neogene stratigraphy of the eastern basin, samos island, greece

NEOGENE STRATIGRAPHY OF THE EASTERN BASIN,

SAMOS ISLAND, GREECE

by

MARC WEIDMANN *, NIKOS SOLOUNIAS **, ROBERT E. DRAKE *** & GARNISS H. CURTIS ***

ABSTRACT R~SUMI~

Revision of the stratigraphy and depositional environments in the Eastern Neogene basin of Samos. Mapping, structural analysis together with new K/Ar dates provide the following general pa t te rn : two fluvial-lacustrine cycles separated by a disconformity. Basal cycle is Astaracian-Vallesian, the disconformity occured between 9 and 8.5 MY, upper cycle is Turo- lian and has yielded the famous << Samos mammal fauna >> wich is between 8.5 and 7.0 MY old.

R6vision de la stratigraphie et des milieux de d6p6t du N6og~ne du bassin oriental de Samos. La cartogra- phic, l'analyse structurale et de nouvelles datations isotopiques mettent en 6vidence deux cycles s6dimen- taires fluvio-lacustres s6par6s par une discordance. Le premier cycle est d'flge astaracien-vall6sien, la discordance se situe entre 9 et 8,5 MA, le deuxi~me cycle est d'iige turolien et comprend la riche faune de mammi- f~res, dite ~de Samos >>, dont l'age se situe entre 8,5 et 7,0 MA.

KEY-WORDS : STRATIGRAPHY, K/AR AGES, TUROLIAN, MAMMAL FAUNA.

MOTS-CL]~S : STRATIGRAPHIE, DATATIONS ISOTOPIQUES, TUROLIEN, MAMMIFI~RES.

* Musde g6ologique, Palais de Rumine, 1005 Lausanne, Switzerland. ** Peabody Museum, Harvard University, Cambridge, MA 02138, USA. *** Department of Geology and Geophysics, University of California, Berkeley, CA 94720, USA.

Geobios, n ° 17, fasc. 4 p. 477-490, 8 fig., 1 tabl. Lyon, aoflt 1984

-- 478

TABLE DES MATII~RES

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 478

Stratigraphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 481

A - Astaracian-Vallesian cycle . . . . . . . . . . . . p. 481

Basement . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 481

Basal Conglomerate Formation . . . . . . . . p. 481

Phythagorion Formation . . . . . . . . . . . . . . p. 482

Hora Formation . . . . . . . . . . . . . . . . . . . . . p. 483

B - Turolian cycle . . . . . . . . . . . . . . . . . . . . . . p. 484

Mytilini Formation . . . . . . . . . . . . . . . . . . . p. 484

Age of the Mytilini Formation . . . . . . . . . . p. 487

Kokkarion Formation . . . . . . . . . . . . . . . . p. 488

Structural evolution . . . . . . . . . . . . . . . . . . . . . . p. 488

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . p. 490

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p. 490

INTRODUCTION

The Neogene Eastern Basin near Mytilini, Samos (fig. 1), has been well known for more than one hun- dred years because of the rich mammalian fauna collected there and subsequently housed in more than thirty natural history museums. Although the fauna has been studied in some detail (Solounias, 1979, 1981a, 1981b for reviews), until recently the geology of the Eastern basin has not. Van Couvering and Mil- ler (1971) were the first to reexamine the basin since Major (1888) ; they dated radiometrically the fossiliferous horizons and reported on the Neogene stratigraphy.

Theodoropoulos mapped the geology of Samos at a scale of 1 : 50'000 during 1973-1974. His map gives a good general view of the island, but this map was published posthumously in 1979 without revision by the author, and is inaccurate in numerous points and too general for the stratigraphy of the Eastern basin.

In 1976, Meissner, proposed an excellent lithostrati- graphic framework which we have adopted in most respects. Meissner's photogeologic interpretations of structure (1976, 1979) are often questionable as to his selection of formations and his specific contacts between different members, but we sould emphasize here the quality for the overall pattern of Meissner's observations, which established a firm basis for the study of the basin.

