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Tectonics and Magmatism in and the Surrounding Area Geological Society Special Publications Series Editors

A. J. HARTLEY R. E. HOLDSWORTH A. C. MORTON M. S. STOKER

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Tectonics and Magmatism in Turkey and the Surrounding Area

EDITED BY

ERDIN BOZKURT Geological Engineering Department, Middle Eastern Technical University, Turkey

JOHN A. WINCHESTER Department of Sciences, University of Keele, UK

JOHN D. A. PIPER Department of Earth Sciences, University of Liverpool, UK

200O Published by The GeologicalSociety London THE GEOLOGICAL SOCIETY

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Published by The Geological Society from: Distributors The Geological Society Publishing House USA Unit 7, Brassmill Enterprise Centre AAPG Bookstore Brassmill Lane PO Box 979 Bath BA1 3JN, UK Tulsa OK 74101-0979 (Orders: Tel. +44 (0)1225 445046 USA Fax +44 (0)1225 442836) Orders: Tel. +1 918 584-2555 Online bookshop: http://bookshop.geolsoc.org.uk Fax +1 918 560-2652 Email [email protected] First published 2000 Australia The publishers make no representation, express or Australian Mineral Foundation Bookshop implied, with regard to the accuracy of the 63 Conyngham Street information contained in this book and cannot accept Glenside any legal responsibility for any errors or omissions South Australia 5065 that may be made. Australia Orders: Tel. +61 88 379-0444 © The Geological Society of London 2000. All rights Fax +61 88 379-4634 reserved. No reproduction, copy or transmission of Email bookshop@amf com.au this publication may be made without written permission. No paragraph of this publication may be Affiliated East-West Press PVT Ltd reproduced, copied or transmitted save with the G-1/16 Ansari Road, Daryaganj, provisions of the Copyright Licensing Agency, 90 New Delhi 110 002 Tottenham Court Road, London W1P 9HE. Users India registered with the Copyright Clearance Center, 27 Orders: Tel. +91 11 327-9113 Congress Street, Salem, MA 01970, USA: the item-fee Fax +91 11 326-0538 code for this publication is 0305-8719/00/$15.00. Email affiliat@nda, vsnl. net.in British Library Cataloguing in Publication Data Japan A catalogue record for this book is available from the Kanda Book Trading Co. British Library. Cityhouse Tama 204 Tsurumaki 1-3-10 ISBN 1-86239-064-9 Tama-shi ISSN 0305-8719 Tokyo 206-0034 Japan Typeset by Type Study, Scarborough, UK Orders: Tel. +81 (0)423 57-7650 Printed by Arrowsmiths, Bristol, UK. Fax +81 (0)423 57-7651 Contents

Introduction vii

Tethyan evolution STAMPFLI, G. M. Tethyan oceans

OKAY,A. L Was the Late Triassic in Turkey caused by the collision of an ? 25

ROBERTSON,A. H. F. & PICKETT, E. A. Palaezoic-Early Tertiary Tethyan evolution of m61anges, rift and passive margin units in the Karaburun Peninsula (western Turkey) and Chios Island () 43

ALTINER, D., OZCAN-ALTINER,S. & KOqYi~iT, A. Late Permian foraminiferal biofacies belts in Turkey: palaeogeographic and tectonic implications 83

ROBERTSON, A. H. F. -Tertiary tectonic-sedimentary evolution of a south Tethyan oceanic basin and its margins in southern Turkey 97

GONCt3OOLU, M. C., TURHAN, N., ~ENTORK,K., [~ZCAN,A., UYSAL,9" • YALINIZ, M. K. A geotraverse across northwestern Turkey: tectonic units of the Central Sakarya region and their tectonic evolution 139

FARINACCI,A., FIORENTINO,A. & RIDOLFI,V. Aspects of Jurassic radiolarite sedimentation in a ramp setting following the 'mid-Late Jurassic discontinuity', Barla Da~ area, Western Taurus, Turkey 163

YILMAZ, A., ADAMIA,S., CHABUKIANI,A., CHKHOTUA,T., ERDOGAN,K., Tvzcc, S. & KARABIYIKO(~LU,M. F. Structural correlation of the southern Transcaucasus (Georgia)- eastern Pontides (Turkey) 171

Neotethyan ophiolites FLOYD,P. A., G/3NCOO~LU,M. C., WINCHESTER,J. A. & YAL1NIZ,M. K. Geochemical character and tectonic environment of Neotethyan ophiolitic fragments and metabasites in the Central Anatolian Crystalline Complex, Turkey 183

YALINIZ, K. M., FLOYD,P. A. & GONCOO~LU,M. C. Geochemistry of volcanic rocks from the t~i~ekda(~ Ophiolite, Central , Turkey, and their inferred tectonic setting within the northern branch of the Neotethyan Ocean 203

PARLAK,O., HOCK,V. & DELALOYE,M. Suprasubduction zone origin of the Pozantl-Karsantl Ophiolite (southern Turkey) deduced from whole-rock and mineral chemistry of the gabbroic cumulates 219

Post-Tethyan basin evolution KAZMIN, V. G., SCHREIDER,A. A. & BULYCHEV,A. A. Early stages of evolution of the 235

G()ROR, N., ~A(]ATAY,N., SAKINq, M., AKKOK, R., TCHAPALYGA,A. & NATALiN,B. Neogene Paratethyan succession in Turkey and its implications for the palaeogeography of the Eastern 251

KARABIYIKO(]LU,M. F., ~INER, A., MONOD, O., DEYNOUX, M., Tuzcu, S. & Q)R~EN, S. Tectonosedimentary evolution of the Miocene Manavgat Basin, western Taurides, Turkey 271 vi CONTENTS

KAYMAK~I, N., WHITE, S. H. & VAN DIJK, P. M. Palaeostress inversion in a multiphase deformed area: kinematic and structural evolution of the ffanklrl Basin (central Turkey), Part 1 - northern area 295

Neotectouics BURCHFIEL, C. B., NAKOV, R., TZANKOV, T. & ROYDEN, L. H. extension in Bulgaria and northern Greece: the northern part of the Aegean extensional regime 325

YILMAZ, Y., GENt, ~. C., GORER, F., Bozcu, M., YILMAZ, K., KARACIK,Z., ALTUNKAYNAK, ~. & ELMAS, A. When did the western Anatolian grabens begin to develop.'? 353

BOZKURT,E. Timing of extension on the Btiytik Menderes Graben, western Turkey, and its tectonic implications 385

