utilization of the observed geological features in...

First International Conference in Basic Science and Their Applications, Al-Bayda, Libya, 2015

Proceeding Book

© 2015 Faculty of Science , O MU Publisher

Pag

e17

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Utilization of the observed geological features in differentiating the

exposed rock units in Al Jabal al Akhdar, Libya

Ahmed M. Muftah*, Mohamed S. Al-Faitouri and Salah S. El-EKhfifi

*University of Benghazi, Faculty of Science, Department of Earth Sciences, P.O. Box 9480, Benghazi-Libya. a_muftah @yahoo.com

ABSTRACT

Specific lithological and paleontological signals in addition to tectonic-induced features, which are observed at Al Jabal al Akhdar

outcrops, allow facilitating the differentiation between the different stratigraphical rock units at first glance. The integration of these

features is used herein to achieve precise identification of each rock unit (Formation). These geological evidences are grouped under

three main categories: 1) Lithomarkers: include, color, the rock durability (chalky andmarly), grain type (glauconites, ooides and peloids), rock type, chert nodules, rhythmic bedding style, and cross-stratification,furthermore, the bituminous odor is also

incorporated under this category; 2) Biomarkers: include, larger foraminifers (Nummulites, Lepidocyclina, Orbitolites, Operculina,

Heterostegina, Gaziryina, and Discocyclina etc..), mollusks (gastropods, pelecypods and cephalopods), echinoids,worm tubes, corals,

bryozoans, crabs, barnacle, vertebrate remains (teeth and bone fragments), ichnofossils (Thalassinoides and Ophiomorpha), and

coralline red algae; 3) Tectono markers, include tectonic related features that observed locally in few forms such as highly jointed, folded (slumped), tilting (angular unconformity) and micro-faults. Fifteen exposed formations were defined based on the above -

mentioned criteria withbrief notes and some illustrations. These are from oldest to youngest, Qasr al Abid, Al Hilal, Al Athrun (the

lateral coevalto Al Baniyah- Al Majahir- WadiDukhan), Uwayliah, Apollonia, Darnah, Shahhat Marl, Al Bayda, Al Abraq, Al

Faidiyah, Al Gaghbub, Benghazi, and Wadi al Qattarah. On the other hand, the pelagic sediments which yielded microscopic

diagnostic (planktic and/or deeper smaller benthic) foraminifers were treated separately; as the microscopic examination is the only way for their identification in order to confirm the Formation name.The XLSTAT- Agglomerative hierarchical clustering (AHC) is

used herein for correlation analysis (similarities and dissimilarities) from which three main clusters are presented.

Keywrods: Cyrenaica, Apollonia, Nummulites, Lithomarker, Glauconite, Libya.

1. INTRODUCTION:

Al Jabal al Akhdar displays carbonate successive exposures

ranging in age from Late Cretaceous to Late Miocene (Fig.

1), these were not exposed in the entire Sirt Basin, and

however they yield thick subsurface sequences as

experienced by the penetrating successions by oil companies .

On the other hand, the Upper Cretaceous -Paleocene sections

in Al Jabal al Akhdar were partially cropped out in response

to the Cyrenaican Orogeny Barr and Berggren, (1980) which

was resulted in emerging of several Cretaceous –Paleocene

inliers, along the ENE-WSW trending anticlines including

the recently discovered Ras al Hilal anticline of El Amawy et

al., (2011) (Fig. 1).

Fig. 1: Geological map of northeastern part of Libya shows

the cretaceous inliers and spatial distribution of the exposed

rock units (Elwerfalli et al., 2000)

Utilization of the observed geological features…

172

2.GEOLOGICALFEATURES“LITHO/BIOMARKERS”

The geological features are grouped under three

categories these are lithomarkers, biomarkers and

tectonomarkers: Several geological signatures expressed in

lithological preserved features that reflect certain

depositional and diagenitic or paleontological remains, while

tectonic induced features are resulted from post-depositional

tectonic structures (Fig. 2). The different observational

criteria that exist at some out crops along wadi-sides, sea-

cliffs, road-cuts and quarries, may aid in the differentiation

of the different rock units (Fig. 3).

Fig. 2: Flow chart shows the different lithological and

paleontological markers of this study.

The geological features are grouped under three categories

(Figs. 3, 4) these are lithomarkers, biomarkers and tectono-

markers:

2. 1. Litho-markers

The different lithologies and/or observed lithological

featuresarethe fundamental categories used indifferentiation

of the exposed rock units, they include:

Limestone: It is the dominant lithology in Al Jabal al

Akhdar, where almost all formations are made of except, Al

Hilal shale and WadiDukhan Dolomite. Although the marly

limestone and marl are also preserved at some levels in the

different exposed rock units.

Fig. 3: Stratigraphic chart shows the Al Jabal al Akhdar

exposed rock units.