The structural history of the Neogene of Samos has been sketched by Angelier (1976, 1979). More recently, the importance of the Samos Neogene in dating the tectogenetic phases of the Cyclades was emphasized by Papanikolaou (1979, 1980), Papaniko- laou & Dermitzakis (1981), BOger (1983).

Since 1975, one of us (N.S.) reexamined the fossil vertebrate collections (primarily mammals) in twenty six European and U.S. museums. The Samos collections constitute approximately 50'000 specimens; 10'000 of these were studied. The fossils are well preserved and commonly identifiable to species level. Some detailed systematic, taphonomic and descriptive work on the fossils and fauna is presented in Solou- nias (1979, 1981a, 1981b).

On Samos we (N.S. and M.W.) have mapped the fossiliferous horizons in detail, relocated the bone beds and revised Meissner's stratigraphy. G.H.C. and R.E.D. have undertaken numerous K/At dates, which modify the previous results by Van Couvering and Miller (1971) and by Solounias (1981a).

Samples dated by the 40K - 40At method were pre- pared by crushing, seiving, and heavy liquid techniques to obtain sanidine or biotite concentrates. Since contamination was a danger in the tuffaceous sam- pies, especially those wich were obviously reworked, only the coarsest, clearly volcanic crystals were used for dating and these were hand picked under binocu- lar microscope to assure effectively pure separates. Samples R 102, 104, 105 and 106 are splits of those dated by Van Couvering and Miller (1971) by 40Ar/ 39At techniques. Examination of these splits showed them to contain some small degree of detrital contamination which we suspect contributed to their somewhat older ages. Most of the samples SK 1 - 19 redate the same tuffaceous horizons represented by the original samples, some of which we also re-dated after further removal of detrital grains. In addition two tufts also yielded biotite as well as sanidine and the concordancy of these mineral pairs further

- - 479 - -

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BASEMENT BASIN

Fig. 1 - - Simplified geological map of the Samos Island (insert map) and of the Eastern Basin. After Meissner (1976), Theodoropoulos (1979) and our observations. Carte g6oiogique sch6matlque de l'lle de Samos (encart) et du Bassin oriental. D'apr~s Meissner (1976), Theodoropoulos (1979) et nos observations.

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supports our results. Final verification of the validity of our dating is that it is upheld by the relative

stratigraphic position of the dated horizons.

STRATIGRAPHY

The following formations and members are presented from older to younger (fig. 2). Stage names are given following Fahlbusch (1981).

A - ASTARACIAN.VALLESIAN CYCLE

Basement

At the base of the sequence are metamorphic and non-metamorphic rocks which have been folded and

imbricated as several nappes (Theodoropoulos, 1979 ; Papanikolaou, 1979). Their age is probably Palaeozoic to Eocene. These nappes belong to the Attic- Cycladic metamorphic window.

Basal Conglomerate Formation

Basal Conglomerate outcrops are restricted to the western margin of the Eastern Basin and to a locality one kilometer west of Hora village. The type section is a recent road cut between Mavradzei Village and

This paper

e. KOKKARION Fm

"" Marker Tufts 0-15

z Main BoneB. < 60-110 o

o White Beds ,~- o LI-- oo

rr 0-20 Z

Gravel Beds -q 10-30 ~- >-

O ld Mill Beds ~ 15-80

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MEISSNER, 1976

KOKARtON-Folge200

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max. 170

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50

THEODOROPOULOS, 1979 ANGELIER,1976

UPPER SERIES 250

CLASTIC

SERIES

max. 400

Basalt-Tuff 15-30

LOWER SERIES

max. 650

CONGLOMERATES -75

FORMATION A

MELANIA cf. ESCHERI

FORMATION

D'AVLAKIA

F i g . 2 - - Formatlonal diagram of the Eastern Basin's Neogene. Thicknesses in meters.

Formations distingu~es et ~paisseurs estim~es (en m~tres) dans le Bassin oriental.