KO~Yi~|T, A., (JNAY,E. & SARAq,G. Episodic graben formation and extensional neotectonic regime in west Central Anatolia and the Isparta Angle: a case study in the Aksehir-Afyon Graben, Turkey 405

TATAR, O., PIPER, J. D. A. & GURSOY,H. Palaeomagnetic study of the Erciyes sector of the Ecemis Zone: neotectonic deformation in the southeastern part of the Anatolian Block 423

Igneous activity BozTud, D. S-I-A-type intrusive associations: geodynamic significance of synchronism between metamorphism and magmatism in Central Anatolia, Turkey 441

ARGER, J., MITCHELL,J. & WESTAWAY,R. W. C. Neogene and Quaternary volcanism of southeastern Turkey 459

YURTMEN, S., ROWBOTHAM,G., ISLER,F. & FLOYD,P. A. Petrogenesis of basalts from southern Turkey: the Plio-Quaternary volcanism to the north of Iskenderun Gulf 489

Index 513

It is recommended that reference to all or part of this book should be made in one of the following ways:

BOZKURT, B., WINCHESTER, J. A. & PIPER, J. D. A. (eds) 2000. Tectonics and Magmatism in Turkey and the Surrounding Area. Geological Society, London, Special Publications, 173.

STAMPFLI,G. M. 2000. Tethyan oceans. In: BOZKURT,B., WINCHESTER,J. A. & PIPER, J. D. A. (eds) Tectonics and Magmatism in Turkey and the Surrounding Area. Geological Society, London, Special Publications, 173, 1-23. Introduction

Tethyan evolution 1) is not the Neotethyan suture. In this scheme the Izmir-Ankara-Erzincan Suture represents Turkey is sited at the collisional boundary be- a Jurassic back-arc oceanic basin opened along tween Gondwana in the south and in the complex pre-existing Karakaya-Palaeo- the north and its geological history records the tethyan suture zone following the northward suturing of a succession of continental frag- of Neotethys since the Late Trias- ments. The Tethyan ocean, which existed be- sic. tween Laurasia and Gondwana, was not a single Okay describes the E-W trending latest continuous oceanic plate, but rather comprised Triassic Cimmeride orogen in northern Turkey variable-sized continental fragments through- (box 2 in Fig. 2). He proposes that the Cimmer- out its history (Fig. 1). These rifted from the ide deformation and metamorphism were Gondwana margin and, as the rifts widened, caused by collision and partial of an created oceans (mainly described as Proto- Early-Middle Triassic oceanic plateau (Nilafer tethys, Palaeotethys and Neotethys in the litera- unit) to the active southern continental margin ture), then subsequently collided with Laurasia of Laurasia, with the Karakaya Complex so that these oceans sequentially closed. The interpreted as a Palaeotethyan subduction- present tectonic regime follows closure of the accretion-collision complex. The age of the Neotethyan ocean. Although Prototethys has Cimmeride deformation in the Sakarya Zone traditionally been regarded as a Late Protero- (Fig. 1) is palaeontologically constrained be- zoic and/or Early Palaeozoic ocean, Palaeo- tween the latest Norian and Hettangian (215- tethys as a Palaeozoic ocean and Neotethys as a 200 Ma), compatible with 40 At- 39 Ar phengite Mesozoic-Early Tertiary ocean, the views ex- cooling ages of 214-192 Ma from eclogites and pressed in this volume show that there is no blueschists in the Niliifer unit. Thick overlying common agreement. Many alternative models Upper Triassic arkosic sandstone sequences have been proposed for their evolution and they containing extensive olistostromes of Permian may, indeed, have overlapped in time. The and Carboniferous limestone (Hodul Unit), are models proposed below differ in subduction interpreted to have formed during collision in polarity, timing of ocean basin opening and foredeep basins in front of south-verging Hercy- closure, and in the location of suture zones. nian continental thrust sheets of the Laurasian Figure 1 is a simplified tectonic map showing margin. Okay views the Izmir-Ankara-Erzin- the location of the main Tethyan sutures and can Suture (Fig. 1) as representing both the neighbouring major continental blocks in Palaeotethyan and Neotethyan sutures and Turkey and its surrounding area. concludes that the Neotethys opened as a sep- The first section on Tethyan evolution opens arate ocean during the Early Triassic. with a broad review of Tethyan ocean develop- Robertson & Pickett discuss Palaeozoic- ment by Stampfli. Following definitions of the Early Tertiary tectonic evolution of part of the main Tethyan oceans and a brief literature Tethyan ocean, based on evidence from the review, Stampfli presents palaeocontinental Karaburun Peninsula (western Turkey) and reconstructions for key stages in the evolution nearby Chios Island (Greece) (Fig. 1; box 3 in of Prototethys, Palaeotethys, Neotethys, the Fig. 2), located near to the northern margin of Variscan, Eocimmerian and marginal oceans the Anatolide-Tauride Platform (Taurides). during the Palaeozoic and Mesozoic. His Here, an exceptionally intact and unmetamor- models also cover the Alpine Tethys, the phosed tectono-sedimentary sequence forms a Central Atlantic and the Vardar, North Atlan- microcosm of the tectonic history of both tic and Valais oceans. After describing the Palaeotethys and Neotethys. A kilometre-thick Tethys sutures in the eastern Mediterranean m61ange containing mainly Silurian-Carbon- area and presenting a tectonic map showing the iferous exotic blocks within a highly sheared present location of these sutures, Stampfli con- matrix of turbidites, pelagic carbonates and cludes that the Cretaceous-aged coloured m61- channellized conglomerates is interpreted as an anges in Turkey and Iran, now located within Upper Carboniferous-Lower Permian subduc- the Eurasian margin to the north of the Neo- tion/accretion complex that developed near the tethys active margin, are separated from the southern margin of Palaeotethys during the Neotethyan suture: this would imply that the collision of a passive margin with a trench. Izmir-Ankara-Erzincan Suture in Turkey (Fig. Unconformably overlying Lower Triassic viii INTRODUCTION