Dolostone: It also called “Dolomite” is a unique lithotype of

WadiDukhan Formation, but dolomitization is also present

as subordinate components in Al Majahir, Al Baniyah and

Benghazi formations at some levels.

Clay: Itis exposed in Al Jabal al Akhdar at two levels the Al

HilalFormation and the lower part of Al Faidiyah Formation.

The former only exposed at Ras al Hilal area, with common

Late Cretaceous calcareous nannofossils and foraminifers for

more information see (E Mehaghag and Muftah, 1996; Barr,

1972;Barr and Hammuda, 1971). On the other hand, Al

Faidiyah Clay unit is mainly glauconitic in composition with

few foraminifers, the thickest exposed part is at Umm el

Rezzam area and excavated by the GOWFE Company for oil

technology as local row materials used in the Bentonite

production El Ebaidi, (2000).

Gypsum:It was deposited in Libya in most cases due to the

isolation of the Paleo-Mediterranean Sea “Tethys” from the

Atlantic Ocean during Messinian time as a result of

thestrongcrustalmovementsandmountainbuildingprocessesthr

oughouttheMediterraneanregion (Pawellek,2007).At Al Jabal

al Akhdar, it is only exposed in ArRajmah area “e.g. Hawa al

Baraq” El Hawat and Shelmani, (1993), where gianttwinned

selenite crystals of thesalina lake facies of Wadi al Qattarah

Formation” (El Hawat and Shelmani, 1993).These gypsums


173

are largely excavated as it forms one of the important row

materials for the cement production due to the high purity.

However, gypsiferous intercalations are present locally at

some localities in the subkahfacies of Wadi al Qattarah

Formation as well.

Chert: Apollonia, Darnah and Al Athrun formations are

characterized by common occurrences of chert nodules with

different shapes, sizes, colors and structure. However, Wadi

al Qattarah and Al Gaghboub formations are rarely yielding

chert nodules at some levels. The Al Athruncherts are the

oldest exposed chert nodules in the Al Jabal al Akhdar, they

are usually small in size (≈10cm), white to milky in color,

occasionally becoming dark brown due to inclusions

“organic matter and/or iron oxides, relic of carbonate”,

discoidal-flattened and largely cracked due to tectonism. The

Apolloniachert nodules however, are usually brownish in

color, small in size, potato to ovoid in shape sometimes

angular as seen in the type locality "Pyramid section" (Fig.

5.1), with concentric growth pattern reflecting

chemicaldiagenetic deposition, in some cases Nummulites

are silicified indicating diagenetic origin rather than biogenic

El Amawy et al., (2011). However, Darnahchert nodules are

similar to that of Apollonia except they are larger in sizes

(from a few centimeters to a few tens of centimeters) with

scattered and intermittent distribution. On the other hand,

cherts in Wadi al Qattarah and Al Gaghbub are rarely present

in local sense; the former is bluish white in color, thin

bedded with pseudomorphs indicating probable chemically

deposited due to silica enrichment, while the latter is

brownish in color, irregular in shape suggesting a diagenetic

origin. It is important to say that some of these cherts

particularly from Al Gaghbub Formation had been used as

source rock during Stone Age for making the prehistoric

lithic and tools in Al Jabal al Akhdar"e.g. arrowhead"Hulin

et al., (2010).

Glauconitization: This diagenetic mineral (glauconite)

resembling feacal pellet-like products. These grains are also

filled partly the tests of nummulitids (Nummulites and

Operculina) of Al Faidiyah Formation which provided post-

depositional conditions ideal for glauconitization. This is a

common lithomarker at the base of Al Faidiyah Formation

(Fig. 5.2), but rarely occurred in Shahhat Marl and AlAbraq

formations. However, locally at Wadi al Athrun there are

two horizons containing inclusions of glauconitic and

phosphatic grains in Apollonia Formation, both horizons

indicated two unconformity surfaces with small scale hiatus

El Hawat and Shelmani (1993); El Hawat and Abdulsamad

(2004). Application of isotope stratigraphy in combination

with biostratigraphy will be useful in the resolution of field-

scale correlations Vahrenkamp (1996).

Alternation of beddings: It displays rhythmic pattern of

beddings between soft, thin-bedded pelagic chalks, to

medium hard, thick-bedded shallower limestones. This is a

common feature in Apollonia (Fig. 6.2), in addition to Al

Athrun and Al Faidiyah formations (Fig. 6.3), and it is

reflecting fluctuation in sea level.

Ooids/peloids:Ooidsare spherical carbonate grains of sand

size range with internal concentric laminar structure,this is

most likely a unique texture of Wadi al Qattarah Formation

and the lateral equivalent "the so-called" Msus Formation in

the western part of Al Jabal al Akhdar.While, the peloids are

smaller in size without internal structure and in most cases of

algal origin which are observed in addition in Al Gaghbub

Formation in the eastern part of al Jabal al Akhdar.

