecypod bioclast. In some places, the high stand Kato mixed carbonate-siliciclastic succession is overlain by Tagaran conglomerate, which may be the deposit of shelf margin system tract (SB2).

Low subsidence and high sea level fall All authors previously studied Tanjero Formation, agreed that it is characterized by rapidly subsiding basin. But the present study proved the opposite (in the studied area), as follows:As previously mentioned in this study, the typical lithology of the formation is deposited above an unconformity (SB1) during sea level fall (LST). This sea level fall occurred by forced regression. This means that the sea level falls were more than subsidence. It is most probable

that the eustatic sea level fall is enhanced by tectonic uplift. This tectonic uplift is associated with source area and probably part of the basin (the shelf of lower sequence). The evidence of the tectonic enhanced eustatic sea level fall is the high thickness of incised valleys sediment fills. In discussion of the foreland basin, Einsele (2000, p.8) [13] mentioned that clastic material influx from the rising mountain belt often keeps pace with or exceeds subsidence and cause basin filling. But during deposition of middle part the basin suffered from rapid clear subsidence demonstrated by deposition of Shiranish- like lithology (Pelagite and Hemipelagite facies).

Atlantic type continental margin Atlantic and Pacific type continental margin (Dickinson 1971) [21], as two different depostional basins between continental and oceanic floor, can be used for comparing with that of Tanjero Formation. When the comparison is made in all aspects, Tanjero basin is more similar to Atlantic type continental margin than Pacific one, while the previous studies such as Jaza (1991) [22] and Numan (1977) [23] put the formation in a basin more similar to Pacific type continental margin. This is because the latter margin has subduction trench and an under-thrusting oceanic plate while Atlantic type margin has no such features. According to Hyndman (1970, p.7) [24] continental margin of the pacific type may revert to Atlantic type with dying out of under-thrusting of the oceanic plate under the continent, cessation of seismic activity, filling and uplift of the trench sediments, and welding of the continental to the oceanic plate. This was what happens to the basin where Tanjero formation is deposited. This is because the basin (or northern part (coastal area) of the basin) was most probably Pacific type during Lower Cretaceous (Qulqula and Balambo Formations) but changed to pacific type during collision of Iranian continent with Arabian one after dying out of oceanic plate and uplift of Qulqula formation, which according to Karim (2003a) [5] was forming sediments of trench before colliding.

Conclusion1-The previously the basin of Tanjero Formation is considered as trench or miogeosyncline but in this study changed to early foreland basin.2-In contrary to previous studies, all parts of the formation have given same degree of tectonics. Moreover, the basin of formation combined tectonically with that of underlying Shiranish Formation in a single basin, which is called initial Zagros Foreland Basin.3-In this basin Tanjero Formation is deposited in near shore area, while Shiranish Formation is deposited in the central part of the basin.4. Most parts of the formation is deposited by forced regression (sea level fall enhanced by tectonic uplift.5. The whole basin was deposited in front southwest advancing of Iranian plate causing continuous migration of depocenter.

References[1]-Buday, T. In: Regional Geology of Iraq Stratigraphy, I.I.M Kassab and S.Z. Jassim (Eds) D. G. Geol. Surv. Min. Invest. Publ.1980,1, 445p.

[2]-Buday, T. and Jassim, S.Z. The Regional geology of Iraq: Tectonism Magmatism, and Metamorphism. I.I. Kassab and M.J. Abbas (Eds), Baghdad, 445 p. 1987[3]-Bellen, R. C. Van, Dunnington, H. V., Wetzel, R. and Morton, D. Lexique Stratigraphique, Interntional. Asie, Iraq,.1959, 3c. 10a, 333 p. [4]-Karim, K.H. Basin analysis of Tanjero Formation in Sulaimaniya area, NE-Iraq. Unpublished Ph.D. thesis, University of Sulaimani, 135p. 2004.[5]Karim, K.H.. A conglomerate bed as a possible lower boundary of Qulqula Formation, from Chuarta-Said Sadiq area, NE-Iraq. Kurdistan Academician Journal (KAJ), University of Sulaimani , 2( 1) Part A. 2003a.[6]-Jassim, S. Z. and Al-Hassan 1977. Petrography and Origin of the Mawat and Penjuin Igneous Complexes. Jour. Geol. Soc. Iraq. Special Issue on 4th Iraqi Geol. Conf., Baghdad[7]- Kettaneh, Y. A. and Sadik, A. J. Mineralogy and geochemistry of Shiranish Formation, North Iraq. Journal of Geological Society, 22(1), 1989.[8]- Lawa, F.A., Al-Karadakhi, A. I, and Ismail, K. M. An interfingering of the Upper Cretaceous rocks in Chwarta-Mawat Region (NE-Iraq). Iraqi Geolo. Jour 31(2), 1998.[9]-Minas, H. A. A. Sequence stratigraphic analysis of the Upper Cretaceous succession of Central and Northern Iraq. Unpubl. Ph. D. Thesis, Univ. Baghdad. 188p.1997[10]-Marouf, Z.M. Dynamic Evolution of the sedimentary Basins in the Northern Iraq and Hydro-carbon Formation, Migration and entrapment. Ph. D. Thesis, University of Baghdad, 243p, 1999.[11]-Bhattacharya, J. P. and Willis, B.J. Lowstand Delta in the Frontier Formation, Powder River Basin, Wyoming: Implications for sequence stratigraphic Models. AAPG Bulletin, 200 ,185 (2). Pp.261-294,.[12]-Bates, R. L., and Jackson, J.A. (ed.). Glossary of Geology, 2ed, American Geological Institute,1980, 749 p..[13]-Einsele, G. Sedimentary Basin: Evolution, Facies and Sediment Budget. 2nd ed. Springer,Verlage Berlin 792p, 2000.[14]-Mial, A.D. Collision related foreland basin in: Tectonics of Sedimentary Basin (Eds. R.V. Ingersol and C. J. Busby) pp 393-424. Black Science, Oxford, 1995.[15]-Doyle, P., Bennett, M.R. and Baxter, A.N. The Key to the Earth History: An Introduction to Stratigraphy. 2nd edition, John Wiley and Sons. New York. 293p. 2001. [16]-Abdel-Kireem, M. R. Planktonic Foraminifera and stratigraphy of the Tanjero Formation (Maastrichtian), NE- Iraq. Micropaleontology, 32 (3), pp.215-231. 1986b.[17]-Costa, E., and Venderville, B. Diaperism in convergent settings triggered by hinterland inch-out of viscous development: A hypothesis from Modeling.In: Koy and Mancktelow (editors).Tectonic Modeling . A volume in honor of Hans Ramberg. AAPG Memoir 193, 276p. 2001.[18]- Haq, B. U. Sequence stratigraphy, sea level change and significance for deep sea. Special. Publs. int. Ass. Sediment, 12. pp.12-39. 1991.[19]-Posamentier, H.W., Allen, G.P., James, D. P. and Tesson, M. Forced regression in sequence stratigraphic framework: concepts, examples, and exploration significance. AAPG Bulletin, 79 (1) pp. 1687-1709. 1992.[20]-Ainsworth, R. B. and Crowley, S. F. Wave–dominated near shore sedimentation and “forced” regression: post abandoned facies, Great Limestone Cyclothem, Stainmore, UK. Jour. of Geological Society, London, 151 (5), pp.681-695. 1994.[21]-Dickinson, W.R.Plate Tectonic Model of Geosynclines. Earth Science Letters, vol. 20, pp.165-174. 1971.[22]-Jaza, I, M. Sedimentary facies analysis of the Tanjero Clastic Formation in Sulaimaniya district, northeast Iraq. Unpubl. MSc thesis, Salahaddin University,121p. 1992.[23]-Numan, N. M. S. A plate tectonic scenario for the Phanerozoic succession in Iraq. Iraqi Geological Journal, 30(2), pp.85-110, 1997.[24] Hyndman, D. W. Petrography of Igneous and Metamorphic Rocks. Mac GrawHill Publishing Company. New York. 533p. 1979.

Sequence Stratigraphy of Late Cretaceous Tanjero Formation in Sulaimaniya Area

b>Sequence Stratigraphy of Late Cretaceous Tanjero Formation in Sulaimaniya Area, NE-Iraq

Kamal Haji Karim1 Ali Mahmood Surdashy2

1: Department of Geology/ College of Science /University of Sulaimani, 2: University of Koyia, College of Engineering of Oli and Mineral/ Kurdistan Region

AbstractOn the basis of the sequence stratigraphy, the whole Upper Cretaceous succession is divided into two depostional sequences, named upper and lower sequences. About 80% of thickness of the Tanjero Formation is deposited in the upper sequence, which is bounded by SB1 and SB2 from below and above respectively. The rest (about 20%) of the formation belongs to the lower sequence. The SB1 is regarded as the major erosional and unconformity surface, which extended down the basin paleoslope from Chuarta area to Sharazoor plain. Thick conglomerate and sandstone wedges are deposited on this surface by forced regression. The regression is resulted from tectonically enhanced eustatic sea level fall. The formation ended by relatively thin conglomerate at the top of the formation and directly below Red Bed Series. This conglomerate, as an unconformity, exists only in some places and changes to correlative conformity in others. Therefore it is regarded as SMST, which is deposited as a result of basin fill (normal regression). Between the two-sequence boundaries and within upper sequence, LST, TST, HST and SMST are identified in addition to their surfaces. The erosion of the shelf of the lower sequence shaped channels and incised valleys. More than four major incised valleys are found in the sediment of the previous HST (shelf and upper slope of lower sequence). The sediments of these valleys consist of low stand wedge of conglomerate and high stand red claystone. Above the sandstone wedge at Dokan, Chaqchaq valley, Sharazoor and Piramagroon plains the transgressive surface can be seen clearly which is represented by sudden change of clean sandstone to marl( Hemipelagic sediments) with some interbeded marly limestone. This surface is the starting point for the deposition of thick transgressive system tract on the shelf. On the slope and basin it is relatively thin (30- 90m), which is lithologically similar to the lithology of Shiranish Formation (marl and marly limestone), of deep marine environment. The maximum flooding surface and possible condensed sections are discussed in detail.Keywords: sequence stratigraphy, Upper cretaceous, Tanjero Formation, Kurdistan geology, Sulaimaniya area.