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• t::l ~ .~o~ ~.'~. INTRODUCTION ix basinal successions record Early Triassic rifting Platform and the Menderes Massif to the of a northerly Neotethyan ocean• Subsequently, south. during Middle-Late Triassic time, the rift basin Altmer et ai. describe the Late Permian overstepped a subsiding shallow-water (Kara- palaeogeography and tectonic evolution of burun) platform bordering the northern Neo- Turkey by analysing characteristics of the Late tethys. Uplift associated with Cimmerian Permian carbonate platform and foraminiferal emplacement of the Karakaya Complex further biofacies belts (box 4 in Fig. 2). The platform is north is recorded by a brief hiatus followed by reconstructed by assembling the Upper Per- deposition of deltaic sediments during latest mian outcrops from different, but juxtaposed, Triassic-Early Jurassic time. During Cam- Triassic and Cretaceous-Tertiary tectonic units. panian-Maastrichtian times, after prolonged Upper Permian marine carbonates occur in passive margin subsidence the Karaburun car- contrasting southern and northern biofacies bonate platform underwent flexural uplift and belts. The Southern Biofacies Belt includes erosion recording initial closure of the north- low-energy inner platform deposits of the Ana- erly Neotethys. The platform then collapsed tolide-Tauride Platform and the Arabian Plat- into a foredeep during Maastrichtian-Danian form (Fig. 1), while the highly deformed and times. During final stages of continental col- fragmented Northern Biofacies Belt includes lision in the Early Tertiary, the mdlange and the Upper Permian of the Karakaya Orogen the unconformably overlying rift and platform and outer platform and platform margin depos- units were deformed and locally interleaved. its of the Anatolide-Tauride Platform. Upper Robertson & Pickett conclude by interpreting Permian blocks in the Karakaya Orogen dis- the Karaburun-Chios Mesozoic platform as play similar palaeontological and biofacies part of the southern margin of a Neotethyan characteristics to the outer platform or plat- ocean basin bordering the Anatolide-Tauride form margin deposits of the Taurides; they