- - 482 - -

Mytilini Village near Kazani district (fig. 3/2). Below the angular unconformity, the basement is often strongly weathered. The Basal Conglomerate begins with poorly sorted angular cobble and pebble horizons with occasional boulders up to one m3 (fig. 3/5). The surrounding matrix is red to brown sand. Cross- bedded sands follow, with channel-fills of rounded gravels. At the top lie red, brown or yellow silts with thick paleosols which are often cut by channel gravels. Terrestrial gastropods are preserved infre- quently. The total thickness is variable, depending on the paleotopography. Clasts were all derived from the basement and the depositional environment is interpreted to represent the proximal to distal floodplain. The Basal Conglomerate formation is not dated. Ten- tative age attribution can be Upper Astaracian.

The thin and finer-grained conglomerate overlying the basement in the eastern part of the basin (fig. 3/6 and 3/7) do not belong to this formation. They have a calcareous and/or tuffaceous matrix and are light green or white in color. They represent the transgres- sive facies of the Mytilini and Kokkarion formations, discussed below.

Pythagorion Formation

To the east of the basin this formation measures about 200 m, with thick-bedded limestones containing freshwater gastropods, stromatolites and onkolites. Bioturbation and silicification are locally important ; dessication-cracks and wave-ripples are common. The rare clastic horizons are thin, with tuffaceous sands and silts or rounded gravels derived from the basement. The depositional environment is interpreted to be shallow lacustrine. The type section is on the Spi- liani Hill, east of Pythagorion Village, between the cape of Kayos Fonias and the main road to Samos City (Vathy).

To the west, the lacustrine facies inter fingers with typical paludal horizons which we named Mavradzei Beds. They are bituminous limestones containing a rich fauna of freshwater molluscs, together with cha- rophytes, phragmites, grey-green lignitic clays and beds of lignite 1-2 cm thick and finally cross-bedded sands and silts. Burrows and dessication cracks are common. Extensive washing of marls has yielded fish bones and teeth, together with two rodent incisors. The type section is a recent road cut from Mavradzei Village down to the Mayradza river, where this member measures 95 m thick.

To the western part of the Eastern Basin, between the Mavradzei beds and the overlying Hora Forma- tion is a 60 m thick conformable volcanic and

volcaniclastic sequence : the Basalt and Tuff Mem- ber, whose type section is the road cut from Pagondas Village to Spartarei Village (fig. 3/4). The top of the lacustrine limestones has been ~ baked ~ by a basalt flow of 3-8 m thickness. Theodoropoulos (1979) has suggested that the basalt is a sill in the Neogene sediments, but we consider, following Meissner (1976), that it is a partly subaqueous flow, limited to the west of the basin. The beige or light grey lahar turfs overlying the basalt are particularly thick to the southwest (50 m, fig. 3/4) and to the west (30 m, fig. 3/1 and 3/2) ; they can be followed eastward as far as Hora village, where they only measure 1-2 m. The turfs locally contain thin flows and small dykes of basalt. Sedimentary structures within the tufts indi- cate a fluvial deposition for the proximal part (southwest and west), but more probably lacustrine deposition to the east.

Near Pagondas Village (fig. 3/4), the basalt is dated 11.2 + 0.7 my. The lahar tuff from the Kastro Lou- loudas section (fig. 3/1) is dated 10.84 ___ 0.4 and 10.88 :~ 0.4 my. Therefore, the age of the Pythago- rion formation is probably Upper Astaracian.

Hora Formation

To avoid confusion, we have adopted Meissner's (1976) lithostratigraphical nomenclature, although the formation names do not accord with location of the namesake villages, as Hora Village is built on the Pythagorion Fm, Mytilini Village is built on the Hora Fm and Kokkarion Village on the Mytilini Fm I The Hora formation outcrops extensively over the central and eastern regions of the Eastern Basin. Three to four superimposed lacustrine facies can be observed (e.g. road-cut Mavradzei-Mytilini Villages, fig. 3/2). From base to top these are :

a) thick-bedded limestones, often somewhat chert-like in consistency, with one or two meter-thick beds of prominent white, chalky pure limestone. A few freshwater molluscs and stromatolites occur. Thickness varies between 30 and 60 m.

b) thin-bedded (2-10 cm) limestones with thin marls and frequent slump features which become more common going upsection. Thickness varies from 30 to 80 m.

c) yellow-green marls with subordinate lime-rich or siliceous paper-shale which are often diatomaceous. Slumping is widespread:meter-scale disharmonic folds that occurred in zemi-lithifled limestones,