IntroductionTanjero Formation is an Upper Cretaceous (Campanian-Maastrichtian) unit, which crops out within the Imbricated and High Folded Zones in Northeastern Iraq (Buday, 1980)[1] and (Buday and Jassim, 1987) [2]. It stretches as narrow northwest-southeast belt near and parallel to the Iranian border (Fig. 1). The formation mainly consists of alternation of clastic rocks of sandstone, marl and calcareous shale with occurrence of very thick conglomerate and biogenic limestone (Bellen et al. 1959) [3]. Karim (2004) [4] studied sedimentary structures, lithology, and environment of the formation. On the basis of main lithological distribution, he divided the formation into three parts (lower, middle and upper parts).These parts are correlated across eight different sections, which represent the available outcrops in Sulaimaniya Governorate in addition to one section inside Iranian land (Fig.2 and photo1). His correlation is based on lithology and stratigraphic position of distinctive conglomerate and its derivative sandstones, which are discussed in detail in different localities. The lower part (lower regressive part) is mainly composed, on the lower slope and basin, of thick aggradation of sandstone (100-400m), whereas on the shelf it is dominated by 500m thick succession of conglomerate (in this study, it called Kato conglomerate). The middle part (middle transgressive part) is composed of 100-300m of bluish white marl and marly limestone on the slope and basin plain whereas it changes to calcareous shale on the shelf and to 20-50m thick of red claystone inside incised valleys at the area of coastal area.The upper part (upper regressive part) is chiefly consisting of 50-200m thick mixed carbonate-siliciclastic successions (in this study, it is named Kat mixed carbonate-siliciclastic successions). The constituents of this succession are alternation of thick biogenic limestone beds and calcareous shale with miner amount of sandstone and conglomerate. In literature, only Minas (1997) [5] referred briefly to the sequence stratigraphy of Tanjero Formation. Sequence stratigraphy Sequence stratigraphy is defined as subdivision of sedimentary basin fill into genetic packages (depositional sequence) bounded by unconformity and their correlative conformities (Emery and Myers, 1996) [6]. In the present study, the method of Vail et al. (1977) [7] is used for division of the rock body of the formation into depostional sequences, this is because the unconformities and correlative conformities can be identified in studied succession. While the method of Galloway, (1989) [8] is not used because it is difficult to be applied on Tanjero formation. In order to indicate the sequence sequence stratigraphic position of the Tanjero Formation, the authors have tried to:Study at least a part of the basin fill succession, which extend beyond Shiranish Formation. The time span and the related outcrops thickness which is treated in this paper, depends on the position of the closest overlying and underlying unconformities. When the unconformities are found the correlative conformities also encountered by us in the Tanjero Formation. It was found that one of the biggest sequence boundaries (SB1) is located within the Tanjero Formation. This means that the formation should be subdivided to two depostional sequences. This forced us to study and find the boundaries of both sequences wherever they are located. Therefore, for finding the type one or two sequence boundary (SB1 or SB2), the extent of this study, has gone vertically beyond underlying Shiranish and Kometan Formations and overlying Red Bed Series. Although the boundaries of the above formations are studied previously, no correlation is done as concerned with traditional and sequence stratigraphy. For this, extensive lateral fieldwork is conducted to find all sedimentary facies deposited in response to relative sea level change. Finally, these facies are organized in system tracts (LST, TST, HST and SMST) and the associated sequence boundaries are identified. The systems and boundaries rarely can be seen in one continuous surface section. As the seismic sequence stratigraphy is not used in this study, therefore different surface sections are studied and combined to compensate to the seismic lack.The first one who classified the formation in viewpoint of sequence stratigraphy is Minas, (1997) [5]. His study depended on the previous traditional stratigraphic studies. He included the lower part and middle parts as sediment of TST and HST respectively. As will be discussed later in this study the result is changed. Before discussion of the system tracts, it is better to see the boundaries between Tanjero and adjacent formations. This is to find the certain starting point of sea level curve (relative sea level change) that enclosing Tanjero Formation in one or more of its cycles.

Boundary between Shiranish and Tanjero Formation In all previous studies concerned with the two formations such as Bellen, et al. (1959) [3] and Buday (1980) [1], it was recoded that the contact between the two formations is gradational. But in the present study, at least in one locality, it was found that the contact is unconformable, as shown below:

Iran Section This section is located inside Iran near the border with Iraq (Fig.1 and 2) on the left bank of the Do Awan River (upstream of Little Zab River) about 4km to the west of Awa Kurte village and about 20 km to the northwest of Mawat Town at the intersection of N 350 37- 20.6= and E 450 35- 16.4= . At this locality the Shiranish Formation (Bluish white marl and marly limestone) is overlain directly by 13 to 150m of conglomerate then comes Red Bed Series exist at the top of the conglomerate. Field study showed that the conglomerate belongs to Tanjero Formation because which is correlated and traced laterally with Kato conglomerate (Fig.4). Moreover, both have similar lithological constituents. The contact between Shiranish and the conglomerate is sharp and erosional. This is also true for one location at the toe of Qandil Mountain (Photo 3). In spite of these two localities, in this study, yet the boundary between the two formations is not regarded as unconformable. This is because the erosional contacts are attributed to position of section where all sediments finer than conglomerate are removed due to elevation of the area in the coastal area and incision by rejuvenated streams. The conglomerate represents onlap on the steep head of the incised valleys. The boundary between the two Formations is conformable in all other localities in side the basin. The conglomerate represents sequence boundary. Emery and Myers (1996, p.98) [6] mentioned that the type one sequence boundary is associated with superimposition of shallow or non-marine deposit on deeper one (when the conglomerate regarded as non-marine or shallow marine deposits and the marl as deep one). Contact between Shiranish and Kometan Formations. All the sections inspected in the studied area (Sulaimaniya Governorate) have gradational contact. So, primarily appear that there is no major break in the sedimentation of Upper Cretaceous except the one inside the Tanjero Formation which represented by Kato conglomerate and its equivalent lithologies.

System Tracts of Tanjero FormationThe subdivision of the formation is depended on the factors such as three-dimensional lithological correlation and facies changes (Fig. 4) in addition to finding marker beds and stratigraphic position of the formation between older and younger units. The main system tracts of

formation are as follows:

Lowstand-system tract of Tanjero Formation It is most probable that the typical lithology of the Tanjero Formation (lower part of the new division) is deposited as lowstand system tract. This is deduced from field study in the proximal area Chuarta and Mawat, Qaladiza and Qandil mountain toe area. In these areas when one cross the upper part of Shiranish Formation, Tanjero Formation begins as alternation of thin sandstone beds and thick dark green calcareous shale. Theses lithologies suddenly change to thick succession (500m) of boulder and pebble conglomerate beds (Kato Conglomerate). This type of upward lithological change represents incised valley sediment overlying the fine sediment of previous HST unconformably.The Kato conglomerate is deposited during late stage of LST when sea level slowly rises. This is because it is equivalent to the low stand wedge on the slope toe. During this slow rise, coarse conglomerate is deposited which shows aggradations stacking pattern demonstrated by 500m of coarse conglomerate beds of nearly same thickness and grain size. The erosional surface below the conglomerate (Fig.2 and photo 2) is a major unconformity of the Upper Cretaceous.

It also stands for a type one-sequence boundary (SB1) on which the huge quantity of sediments are bypassed from the coastal area of prograding fan delta to prodelta slope and basin plain during relative sea level fall. This surface can be identified from Kato Mountain to south of Sulaimaniya city at distance of 25km. This distance is equal to about 30km if folding shortening is eliminated. Near Tanjero stream it changes to correlative conformity, which changes to coarse and fine sandstone. In the toe of northeastern limb of the Goizha and Azmir and Daban anticlines also can be seen in certain places, such as Azimra Bichkola valley, north of Bnawella village in addition to Mararash village. The sediments above the erosional surface show that the shoreline and facies belt is probably shifted basin ward from the mountain to the north of Sulaimaniya city during Upper Cretaceous sea fall. The sea level fall most probably supported by tectonic and eustatic sea level changes. All mentioned for the area between Kato Mountain and Sulaimaniya city is also true for the following areas:A. The area between Mawat Town and Kizlar Village in the Chaqchaq valley.B. The area at Qandil mountain toe and Dokan area.C. Type section at Sirwan valley and Khurmal town. The proximal area inferred indirectly to be near Khurmal town by applying the distance of the two areas of A and B.The proximal sediments (conglomerate) do not exist in the Khurmal area due to later erosion. But their positions are inferred for the sediments of distal area in Sirwan valley and Dokan area. At the distal area such as Dokan, Sharazoor and Piramagroon plains, when one crosses the boundary between the two formations, bluish white marl changes to sandstone and calcareous shale. Emery and Myers (1996) [6] regarded this type of change is regarded as indication of lowstand system tract in deep marine environment.In the present study, the environment of boundary between Shiranish and Tanjero Formations can be regarded as deep environment. The further advance into Tanjero Formation, the sandstone increases and changes to a thick succession (100-400m) sandstone wedge, the base of which consists of clean succession 4-20m thick of sandstone with cross lamination and skolithos escape structures. This succession is equivalent to the erosional surface under the Kato conglomerate (for simplicity it can be assumed as time equivalent of lower part of Kato conglomerate and represent the deposit of the extreme shallowing during lowstand system tract. The whole sandstone wedge is equivalent or derived from Kato conglomerate (Fig.2 and 5).

Components of lowstand system tract

A. Lowstand fanThe lowstand system tract consists of two parts; lowstand wedge and lowstand fan. Low stand fan in turn is divided into slope fan and basin floor fan Emery and Myers (1996) [6]. Tanjero Formation, as has limited outcrops, so the lowstand fans are not clear. But some dirty sandstone beds exist which may represent basin floor fan. These beds exist at Sirwan, Chaqchaq valleys and Dokan area. In these areas, there are two beds of either coarse dirty sandstone or paraconglomerate near the transition zone between Shiranish and Tanjero Formations. These beds are isolated in the marls or calcareous shale. The position of these beds in the succession of the formation and relative sea level change suppose that they deposited during early phase of low stand time when the relative seal level fall was at its maximum rate. These beds are generally massive and dirty (matrix supported) so they, most probably, deposited by debris flow and slumping of the shelf edge (shelf break).