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Fig. 2. Location map showing areas described in the papers in this volume. 2, Okay; 3, Robertson & Pickett; 4, Altlner et al.; 5, Robertson; 6, G6nciio~lu et al.; 7, Farinacci et al.; 8, A. Yllmaz et al.; 9, Floyd et al.; 10, Yahmz et al.; 11, Parlak et al.; 12, Kazmin et al.; 13, G6r~ir et aL; 14, Karablylko~lu et al.; 15, Kaymakql et al.; 16, Burchfiel et al.; 17, Y. Yflmaz et aI.; 18, Bozkurt; 19, Koqyi~it et al.; 20, Tatar et al.; 21, Boztu~; 22, Arger et al.; 23, Yurtmen et al. Geographical location of the paper by Stampfli is not shown since it covers a broad review of Tethyan evolution. x INTRODUCTION represent the northernmost extent of this car- thrusting to form the Southeast Anatolian bonate platform. The absence of transgressive Suture in the Eocene (Fig. 1); younger m61ange Upper Permian deposits resting unconformably occurrences (Misis-Andmn Mountains) suggest on pre-Permian basement of the Sakarya Con- that subduction locally persisted until the Late tinent strongly suggests that the carbonate plat- -Early Miocene. Further west (north form was facing a trough or basin to the north. of the ) an oceanic seaway This would have separated the Late Permian between the eastern and western Anatolide- carbonate platform in the south from the base- Tauride platforms (Isparta Angle) closed in the ment of the future Sakarya in the Late Palaeocene-Early Eocene, while further north. Altlner et al. therefore reject a Gondwa- south, the southernmost oceanic basin pre- nan origin for the Sakarya Continent. served within an embayment of the North Robertson focuses on the Mesozoic-Tertiary Africa/Arabian margin only began to experi- tectonic evolution of the Tethyan ocean (Neo- ence collision-related deformation during Plio- tethyan), based on geological and geophysical Quaternary times. In southern Turkey, border- information from southern Turkey and offshore ing the Mediterranean Sea, the emplaced Neo- areas of the easternmost Mediterranean (box 5 tethyan units are unconformably overlain by in Fig. 2). This region is dominated by the Miocene (to Pliocene) basins which resulted rifting, spreading and closure of several Neo- from regional southward-directed crustal load- tethyan oceanic basins, including the inner ing as convergence of Africa and con- Tauride basin formerly located north of the tinued. They may also have been influenced by present Tauride Mountains. This opened in the the initiation of a north-dipping subduction Early Triassic (see also Robertson & Pickett, zone located south of because the this volume) and, following closure in latest Antalya and Adana-Cilicia basins represent Cretaceous-Early Tertiary times, gave rise to areas of crustal extension behind this zone the regionally extensive Lycian and Beysehir- since the Late Miocene. During Plio-Quatern- Hoyran-Hadim . Further south, the ary times continuing regional convergence was Tauride Mountains originated as continental accommodated by left-lateral strike-slip faulting fragments which rifted from Gondwana in Late along the South Anatolian Permian-Early Triassic time to form the north- which delineated the southern margin of the ern margin of a separate southern Neotethyan during westward 'tectonic oceanic basin. Middle-Late Triassic spreading escape'. Robertson concludes that whereas SE in this basin was followed, during Jurassic-Early Turkey today records a post-collisional setting, Cretaceous time, by construction of Tauride- the easternmost Mediterranean records only fringing carbonate platforms. By the late Early incipient collision: this makes it ideal for the Cretaceous, regional convergence of the Afri- study of diachronous collisional processes. can and Eurasian Plates induced closure of both Giinciio~lu et aL describe the stratigraphy the northern and southern Neotethyan oceanic and tectonic relationships of south-verging basins, activating north-dipping subduction structural units across the root-zone of the zones. Southward 'roll-back' of pre-existing Alpine Izmir-Ankara-Erzincan Suture around cold and dense oceanic lithosphere initiated the central Sakarya area of NW Turkey (Fig. 1; genesis of supra-subduction type ophiolites, box 6 in Fig. 2). In the northern unit (Central which were initially obducted on to the northern Sakarya ), a Triassic rift basin assem- margin of the Tauride carbonate platforms in blage which unconformably overlies a base- latest Cretaceous time. Thrusting to their ment comprising a Variscan ensimatic arc present, more southerly positions in the Late complex and a fore-arc-trench complex, is Eocene (in the east) to Late Miocene (in the itself unconformably overlain by a Liassic- west) resulted from final suturing of the north- Upper Cretaceous platform sequence. The ern Neotethyan ocean. middle tectonic unit (Central Sakarya Ophio- The southern Neotethyan ocean was tectoni- litic Complex) comprises a partly subducted cally disrupted in latest Cretaceous time with Late Cretaceous accretionary complex. The emplacement of ophiolites and m61ange onto southern tectonic unit includes a basement of the Arabian Platform in the east (e.g. Ko~ali Variscan metamorphic rocks formed in a back- ophiolite) and thrusting and strike-slip dis- arc setting, overlain by a Triassic-Lower Cre- placement of continental margin and ophiolite taceous succession interpreted as the passive units in the west (Antalya Complex). Prolonged continental margin of the Anatolide-Tauride and episodic closure history in SE Turkey Platform. Basinal deepening allowed depo- culminated in renewed arc volcanism, extensive sition of a thick synorogenic flysch sequence subduction-accretion (Maden Complex) and subsequently influenced by high pressure/low INTRODUCTION xi temperature metamorphism. GOnc0o~lu et al.'s basins, some of which closed during Oligocene- evolutionary model contrasts with the others in Early Miocene times whereas others, such as the this volume (e.g. Stampfli) in both the palaeo- Black and Caspian Seas, survive as relict basins. geographic distribution of the main plates during the pre-Alpine and Alpine period and in the proposed subduction polarity of the oceanic Neotethyan ophiolites material. When combined with other geological data, Farinacci et al. reconstruct the basinal setting geochemical studies, particularly those using of the Tethyan Jurassic radiolarite deposits from immobile elements from basic extrusive igneous the Barla Da~ area (western Taurides) (box 7 in rocks, are useful for identifying tectonic settings Fig. 2). The main Kimmeridgian radiolarite of units within orogenic belts by comparison of sedimentation occurred within or just below their compositions with rocks from modern the wave base in a storm-influenced carbonate tectonic settings. Turkey is characterized by ramp environment and followed uplift coeval two major E-W trending ophiolite belts with an Early Bajocian-Kimmeridgian dis- (ancient suture zones) that record closure and continuity known as the 'main gap', a hiatus destruction of the Neotethyan oceans: these that lasted about 25 Ma. Pre-existing carbonate comprise the northern Neotethys (the Izmir- platforms were converted into ramps by block Ankara-Erzincan Suture) located between the faulting which produced widespread Late Sakarya Continent in the north and the Anato- Pliensbachian submergence. Change in the lide-Tauride Platform in the south, and the depositional bathymetry of some radiolarites southern Neotethys (Southeast Anatolian suggests replacement of a deep basin by ramps. Suture) that formerly separated Gondwana Farinacci et aL conclude that extensive shallow (Arabian Platform) in the south from the seas and a relatively narrow deep oceanic realm Anatolide-Tauride Platform in the north (Fig. separated the Eurasian and African Plates in the 1). western Tethys. In two successive papers Floyd et al. and A. Ydmaz et ai. describe and correlate Upper Yahmz et al. describe the petrogenesis and Cretaceous-Tertiary units of the Eastern tectonic evolution of little-known Central Ana- Pontides (NE Turkey) and Transcaucasus tolian ophiolites and related rocks (boxes 9 and (Georgia) (Fig. 1) which belong to the same 10 in Fig. 2, respectively). These are found as geological belt and represent the former active allochthonous slices tectonically emplaced onto margin of the (box 8 in Fig. 2). the Klr~ehir Massif (Fig. 1) that represents the The Eastern Pontides, interpreted as the prod- passive margin of the Tauride-Anatolide Plat- uct of interference between a spreading ridge form. In both papers the ophiolitic rocks are and the subduction zone during Late Jurassic- considered to be remnants of suprasubduction Cretaceous time, is divided into three structural zone formed by intra-oceanic units. From north to south, these are (1) the subduction within the izmir-Ankara-Erzincan Southern Black Sea coast-Adjara Trialeti unit, ocean during the early Late Cretaceous. In the (2) the Artvin-Bolnisi unit and (3) the imbri- former paper, the metabasic rock associations cated Bayburt-Karabakh unit. They represent, are interpreted mainly as remnants of a tholeii- respectively, a juvenile Santonian-Campanian tic arc and an adjacent back-arc basin with back-arc, a south-facing arc formed mainly MORB-like compositions. The latter study during Liassic-Campanian time, and a Malm- details the petrology and tectonic setting of a Campanian fore-arc basin of an active conti- dismembered example of the same ophiolitic nental margin. To the south, these tectonic units assemblage which occurs as a huge tectonic are bordered by the Ankara-Erzincan-Lesser slice in the northern Klrsehir Massif. For this Caucasus suture, comprising ophiolites, m61- the authors propose a two-stage emplacement anges and an ensimatic arc association produced model involving earlier obduction of MORB/ during final closure of the Neotethyan ocean. By OIB-type volcanic rocks and accretionary prism contrast, Jurassic-Early Cretaceous rift-related assemblages of the [zmir-Ankara-Erzincan sediments indicate that the western part of the oceanic plate on to the passive margin of the Eastern Pontides was a passive continental Anatolide-Tauride Platform, followed by the margin. This progressive change from east to formation of a new, fore-arc type oceanic crust. west along the Eastern Pontides is explained by The latter was emplaced southwards during the the progressive interaction between a spreading Late Cretaceous on to the Klr~ehir Massif. ridge and subduction zone, which ceased before The Pozantl-Karsantl Ophiolite, one of the the Maastrichtian. During the Middle Eocene largest Late Cretaceous ophiolites in this region, renewed rifting resulted in the formation of new crops out in the eastern Tauride belt of southern xii INTRODUCTION