Chalky nature: Uwayliah and Apollonia formations

characterized by very chalky nature as they composed of

open marine planktic foraminifers and calcareous

nannofossils ooze Muftah et al., (2003) on the other hand Al

Faidiyah Formation is also chalky due to the high purity of

calcite El Ebaidi (2000); El Ebaidi, et al., (2015).

Large scale carbonate concretions, these large distinctive

diagenetic carbonate bodies are observed in Darnah

Formation at Addabusssiyah road cut section (Fig. 5.4).

Cross stratification: This syndepositional sedimentary

structure tells about the paleo-currents and help in

delineating the paleo-shore line as well. It is very distinctive

to both Wadi Al Qattarah Formation (Fig. 5.5) and Al

Gaghbub Formation as observed at some levels.

Bituminous odor: This unique chemical signature can be

applied to differentiate Apollonia Formation from others

such as Darnah Formation in Al Jabal al Akhdar, this

bituminous odor can be sniffed when you hit the

Apollonialimestone using a geological hammer during

sampling Röhlich, (1974).

2.2. Biomarkers

This category in the concerned sections exhibits different

observed paleontological elements, which serve as important

reference lines for stratigraphic correlations. They include:

Bioturbation: Thalassinoides is very characteristics to

Qasr al Abid, Shahhat Marl, Al Abraq and Al Faidiyah

Formation, but rarely observed in uppermost surface

(unconformity) of Al Athrun Formation as seen at

WadiAthrun section. However, Ophiomorpha on the other

hand, developed in Al Abraq and Shahhat Marl formations.

Larger sized burrows are illustrated in Figure (6.5).

Coral reef: It is of great important in oil industries as it forms

excellent reservoirs. The huge coral reef observed in the field

is mostly developed in Darnah and Al Bayda formations in

forms of colonial (Fig. 6.7) and solitary types (Khameisset

al., (2015), however, also some representatives are present in

Al Faidiyah, Al Gaghbub and Benghazi formations in local

basis.

Crabs: Fragments of crabs in form of arms with claws are

scarcely reported in Abraq Formation.


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Dissociated vertebrate elements: These include bone

fragments and teeth as well as undifferentiated phosphatic

grains, they are indicative to unconformity surfaces between

rock units in particular Al Abraq Formation, Al Athrun and

Apollonia formations.

Echinoids: They presentof complete shells of large-sized

such as Echinolampas in Al Abraq and Shahhat Marl; or

asScutella and Clypeaster in Al Abraq, Al Faidiyah, and

Benghazi formations. However, the tiny echinoids

Echinocyamusand the flattened Echinodiscusare indicative

of AlAbraq Formation (Muftah and El Mahdi, 2015).

Large mollusks: The large sized oysters are indicative to

Algal limestone of Al Bayda Formation; Inoceramus

(internal molds) are very characteristic to Al Majahir

Formation (Fig. 6.7), pectinids are observed as common

elements in Al Faidiyah Formation; Rudists are commonly

observed in the MaastrichtianWadiDukhan FormationMuftah

et al., (2011); however, the large sized Ammonites are found

in both Al Baniyah and Al Majahirfromations. Although the

Nautilus is scarcely reported in Darnah Formation (Fig. 6.8).

Red algae: It presents either as branched or rhodoliths as in

both Benghazi Formation (Fig. 6.9) and algal limestone of

Al Bayda FormationMuftah and Erhoma, (2002), however,

the encrusted filamentous type is rarely present in other

formations such as Al Abraq Formation.

Barnacles: The encrusted Balanus assortment is observed in

Miocene Benghazi and Al Gaghbub formations.

Bryoazoa: They are common elements in Al Faidiyah

Formation, as studied in Susa –Shahhatroadcutby El Safori,

and Muftah, (2007) and observed in Wadi Al Shaigh east of

Dernah city.

Worm tubes: The calcified worm tubes are usually indicative

of low energy, shallow water conditions in slow rate of

sedimentation conditions. They are commonly present in Al

Faidiyah Formation in form of relatively large-sized

SerpulidFistulana Cyrenaica (Fig. 6.4);however, they are

scarcely seen in Apollonia Formation at Wadi Al AlAthrun

section. However, Diatruba are seen commonly in Darnah

Formation as at Al Hmidahroadcut.

Larger foraminifers: They can be observed by naked eye,

they are extensively used as formation-indicator and/or as

biostratigraphical tools, especially in Tethyan carbonates

lacking planktic foraminifers. These larger foraminifers in

the visitedsectionsincludemainly Nummulitesassem-

blageassigned toNummulitesfichtelliBiozone of Racey

(1995) (Late Oligocene); andGaziryinapulchelluswith N.

fabianiiwhich assigned to the NummulitesfabianiiBiozoneof

Racey (1995)(Late Eocene) with;

NummulitesgizehensisBiozone (Middle Eocene) Darnah

Formation (Fig. 5.3).However species of, Lepidocyclina,

Discocyclina, Actinocyclina, Orbitolites, Operculina, and

Heterostegina are also restricted to Cenozoic successions.