Above these two beds comes very clear lowstand wedge. The base of this wedge consists of 4-20m thick package of coarse and clean sandstone. This package is in most case associated with thin bed of conglomerate. The position of this package between basin floor fan and lowstand wedge possibly comprises the slope fan. The beds of this fan contain such sedimentary structures that indicate the shallowest environment of the formation during deposition of the lower part (LST) of formation. Karim (2004, p.38-57)(4) discussed in detail these sedimentary structures (large scale cross bedding, hummocky cross stratification plant debris, cruziana and skolithos trace fossils.

B. Lowstand wedges In contrast to lowstand fans, lowstand wedges are very clear as these wedges make up 70% of the whole succession of the lower part of the formation (Photo2). The typical lithology of Tanjero formation (alternation sandstone and shale) consists of these wedges and the slope fans. The wedge is conglomerate-rich in the proximal area, which is represented by 500m of Kato conglomerate. But they are sandstone-rich in the distal area (at Chaqchaq and Shadalla valleys and along foothill area of Azmir and Goizha mountains). The distal sandstone wedge is correlative to the Kato conglomerate.Einsele (1998, p.338 and 339) [10] mentioned that during late lowstand the lowermost portion of incised valley is filled with coarse fluvial sediment (gravel in case of Tanjero Formation) of braided stream. Therefore all thickness of Kato conglomerate (conglomerate wedge) and most of distal sandstone wedges are mainly deposited during late lowstand time when the sea level fall stabilized for considerable time and subsequent slow rise. The thickness and grain size of the wedges are depending on the distance from the shoreline and limit of downward shift of coastal onlap. The wedges show aggradation to progradation stacking patterns with nearly same thickness of the layers. The most important characteristics of sandstone wedge are their abundant content of plant debris on surface of sandstone beds. These plant fragments are derived from plants grown inside incised valleys and on the surface of the sediments of the alluvial fans during middle Maastrichtian. They were then, eroded by severe current of sediment influx from hinterland by river. The incised valleys of the shelf and upper slope are flooded during early slow rise of sea level and during late lowstand forming some swamp and estuaries with possible plant growth.

Erosional surfaces and unconformities below and inside the wedgesAs previously mentioned a major erosional surface (SB1) exists below the Kato conglomerate. This surface is formed after the exposure of the shelf (Mawat and Chuarta areas). According to Van Wagoner et al (1988) [11] type one sequence boundary is characterized by subaerial exposure and concurrent subaerial erosion associated with stream rejuvenation. This erosional surface, as an unconformity, changes to several unconformities toward south and southwest down dip. This occurred during gradual fall of sea level, overlain by more or less thick beds of conglomerate (Fig.4 photo 2). The down dip extension of this surface, with associated conglomerate, reaches the middle part of Sharazoor and Piramagroon plains (to positions beyond Arbat and Piramagroon towns

respectively). In the literature similar type of unconformities are cited by Potter and Pettijohn (1977) [12] in basin margins, they called them “compound unconformity”. In some places, in the plains, the surface becomes correlative conformity. These places represent interfan areas (Fig.5) where the conglomerate changes to sandstones. The sandstones, near the base of the wedge, have coarse and clean texture with high thickness. Both thickness and grain size decrease downward and upward of the sections. Downward, the lithology changes to bluish marl of Shiranish Formation and to marl of Middle part at the top of the wedges.

Incised valleys and their sediment fillIncised valleys are developed during negative accommodation, Mail (2002, p.1209) [13]. This is true for Tanjero Formation which during sea level fall (negative accommodation) the shelf and upper slope of the Tanjero Formation is exposed to subaerial erosion and fluvial incision. The evidences for exposure is the Kato conglomerate and Kato red layers in addition to trace fossils and sedimentary structures (see Karim 2004, p.38-56) [4]. The erosion is initiated as the stream base level is lowered. At least, four incised valleys are indicated (Fig.3). Each one is associated with its prograding lowstand fan in front the valleys. When they fans directly entering the sea, they called lowstand fan delta. Most quantity of the sediment is reworked from the delta front to the deep basin through the by turbidity currents forming submarine fans. The valleys were filled by different sediments when reversal of accommodation from negative (valley cutting) to positive (valley filling

occur (Mail, 2002) [13]. This is exactly what happened during filling of incised valley of Tanjero Formation which are filled by conglomerate during slow rise of see level. Three of valleys are discovered and mapped (depending on availability of outcrops) in the field from shoreline (proximal area) till the distal (basin) area. The characteristics of the three mapped valleys are used for inferring other one. This forth valley is deduced from the lithology of the formation in the basin-distal area at Sirwan valley. At this area the lithology and sedimentary structures are compared with the lithologies of mapped ones at the equivalent locations.These valleys with submarine fans descend from north and northeast toward south and southwest. The first one starts from the area around Mawat area, passing by Qizlar Village at the head of Chaqchaq valley and end at the area around Tasluja Town in the Piramagroon plain. The second mapped one starts from the east of Chuarta town and descends to the south and southeast and ends at the Sharazoor plain at the southwest of Arbat Town near Damirkan Village (6km southwest of the Town). The other one extend from Suwais Village (Qandil mountain toe) to Dokan area (Fig.3). Many evidence exist that the fan associated with this valley has many lobes the largest one delivered thick alternation of conglomerate and sandstone beds to the north of Sulaimaniya city. The width of these valleys is more than 2km and their lengths are more than 9 km. These valleys filled, on the previous highstand shelf area, with 500m of Kato conglomerate and about 50 m of red layers (photo 5.5). The thickness and grain size of this conglomerate changes rapidly and laterally in distance of one or few

kilometers (Photo 2). In some cases the thickness change, along the depositional strike, from 500 to 10m in distance of two kilometers and grain size change to sandstone in the same distances. This sedimentological phenomena also observed by Karim (1997) [14] in Gercus Formation in Sartaq-Bamo area. The hard and well lithified conglomerate of these valleys, now, forms high mountains such as Kato, Gaza and Talishk Mountains. These mountains are formed by reciprocal of topography. The conglomerate of Tanjero formation is deposited during late lowstand system tract. In this connection Haq (1991)[15] mentioned that during low stand system tract when the relative sea level begins to rise slowly the stream incision is stopped and the existed incised valley may begin to be filled with coarser braided stream sediments (coarse conglomerate in case of Tanjero Formation). The evidence, which proves that Kato conglomerate is deposited subaerially in the proximal area, is that red layers that overlie it. These layers represent deltaic deposits during TST. At Iranian section this conglomerate (13-150m thick) which is rested directly on Shiranish Formation. This condition reflects the most landward occurrence of the incised valleys deposits where the conglomerate terminated (on-lapped) against the steep slope of the source area. The shape of the valleys and their sediment fills can be reconstructed from some outcrop sections exist in the studied area. One of these sections (Photo 2) can be seen at the northern part of Kato Mountain directly west of Suerala village. This section is scored by recent stream perpendicularly on the elongation of Kato conglomerate. The section shows thick beds of the conglomerate, which are tilted at about 35 degrees toward southwest. Tilt correction shows that the form of the paleo-valley has obtuse v-shaped form (Photo 2). This latter photo shows only part of the valley, which is not more than 1km wide. The obtuse shape of the valley is most possibly attributed to the fact that the incised valleys were scoured in soft sediments (partially lithified calcareous shale and marl of the HST deposits of lower sequence). The thickest and thinnest part of the conglomerates exists at center and side of valley respectively. Although the original outlook of the conglomerate layers in the incised valleys are tilted and mostly eroded but the form and wideness of one valley is reconstructed as shown in the photo 2. In the field the bottom of the valleys (as shown by sediments fills) is convex downward and planner at the top (Photo 2.1).The precise position of the Kato and Tagaran conglomerates is shown in sequence stratigraphic model. In the model, the system tracts are illustrated by the Wheeler diagram (time expanded section) and depth section. These sections are so drawn to pass through the incised valleys (Fig.6and 7). According to Emery and Myers, (1996, p.140) [6] as a result of river rejuvenation; incised valley commonly contains the coarsest sediment available locally. They added (p. 137) if the new river course is steeper than equilibrium river profile, the river would firstly straighten coarse and then incise to form a valley. Furthermore, they mentioned that these valleys are important because they represent unequivocal evidence of a sequence boundary and they can form stratigraphic traps for hydrocarbon.

Possible incised canyonAccording to Bate and Jackson (1980)[16] a canyon is defined as erosional geomorphologic features, which are long, deep, relatively narrow steep-sided valley confined between high and nearly vertical walls in mountainous area, often with a stream at the bottom. According to Emery and Myers (1996, p.140) [6] the thickness of incised valley fill cannot exceed 100m but submarine canyon can exceed this thickness. In the Bangal Gulf, Kottke et al (2003) [17] has found submarine canyon which occurred as conduit for discharge fluvial sediments that by pass the shelf and reach deep sea fan. In the studied area, there are many places (at proximal area); the thickness of the Kato conglomerate reaches 500m. But the sides of the valleys are not steep. These suppose that these locations (Kato Mountain and south and west of Mawat town) are position of Upper Cretaceous canyons that developed by subaerial and possibly by submarine erosion. These canyons are most possibly located on the previous lower shelf and upper slope. Field studies showed that the floor of the canyons (base of Kato conglomerate) is resting sharply on the alternation of calcareous shale and sandstone of HST of the previous shelf and upper slope. The scouring of the deep canyon is attributed to the softness of the lithology on which the regression (sea level fall) occurred on the previous HST. This softness (not lithified) is resulted from the lapse of short time between previous HST and the new LST that caused rejuvenation of the stream and canyon formation.

C. Channels and their sediment fillIn the definition of canyons, it was mentioned that there is a stream on the bottom. This is also true for the incised valleys. Lots of evidence has been observed in the field, which show channels on the floor of the incised valley at southeastern side of Kato mountain very clear channel is exposed under the Kato Conglomerate. It is filled with about 20m wide coarse conglomerates and located inside the calcareous shale of sediment of HST of the lower sequence (Photo 2). The layers of the conglomerate pinch out rapidly against the channel wall and in some cases change to sandstone on the paleo flood plain. The pinching out give the conglomerate lensoidal form.The channel shows at least two stages of incision at different levels. The lower level is narrower than the upper one (Photo 2.1 shows channel below the valley). They represent the depth reached by the stream during consecutive and falling by coarse sediment in late lowstand system tract when the sea level gradually rises .The streams were, most possibly, of braided type by which the thick pile of Kato conglomerate is laid down during late LST.