Turkey and is described by Parlak et al. (box 11 Eastern. The Eastern Paratethys (EP) covers in Fig. 2). It covers an area of approximately areas of the Black, Caspian and Aral Seas. 1300 km ~ between the sinistral Ecemis Fault G0rtir et al. detail the tectono-sedimentary and Zone to the west and the sinistral East Ana- palaeo-oceanographic history of the EP be- tolian Fault Zone to the east. The whole-rock tween the Tarkhanian (Middle Miocene) and and mineral chemistry of gabbro-norites from Cimmerian (Pliocene) and describe the Neo- the ophiolite indicate production in a supra- gene marginal succession in the southern Black subduction zone tectonic setting related to Sea coast and the Marmara regions of Turkey, north-dipping subduction of the northern Neo- supported by palaeogeographic maps. In the tethyan ocean by the beginning of the Late Tarkhian, the southern margin of the EP was a Cretaceous. Intra-oceanic subduction induced carbonate platform which emerged during the formation of the metamorphic sole and the Late Tarkhian to Early Chokrakian. Isolation of generation of dyke swarms. Parlak et al. con- the basin during the Karaganian was followed clude that the ophiolite continued to accrete by marine conditions which prevailed until the mdlange and was finally obducted over the Early Konkian when the EP was connected to Anatolide-Tauride Platform during the Late the Indo-Pacific Ocean. Ensuing brackish con- Cretaceous or Early Palaeocene. ditions were followed by the widespread Early Sarmatian transgression, after which the EP was Post-Tethyan basin evolution again isolated during Middle-Late Sarmatian. During the Pontian the EP was connected to the Following Late Cretaceous-Tertiary closure of Marmara and NE Aegean regions but the link the Neotethys ocean by collision of dispersed with the Mediterranean via the Marmara region pieces of Gondwana with Eurasia, several post- did not form until the Late Akchaglylian. In this orogenic Neogene basins of various sizes were respect, the model by G6rtir et al. contradicts developed. The third group of papers presents previous claims that the Marmara region detailed description of basin-fill and basin- formed a link between the Mediterranean and bounding structures and provides important the Paratethys during most of the Middle evidence about the tectono-sedimentary and Miocene. palaeoceanographic evolution of these basins. In the Manavgat Basin, on the eastern flank of Kazmin et ai. report that the Black Sea the 'Isparta Angle' in the western Taurides (box comprises western and eastern sub-basins (Fig. 14 in Fig. 2) Karabtytko~,lu et al. show that 1; box 12 in Fig. 2), which mainly opened in the Miocene basin fill unconformably overlies Eocene. Two depocentres in the western Black Mesozoic rocks which had been imbricated and Sea are interpreted as products of early back-arc overthrust by the Antalya Nappes and Alanya extension which formed in Barremian-Albian Massif metamorphic rocks during the Eocene. time north of the Pontide arc. By contrast, the Irregularly distributed Burdigalian-Lower central and eastern part of the basin opened as Langhian coarse clastic rocks (fluvial/alluvial an inter-arc basin induced by the rifting of the fan and fan delta complexes) prograded into a Late Cretaceous arc. Following compression in shelf area filling the pre-existing topography. the Eastern Pontides, the eastern Black Sea They are overlain by transgressive Langhian basin opened mainly in the Middle Eocene. reefal shelf carbonates that onlap fan delta Simultaneous opening of the central-eastern sediments and record a sharp rise in relative part of the Western Black Sea Basin and the sea-level together with a decrease in sediment Eastern Black Sea Basin (Fig. 1) is attributed to supply. Syn-sedimentary block faulting resulted southward drift of the Pontides and clockwise in fragmentation and sudden deepening of the rotation of the Andrusov Rise. carbonate shelf during which Upper Langhian G~riir et al. discuss Paratethyan evolution to Serravalian breccias, debris flows and (box 13 in Fig. 2). Neogene basins of varying hemipelagic sediments characterized by slumps sizes formed after the Late Cretaceous to and rock falls/slides were deposited. From the Tertiary collision of Gondwana with Eurasia. Tortonian until the Messinian, sedimentation Paratethys, defined as an E-W trending land- was largely controlled by progressive uplift of locked basin extending from the Rhone Valley the hinterland as shown by the rapid passage in the west to the Aral Sea in the east, forms one from high density currents and debris flows to of them. Its isolation from marine realms such as turbulent coarse-grained fan deltas. These sedi- the Mediterranean Sea caused drastic changes ments were later folded during end-Miocene N- in palaeo-oceanographic conditions. From the S compression, and unconformably overlain by distribution of these changes Paratethys is sub- undeformed Pliocene fluvial conglomerates. divided into three parts: Western, Central and Three distinct episodes in the evolution of the INTRODUCTION xiii

Manavgat Basin are distinguished as an Early Late Palaeocene to Aquitanian) phases were Miocene fan-delta deposition, followed by Late characterized by thrusting and folding during Burdigalian to Langhian reef limestones and the final northward subduction of Neotethys finally thick turbidites. Karablylkofglu et al. beneath the Pontides along a roughly E-W conclude by suggesting that the Manavgat trending trench. The authors suggest that Basin and the northern part of the Adana Basin oblique transpression occurred and propose display similar evolution and might have been that subduction had a dextral strike-slip com- connected. ponent. The ~-shape of the basin is attributed to Kaymak~a et al. report that the ~ankm Basin a 30 ° and 50 ° clockwise rotation along the (Central Anatolia; box 15 in Fig. 2), located western and eastern margins respectively where the Sakarya Continent became attached during Eocene to Oligocene times, which re- to the Pontides and the .Klr}ehir Massif collided sulted when collision of a promontory of the and sutured along the Izmir-Ankara-Erzincan Klr~ehir Massif indented the Sakarya Continent Suture (Fig. 1), experienced post-Middle Mio- (Fig. 1). The third phase was a Burdigalian to cene (c. 9.7 Ma) deformation during extrusion- pre-Tortonian (20.5 Ma to 9.7 Ma) extensional related transcurrent motions along the North deformation, driven by gravitational collapse of Anatolian and East Anatolian fault zones. The the orogen following collision and further con- main structures moulding the f~-shaped ~ankm vergence of the Sakarya Continent and the Basin, which contains more than 4 km of Upper Klr~ehir Massif. During this phase, compression Cretaceous to Plio-Quaternary sediments, are was replaced by extension and multidirectional thrust faults defining its western and northern normal faults were formed. In the final phase, rims and a belt of NNE-striking folds marking linked to regional strike-slip deformation be- its eastern margin. In the south, the basin fill tween the post-Middle Miocene (Tortonian, 9.7 onlaps on to the Klr~ehir Massif. Other major Ma) and the present, most pre-existing struc- structures affecting the basin are the dextral tures were reactivated along inherited planes of Klzdlrmak and Sungurlu fault zones (KFZ and weakness. The western margin, dominated by a SFZ, respectively), which are splays of the pre-existing belt, was reactivated Zone. In making a into a zone of sinistral transpression as the kinematic and structural analysis of these struc- conjugate of the KFZ and SFZ. tures by applying palaeostress inversion studies usingfaultslipdatafromfoursub-areas,Kaymakq] Neotectonics et al. recognize four deformational phases and construct the palaeostress configuration for As the 1999 earthquakes remind us, Turkey is each. The first two (pre-Late Palaeocene and located on the seismically active 'Mediterranean