The Middle Eocene species of Nummulites, Discocyclina,

ActinocyclinaandOrbitolitesare restricted to Darnah

Formation. The Oligo-Miocene species of Lepidocyclina,

Operculinaand Heterostegina, are restricted to Al Bayda, Al

Abraq, Al Faidiyah and Benghazi formations .In the

laboratory, more investigations can be performed for

identification of fossils in particular the planktic

foraminifers, where the biozonation is the precise key for

dating the sediments and therefore, we can name the hosted

rock unit more precisely, in particular the deep marine facies

(lacking macrofossils and larger benthic foraminifers) of the

exposed rock units in Al Jabal al Akhdar, as briefly

mentioned below:

Qasr Al Abid Formation (Cenomanian): The diagnostic

benthic foraminifera Thomasinellapunica, as well as the

planktic representatives Rotliporacushmani, R.

greenhornensis, Praeglobotruncanastephani could be washed

from Qasr al Abid marls.

Al Hilal Formation (Coniacian-Santonian):

Concavutruncanaconcavataand C. asymetricabiozones are

assigned to the exposed rocks at Al Hilal Sea cliff and at the

mouth of Wadi al Qalah sections, in which C. asymetrica, C.

concavata, Marginotruncanasinuosa, M. coronata, M.

undulata, M. schneegansi, M. pseudolinnieana, M.

marginata, M. sigali, M. renzi, Clavihedbergella simplex,

Hedbergellaflandrini, H. planispiraandSigaliacarpaticaare

documentedEl Mehaghag and Muftah (1996).

Al Athrun Formation: The planktic for aminiferalbiozones

Globotruncanaconcavata, Globotruncanaelevata,

Globotruncanatricarinate, Globotruncanagansseri and

Abathomphalusmayararoensisbiozones are recognized in this

Formation by Barr and Hammuda (1971) in Wadi al Qalah

section.

AlU wayliah Formation The plankticforaminiferal

Planorotalitespseudomenardii Zone is assigned to the

exposed Al Uwayliah quarry, where the following is

commonly reported P. pseudomenardii, P. chapmani,

Morozovellavelascoensis, M. occulosa, M. cf. M. aequa, M.

cf. M. angulata, Muricoglobigerinamckannai, Acarinina

primitive andSubbotinavelascoensisMuftah et al., (2002).

Apollonia Formation: Early-Middle Eocenewith

interfingering relationship (Röhlich, 1974). However,

according to El Koudary, (1991)(Middle-Late Eocene) as the

recognized Globorotaliacerroazulensiss.l. biozone,

Globigerinathekasemiinvolutabiozone, (Late Eocene).While

Truncorotaloidesrohreibiozone, Orbulinoidesbechmannibioz-

one, Globorotalialehneribiozone and Globigerinathe-

kasubconglobosabiozone are indicative to Middle Eocene at

Wadi al Bahur section.


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2.3. Tectono markers

These are the tectonic induced features which are recognized

at some localities.

Folds: These are well developed in Al Athrun Formation

where the folded beds are seen (Fig. 5.6). However, the

related sedimentary structure “convolution structure” has

been reported in Al HilalFormation by El Amawy, et al.,

(2011).

The highly jointed beds with 3-trending sets and microfaults

as well as folds as seen in the Al Athrun Formation are also

included (Fig. 5.7).

3.AGGLOMERATIVEHIERARCHICAL

CLUSTERING (AHC) USING XLSTAT:

Using the dendrogram with some other statistical methods

proved to be very useful tools in geological sciences the

work of Dimizaet al., (2015) is an example. Cluster analyses

were carried out to see the similarity and dissimilarities

(compositional variation) between all rock units which

reflect the correlation between the different rock units

(Formations) based on 36 variables (lithological and

paleontological and tectonomarkers) listed in table (1).

The result of hierarchical clustering analysis in Table (2)

shows the data range and the analysis used quantitative data

with Euclidean distance matrix to cluster by the nearest

neighborhood method.

The dendrogram shows the pattern of clustering with a

vertical axis representing the range of distance from 0 to 18.

Three clusters have been obtained from the dendrogram (Fig.

4):

Cluster 1 (C1) shows WadiDukhan and Al Baniyah

formations are very identical as indicated by the distance

matrix, moreover, both are very close to Al

MajahirFormation. Also the same scenario can be applied to

Qasr al Abid and Al Hilal formations as well as Al Athrun

and Uwayliah formations. Moreover, both Al Athrun and

Uwayliah formation are very close to Apollonia Formation

Table 1: Class centroids

Table 2: Distances between the class centroids

1 2 3

1 0 2.096 2.744

2 2.096 0 2.676

3 2.744 2.676 0

as we can read from the matrix table (Tables 2 and 3). In

order to differentiate the closest rock unit as in Al Athrun

and Uwayliah formations for example we need to apply

adifferent statistical method that shows the small variety

between them (see the matrix Table 3).

