tectonic evolution of a part of the tethyside orogenic collage the kargi massif northern turkey the central part of the rhodope pontide fragment one of the major tectonic units in turkey provides critical data for evaluating the cimmeride and alpide evolution of the mediterranean tethysides tectonic events that affected the central part of the rhodope pontide fragment since the end of the paleozoic generated east west trending belts with the event of every episode redeforming and partly obliterating the structures of previous episodes this evolution may be conveniently described in terms of three major episodes 1 two different realms of pre dogger oceanic rocks are present in the area the northern realm coincided with main branch of paleo tethys that was being actively destroyed by south dipping subduction the southern realm the karakaya ocean a back arc basin related to this subduction began opening by rifting of a retroarc carbonate platform during the permo triassic to the west a continental domain with sparse magmatism seperated the two oceanic areas toward the east the two oceans become united by the wedging out of the continental domain these two pre dogger oceans closed during the lias and their remnants were emplaced between the southern margin of laurasia and the fragments of the cimmerian continent 2 the second episode partly overlapped the first with rifting south of the cimmerian continent fragment during the lias this rifting was followed by a transgression which covered the ruins of the cimmeride orogenic belt by the malm this rifting concurrently led to the development of the northern branch of the neo tethys and a south facing atlantic type continental margin a southerly thickening sedimentary prism developed on this margin during the lias to early cretaceous interval 3 the floor of the northern branch of neo tethys began to be consumed along the north dipping subduction zone beneath the previosly constructed continental margin this convergent margin generated a magmatic arc to the north and to the south a subduction accretion complex present width of which approaches 80 km to the south of the subduction accretion complex yet another convergent margin is indicated by the presence of the remnants of an ensimatic arc the northern branch of the neo tethys was totally consumed in the late cretaceous to eocene interval

role of tectonic sedimentary melange and permian triassic cover units central southern turkey in tethyan continental margin evolution abstract melanges play a key role in the interpretation of orogenic belts including those that have experienced deformation and metamorphism during continental collision this is exemplified by a palaeozoic tectonic sedimentary melange part of the konya complex that is exposed beneath a regionally metamorphosed carbonate platform near the city of konya in central anatolia the konya complex as a whole comprises three units a dismembered latest silurian early carboniferous carbonate platform a carboniferous melange made up of sedimentary and igneous blocks in a sedimentary matrix also known as the halici group or sizma group and an overlying volcanic sedimentary unit earliest permian the palaeozoic carbonates accumulated on a subsiding carbonate platform that bordered the northern margin of gondwana perhaps as an off margin unit the matrix of the melange was mainly deposited as turbidites debris flows and background terrigenous muds petrographic evidence shows that the clastic sediments were mostly derived from granitic and psammitic pelitic metamorphic rocks typical of upper continental crust both extension and contraction related origins of the melange can be considered however we interpret the melange as a carboniferous subduction complex that formed along the northern margin of gondwana related to partial closure of palaeotethys blocks and slices of upper palaeozoic radiolarian chert basic igneous rocks and shallow water carbonates were accreted and locally reworked by gravity processes large up to km sized blocks and slices of shallow water limestone were emplaced in response to collision of the palaeozoic carbonate platform with the subduction zone the overlying volcanic sedimentary unit earliest permian comprises alkaline lava flows interbedded with volcaniclastic debris flows and turbidites volcanogenic shales and tuff the complex as a whole is overlain by shallow water mixed carbonate siliciclastic sediments of mainly late permian age that accumulated on a regional scale shelf adjacent to gondwana successions pass transitionally into lower triassic rift related shallow water carbonates and terrigenous sandstones in the southwest of the area in contrast triassic sediments in the southeast overlie the melange unconformably and pass upwards from non marine clastic sediments into shallow marine calcareous sediments of mid triassic age marking the base of a regional mesozoic carbonate platform during the latest cretaceous early cenozoic the entire assemblage subducted northwards and underwent high pressure low temperature metamorphism and polyphase folding as a part of the regional anatolide unit