Sediment fill of the incised valleys during TSTAt southwestern side of Kato Mountain there are abnormal occurrence of 50m of red layers (red beds), which are composed of red claystones and sandstone with intercalation of some thin bed of conglomerate (Photo5.5). These layers are called “Kato Red Layers”. These layers

are underlain and overlain by Kato conglomerate and Kato mixed carbonate-siliciclastic succession respectively. This succession consists of alternation of more than 10 beds of rudist-bearing limestone and shale (Photo 5.4). The thickness reaches, in some place, more than 150m. These red layers are also present at the area south of Mawat town near Qashan Bridge and directly east of Yalanqoz village (N: 35o 51- 24=, E: 45o 24- 29.3=), which reach only 20 m in thickness. These exist in the proximal area (near source area) while they are not observed in the distal area. Their equivalent lithology in the latter area is marl on the slope and calcareous shale one shelf area. The red layers and their equivalent represent the sediment of transgressive system tract (TST), which is deposited during the valleys flooding. They closely resemble Red Bed Series but can be differentiated by their stratigraphic position, which is located between lower and upper parts of the formation between Kato conglomerate and Kato mixed carbonate-siliciclastic succession.These red layers have great importance in the study of Tanjero Formation because one can decide that the Kato Conglomerate represents continental or coastal area deposits and not deep deposits. This is because these layers contain lenses of conglomerate and the cooked samples yield no planktonic forams. During the time of late LST the Kato Conglomerate is deposited. After the Kato conglomerate the red layers are deposited during rapid flooding of early TST when the deposition of the conglomerate sequestered.

Transgressive system tract of Tanjero Formation The deposit of the transgressive system tract is very clear which is overlying directly the low stand system tract (lowstand sandstone wedge and Kato conglomerate) of the formation. This deposit consists of bluish marl in the Sulaimaniya, Sharazoor and Piramagroon areas, whereas in Chuarta and Mawat area it consists of thick succession of dark green calcareous shale with some marls which change to red layers at south of Yallanqoz village and southern side of Kato mountain inside incised valleys. At Sirwan valley the lithology of HST is nearly the same as Chuarta with some sandstone layers and rare conglomerate intercalation, while in Dokan area it is relatively thin (no more than 130 meters). During deposition of this system, Tanjero environment has suffered sudden deepening demonstrated in the field by sudden vertical change of sandstone of LST to hemipelagic marls, while at Kato Mountain, the conglomerate; it changes with the same manner to Red claystone. Because of deepening, this system tract has no sedimentary structures and fossils found in the lower LST and upper HST. They contain only Upper Cretaceous planktonic forams and shows retrogradational parasequences. This is also confirmed by Smith and Jacobi (2001, p.21) [18] during study of stratigraphy and sea level change of Upper Devonian Canadaway Group in New York State.

Highstand-system tract In Tanjero Formation, this system tract consists of mixed siliciclastic-carbonate succession. In this study, it called Kato mixed siliciclastic-carbonate succession). This succession is more than 150m thick in some places and consisting of alternation of thick beds of biogenic limestone and calcareous shale on the shelf (Chuarta area). Lawa et al (1998) [19] called this succession ”interfingering of Aqra with Tanjero Formation”. The biogenic limestone laterally changes, in most cases, to sandy limestone or calcarenite (detrital limestone). Fossils of rudists, belemnites, and gastropods (or their bioclast) are densely concentrated in some beds of biogenic limestone (Photo5.4 and 5.5). Other beds contain pelecypods, large forams (Discocyclina, Loftusia, Amphalocyclus), echinoderm and pelecypods or (their bioclast)Lawa et al(1998) [19]. In many places the calcarenite beds are cross-bedded and burrowed by Planolite and Cruziana trace fossils.The repetition of these beds suggests aggradation parasequence. Above the mixed carbonate-siliciclastic parasequence come another parasequence, which consist of alternation of calcareous shale, sandstone and conglomerate (of Tagaran type). This pure clastic parasequence grades vertically into lithology of Red Bed Series. This parasequence does not exist in all places such as near Mokaba village where the biogenic limestone grade in to Red Bed Series). So the contact of the Red Bed Series and Tanjero Formation (including

Aqra Lens) is gradational in some place and unconformable in others. The unconformable contact is very clear near Zarda Bee village and at Barda Qal and Siramerg valleys.The explanation of Haq (1991, p.22) [15], can be accepted for alternation of biogenic carbonate and calcareous shale in Tanjero basin. He mentioned that during lowstand, siliciclastic is deposited while in highstand carbonate is deposited. This is true when each thick couplet of carbonate –shale is regarded as minor forth or fifth order cycles which suffered from the high and low stand. The field evidence in Chuarta agreed with that mentioned by Haq (op.cit) that in such successions limestones are mostly deposited in the early high stand when the accommodation on the shelf is plentiful, while during the late high stand, in Chuarta area, shale, sand and conglomerate are deposited when accommodation decreases and shore line prograde basinward as can be seen near Zarda Bee village.

Condensed sectionCondensed sections as thin marine stratigraphic horizons are composed of pelagic and hemipelagic sediments characterized by very slow sedimentation rate (Loutit et al. 1988) [20]. Within depositional sequence, the condensed section occurs partly at the top of transgressive system tract and partly within high stand system tract. They represent the maximum landward extent of marine condition. Marine condensed sections are created by sediment starvation and thus characterized by apparent hiatus, thin zones of burrowed and somewhat lithified beds (Haq 1991) [15].Only few of these characteristics fit some beds within Tanjero Formation, so no typical condensed sections are found. This may be returned to high sedimentation rate of formation in the relatively active foreland basin and to shallower water than Shiranish Formation. This latter formation contains at least one typical condensed section, which is located at the top (in Dokan area) of the formation in the middle of the formation (in Chuarta area). But, in the Tanjero Formation, the beds resembling or related to condensed section are as following: In the proximal area (coastal area during LST) there is a biogenic limestone bed about 7m thick (Photo 5.4 and 5.4). These limestones are located

directly above Kato Red Layers. The position of this bed is directly above TST can be confidently regarded as a kind of condensed section or proximal equivalent deposit of a condensed section. It is deposited during maximum flooding of the sea (maximum landward extent of marine condition of Tanjero Formation) when the basin starved as concerned to terrigenous clastic influx from source area. This bed

consists of several horizons of limestones rich in Upper Cretaceous fossils (Photo 5.5) with or without their bioclasts. On the shelf (toe of northeastern limb of Azmir, Goizha anticlines) very thick TST calcareous shale is capped by biogenic limestone (0.3 – 2m). The fossils content shows densely populated by diverse organisms such as rudist (Photo 6.7) and gastropod (photo 6.2) this assemblage laterally changes to other ones such as: pelecypods (Gryphaea) (Photo 6.3) large forams, and echinoderm, large ammonite (Photo 6.) in other places changes to bioclast of these organisms. These types of bed are not unique but repeat several times upward in the HST. C. The most well developed condensed section-like bed is a fine grain gray (white weathering) limestone occur nearly at the middle of the formation at west of Diana town on the left bank of Balakian stream (GPS reading: N: 36o 47- 56.2 =, E: 44o 22- 55.1= ) . This bed is 1.5 m thick and lithologically very similar to Kometan Formation both in color and lithology as it contains Upper Cretaceous planktonic forams (Photo 5.3). In the Piramagroon and Sharazoor plain in addition to Dokan area, there are many thin beds and lamina of marly limestone in the middle part (TST). These may be regarded as relatively a kind of condensed section that represents time of non-deposition.

Shelf margin system tract (SMST) and type two-sequence boundary (SB2)As mentioned above an alternation of dark color conglomerate (Tagaran type) and shale (with or without sandstone) exist, in some places, at the top of Kato mixed carbonate –siliciclastic succession. The thickness of this succession is about 50m near Tagaran and Zarda Bee villages. In the other area (with same tectonic setting) such as area around Mokaba, Homarakh, Konamassi and Harmin villages these conglomerates are not present. But the succession goes more or less gradationally to Red Bed Series. This type of contact and lithologic change is evidence of shelf margin system tract at the end of basin fill of Tanjero Formation and the underlying surface is type two-sequence boundary. This SB2 may be changed to SB1 in other areas such as toe of Qandil Mountain at the north of Kometan village (Photo 3). This lateral change of sequence boundary may be returned to high tectonic of the source area and part of the basin. Emery and Myers (1996) [6] mentioned that SB2 and overly shelf margin system tract might be very difficult to recognize in outcrops. They added that could be differentiated from underlying HST by subtle (minor) unconformity.Finally it seems that all system tracts of Tanjero formation belonged and deposited during third order eustatic sea level change. In literature Cunningham and Collins (2001) [21] studied the similar system tract in Morocco during Miocene and concluded that they belonged to third order sea level change cycles.