Cluster 2 (C2) shows Al Bayda algal limestone and

Benghazi formations are very identical as indicated by the

distance matrix; moreover, both are very close to Darnah

Formation. Similarly, Al Gaghbub and Wadi al Qattarah

formations are identical. In order to differentiate between

them we need to apply a different statistical method that

shows the small variety between them (see Table 3).

Cluster 3 (C3) shows Shahhat Marl and Al Abraq formations

are very identical as indicated by the distance matrix.

Moreover, both formations are very close to Al Faidiyah

Formation as we can read from the matrix table (Tables 2

and 3). In order to differentiate the closest rock unit of

Shahhat and Al Abraq we need to apply a different statistical

method that shows the small variety between them (see the

matrix Table 3).

CONCLUSIONS

The syndepositional, postdepositional observational

lithologic features, fossils and trace fossils as well as tectonic

induced structures are merged together in order to facilitate

determination and differentiation between the exposed rock

units in Al Jabal al Akhdar. Microscopic examination is

recommended to confirm the field investigation in particular

to the deep marine sediments or shallow marines which

lacking macrofossils. The rock units that possess unique

lithomarker or biomarker are easy to identify, but others who

sharing several features are presented by the help of

hierarchical dendrogram. Using Geostatic science is very

helpful in understanding and displaying the data in very

potential way. The enigmatic horizons “i.e. patchy and

sporadic occurrences” where they are difficult to name or

identify the rock unit, the microscopic examinations

(petrographic and microfossils examinations) are the only

solution, otherwise the stratigraphical position is the

alternative.


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Table 3: Gives the correlation coefficient (R) for all of the combination of the study variables. (R1 is for any variable

correlatable with itself ; -1< R >1is for all other combinations. Alternation of beds and microfaults R= 0.823 meaning very

strong; Gupsum and Oolitic R= 0.683 meaning strong correlation; Chert and Glauconite R = 0.022 meaning no correlation

between them).

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Limestone 1.000 -0.092 -0.333 0.149 -0.218 0.218 0.218 0.389 -0.092 0.333 0.277 0.218 0.277 -0.447 0.277 -0.218 0.149 0.277 -0.218 0.149 -0.447 0.149 0.277 -0.218 0.149 0.389 -0.333 -0.092 -0.462 0.078 -0.218 0.149 0.277 0.218 0.218 0.277

Dolostone -0.092 1.000 -0.277 -0.124 -0.182 -0.182 -0.182 -0.324 -0.231 -0.277 0.179 0.303 -0.231 -0.124 -0.231 -0.222 -0.372 -0.231 -0.182 -0.372 -0.124 -0.124 -0.231 -0.182 -0.124 -0.324 -0.277 1.000 0.179 -0.324 -0.182 -0.124 -0.231 -0.182 0.787 -0.231

Marl/ Marly ls-0.333 -0.277 1.000 -0.149 0.218 -0.218 -0.218 -0.389 0.462 0.000 -0.277 -0.218 -0.277 -0.149 -0.277 0.509 0.447 0.462 0.218 0.447 0.447 -0.149 -0.277 0.218 0.447 -0.078 1.000 -0.277 0.092 0.545 0.655 0.447 0.092 0.218 -0.218 0.462

Gypsum 0.149 -0.124 -0.149 1.000 -0.098 0.683 0.683 0.383 -0.124 -0.149 -0.124 -0.098 -0.124 -0.067 -0.124 -0.293 -0.200 -0.124 -0.098 -0.200 -0.067 -0.067 -0.124 -0.098 -0.067 -0.174 -0.149 -0.124 -0.124 -0.174 -0.098 -0.067 -0.124 -0.098 -0.098 -0.124

Clay -0.218 -0.182 0.218 -0.098 1.000 -0.143 -0.143 -0.255 0.303 0.218 -0.182 -0.143 -0.182 0.683 -0.182 0.333 0.098 0.303 -0.143 0.098 -0.098 -0.098 -0.182 -0.143 0.683 0.153 0.218 -0.182 0.303 0.153 -0.143 -0.098 0.303 0.429 -0.143 0.303

Oolitic 0.218 -0.182 -0.218 0.683 -0.143 1.000 1.000 0.561 -0.182 -0.218 -0.182 -0.143 -0.182 -0.098 -0.182 -0.429 -0.293 -0.182 -0.143 -0.293 -0.098 -0.098 -0.182 -0.143 -0.098 0.153 -0.218 -0.182 -0.182 -0.255 -0.143 -0.098 0.303 0.429 -0.143 -0.182