24 ° 28 ° 32 40 44 i ~1 III IIII II ~ I i I ~ I m /~-~~URASIAN PLATE

38 ~=:~~---- Antalya Ada~a-~ (t

"~/'/~ t~ I ..... I km

CT- Cyprean Trench HT- DSFZ- Dead Sea Fault Zone NAFE- North Anatolian Fault Zone EAFZ- East Anatolian Fault Zone SAS- Southeast Anatoli~ Suture I , I I ,I I I

Fig. 3. Simplifed neotectonic map of Turkey showing its major structures. Heavy lines with half arrows are strike-slip faults with arrows showing the relative movement sense. The heavy line with filled triangles shows a major fold and thrust belt (Southeast Anatolian Suture): small triangles indicate direction of vergence. The heavy line with open triangles indicates an active subduction zone, its polarity indicated by the tip of small triangles. Bold filled arrows indicate relative movement direction of African, Arabian and Eurasian Plates; open arrows, relative motion of Anatolian Plate. xiv INTRODUCTION

Earthquake Belt'. The Turkish section is out- Albania. N-S extension along E-W striking lined by three major structures (Fig. 3). The first faults in central Bulgaria began at c. 9 Ma and of these is the Hellenic-Cyprus Trench, a con- extended westward, with decreasing magnitude, vergent plate boundary between the African into SW Bulgaria and FYR Macedonia in the Plate in the south and the Anatolian Plate in Quaternary, cutting across older NW-trending the north. The is descending down grabens. This continued extension is ascribed the trench towards the NNE beneath the Ana- either to trench roll-back along the southern tolian Plate. The other two major structures are part of the Hellenic subduction system or to the dextral North Anatolian and sinistral East local anticlockwise rotation of NW Anatolia Anatolian fault zones (Fig. 3). Along these relative to part of Eurasia, including NW intracontinental strike-slip fault zones, the Ana- Greece and Albania (western Hellenides). In tolian Plate is being extruded towards the WSW the Late Pliocene a widespread major erosion between the converging Eurasian and Arabian surface referred to as the 'sub-Quaternary sur- Plates. The western half of the Anatolian Plate face' developed and is marked by an angular is dominated by N-S directed extension and unconformity or disconformity between Upper consequent E-W, NE- and NW-trending horst Pliocene and Lower Quaternary strata. The and graben structures. presence of this surface high in the mountains Western Anatolia is a part of the Aegean (e.g. Rhodopian Mountains) demonstrates sig- extensional system, embracing a large area that nificant Quaternary displacements along normal also includes much of Greece, Macedonia, faults associated with N-S extension. During the Bulgaria and Albania. The origin and age of Late Pliocene (c. 3-4 Ma), deformation in SW extension in the Aegean have long been Bulgaria and northern Greece was expressed by debated and the papers contained in the Neo- continued NE-SW to N-S extension and associ- tectonics section provide new evidence that ated NE- to E-W striking dextral strike-slip contributes to a better understanding of this faults; these functioned as transfer faults be- complex area. Following a broad review of tween areas of extension. This deformation is (Burchfiel et aL and Y. thought to have resulted from propagation of Yllmaz et al.), more geographically focused the dextral North Anatolian Fault Zone into the studies are described by Bozkurt, Koqyi~it et al. northern Aegean and formation of parallel and Tatar et al. faults to the north. In addition to these two Evidence from the southern Balkan Penin- different tectonic regimes, a third phase of E- sula and the northern part of the Aegean ex- W extension related to continued trench roll- tensional system is presented by Burchfiel et al., back along the northern part of the Hellenic who review Middle Miocene to Recent tectonic subduction system prevailed in western FYR evolution of Bulgaria and northern Greece (box Macedonia and eastern Albania. This, in turn, 16 in Fig. 2). They suggest that Late Eocene to suggests that there were three areas with diffuse Early Miocene arc-normal extension continued boundaries characterized by different styles of contemporaneously with convergence in extensional tectonism in the southern Balkan Greece, FYR Macedonia, Bulgaria and Turkey region during the last 4 Ma: (1) N-S extension in and was induced by crustal weakening due to central Bulgaria; (2) coupled strike-slip and magmatic and radiogenic heating of thickened NE-SW extension in SW Bulgaria, northern crust following final closure of the Vardar- Greece and central FYR Macedonia; and (3) Izmir-Ankara Zone (Fig. 1) by northward sub- E-W extension in western FYR Macedonia and duction. eastern Albania. In Early or Middle to early Late Miocene Based on evidence from seismicity and GPS time (26-21 Ma), major regional lithospheric studies, Burchfiel et al. propose that the active extension occurred along NW-trending struc- deformation in northern Greece, SW Bulgaria tures oblique to an older magmatic arc. A and FYR Macedonia is Late Quaternary N-S second phase of NE-directed extension pro- extension, and that dextral strike-slip movement duced low-angle detachment faults and was on the North Anatolian Fault Zone must have accompanied by a short period of coeval com- begun at about 4 Ma. Finally they conclude that pression. Extension then migrated northward mountainous topography in the southern into SW Bulgaria at c. 16 Ma. Burchfiel et aL Balkan region results from Miocene to Recent interpret this extension in terms of roll-back of extension with different causes involving a com- the Hellenic Trench, which is also expressed by plex interplay between the Hellenic Trench, southward migration of the Hellenic volcanic westward escape of Anatolia, and N-S exten- arc. They speculate that this may also have sion and rotation of Anatolia (Fig. 3). occurred in FYR Macedonia and eastern Y. Yllmaz et al. use new data to explain the INTRODUCTION xv timing and mechanism of the western Anatolian faults, Upper Miocene sediment deposition was graben system, and distinguish five major stages controlled by developing N-S trending cross- in the tectonic evolution of western Anatolia grabens. The graben-bounding cross-faults rep- (box 17 in Fig. 2). The first stage is the Late resent reactivated faults that controlled Early Cretaceous-pre-Miocene pre-graben stage. Miocene E-W extension. They also suggest Late Cretaceous to pre-Middle Eocene collision that E-W trending normal faults and associated between the Sakarya Continent and Anatolide- grabens, which initially began to develop Tauride Platform along the Izmir-Ankara- during the Late Miocene, were linked to the Erzincan Suture was followed by compression. extrusion of 9-6 Ma alkaline basaltic lavas. N- This produced N- and S-directed thrusting S extension ceased at the end of the Late which continued until the Late Eocene-Oligo- Miocene and uplift produced a major erosion cene in the Pontides and the Late Miocene in surface marked by an angular unconformity or the Taurides. Eocene crustal thickening and disconformity above Upper Miocene-Lower synchronous HT/M-HP metamorphism (main Pliocene strata (fourth stage). The presence of Menderes metamorphism) in the Menderes this erosion surface high in the mountains Massif (Fig. 1) was associated with widespread demonstrates that N-S extension was rejuve- upper mantle and crustal melting. By the Early nated (fifth stage, a later stage of N-S exten- Miocene uplift and exhumation of the Menderes sion) and that significant Plio-Quaternary Massif had already occurred along low-angle displacements occurred along these normal thrusts, back thrusts and the associated normal faults. Late Miocene structures were cut and faults recognized extensively in the massif. displaced during this phase. This second, Plio- In the second stage during the Early Miocene, Quaternary, phase of N-S extension produced N-S trending grabens were initially formed in the existing E-W trending grabens in western an E-W extensional regime. The graben-bound- Anatolia. The Lower-Middle Miocene fluvial- ing faults, which