ConclusionThe study revealed the following results:1-The whole rock body of the formation is divided into two main depostional sequences and correlated in eight sections, which are named lower and upper sequences. About 80% of the formation is deposited in the upper sequence while the rest is deposited in the lower sequence.2. In the upper sequence, the LST, TST and HST are identified with a SMST at the top of the formation.3. The lower sequence can be identified at the Chuarta, Mawat, Qandil area (proximal area) while at Sharazoor- Piramagroon plain, Dokan area it grade with Shiranish Formation and can not be identified.4. A type one and two sequence boundary (SB1 and SB2) is identified; they located at lower and middle part of the formation respectively. Above each 500m and 30m of conglomerate are deposited respectively.5. The (500m) conglomerate has aggradational stacking pattern, which deposited inside more than four the incised valleys during sea level fall. This conglomerate changes to thick low stand wedge of sandstone at the distal area.6. The transgressive surface and condensed sections are identified.7. All the system tracts in the studied area are as following: Qamchuqa Formation… LSTKometan Formation… TSTTanjero Fn…..late HST, LST, TST and HST

References[1]-Buday, T. Regional Geology of Iraq: vol. 1, Stratigraphy, I.I.M Kassab and S.Z. Jassim (Eds) D. G. Geol. Surv. Min. Invest. Publ. 445p. 1980.[2]-Buday, T. and Jassim, S.Z. The Regional geology of Iraq: Tectonism Magmatism, and Metamorphism. I.I. Kassab and M.J. Abbas (Eds), Baghdad, 445 p. 1987

[3]-Bellen, R. C. Van, Dunnington, H. V., Wetzel, R. and Morton, D. Lexique Stratigraphique, Interntional. Asie, Iraq, 3c (10a) 333 . 1959[4]-Karim, K.H. Basin analysis of Tanjero Formation in Sulaimaniya area, NE-Iraq. Unpublished Ph.D. thesis, University of Sulaimani University, 135p. 2004.[5]-Minas, H. A. A. Sequence stratigraphic analysis of the Upper Cretaceous succession of Central and Northern Iraq. Unpubl. Ph. D. Thesis, Univ. Baghdad. 188p.1997[6]-Emery, D. and Myers, K. Sequence Stratigraphy. Blackwell Scientific Limited. 297p. 1996.[7]-Vail, P.R., Mitchum, R.M., Todd, R. G., Widmier, J.M. and Hatleid, W.G. Seismic stratigraphy and global changes in sea level. In: seismic Stratigraphy –Application to Hyrocarbon Exploration (ed. by C. E. Payton). Memoir of the American Association of the Petroleum Geologists, Tulsa, 26, pp.49-62. 1977a.[8]-Gallaway, E. W. Genetic stratigraphic sequences in basin analysis: Architecture and genesis of flooding- surface bounded depositional units. AAPG,73(2) p.125-142. 1989[9]-Jassim, S. Z. and Al-Hassan. Petrography and Origin of the Mawat and Penjuin Igneous Complexes. Jour. Geol. Soc. Iraq. Special Issue on 4th Iraqi Geol. Conf., Baghdad. 1977.[10]-Einsele, G. Event Stratigraphy: Recognition and interpretation of Sedimentary Even Horizons, in: Doyle, P. and Bennett, M. R. (editors). Unlocking the Stratigraphical Record, John Wiley & Son, New York, and 532 . 1998.[11]- Van Wagoner , J.C., Posamentier, H.W., Mitchum, R.M., et al., , , An overview of the fundamentals of sequence stratigraphy and key definitions, in Wilgus, C.K., et al., eds., Sea level changes: an integrated approach: SEPM Special Publication 42, p. 39-45. 1988.[12]- Potter, F. J. and Petijohn, F. J. Paleocurrent and Basin analysis. Springer Verlag. 145p.1977. [13]-Mail, A. D. Architecture and sequence stratigraphy of Pleistocene fluvial system in the Malay Basin, based on seismic time –slice analysis. AAPG Bulletin. 86(7) pp.1201-1220. 2002.[14]-Karim, K. H. Stratigraphy of Sartaq-Bamo Area from northeastern Iraq. Iraqi Geological Journal, 31(1 ) 1997.[15]- Haq, B. U. Sequence stratigraphy, sea level change and significance for deep sea. Special. Publs. int. Ass. Sediment, 12. pp.12-39. 1991.[16]-Bates, R. L., and Jackson, J.A.(ed.). Glossary of Geology, 2ed, American Geological Institute, 749 p. 1980.[17]- Kottke, b., Schwenk, T., Breitzke, M., Wiedicke, M., Kurdrass, H. R. and Spiess, V. Acoustic facies and depostional processes in the upper submarine canyon swatch of No Ground (bay of Bengal), Deep-Sea Research, 11(50), pp.979-1001. 2003.[18]-Smith, G. J. and Jacobi, R. D. ,Tectonic and eustatic signal in the sequence stratigraphy of the Upper Devonian CanadaWay Group, New York State, AAPG,. 85 (2), Pp. 325-360. 2001.[19]- Lawa, F.A., Al-Karadakhi, A. I, and Ismail, K. M. An interfingering of the Upper Cretaceous rocks in Chwarta-Mawat Region (NE-Iraq). Iraqi Geolo. Journal. 31(2), 1998.[20]-Loutit, T. S., Hardenbol, J., Vail, P. R., and Baum, G.R. Condensed section: The key to the age dating and correlation of continental margin sequences. In: sea level change: an integrated approach (Eds Wilgus. C. K., Hastings, B.S., Kendall, C. G. St. C., Posamentier, H., Ross, C. A. and Van Wagner , J.) Soc. Econ. Paleontol. Mineral., Spec., Publ. 42 . Pp.183-215. 1988.[21]- Cunningham, K. J. and Collins, L. S. Control on facies and sequence stratigraphy of an upper Miocene carbonate ramp and platform, Melilla basin, NE- Moracoo. Journal of Sedimentary Geology, 146 (2), pp.75-89.2002. [22]-Haq, B. U., Hardenbol J. and Vail P.R. Chronology of fluctuating sea levels since the Triassic. Science, 235(3) , 1156-1167.1987. [23]-Abdel-Kireem, M. R. Planktonic Foraminifera and stratigraphy of the Tanjero Formation (Maastrichtian), northeastern Iraq. Micropaleontology, 32 (3), pp.215-231. 1986b.

Sequence Stratigraphy of Gercus Formation (Middle Eocene) in Sulaimaniya area, NE-Iraq

Bakhtiar M. AmeenBakhtiar65@yahoo.comDepartment of Geology, College of Science, University of Sulaimani

published in: Iraqi Journal of Earth Science, Vo.6, No.2, p.23-32,2006.

ABSTRACTThe Middle Eocene Red Beds known as typical facies of Gercus Formation in north and northeastern Iraq.In the field they cropout as red succession of claystone, lensoidal sandstones and conglomerates. Tectonically the beds are exposed in the folded area of the Zagros Fold-Thrust belt of northeastern Iraq. The whole formation consists of major low stands system tract within stratigraphic record of Tertiary which belongs to 2nd order sea level change. This major lowstand system tract is divided into two depositional sequences named upper and lower sequences which are modulated within 3rd order sea level change. About 90% of its thickness is deposited in the lower sequence, and 10% in the upper one. The lower sequence bounded by SB1 and SB2 from the bottom to the top respectively. It is comprised of SMST, TST and HST. Only the LST of the upper sequence is represented in the Gercus Formation, while the other systems tracts are possibly included in the carbonate of PilaSpi Formation. The SMST consists of alternation of red claystone and marl which are locate at the top of Khurmala Formation. The TST (middle part of Gercus Formation) is composed of grey marl and laminated marly limestone. The HST consists of alternation of red claystone, laminated sandstone and calcareous shale.The LST consists of 1-4m of rounded and sorted conglomerate located at the upper part of Gercus Formation. This system tract is underlain by an erosional unconformity. The inferred depositional environment is most possibly braided delta plain which is prevailed by fresh water influx and flooding by marine water. This is shown in the field by mud cracks, marl marine sediments and laminated sandstone which deposited in upper flow regime.Keywords: Gercus Formation, sequence stratigraphy, molasse facies, systems tract, Khurmala formation, Pila Spi Formation.

التتابع الطباقي لتكوين الجركس(االيوسين االوسط)في منطقة السليمانية-شمال شرق العراق

الملخص

ان التتابعات الفتاتيةالحمراء لتكوين جركس العائد لفترة االيوسين االوسط تمثل سحنات نمودجية للموالس في شمال وشمال شرق العراق .حيث تظهر الطبقات الحمراء في الحقل عتى شكل الحجر الطيني ،الحجر الرملي والكونكلومريت .تكتونيا تظهر الطبقات في منطقة حزام الطيات العالية ومنطقة الزحف لسلسلة الزاكروس في شمال

من السمك الكلي للتكوين قد ترسب فى التتابع االسفل والمتبقي 90شرق العراق . لقد امكن تميز تتابعين طباقيين في هدا التكوين سميتا بالتتابع االسفل واالعلى ،ان % , SMS, TST )يحتوي التتابع السفلي كل من االنظمة المسارية.) SB1 (بينما الحد االعلى ب (SB2)منه قد ترسب في التتابع االعلى.يكون الحد االسفل للتتابع االسفل بHST) بينما تظهر LST) ( العائدة للتتابع االعلى في الجزء العلوي من تكوين الجركس, اما االنظمة االخرى فتتواجد في تكوين البالسبي. ان SMST) ( يتكون من تعاقبالجزء االوسط من التكوين وتحتوي على المارل الرصاصي مع طبقات رقيقة من الحجر ) (TST الحجر الطيني االحمر مع المارل فوق الجزء العلوي لتكوين خورمالة .تمثليتكون من طبقة كونكلوميريت ) LST ( فهو مكون من تعاقب الحجر الطيني االحمر، الحجر الرملي المترقرق والحجر الجيري الطيني.ان) ( HST الجيري المارلي، اما ال

) م والذي يقع في اعلىتكوين جركس تحت الحد الفاصل مع تكوين بالسبي.ان البيئة الترسيبية افترضت بان تكون سهول دلتاوية ضفائرية غمرت بمياه 4 الى 1ذات سمك( عذبة مع احتمالية طغيانه بمياه البحرفي بعض االحيان. وقد تم االستدالل على تلك البيئة في الحقل من خالل مالحظة وجود الشقوق الطينية, والترسبات البحرية( المارل) .وطبقات رقيقة من الحجر الرملي والتي ترسبت خالل التدفق العالي للجريان

INTRODUCTIONGercus Formation is a Middle Eocene unit, which crops out within the boundary between High and Low Folded Zones in Northeastern Iraq (Budy, 1980, Budy and Jassim, 1987). It stretches as narrow northwest-southeast belt near and parallel to this boundary (Fig. 1). The sections are exposed across the scarp slope of elongate homocline which extends from Koya town to the Derbendekhan area. This homocline has many local names like Haibat Sultan, Baranan and Berke Mountain. At the northeastern of this homocline three sections are selected for the study. These sections are: Haibat Sultan, Kalka Smaq and Dara Rash sections which are correlated on the basis of lithology and stratigraphic position (Fig1). The formation mainly consists of alternation of clastic rocks of claystone, sandstone, marl and calcareous shale with occurrence of conglomerate (Bellen et al. 1959). Al-Rawi, (1980) studied the petrology and sedimentology of Gercus Formation in Shaqlawa and Darbandekhan area. Al-Rawi (1983) studied the origin of red pigment and mentioned that the Gercus Formation in northeastern Iraq consist of a fluvial sequence of associated red and drab beds deposited under an arid to semi-arid climate. Dhannoun H.Y.et.al., (1988) studied the geochemistry of Gercus red beds Formation of northeast Iraq. Dhannoun, (1989) studied the geochemical significance of the distribution of Ni and Co in clayey-siltstone associated with the Gercus Formation of northern Iraq. Al-Qayim and Al-Shaibani 1991, suggested that sediments in Gercus Formation are deposited in a clastic dominated tidal flat. On the basis of main lithological distribution the formation was divided by Ameen (1998) into three parts (lower, middle and upper parts).The aim of this study is to investigate the position and amplitude of sea level change as represented by the lithology and the boundary with other formations.