Cross Stratification0.218 -0.182 -0.218 0.683 -0.143 1.000 1.000 0.561 -0.182 -0.218 -0.182 -0.143 -0.182 -0.098 -0.182 -0.429 -0.293 -0.182 -0.143 -0.293 -0.098 -0.098 -0.182 -0.143 -0.098 0.153 -0.218 -0.182 -0.182 -0.255 -0.143 -0.098 0.303 0.429 -0.143 -0.182

chert 0.389 -0.324 -0.389 0.383 -0.255 0.561 0.561 1.000 0.022 0.234 0.367 0.153 0.367 -0.174 0.367 -0.221 0.035 -0.324 0.153 -0.244 -0.174 0.383 0.022 -0.255 -0.174 0.127 -0.389 -0.324 -0.324 -0.455 -0.255 -0.174 0.022 0.153 -0.255 0.022

Glauconite -0.092 -0.231 0.462 -0.124 0.303 -0.182 -0.182 0.022 1.000 0.462 0.179 -0.182 0.179 -0.124 0.179 0.424 0.289 0.179 -0.182 -0.041 -0.124 -0.124 -0.231 -0.182 0.537 0.022 0.462 -0.231 0.179 0.022 -0.182 -0.124 0.179 0.303 -0.182 0.590

alternation of beds0.333 -0.277 0.000 -0.149 0.218 -0.218 -0.218 0.234 0.462 1.000 0.462 0.218 0.832 -0.149 0.832 0.509 0.149 0.092 -0.218 -0.149 -0.149 -0.149 -0.277 -0.218 0.447 -0.078 0.000 -0.277 -0.277 -0.078 -0.218 -0.149 0.092 0.218 -0.218 0.462

folds 0.277 0.179 -0.277 -0.124 -0.182 -0.182 -0.182 0.367 0.179 0.462 1.000 0.787 0.590 -0.124 0.590 0.424 -0.041 -0.231 -0.182 -0.372 -0.124 -0.124 -0.231 -0.182 -0.124 -0.324 -0.277 0.179 0.179 -0.324 -0.182 -0.124 -0.231 -0.182 0.303 0.179

Joints/fractures0.218 0.303 -0.218 -0.098 -0.143 -0.143 -0.143 0.153 -0.182 0.218 0.787 1.000 0.303 -0.098 0.303 0.333 -0.293 -0.182 -0.143 -0.293 -0.098 -0.098 -0.182 -0.143 -0.098 -0.255 -0.218 0.303 0.303 -0.255 -0.143 -0.098 -0.182 -0.143 0.429 -0.182

Microfault 0.277 -0.231 -0.277 -0.124 -0.182 -0.182 -0.182 0.367 0.179 0.832 0.590 0.303 1.000 -0.124 1.000 0.424 -0.041 -0.231 -0.182 -0.372 -0.124 -0.124 -0.231 -0.182 -0.124 -0.324 -0.277 -0.231 -0.231 -0.324 -0.182 -0.124 -0.231 -0.182 -0.182 0.179

convolution -0.447 -0.124 -0.149 -0.067 0.683 -0.098 -0.098 -0.174 -0.124 -0.149 -0.124 -0.098 -0.124 1.000 -0.124 0.228 -0.200 -0.124 -0.098 -0.200 -0.067 -0.067 -0.124 -0.098 -0.067 -0.174 -0.149 -0.124 0.537 -0.174 -0.098 -0.067 -0.124 -0.098 -0.098 -0.124

Chalky 0.277 -0.231 -0.277 -0.124 -0.182 -0.182 -0.182 0.367 0.179 0.832 0.590 0.303 1.000 -0.124 1.000 0.424 -0.041 -0.231 -0.182 -0.372 -0.124 -0.124 -0.231 -0.182 -0.124 -0.324 -0.277 -0.231 -0.231 -0.324 -0.182 -0.124 -0.231 -0.182 -0.182 0.179

Planktonic Forams-0.218 -0.222 0.509 -0.293 0.333 -0.429 -0.429 -0.221 0.424 0.509 0.424 0.333 0.424 0.228 0.424 1.000 0.163 0.101 -0.048 -0.098 0.228 -0.293 -0.545 -0.048 0.228 -0.493 0.509 -0.222 0.424 0.051 0.333 0.228 -0.222 -0.048 -0.048 0.424

Nummulites 0.149 -0.372 0.447 -0.200 0.098 -0.293 -0.293 0.035 0.289 0.149 -0.041 -0.293 -0.041 -0.200 -0.041 0.163 1.000 0.620 0.488 0.733 0.333 0.333 0.289 0.488 0.333 0.313 0.447 -0.372 -0.372 0.592 0.488 0.333 -0.041 0.098 -0.293 0.620