are strike-slip faults with con- lacustrine sediments have no genetic relation- siderable dip-slip movement, form conjugate ships to these grabens, as recently suggested. Y. pairs possibly developed during a N-S com- Yflmaz et al. conclude that the timing of west- pression which is also indicated by development ward escape of Anatolia along its boundary of gentle E-W trending folds and local reversed faults was synchronous with, and may be re- faults in the Lower Miocene successions. The sponsible for, rejuvenation of N-S extension Kale-Tavas Basin, initiated during the Chattian and development of the neotectonic ex- (Late Oligocene), earlier than the other N-S tensional regime in western Anatolia. grabens, and previously regarded as a molasse This paper also distinguishes two magmatic basin with respect to the Menderes Massif, is episodes: (1) an Oligocene-Early Miocene high- interpreted here as a piggyback basin situated K calc-alkaline hybrid magmatism that is late/ above the southerly transported Lycian Nappes. post collisional with respect to Tethyan con- The authors also note the lack of stratigraphic vergence; (2) Late Miocene-Pliocene alkaline contact between the Kale-Tavas Basin and the continental rift-related volcanism. The non- Menderes Massif and suggest that this part of volcanic period (14-10 Ma) between these two the Menderes Massif remained buried beneath phases corresponds to the time of transition the Lycian Nappes throughout the Late Oligo- from N-S compression to N-S extension in cene. Western Anatolia. This period has been evalu- N-S extension in western Anatolia began ated as late orogenic extension following exces- during the Late Miocene (third stage, early N- sive crustal thickening. S extension). During this stage, major N- and S- In two successive papers Bozkurt and Ko~:yi- facing breakaway faults (low-angle detachment ~it et al. describe new structural and strati- faults) were formed to bound the southern and graphic evidence for episodic two-stage graben northern flanks of the Bozda~ horst in the formation in two case studies from the Biiytik central Menderes Massif. Along these detach- Menderes Graben in western Anatolia and the ments the footwall high-grade metamorphic Aksehir-Afyon Graben in west Central Ana- rocks and Miocene pre-tectonic granites of the tolia, respectively (boxes 18 and 19 in Fig. 2, Menderes Massif were progressively deformed, respectively). The basin fill in both grabens uplifted and juxtaposed against Upper Miocene consists of two major sequences: deformed continental red beds on the hanging wall. The Miocene fluvio-lacustrine sediments overlain faults remained active during the Late Mio- unconformably by undeformed, nearly horizon- cene, later than previously considered (Early tal Plio-Quaternary sediments. The older infill is Miocene). Further away from the Bozda~ folded and thrust faulted in the Ak~ehir-Afyon horst, in the hanging wall of the detachment Graben while it is back-tilted northward and xvi INTRODUCTION locally folded in the Btiytik Menderes Graben. summarize palaeomagnetic evidence for neo- Both grabens exhibit evidence for two-stage tectonic deformation across a broad zone extension where an initial phase of extension extending for at least 300 km between the related to orogenic collapse of the overthick- sinistral East Anatolian and dextral North ened crust, which followed Late Palaeogene Anatolian fault zones. Their palaeomagnetic collision across the Neotethyan ocean, was study of young (1-2 Ma) lava flows across the superseded by later and steeper normal faults Ecemis Fault Zone identifies block rotations in during the Pliocene. The deformation of older this part of Anatolia of c. 10 ° counterclockwise basin fill is attributed to a short phase of com- during the last 1 million years. Between the East pression resulting from a probable variation in Anatolian Fault Zone in the south and the kinematics of the Eurasian and African Plates in North Anatolian Fault Zone in the north, the the Late Miocene, a time which also corre- degree of counterclockwise rotation during the sponds to a major break in sedimentation and tectonic escape within the last 2-3 Ma magmatism, and a regional folding event, across diminishes from c. 25 ° in the east to c. 10 ° in many western Anatolian basins. Bozkurt further the SW. This reflects a transition from highly suggests that the Miocene sediments were strained to less strained crust as the width of the deposited on the hanging wall of the normal Anatolian Plate confined between the Arabian- fault(s) and that the metamorphic rocks of the Eurasian pincer broadens to the west. Menderes Massif in the footwall were deformed, mylonitized and progressively Igneous activity exhumed. The second, neotectonic phase of extension, was triggered by the initiation of Although volcanism in Turkey is currently strike-slip movement along the North Anatolian quiescent, there is abundant evidence that and East Anatolian fault zones during the Plio- magmatism has been associated with all stages cene and is attributed to the westward tectonic in its tectonic evolution. Studies of both intru- escape of the Anatolian Plate along these struc- sive and extrusive rocks, their geochemistry and tures. The fault controlling the early phase of the relationship between deformation and their extension in the Btiytik Menderes Graben may age of emplacement therefore provide vital have been reactivated during the second phase. additional information about the progressive Ko~yi~it et al. conclude that the Aks, ehir Fault is tectonic evolution of the area. an oblique-slip normal fault forming part of the Boztu~ describes the mineralogy and whole- current extensional regime of west Central rock major and trace element geochemistry of Anatolia and the Isparta Angle region; this intrusive associations in the Kyr~ehir Massif contrasts with previous interpretations which (Fig. 1; box 21 in Fig. 2). He evaluates the interpreted it as a reverse fault belonging to a geodynamic significance of these data in the compressional neotectonic regime. Bozkurt context of the Late Cretaceous synchronicity of further suggests that the basal Miocene red these collision-related granitoids with meta- clastic rocks cannot be regarded as passive morphism in the massif. The intrusive associ- graben fill. Because the initiation of movement ations record differences in geological setting on younger faults bounding the present graben and are classified into three groups: (1) syn- floor is constrained to c. 1 Ma, the age of the collisional, S-type peraluminous two-mica Btiytik Menderes Graben is Pliocene, younger leucogranites; (2) post-collisional, I-type meta- than previously considered (Early-Middle Mio- luminous hybrid monzonites; and (3) post- cene). He concludes that western Anatolia is an collisional and within-plate, A-type alkaline example of a region that experienced two modes rocks including monzonites and syenites. of extension: 'core-complex mode' and 'wide- Boztu~ suggests that metamorphism and rift mode', reflecting significant changes in the magmatism were synchronous during Late tectonic setting of western Anatolia which can Cretaceous Anatolide-Tauride Platform and be attributed to orogenic collapse followed by Pontide collision along the Izmir-Ankara- tectonic escape. Erzincan Suture Zone (Fig. 1). The metamorph- The eastern and central parts of the Anato- ism inverted the passive margin of the Ana- lian Plate are dominated by active, intraconti- tolian Plate during collision, accounting for a nental dextral and sinistral strike-slip faults. decrease in metamorphic grade from north to Tatar et al. report a palaeomagnetic study from south. Subsequent magmatism along the Ana- the Erciyes sector of the sinistral Ecemis (or tolian passive margin is manifested by success- Central Anatolian) Fault Zone and comment on ive episodes of syn-collisional peraluminous, neotectonic deformation in the SE part of the post-collisional calc-alkaline hybrid and post- Anatolian Plate (box 20 in Fig. 2). They also collisional within-plate alkaline pulses. INTRODUCTION xvii