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breccia of unsorted limestone fragments in a shaly matrix. During deposition, sliding and tilting occurred of large blocks of lithified limestones (up to 100 m length and 10 m thickness). The bases of the lithified limestones are commonly characterized by folded, laminated and boudinaged horizons, whereas their tops are disconformably overlain by later sediments. Small gastropods, ostracods, diatoms and plant debris occur throughout. Thickness exceeds 250 m. d) thinly bedded limestones (5-20 cm) with occasional marly intervals. Molluscs, ostracods and stromatolites occur. Thickness reaches 50 m.

Coarse elastic horizons are virtually absent in this fairly deep lacustrine sequence. A grey-brown tuffaceous turbidite can be followed for over 3 kin, from the Kavouraki valley (northwest, where it is 4 m thick) through Vrysi Kondaxi (8 m) to the Vrysi Kalatis valley (southeast, where it is 2 m thick).

Radiometric dating of the tuffaceous turbidite sampled at 1700 m west of Mytilini Village, gives an age of 9.0 ± 0.3 my. Hence the age of the formation is probably VaUesian.

Meissner (1976) estimated the Hora formation to be only 50 m thick, but our observations show that locally it may be more than 400 m thick. These extreme variations are due to the fact that the Hora formation was folded and eroded before deposition of the Mytilini formation.

B - TUROLIAN CYCLE

Mytilini Formation In the western part of the basin, the Mytilini forma-

tion overlies the folded and eroded Hera formation with a discordance or pseudocencordance (figs. 3/1 to 3/4 and 6) whereas to the southeast the Mytilini formation lies directly on the Pythagorion formation or on the basement (figs. 3/6 and 8). For more details on the Mytilini formation, see Solounias (1981a, p. 10-17).

The type area lies 2-3 km north-northwest of Myti- lini Village, in the districts of Theopiito Gefiri, Ron- gia, Potamies, Andrianos and Tsarouhis (figs. 4 and 5). Most of the mammalian bone-beds are located there along creeks. The formation may be divided into five members, from base to top :

Old Mill Beds are comprised of 15-80 m of sands, silts and tuffaceous marls. There are a few beds of massive gravelly tufts, which are pink, beige or white. These horizons of distal fluviatile facies, contain occasional channels with rounded basement derived gravels. Individual cycles are often capped by biotur- bated paleosoils with land molluscs and insect burrows. Two silty marls of this member have yielded mammal bones (sites QX and G, fig. 4). Quarry 6

which occurs in the Tholorema creek 2.5 km southeast of Kokkarion Village, probabily belongs to the Old Mill Beds : tufts associated with the Quarry 6 bone bed are dated 8.26 ± 0.08 and 7.8 ± 0.4 my. Sample 104 was collected by Van Couvering and Mil- ler (1971) near the base of the member ; it was reprocessed and the new dates are 8.00 ± 0.08 and 8.57 ± 0.19 my. Another sample collected near the top of the member is dated 8.38 ± 0.07 and 8.57 ± 0.28 my. Mean age of the Old Mill Beds is 8.26 my.

m bone I beds

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Diagrammatic Ilthologtcai sections of the Mytiilnl and (in part) Kokkarion formations. Location of the old and recent quarries of the bone beds is given on map fig. 5. Quarries as in Solounias (1981a and b). Location of the sections, see map fig. 1. Coupe lithologique synth~tique n ° 8 darts les Forma- tions de Mytlllnl et de Kokkarlon (pro parte). La situation des gisements fossilif~res exploit~s se trouve sur la fig. 5 et dans Solounias (1981 a e t b).

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Fig. 5 Geological map of the bone beds area and location of the quarries. Geology after Meissner (1976), slightly modified• Carte g~oiogique (d'apr~s Meissner 1976, modifi~e) du secteur fossilifi~re de ia Formation de Mytilini et situation des gisements exploit~s.