Lepidocyclina0.277 -0.231 0.462 -0.124 0.303 -0.182 -0.182 -0.324 0.179 0.092 -0.231 -0.182 -0.231 -0.124 -0.231 0.101 0.620 1.000 -0.182 0.620 -0.124 -0.124 0.179 0.303 0.537 0.367 0.462 -0.231 -0.231 0.713 0.303 0.537 0.179 0.303 -0.182 0.590

Discocyclina -0.218 -0.182 0.218 -0.098 -0.143 -0.143 -0.143 0.153 -0.182 -0.218 -0.182 -0.143 -0.182 -0.098 -0.182 -0.048 0.488 -0.182 1.000 0.488 0.683 0.683 0.303 0.429 -0.098 0.153 0.218 -0.182 -0.182 0.153 0.429 -0.098 -0.182 -0.143 -0.143 -0.182

Operculina 0.149 -0.372 0.447 -0.200 0.098 -0.293 -0.293 -0.244 -0.041 -0.149 -0.372 -0.293 -0.372 -0.200 -0.372 -0.098 0.733 0.620 0.488 1.000 0.333 0.333 0.620 0.488 0.333 0.592 0.447 -0.372 -0.372 0.870 0.488 0.333 0.289 0.098 -0.293 0.289

Gazerina -0.447 -0.124 0.447 -0.067 -0.098 -0.098 -0.098 -0.174 -0.124 -0.149 -0.124 -0.098 -0.124 -0.067 -0.124 0.228 0.333 -0.124 0.683 0.333 1.000 -0.067 -0.124 0.683 -0.067 -0.174 0.447 -0.124 -0.124 0.383 0.683 -0.067 -0.124 -0.098 -0.098 -0.124

Orbitolites 0.149 -0.124 -0.149 -0.067 -0.098 -0.098 -0.098 0.383 -0.124 -0.149 -0.124 -0.098 -0.124 -0.067 -0.124 -0.293 0.333 -0.124 0.683 0.333 -0.067 1.000 0.537 -0.098 -0.067 0.383 -0.149 -0.124 -0.124 -0.174 -0.098 -0.067 -0.124 -0.098 -0.098 -0.124

Red algae 0.277 -0.231 -0.277 -0.124 -0.182 -0.182 -0.182 0.022 -0.231 -0.277 -0.231 -0.182 -0.231 -0.124 -0.231 -0.545 0.289 0.179 0.303 0.620 -0.124 0.537 1.000 0.303 -0.124 0.713 -0.277 -0.231 -0.231 0.367 -0.182 -0.124 0.179 -0.182 -0.182 -0.231

Large Oyster -0.218 -0.182 0.218 -0.098 -0.143 -0.143 -0.143 -0.255 -0.182 -0.218 -0.182 -0.143 -0.182 -0.098 -0.182 -0.048 0.488 0.303 0.429 0.488 0.683 -0.098 0.303 1.000 -0.098 0.153 0.218 -0.182 -0.182 0.561 0.429 -0.098 -0.182 -0.143 -0.143 -0.182

Pectinid 0.149 -0.124 0.447 -0.067 0.683 -0.098 -0.098 -0.174 0.537 0.447 -0.124 -0.098 -0.124 -0.067 -0.124 0.228 0.333 0.537 -0.098 0.333 -0.067 -0.067 -0.124 -0.098 1.000 0.383 0.447 -0.124 -0.124 0.383 -0.098 -0.067 0.537 0.683 -0.098 0.537

Coral 0.389 -0.324 -0.078 -0.174 0.153 0.153 0.153 0.127 0.022 -0.078 -0.324 -0.255 -0.324 -0.174 -0.324 -0.493 0.313 0.367 0.153 0.592 -0.174 0.383 0.713 0.153 0.383 1.000 -0.078 -0.324 -0.324 0.418 -0.255 -0.174 0.713 0.561 -0.255 0.022

Thalassinoides-0.333 -0.277 1.000 -0.149 0.218 -0.218 -0.218 -0.389 0.462 0.000 -0.277 -0.218 -0.277 -0.149 -0.277 0.509 0.447 0.462 0.218 0.447 0.447 -0.149 -0.277 0.218 0.447 -0.078 1.000 -0.277 0.092 0.545 0.655 0.447 0.092 0.218 -0.218 0.462

Rudists -0.092 1.000 -0.277 -0.124 -0.182 -0.182 -0.182 -0.324 -0.231 -0.277 0.179 0.303 -0.231 -0.124 -0.231 -0.222 -0.372 -0.231 -0.182 -0.372 -0.124 -0.124 -0.231 -0.182 -0.124 -0.324 -0.277 1.000 0.179 -0.324 -0.182 -0.124 -0.231 -0.182 0.787 -0.231