Arger et al. present evidence for two episodes basalts and subduction-related basalts although of basaltic magmatism in southeastern Turkey a tectonic interpretation is precluded by absence (box 22 in Fig. 2) at c. 19-15 Ma and c. 2.3- of local extension, subduction or mantle plume 0.6 Ma based on K-Ar dating. Each episode activity in this region. produced olivine-titanaugite basalts in both the Anatolian Plate and the which The thematic set of papers in this volume have been are difficult to classify using any conventional selected from papers presented at the Third Inter- model. Because Miocene magmatism predated national Turkish Geology Symposium, held at the the onset of the modern strike-slip regime in Middle East Technical University (METU), Ankara during September 1998. This meeting was sponsored eastern Turkey, but the Plio-Quaternary mag- by the Middle East Technical University, the Scientific matism did not, there is no obvious tectonic and Technical Research Council of Turkey explanation for the timing or chemistry of this (TOBITAK), the American Association of Petroleum volcanicity. The authors therefore propose that Geologists (AAPG) and a range of industrial spon- both episodes, together with associated crustal sors, including the Turkish Petroleum Corporation thickening and uplift, resulted from inflow of (TPAO), BP Exploration, Etibank, Perenko, Rio Tur plastic lower crust from adjoining regions. Thus, Madencilik A.$. (Rio Tinto), Perenko, Cominco and although this region has remained in a plate Arco. The editors would like to thank all reviewers, boundary zone for tens of millions of years, the Organizing Committee, the staff and students at METU who helped to ensure that the conference ran volcanism has no direct relationship to local smoothly. Facilities supplied by the departments of plate motions. They suggest that both episodes Geological Engineering at METU, Earth Sciences at of volcanism are the result of loading effects Keele University and Earth Sciences at Liverpool induced by glacial sea-level variations which University during preparation of this volume are caused net flow of lower crust from beneath the gratefully acknowledged. Thanks are due to Dr R. E. offshore shelf to the land; this could have been Holdsworth (Series Editor) for his continuous encour- contemporary with Early-Middle Miocene agement, help and comments during the preparation moderate glaciation of Antarctica and more of this volume and to the Geological Society Publish- intense lowland glaciation of the northern hemi- ing House, particularly to Joanna Cooke for her edi- torial work and Angharad Hills for her continuous sphere which began around 2.5 Ma. help at every stage of this volume. Finally, in a study of some of the most recent volcanic rocks in the area, and rocks which can be most closely associated with the present References tectonic regime, Yurtmen et al. describe petro- ALTINER, D., OZKAN-ALTINER,S. & KOqYI~iT, A. 2000. graphical and geochemical characteristics of Late Permian biofacies belts in Turkey: palaeo- Plio-Quaternary volcanicity represented by geographic and tectonic implications. This small scoria cones and associated basanite and volume. alkali-olivine basalt lavas north of [skenderun OKAY, A. i. & TOYSOZ, O. 1999. Tethyan sutures of Gulf (Southern Turkey) (Fig. 1; box 23 in Fig. northern Turkey. In: DURAND, B., JOLiVET, L., 2). These volcanic rocks lie along the active HORVATH, F. & S~RANNE, M. (eds) The Mediter- sinistral NE-SW trending Karata,s-Osmaniye ranean Basins: Tertiary Extension within the Fault Zone (KOFZ) which forms part of the Alpine Orogen. Geological Society, London, modern Anatolide-African plate boundary and Special Publications, 156, 475-515. ROBERTSON, A. H. F. 2000. Mesozoic-Tertiary tec- the southern Neotethys suture. The main ex- tonic-sedimentary evolution of south-Tethyan posures are concentrated at the intersection of oceanic basins and its margins in southern these two structures. The chemistry of the alka- Turkey. This volume. line lavas resembles ocean island basalts (OIB) ROBERTSON, A. H. F. & PICKETT, E. A. 2000. Palaeo- and intra-continental plate basalts, with a mag- zoic-Early Tertiary Tethyan evolution of m61- matic source in the asthenosphere similar to anges, rift and passive margin units in the OIB. This source has HIMU character and is Karaburun Peninsula (W Turkey) and Chios regarded as a mixture of depleted mantle with a Island (Greece). This volume. plume component; it is classified as one of the STAMPFLJ, G. 2000. Tethyan oceans. This volume. mantle end-members for young extension- YILMAZ, A., ADAMIA, S., CHABUK1AN1,A., CHKHOTUA, related alkaline basalts. Based on the similarity T., ERDOGAN,K., Tuzcu, S. & KARABIYiKOGLU,M. 2000. Structural correlation of the southern of geochemical characteristics of the iskenderun Transcaucasus (Georgia)-eastern Pontides Gulf volcanics with OIB, Yurtmen et al. empha- (Turkey). This volume. size the importance of extension-related alkali