SEQUENCE STRATIGRAPHYSequence stratigraphy is defined as subdivision of sedimentary basin fill into depositional packages bounded by unconformity and their correlative conformities, (Emery and Myers, 1996). In this study the method of Vail et al., 1977 is used for division the rock body of the formation into depostional sequences, this is because the unconformities and correlative conformities can be identified. The time span and thickness of the part treated in this paper depends on the position of the closest overlying and underlying unconformities and correlative conformities that bound the Gercus Formation in addition to systems tracts (LST, TST, and HST) and the associated sequence boundaries. For clear sequence stratigraphic study of the Gercus Formation it is necessary to study the underlying Sinjar (or Khurmala) and overlaying Pila Spi Formations. Although the boundaries of the above formations are studied previously, no correlation is done as concerned with traditional and sequence stratigraphy.

Fig. (1) Geological map of northern Iraq (Buday and Jassim, 1987) showing location of the studied section.

LOWER BOUNDARY OF GERCUS FORMATIONThe lower boundary of this formation is gradational in Iraq (Buday, 1980), but Bellen et al, 1959) recognize a brake in sedimentation and unconformity, with the underlying Kolosh Formation. Al-Qayim and Salman (1986, p.158) mentioned that the contact seems to be gradational and conformable with Kolosh Formation in Shaqlawa area. The lower contact with Khurmala Formation is gradational (Al-Qayim and Nissan, 1989, Ameen, 1998).Surdashi and Lawa (1993) mentioned that the lower contact of the formation is gradation with Sinjar formation. But Lawa 2004 mentioned a gap (major unconformity) at right side of Dyiala River, between these later formations which spanned about 5m.y. In the studied area the Gercus Formation is overlying Khurmala Formation (or its equivalent Sinjar Formation) and the contact is clearly gradational in all three studied sections. In the field the contact appear as intercalation of thin beds of limestone and brown claystone. The claystone changes gradually to thick beds of red claystone (Gercus Formation). This type of lithologic change is assigned, in this study, as conformity relationship at distal area which changes to minor unconformity up dip the paleoslope near the shoreline. Therefore the contact and the red claystone of lower part of the Gercus Formation are allocated as shelf margin system tract (SMST). In the north and east of Darnabdikhan town both Gercus and Sinjar Formations are mixed as mixed carbonated and siliciclastic successions. These successions can be seen clearly at the left shoulder of Darbandikhan dam (fig.2C).

Boundary between Gercus and Pila Spi FormationsThe upper boundary of Gercus Formations is conformable with Pila Spi Formation (Buday, 1980). Conversely, (Shaikh et al.1975, Al-Qayim and Nissan, 1989) observed both unconformable and conformable contact between the two formations. Ameen (1998) has recorded unconformable contact between the two formations in the area between Darbandikhan and Dokan dams. In the present paper this contact is restudied in detail and concluded that it is unconformable, at least, in the most sections (Photo.1 A and B). In the area to the east Darbandikhan dam, there are some indications that change to conformity. This observation is ascertained by Karim (1997) who mentioned gradational contact between the two formations in the Sartak-Bamo Valley.In the studied area this unconformity is manifested by about one to four meters of polymictic conglomerate which has well sorted and rounded pebbles (photo 6A). The problem with this conglomerate is highly modified by diagenesis. This is manifested by removal of many unstable pebbles by solution with only their cast remained. This removal is attributed to the imperviousness of the underlying rocks (mainly clays). The claystone of Gercus forced the groundwater movement to be concentrated in side the conglomerate at the base of permeable Pila Spi Formation. Therefore, in most case the pebbles are mostly removed in the contact and the conglomerate appears a porous limestone (photo 5A) as can be seen in some locality along Haibat Sultan homocline. It seems that most igneous pebbles are removed due to this solution.

SYSTEMS TRACT OF GERCUS FORMATIONThe formation generally deposited as a result of relatively severs tectonic uplift of the northern Iraq especially the area near the Iranian border. The effect of the uplift is modulated more or less by 2nd and 3rd order cycles of sea level changes. The formation as whole can be assumed as level change. These sea level changes can be seen from facies change which arranged in system tracts and depositional systems. The wide-ranged LST of 2nd cycle is divided into two 2nd order cycles which inferred from the ages given by (Buday, 1980 and Bellen et al.1959) which estimated to be about 5millon years (middle Eocene). The lithologic change shows that the two cycles are also modulated by 3rd order cycles. Because of the interference between eustaic sea level change and tectonic uplift and subsidence, the systems tracts are not much clear, due to deposition in nearly similar environments. These factors also forced the system tracts to be not similar in different areas. For example in Sartak Bamo valley, only one system tract is exist which consists only of conglomerate and sandstone that recognized by Karim, (1997) and Lawa (2004). In this area the only one LST can be identified.

Photo. (2) A: The unconformable contact between Pila Spi and Gercus Formations manifested by two thick beds (6m each bed) of conglomerate which represent LST. B: Same situation exists at Qaradagh area, Sagrma Mountain between the two formations which is represented by 4m pebble conglomerate. C: Mixing (intercalation) of Gercus and Sinjar Formations along left shoulder of Darbandikhan dam.

SHELF MARGIN SYSTEMS TRACTAs mentioned above the lower part of Gercus Formation is deposited during minor sea level change (SMST) (photo 5). The thickness of this systems tract is about 12m and consists of red claystone (photo 4) with interbeds of laminated marly limestone and pure limestone (photo3). This lithology (or facies) without conglomerate and sandstone is evidence for the fact that it deposited as shelf margin system tract. The environment of this systems tract can be considered as delta front and the underlying Khurmala (or Sinjar) Formation as clear water of shelf environment. When the sea level fall is occurred the shelf is not exposed totally. Only part of the shelf is exposed as a delta and the rest remained as delta front depositing red claystone and limestone laminae. In this environment, the limestone lamine are attributed to the short interval of clastic influx impeding. The shelf margin systems tract is underlain by high stand systems tract of Khurmala or Sinjar Formations. These two formations are assigned as HST according to the exposed lithologies and facies cited by Surdashy (1989) Al-Barzinjy, (1990) which are mostly consist of reef and fore reef facies (algal and bioclast limestones) in the east to Koysinjaq town. Moreover Al- Eisa(1983) found planktonic forams in Khurmala Formation at the east of the town ( Shaqlawa area). The relations between carbonate and high stand systems tract are shown, in literature, as following: Firstly, according to Hanford and Louks, (1994) carbonates or evaporites are mainly deposited during HST and carbonate sedimentation is usually greatest during high stands of sea level because the wide extent of platform flooding. Secondly, according to Sarge (1988), extensive carbonate reef is developed during last Holocene sea rise. Thirdly, carbonate production keeps up with relative sea-level rise, and excess carbonate sand and mud are reworked and deposited in surrounding basins (Doyle and Bennet, 1998).

TRANSGREESSIVE SYSTEMS TRACTThis systems tract comprised the middle part of the formation. It consists of alternation of grey marl (or calcareous shale) with laminated marly limestone. This type of lithology is clearly showing sudden deepening of the basin which is representing transgressive systems tract. The environment of this systems tract can be located at the distal part of delta slope which intermittently supplied by influx of fine clastics. The thickness of this interval is about 15m and called Avanah tongue inside Gercus Formation (Al-Qayim and Nissan, 1989). In so called “Avanah tongue” no fossil was found. No clear maximum flooding surface was found because of shallowness of the environment. But it is possible that the marly limestone beds that located at the top of this system tract may represent equivalent of maximum flooding surface.

Photo(3):Scarp slop showing lithology and sequence stratigraphy of Haibat Sultan homoclne.

Photo. (4)Lithology and sequence stratigraphy of Gercus Formation at south east of Kalka Smaq village,Dokan area.

HIGHSTAND SYSTEMS TRACTThe deposition of this systems tract occurred during the late part of the eustatic rise, a stillstand, and the early part of a eustatic fall (Van Wagoner et al. 1988). In the field, the further advance into Gercus Formation, through the TST, the marl and limestone change gradually to red claystone and brown sandstone with a thickness more than 70m (photo2). The environment of this systems tract can be assigned as subaqueous and subaerial delta plain which contain mud cracks (photo 6B). The occurrence of mud cracks is resulted from the intermittent covering by flooding manifested laminated sandstone (photo 7A). The distributaries channels on the plain can be seen as lens of sandstone beds (photo 6C).The explanation of Haq(1991) can be accepted for alternation of carbonate and calcareous shale in Gercus formation. He mentioned that during lowstand, siliciclastic is deposited while in highstand carbonate is deposited. This is true when each thick couplet of carbonate –shale is regarded as minor forth or fifth order cycles which suffered from the high and low stand.

LOW STAND SYSTEMS TRACTThe lithology of this systems tract is the coarsest in the succession of the Paleogene in the studied area, as consisted of a bed of polymictic conglomerate about 4m thick. It comprised of gravels which have moderate sorting and roundness (photo 6A). This systems tract is located directly below the Pila Spi Formation. The environment of conglomerate is most possibly consisting of channel of distal braded river which is filled with conglomerate as channel lag deposit. According to Emery and Myers, (1996, p.140) as a result of river rejuvenation; incised valley (which contained a river) commonly contains the coarsest sediment available locally. They added (p.137) if the new river course is steeper than equilibrium river profile, the river would firstly straighten coarse and then incise to form a valley. The shape is lensoidal which is taken the shape in the channel in which it deposited.

Photo(5)Outcrop section of Dararash valley at the northeastern side of Baranan homoclne.

Photo. (6) A: The conglomerate between Gercus and Pila Spi Formations. B: Mud crack found in the middle part of Gercus Formation in Haibat Sultan Mountain. C: Sandstone package pinches out rapidly represents channel deposits.

Photo. (7) A: Parallel laminated sandstone in the middle part of the formation (HST). B: Alternation of calcareous laminated claystone and marly limestone in TST (middle part).