- - 486

G r a v e l s B e d s show a similar lithology to the Old Mill Beds, but channels now predominate. Channel- fills are deep (up to 5 m), but have little lateral exten- sion, and are interpreted as the result of immature streams and run offover areas without much vegetation cover. Clasts are mostly well rounded and

basement-derived (60-95 %), although some clasts come from the Pythagorion and Horn formations. In the proximal part of the basin (northwest), the conglomerates are thick and coarse-grained and often directly overlie the Horn formation (fig. 6/2, 6/3 and 6/4).

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G :GRAVEL BEDS

OM:OLD MILL BEDS

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Fig. 6 - - Field sketches of the disconformity between the Horn formation and different members of the Turolian Mytilini formation. Percen- tages give the proport ion of Horn limestone pebbles ; the other pebbles are mainly derived f rom the Basement. 1 - crest line at Kastro Louloudas, 4 km N N W of Mytilini Village. 2 - unnamed small EW valley, 1.5 km SSW of Kokkarion Village. 3 - 1 km south of Kokkarion Village. - 4 left side of the Kavouraki Valley, near Zoodochos Pighi.

Coupes illustrant ia discordance entre la Formation de Horn et divers Membres de ia Formation de Mytilini. Les pourcentages indi- quent la proport ion de gaiets repris de la Format ion de Horn ; les autres galets proviennent principalement du socle. 1 - ligne de cr~te & Kastro Louloudas, 4 km au N N W de Mytilini. 2 - vallon EW non dgnomm6, 1.5 km au SSW de Kokkarion. 3 - 1 km au S de Kokkarion. 4 - flanc gauche de la vall6e de Kavouraki , pros de la source de Zoodochos.

W h i t e B e d s are essentially silty or chalky lacustrine limestones, yellow or white colored and often are meter-thick beds of poorly sorted limestone breccia. These breccia do not form channels in the Potamies or Tholorema districts. To the west, at Kastro Lou- loudas, the breccia form thick sheets (8-15 m or more) that are laterally extensive ; they contain blocks of undeformed Horn formation. These sheet-breccia are presently exposed by differential weathering and constitute small hill tops or ridges (fig. 6/1). These

deposits imply the existence of a considerable paleo- relief of the Horn formation and catastrophic events (earthquakes, landslides or flash-floods), occasionally giving rise to sediment flows. In the White Beds, the clasts are only rarely derived from the basement.

These facies are not spread uniformly across the basin. In the Tholorema district, for instance, there are only two breccia beds.

The White Beds member contains a few freshwater gastropods and one bone bed (Q4) at the very top.

- - 487 - -

Main Bone Beds are essentially tuffaceous marls, silts and sands measuring 60-110 m. There are several beds of graded tufts and small channel-fills containing rounded pebbles of basement, and Hora formation. Paleosoils are common but not thick. The depositional environment was fluvial, mainly overbank and floodplain deposits, with occasional meandering channel sands and gravel lags.

The bone beds are geographically restricted to an area between Rongia (North) and Stephana (South) districts and are stratigraphically located both near the base and near the top of the member (figs. 4 and 5).

Within the Main Bone Bed member, most of the bone was accumulated on the flood plain and was buried by overbank flood deposits (tuffaceous marls and silts). In some cases bones are preserved in soil horizons. The quality of bone preservation suggests rapid burial and minimum transport. Most of the fossils are medium and large-sized mammals, although a few lower vertebrates, land gastropods, insect burrows and small mammals have been found.

Three new tuffaceous samples were dated from the Main Bone Beds : 7.52 + 0,16, 7.75 _+ 0,08 and 6.98 _+ 0.15 my. Samples 102 and 106 from Van Couve- ring and Miller (1971) were reprocessed : ages range from 7.55 to 6.89 my. Mean age of the Main Bone Beds is 7.35 my.

Marker Tufts usually comprise five tufts interbedded with marls and tuffaceous silts. This conspicuous member is most useful for mapping the fault pattern and locating stratigraphically the bone beds. To the southeast (Stephana Hill), the Marker Tufts wedge out, interfingering with the lacustrine limestone of the Kokkarion Formation.

Three new tuff samples were dated from the Marker Tuffs : 6.14 + 0.119, 6.14 _+ 0.04 and 5.41 + 0.17 my. Sample 105 from Van Couvering and Miller was reprocessed : 6.51 ± 0.14 and 6.74 + 0.11. Mean age of the Marker Tufts is 6.18 my.