Inoceramus -0.462 0.179 0.092 -0.124 0.303 -0.182 -0.182 -0.324 0.179 -0.277 0.179 0.303 -0.231 0.537 -0.231 0.424 -0.372 -0.231 -0.182 -0.372 -0.124 -0.124 -0.231 -0.182 -0.124 -0.324 0.092 0.179 1.000 -0.324 -0.182 -0.124 -0.231 -0.182 0.303 -0.231

Echinolampas0.078 -0.324 0.545 -0.174 0.153 -0.255 -0.255 -0.455 0.022 -0.078 -0.324 -0.255 -0.324 -0.174 -0.324 0.051 0.592 0.713 0.153 0.870 0.383 -0.174 0.367 0.561 0.383 0.418 0.545 -0.324 -0.324 1.000 0.561 0.383 0.367 0.153 -0.255 0.367

Echinocyamus-0.218 -0.182 0.655 -0.098 -0.143 -0.143 -0.143 -0.255 -0.182 -0.218 -0.182 -0.143 -0.182 -0.098 -0.182 0.333 0.488 0.303 0.429 0.488 0.683 -0.098 -0.182 0.429 -0.098 -0.255 0.655 -0.182 -0.182 0.561 1.000 0.683 -0.182 -0.143 -0.143 0.303

Crab 0.149 -0.124 0.447 -0.067 -0.098 -0.098 -0.098 -0.174 -0.124 -0.149 -0.124 -0.098 -0.124 -0.067 -0.124 0.228 0.333 0.537 -0.098 0.333 -0.067 -0.067 -0.124 -0.098 -0.067 -0.174 0.447 -0.124 -0.124 0.383 0.683 1.000 -0.124 -0.098 -0.098 0.537

Balanus 0.277 -0.231 0.092 -0.124 0.303 0.303 0.303 0.022 0.179 0.092 -0.231 -0.182 -0.231 -0.124 -0.231 -0.222 -0.041 0.179 -0.182 0.289 -0.124 -0.124 0.179 -0.182 0.537 0.713 0.092 -0.231 -0.231 0.367 -0.182 -0.124 1.000 0.787 -0.182 0.179

Bryozoa 0.218 -0.182 0.218 -0.098 0.429 0.429 0.429 0.153 0.303 0.218 -0.182 -0.143 -0.182 -0.098 -0.182 -0.048 0.098 0.303 -0.143 0.098 -0.098 -0.098 -0.182 -0.143 0.683 0.561 0.218 -0.182 -0.182 0.153 -0.143 -0.098 0.787 1.000 -0.143 0.303

Ammonites 0.218 0.787 -0.218 -0.098 -0.143 -0.143 -0.143 -0.255 -0.182 -0.218 0.303 0.429 -0.182 -0.098 -0.182 -0.048 -0.293 -0.182 -0.143 -0.293 -0.098 -0.098 -0.182 -0.143 -0.098 -0.255 -0.218 0.787 0.303 -0.255 -0.143 -0.098 -0.182 -0.143 1.000 -0.182

Serpulid worm tobes0.277 -0.231 0.462 -0.124 0.303 -0.182 -0.182 0.022 0.590 0.462 0.179 -0.182 0.179 -0.124 0.179 0.424 0.620 0.590 -0.182 0.289 -0.124 -0.124 -0.231 -0.182 0.537 0.022 0.462 -0.231 -0.231 0.367 0.303 0.537 0.179 0.303 -0.182 1.000

Fig. 4: Dendrogram of hierarchical clustering illustrating the variety of exposed rock units (Formations) in Al Jabal al Akhd ar.


177

Fig. 5: 1. Chert nodule from Apollonia Formation, Karsa-Darnah road cut; 2. Al Faidiyah glauconitic marl Burdi area; 3. Nummulitesgizehensis

with Spirorbis sp. Susah-Shahhat road cut; 4. Limestone concretion Darnah Formation, Addabussieyyah road cut; 5. Cross lamination in Wadi al

Qattarah Formation at Msus road cut section; 6. Folded beds in Al Athrun Formation at Wadi al Athrun; 7. Microfault in Al Athrun Formation at

Wadi al Athrun.

Fig. 6: 1. Bryozoa from Al Faidiyah Formation at Wadi al Shaigh, Tobruq; 2. Alternation of soft and hard beds in Apollonia Formation at

Karsa-Darnahroadcut; 3. Alternation of beds from Al Faidiyah Formation at Al Burdi area; 4. Serpulid worm tubes (Fistulanacyreniaca) Al

Faidiyah Formation in Wadi al Hash, Tobruq; 5. Bioturbation in Al Faidiyah Formation in Al Faidiyah village; 6. Coral reef in Al Bayda Formation at Addabussieyyahroadcut; 7. Inoceramus from Al AlMajahir Formation at Got Sas area; 8. Nautilus from Darnah Formation at

Wadi Al Hash; 9. Red algae from Benghazi Formation at Daryanah-Abyarroadcut.


178

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