CONCLUSIONThe study revealed the following results:1-The whole rock body of the formation is divided into four systems tract SMST, TST, HST and LST. These systems tracts are deposited during two depositional sequences. The first three systems tract are belongs to Gercus Formation. They called lower depositional sequence while the last one belongs to another depositional sequence which is including Pila Spi Formation.2- The formation, bounded by SB2 and SB1 from below and the top respectively.3- The depositional environment is mainly braided delta plain with intermittent influx of marine water. 4- The systems tracts are relatively lithologically similar to each other which attributed to closely related transitional environments of deposition.

REFERENCESAl-Barzinji, S.J.,1990: Microfacies study of Khurmalla Formation in NE –IraqUn.Pub.Ms.C.thesis Unv. Salahadin, 130p.Al-Eisa,M.I.S.,(1983): Study of the Foraminifera and the depositional environment of fossils in the Khurmala Formation, Shaqlawa area .Un.Pub.Ms.C.thesis Unv.Mosul, 94p.Al-Rawi, Y., 1980: Petrology and sedimentology of the Gercus red bed Formation(Eocene) NE Iraq. Iraqi J.sci.21 ,1, 1980.Al-Rawi, Y., 1983: Origin of red color in the Gercus formation (Eocene) NEIraq,J.Sedi.Geol. 35,P 177-192.Al- Surdashy,A.M, 1988, Lithological, facies and environmental study of Sinjar Formation in selected sections from Sulaimanyia area, Northeast of Iraq; Unpubl., M. Sc.Thesis, University of Salahaddin.Al-Shaikh, Z. D., Saleh, S. A., and Abdo, H.F.1975: Contribution to the Geology ofShqlawa-Harir Area Iraq.jour.Geol.Soc.Sepecial Issue.

Al-Qayim, B. and Salman, L. 1986 : Lithofacies analysis of Paleogene mixed carbonatearea north Iraq.jour.Geol. Soc. vol.19.,No.3.Al-Qayim, B., and Nisan B. 1989 :Sedimentary facies analysis of A Paleogene mixedCarbonate-Clastic Sequence,haibat-Sultan ridge, northeast Iraq.jour.Sci. 30, 4.Al-Qayim, B., and Al-Shaibani S.,. 1991 :A bimodal tidal depositional system of theGercus Formation ,Shqlawa area Northeastern Iraq. Salahadin University jour.Sci.1991.Ameen, B.M .1998 : Sedimentological Study of Gercus Formation in NE –iraqUn.Pub.Ms.C.thesis Unv. Baghdad, 103p.Buday, T. C ,1980: Regional Geology of Iraq: vol. 1, Stratigraphy, I.I.M Kassab and S.Z. Jassim (Eds) D. G. Geol. Surv. Min. Invest. Publ. 445p. Buday, T. and Jassim, S.Z. 1987. The Regional geology of Iraq: TectonismMagmatism, and Metamorphism. I.I. Kassab and M.J. Abbas (Eds), Baghdad,445 p. Bellen, R. C. Van, Dunnington, H. V., Wetzel, R. and Morton, D. 1959.LexiqueStratigraphique, Interntional. Asie, Iraq, 3c. 10a, 333 p.Dhanoun H.Y.et.al.,1988; The geochemistry of the Gercus red bed Formation ofNortheastern Iraq Chemical Geology, Elsevier Science Publishes B.V., Amsterdam-prited in theNetherlands 69,1988 P 87-93.Dhanoun H.Y.,1989: The geochemical significance of the distribution of Ni and Co inclayey-siltstone associated with the Gercus Formation (Middle Eocene)of northernIraq.Jorn.Geol.Soc.Iraq.1989, 22, 1,PP.140-145.Doyle P., Bennet M.R., 1998: Unlocking the Stratigraphical record, Advance in modernstratigraphy ,.Fluvial sedimentation within a sequence stratigraphical frame work, p336-345.Emery, D. and Myers, K.1996 : Sequence Stratigraphy. Blackwell Scientific Limited. 297p. Gallaway, E. W. 1989: Genetic stratigraphic sequences in basin analysis Architecture andgenesis of flooding- surface bounded depositional units. (AAPG), 73, 2, p.125-142. Hanford and Lauks 1994In loucks, R.G and Sarg, J.F (Rick) eds, carbonate sequencestratigraphy, (AAPG), Memoir 57, P 3-41.Karim, K. H. 1997.Stratigraphy of Sartaq-Bamo Area from northeastern Iraq. IraqiGeological Journal, 31, 1 .Sarg J.F., 1988, Sea level changes-An integrated approach Carbonate sequence stratigraphyP(156-179).Lawa, F.A.. 2004. Sequence stratigraphic analysis of the middle Paleocene –Middle Eocenein the Sulaimani District( Kurdistan Region). Unpublished Ph.D. thesis, University of Sulaimani.Shaikh et.al.1975 Contribution to the geology of Shaqlawa-Harir area. Journal of thegeological Society of Iraq, Special Issue,pp.55-67 .Surdashi,A.M.and Lawa,F.A.1993:Stratigraphy,Microfacies and Depositional Environmentof Sinjar Formation in studied section ,NE. Iraq. Special Issue of procceding of 2nd scientific conference of University of Salahaddin-Erbil ,PP.77-110.Vail, P.R., Mitchaum, R.M., Todd, R. G., Widmier, J.M. and Hatleid, W.G.1977. Seismicstratigraphy and global changes in sea level. In: seismic Stratigraphy –Application toHyrocarbon Exploration (ed. by C. E. Payton). Memoir of the American Associationof the Petroleum Geologists, Tulsa, 26, pp49-62.Van Wagoner , J.C., Posamentier, H.W., Mitchum, R.M., et al., , 1988, An overview ofVial,r.r.,Sarg.J.F.,Loutit,T.S.,Hardenbol, the fundamentals of sequence Stratigraphyand key definitions, in Wilgus, C.K., et al., eds., Sea level changes: an integrated approach: SEPM Special Publication 42, p. 39-45.Mail, A. D. 2002. Architecture and sequence stratigraphy of Pleistocene fluvial system in the Malay Basin, based on seismic time –slice analysis. American Association of the Petroleum Geologists (AAPG) Bulletin. 86. 7.pp1201-1220

UPPER BOUNDARY OF QAMCHUQA FORMATION (EARLY CRETACEOUS)

NEW SEDIMENTOLOGIC AND STRATIGRAPHIC CHARACTERISTICS OF THE UPPER BOUNDARY OF QAMCHUQA FORMATION (EARLY CRETACEOUS) AT NORTHWEST OF ERBIL, KURDISTAN REGION, NE/IRAQ

Bakhtiar M. Ameen and Kamal H. Karim

Published in: Iraqi Bulletin of Geology and Mining, Vol.4, No.2, 2008, p.1 -13

ABSTRACT

The contact between Qamchuqa (Early Cretaceous) and Bekhme (Late Cretaceous) formations is studied in the field and laboratory. On the basis of lithology, the contact is described and analyzed in four different sections. In all four sections the result of the study showed gradational boundary, two of four sections (Zante gorge and Perse Mountain) are barren of conglomerate, breccias or erosional surfaces, so the contact seems to be conformable in the field. The other two sections (outlet and inlet of Bekhme gorge) contain beds of apparent conglomerate (or conglomerate–like masses), which in the present study are inferred to be not depositional, but diagenetic in origin. They are secondary ball and pillow structures, which formed during burial by tectonic or lithostatic stress. In the inlet of the Bekhme gorge section, there is a mass of breccias (about 1.5m thick), which is located 10m above the ball and pillow beds. This breccia is not depositional as it consists of extremely angular clasts of limestone. These clasts are believed to be tectonic in origin and derived from younger beds above the contact, which is not more than 20m higher from their location. The clasts are transferred to this location possibly reverse fault across Great Zab River. In contrast to previous studies, the contact suffered from deepening relative to the overlying and underlying Bekhme and Qamchuqa formations, respectively. This is manifested by green marl, marly limestone, limestone bearing planktonic forams and breccias. The soft succession at the boundary (about 30m thick) is most possibly deposited during the previously suggested gap or unconformity.

INTRODUCTIONAccording to Bellen et al. (1959) the type section of Bekhme Formation is located in the Bekhme Gorge in the High Folded Zone (Fig.1). It consists of nearly same lithology as of Qamchuqa Formation According to the all previous studies, the Qamchuqa Formation is overlain by Bekhme Formation unconformably. Bellen et al (1959) mentioned the occurrence of polygenetic and basal conglomerate and breccias (about 10m thick) between the two formations. He mentioned that the conglomerate represents a gap, which extends from Late Albian to Early Campanian. Buday (1980) mentioned that the contact is as a rule unconformable due to occurrence of conglomerate at base of Aqra-Bekhme Formation. Recently Al-Qaradaghy (1989), Al-Qayim and Shaibani (1995), Omar (2006), and Jassim and Golf (2006) have mentioned unconformable contact too.

Fig.1: Location map and simplified geological map of the studied area (Modified from Sissakian, 2000). X1, X2, X3, X4, are studied sections of Bekhme gorge inlet and outlet, Zanta and Perse sections respectively.