The elastic sources and paleocurrents of the Mytilini formation in general have been established by measu- rements of clast size, channel orientation and pebble imbrication. These analyses were carried out across the whole basin and throughout the entire formation. The source was located to the west-northwest ; there were two transport directions, east (90 ° ) and southeast (140°). No directional changes occur either geographically or stratigraphically.

Age of the Mytilini formation

Fig. 4 gives the stratigraphic position of the K/At samples. Accurate correlation and relative position of the samples are often difficult to establish because : 1) the thickness of the sediments varies due to paleoto- pogaphy, 2) there is an extensive vegetation cover and commonly individual beds cannot be traced physically laterally for long distances, 3) being flood plain deposits, numerous horizons thin out laterally or change into other lithologies, and 4) there are numerous local faults and a few folds (Meissner, 1976).

The maximum age for the Mytilini formation is the age of the base of the Old Mill Beds : about 8.5 my. Similarly the minimum age is the mean age of the Marker Tufts : about 6.2 my. That is a possible span of 2.3 my. Hence the age is exclusively Turolian.

To be more specific, the age of the most important bone beds can be inferred from the K/Ar dates of the Main Bone Beds : between 6.9 and 7.75 my, that is a possible span of 850'000 years. The depositional rate of the Main Bone Beds is therefore about 1 m per 10'000 years. Actually the quality of preservation of the bones suggest a (more episodic) more rapid depositional rate which means that during the 0.85 my large gaps of time include no depositional record.

Most of the fossil taxa have been sampled from sin- gle quarries confirming that there is no major diffe- rences between quarries. Some quarries are older than others : QX, G and probabily Q6 are older than Q4. The rest of them are younger, but all are stratigraphi- eally very close to each other. In conclusion, it is incorrect to separate the Samos mammalian fauna into two associations : Samos 1-4 and Samos 5 res- pectively ; see discussions in Solounias (1981a and b) and also the comments by Van Couvering in Bernor & alii (1980). In summary, all the bone beds were approximately deposited between 7.0 and 8.5 my and this is in agreement with the biostratigraphic and fau- nal stasis observed between the different horizons within the Mytilini formation (Solounias 1979, 1981a and b).

The vertebrate fauna of Samos is exceptional for four reasons not common to other late Miocene (Turolian) localities : 1) the fossils are well preserved, whole skulls are abundant and isolated teeth are rare to absent ; 2) the diversity is high, with approximately 100 taxa and 50'000 specimens ; 3) the bones were deposited during a relatively short period of time,

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about 1.5 million years ; and 4) the bone beds are well dated.

Hence the Samos fauna can be used as a reference locality for the biostratigraphy and zoogeography of the Eastern Mediterranean Turolian.

K o k k a r i o n F o r m a t i o n

This formation, outcropping to the east and south of the basin, conformably overlies and interfingers with the top of the Mytilini Formation (figs. 2, 4 and 8). Thick-bedded porous lacustrine limestones predominate to the southeast, with abundant onkolites,

stromatolites and frequent fresh-water gastropods. In the bone bed region (fig. 5), the limestones (2-20 m) are interbedded with marls and tuffaceous silts up to 10 m thick. Further northwest, this formation beco- mes thinner and is primarily limestones (10-20 m thick).

The Kokkarion Formation was deposited in lakes encroaching from the southeast. Its top is an erosio- nal surface.

The age of the Kokkarion Formation was assigned to the Pliocene by Meissner (1976) and Theodoropou- los (1979), but without radiometric or paleontologic evidence.

STRUCTURAL EVOLUTION

The synthesis of data from Meissner (1976), Ange- lier (1976, 1979) and Theodoropoulos (1979), together with our own observations, provides the following model :

1) Astaracian-VaUesian cycle : from 12 my (?) and up to about 9 my.

- tensional faulting and warping - accumulation of Basal Conglomerate, Pythago-

rion and Hora formations. Depositional environments fluvial, then lacustrine. Strong subsidence, active synsedimentary volcanism and tectonics

- diagenesis, in particular silicifications.

2) During a short time span : between 9 and 8.6 my.