geochemical constraints on the provenance and depositional setting of sedimentary rocks from the islands of chios inousses and psara aegean sea greece implications for the evolution of palaeotethys the provenance and depositional setting of late palaeozoic and early mesozoic clastic sediments from the eastern aegean archipelago are examined here for the first time using whole rock geochemistry and composition of detrital chrome spinel major and trace element data for late palaeozoic and permo triassic clastic sediments from the lower and upper units of chios are compatible with an acidic to intermediate source minor input of ultra mafic detritus and recycling of older sedimentary components chondrite normalized ree profiles are uniform with light ree enrichments la n yb n c 7 7 negative eu anomalies eu eu c 0 67 and flat heavy ree patterns gd n yb n c 1 5 indicating an upper continental crustal source and or young differentiated arc material detrital chrome spinel from the clastic sediments of chios has cr number cr cr al values between 0 29 and 0 89 and mg number mg mg fe 2 values between 0 24 and 0 70 suggesting a probably mixed ultra mafic source involving ridge peridotites mid ocean ridge type fore arc peridotites and island arc basalts the metasediments from the islands of inousses and psara have similar whole rock chemical signatures to those of chios although no evidence was found for an ultra mafic source we conclude that both the late palaeozoic sediments from the lower and upper units of chios and the metasediments from inousses and psara were deposited in a continental island arc setting until at least late permian times probably at a single palaeotethyan margin they are interpreted to be allochthonous tectonically transported to their present position by late mesozoic to cenozoic orogenic processes

removing a mask of alteration geochemistry and age of the karadag volcanic sequence in se crimea abstract the karadag massif in south eastern crimea hosts a thick sequence of volcanic rocks which underwent significant secondary alteration here we deduce the effects of alteration remove their mask and estimate the primary chemical composition and age of these volcanic rocks using their bulk chemical analyses as well as chemical data from plagioclase ortho and clinopyroxene hosted melt inclusions and ar isotope analyses of plagioclase and groundmass from the freshest andesite our data reveal two distinct magmatic series in the karadag massif the first defines a subalkaline calcic medium k series with high enrichment in lile u th and lree relative to hree y zr hf nb and ta which is typical of supra subduction volcanic rocks according to previously published trace element data most of the karadag volcanic rocks belong to this series we use ar isotope data to argue that the age of these rocks is 172 8 4 5 ma which is consistent with the biostratigraphy no reliable major element chemical data and no isotopic data were obtained from the second series although its trace element signature is similar to that of some nb enriched supra subduction volcanic rocks it is characterised by less pronounced enrichment in lile u th and lree relative to hree y zr hf nb and ta and relatively high contents of nb and ta typical supra subduction series of the karadag massif is similar to other pre cretaceous magmatic rocks exposed in crimea and hence likely formed in a similar environment literature data on middle jurassic magmatic rocks of the pontides belt in northern turkey also allow to distinguish two magmatic series which closely correspond to the magmatic rocks in crimea this is consistent with palaeotectonic reconstructions which suggest that the pontides belt was joined to crimea prior to the opening of the black sea and they formed a single volcanic arc

tectonics and magmatism in turkey and the surrounding area this volume contains 23 papers from a range of international contributors describing recent research into the tectonics and magmatism of turkey and its surroundings this region is sited at the collision zone between eurasia and afro arabia and as such provides an extraordinarily complete and well exposed record of the staged tectonic evolution of this sector of the alpine himalayan orogen the geological history of this area involves separation of continental fragments from the margin of gondwana their migration across the tethyan oceans the subsequent closure of these oceans and finally the development of the neotectonic regime which continues to evolve to the present day such a comprehensive record is relevant to the understanding of collisional zones worldwide the volume is divided into five sections tethyan evolution neotethyan ophiolites post tethyan basin evolution neotectonics and igneous activity the first two sections deal with tethyan oceans whose growth and subsequent closure dominated the geodynamic framework in the mesozoic and cenozoic the subsequent sections deal with more recent geological developments from the balkan peninsula in the west to the transcaucasus in the east that followed consumption of the tethyan oceans there is a broad mix of papers throughout the volume wide ranging review papers on ocean development and extensional tectonics are followed by detailed descriptions of petrology and geochemistry and geographically focused studies on basin evolution specific aspects of extensional and strike slip tectonics and discussions of the relationship of magmatic activity to the tectonic development of the area tectonics and magmatism in turkey and the surrounding area presents up to date results and ideas from a large number of international contributors on a wide range of current research activity in this region it is essential reading for all geoscientists with an interest in both academic and applied aspects of eastern mediterranean geology