LITHOLOGY AND STRATIGRAPHY OF THE BOUNDARYRecently and during fieldworks, new observations are recorded in many different localities that show that shows a probable conformable boundary between the two formations. Considering the basin analysis of northern Iraq, the boundary, in all observed sections, seems to be continuous in deposition while yielded more or less similar lithologies (Fig.2). The nature of the boundary is relatively soft, which consists of marl, marly limestone, white and nodular beds of limestone with breccia. To explain why this contact was assigned, previously by all authors, as unconformable and repeatedly mentioned and ascertained to be represented by basal conglomerate, the following eight points must be taken into consideration: The first point is, at the type locality of Aqra–Bekhme Formation, breccias and conglomerate-like beds of limestone are observed by present authors (Fig.3).These beds, most possibly, are those “sedimentary breccias and basal conglomerates” that are mentioned by Bellen et al. (1959) at the base of Bekhme Formation. The approximate location of the breccias and basal conglomerate as given by Bellen et al. (1959, p.61) has latitude (36o 41- 45=) and longitude (44o 16- 30=) which is located by GPS. These two lithologies are associated with bluish white marl and milky marly limestone. Field and laboratory studies showed that the observed breccias are not sedimentary but tectonic and occur at one section out of four. This section is located at the right side (down stream) of the inlet of the Bekhme gorge at the contact of the two formations and along the bank of Greater Zab River (Fig.4A). The development of the breccias (Fig.5) is attributed to a reverse fault that extends across the riverbed and both sides of the gorge, directly at the south of the proposed dam site. The clasts of the breccias are extremely angular (show no transportation) and derived from the nearby beds (such as finely laminated and massive limestone clasts). The parent rocks of these clasts are located at younger level than the breccias, which is located no more than 20m far from the place of the breccias that are transported to. The most obvious evidence for the fact that the clasts are

not sedimentary, is that their parent rocks (layers) are located, stratigraphically, at higher level (have younger age) than the stratigraphic position of breccias. The younger stratigraphic position of the parent rocks of the breccias is very clear along the inlet of the Bekhme gorge. When one crosses 300m, from the upper part of Bekhme Formation to lower part along the stream, three beds (each 10cm thick) of grey laminated limestone can be observed in their depositional place near the contact (Fig.4A). After that, blocks of breccias appear at 20 meters above the laminated limestone. The breccias contain clasts (2-5cm in width) of same lithology of the laminated limestone (Fig.4A). It appears that the movement along of the fault has transferred the clasts of the breccias to horizons stratigraphically older than the original parent rocks of the clasts. Consequently, the clasts are lithified to form fault breccias. The resting of the block in the zone of the boundary between the two formations is attributed to softness of the boundary, which can act as a host for foreign bodies. The marly boundary is cited by Bellen et al. (1959) and Sissakian and Youkhana ( 1984) was seen by the present authors in all sections as shown in the (Figs. 2 and 4).The second point is the conglomerate that is described by Bellen et al. (1959) and seen by the present authors is not sedimentary in origin. They are ball and pillow-like structures which are formed by the pressure due to presence of alternation of competent limestone beds with incompetent beds of marl (Fig.8).The origins of these conglomerate-like structures (ball and pillow) are described in detail by Karim (2006) in the Tanjero and Kolosh formations. He found these structures in sandstones, limestones and in igneous rocks too in the Sulaimanyia Governorate showing more than 10 photos and diagrams to explain the development of these structures by stress during burial (Fig.10 as an example). Tucker (1991, p.163) mentioned that pelagic limestones (present marl and marly limestone) are characterized by nodular structure which surrounded by pressure solution clay seems. The photo that given by him is highly resembles those recorded in present paper.

Fig.2: Conformable boundary between Qamchuqa and Aqra-Bekhme formations at three different sections in Bekhme and Zante gorges and Perse anticline.

Fig.3: Boundary between Qamchuqa and Aqra–Bekhme formations at two different sections which are showing secondary ball and pillow- like structures that previously might be assigned as depositional conglomerate. A) Bekhme outlet and B) inlet (according to stream flow direction).

Fig.4: A) Boundary between Qamchuqa and Aqra–Bekhme formations at Bekhme inlet (according to stream flow direction) showing location of Ball and pillow-like structures(C), breccias (D). The trace of possible reverse fault is indicated across the valley surface by white line. B) The close up photo of laminated limestone beds (L).

Fig.5: Extremely angular fault breccia between Qamchuqa and Aqra–Bekhme formations at the left side of inlet of Bekhme Gorge. A) The clasts are all derived from nearby laminated beds. B) All clasts are white thin beds of limestone that are located at the higher stratigraphically level.

Fig.6: Four stages of development of ball and pillow structure by tectonic stresses when competent and incompetent beds are associated (Karim, 2006).

Bellen et al. (1959) have mentioned variable character and thickness of the conglomerate even over very small exposed area of the gorge section. They added that the conglomerate change laterally to marl and in other place, it is 3 meters thick and laterally changes to massive bed of about 20m thick. These conglomerate-like masses, in the present study, are found (as beds) in three localities of the inlet and outlet of the Bekhme Gorge. At these localities, the white and rounded ball and pillows are concentrated in marly matrix as beds of limestone about (0.2 -1)m thick (Figs. 4 and 7). These balls and pillows are very similar to the sedimentary conglomerate in appearance but in close looks and under microscope they are all consisting of same lithologies (fine grain limestone with same type of planktonic forams). Tucker (1990, p.163) described deep water limestones (pelagic limestones) and mentioned that they contain nodular limestone which are surrounded by clay seems due to pressure solution.

Fig.7: Conglomeritic-like ball and pillow formed in marly limestone bed near the boundary of the two formations.

The third point is that the claimed or assumed conglomerate (present ball and pillow) is located inside the bluish green marl, which contains planktonic forams. Moreover, it is not associated with sandstone or sand size clasts, this give an other evidence of non-sedimentary origin of the conglomerate that mentioned by Bellen et al (1959) and other authors. The matrix of the previously supposed conglomerate is marl. The deposition of marl and conglomerate (gravels and boulders without sand) is abnormal in the view of hydrodynamic (hydraulics grain equivalent) and sedimentologic principles, if not associated with more or less sand size grains Blatt et al. (1980). The fourth point is that, in the 10m thick lower division of Aqra–Bekhme formations, Bellen et al. (1959) mentioned the occurrence of marl and Globigerina forams. It is clear that, the environment, across the boundary, is deepened instead of shallowing. Most possibly the environment changed from reef to fore reef environment at the boundary. In sequence stratigraphy literatures by Vail et al. (1977), Loutit et al. (1988), Haq (1991), Emery and Myers (1996), the conglomerate is deposited during regression (lowstand systems tract). However, the coexistence of marl and planktonic formas in the boundary is evidence of transgression (high stand system tract) and deepening. But the submarine erosions must not be excluded which occur in many formations. The fifth point is that at the Zanta gorge 35km to the west of Bekhme gorge, the contact contains neither erosional surface nor breccias (or ball and pillows). At these localities, the massive Aqra–Bekhme Formation changes, across the boundary, to well-bedded limestone and marly limestone then changes downwards to massive Qamchuqa Formation. Therefore it seems that the contact is gradational in this locality (Fig.8).The sixth point is that no previous studies have shown any clear photos for the occurrence of conglomerates between the two formations. Omer (2006) showed two color photos (Fig.9) for the unconformity nature of the contact between the two formations. However, none of them shows clear conglomerate, as the first one which more likely appears to be solution cavity that is covered internally by white coating (Fig.9A). The second photo (Fig.9B) shows saccaroidal dolomite. This type of dolomite could be generated by groundwater erosion. Karim, et al (2000) found same type of dolomite (they called it friable dolomite) in the Qamchuqa Formation in the southwestern limb of Piramagroon anticline. They attributed the generation of these friable dolomites to be due to the percolation of groundwater.

Fig.8: Boundary between Qamchuqa and Bekhme Formations at southwestern and northeastern upper limb of Perse anticline at northeast of Dinarta town. The boundary consists of intercalation of marl and bioturbated dolomitic limestone, which is possibly gradational.

Fig.9: Two photos with their title and plate numbers as prepared by Omer (2006) for unconformity between Qamchuqa and Bekhme Formations.

The seventh point is that Sissakian and Youkhana (1984) have surveyed and mapped the area around Shaqlawa town including Safeen, Harir and Shakrook anticlines. In their survey, they are found neither conglomerate nor erosional surface between the two formations. Moreover, they have found a succession of 65 m of soft rock (green marl and marly limestone) that is located at the top Qamchuqa Formation. They claimed Albian age to this succession depending on the recorder following fossils: Orbitulina spp. Valvulammina sp., Pseudolituonella sp., pseudocrysalidea sp. Orbitolina cf. discoidea(GRAS) Guneolina sp., Iraqia sp., Orbitolina cf. concava ( LMARK).Moreover, they claimed unconformable contact between the two formations. But, the authors believe that some of the identified fossils indicate Cenomanian age and the soft rock successions could be correlated with Kometan Formation, age wise The eighth point is that Al-Jassim et al.(1989) studied biostratigraphy of Kometan Formation in the Qarachuq well No.1, Kirkuk and Well No. 166. In these wells they concluded and mentioned the following:• The age of Kometan Formation Late Turonian–Early Campanian • In two of the three wells, the Kometan Formation consists of shale and marly limestone.•In the two wells, they did not observe any unconformity or missed ages from Turonian till Middle Campanian.The result of the above study supports the result of the present study according to the following points:•Kometan Formation was continuous in deposition in all northeastern Iraq, but as different facies. The well bedded limestone of type section is changed, in some place, to shale, marl and marly limestone as in the wells studied by Al-Jassim et al. (1989) and in the Qamchuqa Gorge as mentioned in the present study. •If there are no unconformities, in Kirkuk–Qara Chuq vicinity areas (as mentioned by Al-Jassim, et al. (1989) respectively, why must be unconformity in the Bekhme Gorge and extend from Late Albian to Early Campanian as suggested by Bellen et al.(1959)?. This gorge is only about 50 and 100kms far from Safeen and Qarachuq anticlines respectively.

CORRELATION OF THE STRATIGRAPHIC POSITION In the present study, samples are taken from marl, marly limestone and white limestone in the boundary zone between the two formations, but none of them yielded identifiable planktonic forams. This is true for the study of Bellen et al.(1959), Buday, (1980), Al-Qayim and Shaibani (1995), and Jassim and Golf (2006). They did not mention any index forams that were related to the boundary Zones between Qamchuqa and Bekhme formations. As the authors are aware, the study of the Al-Qaradaghy (1989) did not record any index planktonic forams for age determination across the contact. The absence of index forams either attributed to environmental constrain which was not suitable for surviving certain organisms or may be related to destruction by diagenesis. Therefore, the age determination and correlation of the stratigraphic position of the boundary zone with other sections (of same age) in the surrounding that are related claimed unconformity (or gap) are base on Bellen et al ( 1959). As previously mentioned in the Bekhme gorge there is about 30m of soft lithologies between the two formations. In Kirkuk and Qarachuq areas, same lithologies are recorded by Al-Jassim et al. (1989) respectively. These lithologies nearly located in the same stratigraphic position and have same age of the claimed unconformity. These lithologies are well dated by planktonic zonation in the Kirkuk well No.166 and Qarachuq Well No.1. (Fig.10). The correlation is shown in Fig. (10) between these two wells with the soft lithologies of the Bekhme gore at the boundary between the two formations.