- regional compression resulting in NW-SE folds - uplift, tilting and erosion.

3) Turolian cycle : between 8.6 and 6.2 my (Mytilini formation) and up to (?) 5 my (Kokkarion formation).

- accumulation of Mytilini and Kokkarion formations in a fluvial and subsequently lacustrine environment. Active synsedimentary volcanism and tectonics. Strong subsidence with migration of the depo- center to the East.

4) Pliocene-Pleistocene-Holocene. - compression with folding and faulting - tensional faulting (Recent).

This preliminary tectonic model has been established only for the Eastern Basin and needs corrobora- tion from the other Neogene basins of Samos, such as the Western Karlovassi basin. However, the latter is only known from reconnaissance surveying (Theodo- ropoulos, 1979). Six fluviatile and lacustrine formations have been ascribed to the Miocene and Pliocene by Theodoropoulos without either paleontological or radiometric data. Facies are somewhat different from those of the Eastern Basin, particularly with the pre- sence of evaporites (gypsum) in the <~ Lower Series >>, although the ages may indeed be similar. Confronted with the lack of precise dating, distant lateral correla- tions such those proposed by Meissner (1976, fig. 6), Besenecker & Btlttner (1978), Willmann (1980) or B0ger (1983), should be treated with caution.

The emplacement of the << Non-metamorphic Cycladic nappe )) (Papanikolaou & Dermitzakis, 1981), or << Aegean nappe )) (Bagel 1983), has tenta- tively been dated within a wider tectonic context. On Kos island, this event occured between 12 and 10.4 my (Willmann, 1983). On Samos, our data contradict BOger's model;emplacement would seem to have been before 12 my, i.e. before the onset of the Astaracian- Vallesian cycle. However, we cannot rule out the possibility that the 9 to 8.6 my tectonic phase played a role at one stage of the emplacement (D. Papanikolaou, pers. comm.).

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~ ORION Fm

I j I

I j

E MYTILINI Fm ~ k KOKKAR i

~~ooel".T.~ I I

I Wq [

HORA Fm

t I

- - - 4 - - l

% tON Fm

proximal

floodplain

distal

floodplain

palustrine

shallow

lacustrine

deep

Fig. 7 - - Depositional environments of the Eastern Basin's Neogene.

Succession des milieux de d~pSt daus le N6og~ne du Bassin oriental.

Mavradzei-Pagondas Hora-Mytilini Mesokampos ! I I

:

Mavradzei PY T HAGOR I0 N o4°°E

BASAL CONGLOMERATE _..z~ ,^,- =

Fig. 8 - - Diagrammatic E-W stratigraphicai section through the Eastern Basin. Very approximate scales.

Coupe sch~matique EW ~ travers le Bassin oriental, illustrant les relations entre les diverses Formations distingn~es. Echelles tr~s approximatives.

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A c k n o w l e d g m e n t s

We thank the Institute of Geological and Mining Research of Greece, and especially the directors, Drs. John Bornovas and George Katsikatsos, for permission to do the stratigraphic study. Our research was supported by the National Science Foundation (USA) Grants EAR-76-00515 and BNS- 772-5984, BNS-81-40818, a Grant in Aid of research from Sigma Xi, several grants from the Walker Van Riper Fund (University of Colorado Museum) and a grant from the M.

Graham Netting Research Fund of Carnegie Museum of Natural History through a grant from the Cordelia Scaife May Charitable Trust.

We would also like to thank Malcolm McKenna and John Van Couvering (AMNH, New York), Dimitri Papanikolaou (University of Athens), Peter Homewood (University of Fri- bourg) and David Pilbeam (Harvard University).

R E F E R E N C E S

ANGELIER J. (1976) - Sur l 'alternance mio-plio-quaternaire de mouvements extensifs et compressifs en Eg6e orien- tale : l'$1e de Samos (Grace). C.R. Acad. Sc., Paris, 283 D, 463-466.

ANGELIER J. (1979) - N6otectonique de l 'arc 6g6en. Soc. g~oL Nord, Lille, publ. 3, 1-417.