paleogeographic evidence on the jurassic tectonic history of the pontides new paleomagnetic data from the sakarya continent and eastern pontides the jurassic paleogeographic position of the pontides is not well studied because of insufficient paleomagnetic data for this reason a paleomagnetic study was carried out in order to constrain the paleolatitudinal drift of the turkish blocks during the jurassic period a total of 32 sites were sampled from volcanic and volcanoclastic rocks of the lower middle jurassic kelkit formation eastern pontides mudurnu formation sakarya continent and upper jurassic lower cretaceous ferhatkaya formation exposed around amasya region eastern pontides rock magnetic experiments demonstrate that the main ferromagnetic mineral is pseudo single domain titanomagnetite in these rocks paleomagnetic analysis revealed two main components of the natural remanent magnetization during stepwise thermal and alternating field demagnetization the first component is a low coercivity unblocking temperature component with a direction sometimes similar to that of the earth s present field or a viscous component the second component which is interpreted as the characteristic remanent magnetization chrm direction has low to high coercivity properties between 20 and 100 mt or unblocking temperatures between 300 and 580 c a positive fold test at the 95 level of confidence proved that the chrm of the sites is primary paleomagnetic directions calculated for the kelkit formation in the eastern pontides have a mean direction of d 334 8 i 49 7 95 7 1 after tilt correction a mean direction of d 332 2 i 48 5 95 14 6 was obtained from the volcanoclastic rocks of the mudurnu formation and d 324 3 i 43 3 95 9 5 was calculated for the upper jurassic lower cretaceous limestones ferhatkaya formation of the amasya region the jurassic rocks in the eastern pontides and mudurnu region are considered to represent products of the rifted neo tethys ocean while the upper jurassic lower cretaceous sediments in amasya are related to basin filling materials the data suggest that the kelkit formation was formed at 30 5 n paleolatitude and the equivalent mudurnu formation at 29 5 n paleolatitude the paleolatitude of the eastern pontides indicates that this rifting block was separated from eurasia by a marginal basin instead of being a part of eurasia the lower paleolatitude of the amasya region at 24 8 n in the upper jurassic to lower cretaceous clearly indicates southward drift of the turkish blocks during the jurassic to lower cretaceous period together with the motion of eurasia

geological evolution of the late mesozoic continental margin of northwestern anatolia abstract the armutlu peninsula is a composite tectonic entity made up of sections of the sakarya continent the rhodope pontide fragment and an ophiolite these were assembled following a continental collision between gondwanaland and laurasia during the late cretaceous the northern margin of the sakarya continent underwent progressively increasing deformation prior to and during the advancing collision due to continued convergence between the two continents initially the leading edge of the continent subsided under the load of an approaching ophiolitic slab following this a north directed thrusting and folding occurred during the turonian progressive elimination and eventual closure of the ocean preceded the thrusting of northerly situated collisiondashinduced nappe packages over the leading edge of the sakarya continent the nappe laden edge of the continental margin then collapsed and steadily subsided under the heavy load of the ophiolitic slab and the northern continental fragment consequently the nappe packages and the ophiolite were collectively metamorphosed during the coniaciandashsantonian interval during the subsidence the main body of the sakarya continent partially detached from its collapsed edge along a fault zone and thus suffered an independent but less severe deformation which lasted until the uplift of the collapsed edge in the campanian from the late campanian onward throughout later orogenic stages the metamorphic and nondashmetamorphic units amalgamated into a single tectonic entity forming a basement for younger cover rocks

the almacik mafic ultramafic complex exhumed sakarya subcrustal mantle adjacent to the istanbul zone nw turkey the almacik mountains in northwestern turkey expose an upper amphibolite facies complex consisting of alternating ultramafic harzburgitic and websteritic and mafic metagabbroic rock types in the eastern part of this complex are island arc meta tholeiites and transitional to calc alkaline metabasites that are chemically quite similar to those of the permo triassic cele mafic complex north of bolu and this suggests an equivalence however much of the section exposes structurally deeper and chemically different mafic and ultramafic rocks which have no equivalent in the cele mafic complex and isotopic dating has suggested that these rocks also formed during the permian period and underwent triassic and jurassic metamorphism furthermore sparse inherited ages unlike those from istanbul zone granitoids suggest a link with north african derived armorican type basement and hence the sakarya zone rather than amazonia derived avalonian basement alternating mafic and ultramafic rocks suggest structural repetition supported by the exposure of discrete high strain zones or poorly exposed shattered rock west of each outcrop of ultramafic rocks the high grade of metamorphism and the absence of either extrusive lavas or sheeted dyke rocks suggests that the almacik complex was not an ophiolite but formed instead as subcontinental lower crust and subjacent mantle dominantly calc alkaline geochemistry suggests that it formed the basement to an active continental margin bounding the north side of the sakarya continent with s dipping subduction of palaeotethys the almacik complex was uplifted as a late result of compression against the southern margin of the istanbul zone in the jurassic period lack of coeval high grade metamorphism in the istanbul zone indicates that the latter was overthrust southwards over the sakarya margin and that there was therefore a change of subduction polarity in the triassic period the evidence further casts doubt on the existence of a mesozoic intra pontide ocean in northwestern turkey and suggests that the latest permian magmatism with subsequent triassic and jurassic metamorphism was instead related to the closure of the palaeotethyan ocean

early carboniferous subduction zone metamorphism preserved within the palaeo tethyan rasht ophiolites western alborz iran a polyphase history of oceanic construction and consumption is documented by the distribution of the tethyan ophiolitic suture zones in iran despite the geodynamic significance of these suture zones few modern petrological and geochronological data are available from these ophiolitic domains hampering a full assessment of the timing thermobaric regimes and palaeotectonic scenarios leading to oceanic suturing and continental assembly in iran and more in general along the southern margin of eurasia in this paper we describe a newly discovered hp ophiolite melange within the rasht ophiolites at the nw termination of the palaeo tethyan suture in iran petrological investigations on the metamorphic units embedded within the ophiolite melange are integrated with whole rock geochemistry and ar ar phengite geochronology to constrain the geotectonic setting of formation and to define the associated p t t paths we provide evidence that the rasht ophiolite domain corresponds to an exhumed subduction complex formed during early carboniferous c 350 ma subduction of a branch of the palaeo tethyan oceanic realm with peak metamorphism equilibrated under blueschist to eclogite facies metamorphic conditions implications of these data for the palaeotectonic reconstruction during closure of the palaeo tethyan ocean and the terminal collisional assembly along the southern margin of the eurasia plate are also discussed supplementary material analytical methods and protocols are available at https doi org 10 6084 m9 figshare c 3706852

cenozoic evolution of the eastern black sea a test of depth dependent stretching models abstract subsidence analysis of the eastern black sea basin suggests that the stratigraphy of this deep extensional basin can be explained by a predominantly pure shear stretching history a strain rate inversion method that assumes pure shear extension obtains good fits between observed and predicted stratigraphy a relatively pure shear strain distribution is also obtained when a strain rate inversion algorithm is applied that allows extension to vary with depth without assuming its existence or form the timing of opening of the eastern black sea which occupied a back arc position during the closure of the tethys ocean has also been a subject of intense debate competing theories called for basin opening during the jurassic cretaceous or paleocene eocene our work suggests that extension likely continued into the early cenozoic in agreement with stratigraphic relationships onshore and with estimates for the timing of arc magmatism further basin deepening also appears to have occurred in the last 20 myr this anomalous subsidence event is focused in the northern part of the basin and reaches its peak at 15 10 ma we suggest that this comparatively localized shortening is associated with the northward movement of the arabian plate we also explore the effects of paleowater depth and elastic thickness on the results these parameters are controversial particularly for deep water basins and margins but their estimation is a necessary step in any analysis of the tectonic subsidence record stored in stratigraphy

sources of fluids and gases expelled at cold seeps offshore georgia eastern black sea four seep sites located within an 20 km2 area offshore georgia batumi seep area pechori mound iberia mound and colkheti seep show characteristic differences with respect to element concentrations and oxygen hydrogen strontium and chlorine isotope signatures in pore waters as well as impregnation of sediments with petroleum and hydrocarbon potential all seep sites have active gas seepage near surface authigenic carbonates and gas hydrates cokheti seep iberia mound and pechori mound are characterized by oil stained sediments and gas seepage decoupled from deep fluid advection and bottom water intrusion induced by gas bubble release pechori mound is further characterized by deep fluid advection of lower salinity pore fluids the pechori mound pore fluids are altered by mineral water reactions at elevated temperatures between 60 and 110 c indicated by heavier oxygen and lighter chlorine isotope values distinct li and b enrichment and k depletion strontium isotope ratios indicate that fluids originate from late oligocene strata this finding is supported by the occurrence of hydrocarbon impregnations within the sediments furthermore light hydrocarbons and high molecular weight impregnates indicate a predominant thermogenic origin for the gas and oil at pechori mound iberia mound and colkheti seep c15 hydrocarbons at the oil seeps are allochtonous whereas those at the batumi seep area are autochthonous the presence of oleanane an angiosperm biomarker suggests that the hydrocarbon source rocks belong to the maikopian formation in summary all investigated seep sites show a high hydrocarbon potential and hydrocarbons of iberia mound colkheti seep and pechori mound are predominantly of thermogenic origin however only at the latter seep site advection of deep pore fluids is indicated