BERNOR R.L., WOODBURNE M.O. & VAN COUVERING J.A. (1980) - A contribution to the chronology of some Old World Miocene faunas based on Hipparionine hor- ses. Geobios, Lyon, 13/5, 705-739.

BESENECKER H. & BI~TTNER D. (1978) - Late Cenozoic sediments on the islands between Euboea and Turkey. In : Closs H., Roeder D. & Schmidt, K (editors) : Alps, Apennines, Hellenides. Schweizerbart'sche, Stuttgart, 502-505.

BLACK C.C., KRISHTALKA L. & SOLOUNIAS N. (1980) - Mammalian fossils of Samos and Pikermi. Part I : The Turolian rodents and insectivores of Samos. Ann. Car- negie Mus., Pittsburg, 49, art. 21,359-378.

BOGER H. (1983) - Stratigraphische und tektonische Verk- nllpfungen kontinentaler Sedimente des Neogens im .~gais-Ranm. GeoL Rundschau, Stuttgart , 72/3, 771-814.

FAHLBUSCH V. (1981) - Miozan und Pliozan - Was ist was Zur Gliederung des Jungtertiars in Stlddeutschland. Mitt. Bayer. Staatsslg. Paldont. hist. GeoL, Mllnchen, 21, 121-128.

MAJOR C.I.F. (1888) - Sur un gisement d'ossements fossi- les dans l'~le de Samos, contemporains de l'~tge de Pikermi. C.R. Acad. Sc. Paris, s6ance du 31 d6c., 3.

MEISSNER B. (1976) - Das Neogen von Ost-Samos. Sedi- mentations-geschichte und Korrelation. N. Jb. Geol. PaRlont., Stuttgart, 152/2, 161-176.

MEISSNER B. (1979) - Untersuchungen zur Bruchtektonik in der Zentralagais. Berliner Geowiss., Berlin, Abh., A, 17, 1-111.

PAPANIKOLAOU D. (1979) - Unitds tectoniques et phases de d6formation darts Pile de Samos, Mer Eg~e, Grace. Bull. Soc. g~ol. Fr., Paris, (7), 21/6, 745-752.

PAPANIKOLAOU D. (1980) - Les 6callles de l'~le de Thy- maena ; t~moins d 'un mouvement tectonique miocene vers l'int6rieur de l 'arc 6g~en. C.R. Acad. Sc., Pads, 290 D, 307-310.

PAPANIKOLAOU D. & DERMITZAKIS M.D. (1981) - The Aegean Arc during Burdigalian and Messinian : a com- padson. Riv. ital. Paleont. Stratigr., Milano, 87/1, 83- 92.

SOLOUNIAS N. (1979) - The Turolian fauna from the island of Samos, Greece, with special emphasis on the Hyae- nids and the Bovids. Unpublished Ph. D., Univ. Colo- rado, Dpt. of Geol. Sc., Boulder, Colorado, 1-422.

SOLOUNIAS N. (1981a) - The Turolian fauna from the island of Samos, Greece. Contr. Vertebr. Evol., Basel, 6, 1-232.

SOLOUNIAS N. (1981b) - Mammalian fossils of Samos and and Pikermi. Part II : Resurrection of a classic Turolian fauna. Ann. Carnegie Mus., Pittsburg, 50, art. 8, 231- 270.

THEODOROPOULOS D. (1979) - Samos Island, Geological Map 1 : 50'000, with explanations. Inst. Geol. Mining Research, Athens.

VAN COUVERING J.A. & MILLER J.A. (1971) - Late Miocene marine scale and non-madne time scale in Europe. Nature, London, 230, 559-563.

WILLMANN R. (1980) - Die Alterstellung kontinentaler Neogen ablagerungen in der st~d0stlichem.~gais (Rhodos und Kos/Dodekanes, Datga/Stldwestanatolien). Newsl. Stratigr., Leyden, 9/1, 1-18.

WILLMANN R. (1983) - Neogen und jungtertiare Entwick- lung der Insel Kos (~gais, Griechenland). Geol. Runds- chau, Stuttgart, 72/3, 815-860.

Manusc r i t d6f in i t i f re~u le 05.04.1984

neogene stratigraphy of the eastern basin, samos island, greece

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