upper palaeozoic subduction accretion processes in the closure of palaeotethys evidence from the chios melange e greece the karaburun melange w turkey and the teke dere unit sw turkey abstract during late palaeozoic time a wide ocean known as palaeotethys separated the future eurasian and african continents this ocean closed in europe in the west during the variscan orogeny whereas in asia further east it remained open and evolved into the mesozoic tethys only finally closing during late cretaceous early cenozoic three upper palaeozoic lithological assemblages the chios melange on the aegean greek island the karaburun melange westernmost aegean turkey and the teke dere unit lycian nappes sw turkey provide critical information concerning sedimentary and tectonic processes during closure of palaeotethys the chios and karaburun melanges in the west are mainly terrigenous turbidites with blocks and dismembered sheets of silurian upper carboniferous platform carbonate rocks shallow water and slope facies and poorly dated volcanic rocks the teke dere unit to the southeast begins with alkaline within plate type volcanics depositionally overlain by upper carboniferous shallow water carbonates this intact succession is overlain by a tectonic slice complex comprising sandstone turbidites that are intersliced with shallow water slope and deep sea sediments locally dated as early carboniferous sandstone petrography and published detrital mineral dating imply derivation from units affected by the panafrican cadomian and variscan orogenies all three units are interpreted as parts of subduction complexes in which pervasive shear zones separate component parts silurian lower carboniferous black cherts lydites and slope carbonates accreted in a subduction trench where sandstone turbidites accumulated some blocks retain primary depositional contacts showing that gravitational processes contributed to formation of the melange detached blocks of upper palaeozoic shallow water carbonates e g chios are commonly mantled by conglomerates which include water worn clasts of black chert the carbonate blocks are restored as one or several carbonate platforms that collided with an active margin fragmenting into elongate blocks that slid into a subduction trench this material was tectonically accreted at shallow levels within a subduction complex resulting in layer parallel extension shearing and slicing the accretion mainly took place during late carboniferous time alternative sedimentary tectonic models are considered in which the timing and extent of closure of palaeotethys differ and in which subduction was either northwards towards eurasia or southwards towards gondwana or both terrane displacement is also an option a similar but metamorphosed accretionary unit the konya complex occurs hundreds of kilometres further east all of these units appear to have been assembled along the northern margin of gondwana by permian time followed by deposition of overlying tauride type carbonate platforms northward subduction of palaeotethys beneath eurasia is commonly proposed however the accretionary units studied here are more easily explained by southward subduction towards gondwana palaeotethys was possibly consumed by long lived late palaeozoic northward subduction beneath eurasia coupled with more short lived late carboniferous southward subduction near gondwana during or soon after closure of palaeotethys in the balkan region to the west

submarine geomorphology of northeast baffin bay and its implications for local paleo ice sheet dynamics abstract high resolution bathymetric data from close to the northwest greenland coast in northern melville bay northeast baffin bay reveal a range of glacial and nonglacial landforms the glacial landforms include crag and tails mega scale glacial lineations msgl rock drumlins and roche moutonnees that indicate paleo ice sheet dynamics the nonglacial landforms include steep ridges that are interpreted as volcanic dykes neoproterozoic thule dyke swarms and paleoproterozoic melville bugt dyke swarms these dykes are glacially overprinted and may have channeled ice and subglacial meltwater flow through narrow subglacial cavities some of the glacial landforms eroded into bedrock indicate a southward paleo ice stream orientation while other glacial landforms including the sedimentary depositional landforms indicate a westward paleo ice stream orientation the glacial landforms were likely produced during at least two epochs and under changing thickness of the ice streams the glacial landforms eroded into the bedrock are likely older than the sedimentary glacial landforms and were likely produced by a thin south southeastward ice stream that allowed cavity formation the westward oriented glacial landforms were likely produced by a thick ice stream that was probably active during the last glacial maximum lgm the different orientations of the glacial landforms indicate a reorganization of the ice streams that may have occurred during retreat and subsequent readvance this reorganization likely coincided with a migration of the ice divide from south to north

late palaeozoic marginal basin and subduction accretion the palaeotethyan kure complex central pontides northern turkey the kure complex located in the central pontides of northern turkey is a c 20 km thick pile of thrust imbricated deep sea sediments intercalated with a dismembered ophiolite the ophiolitic rocks include serpentinized harzburgite massive gabbro cumulate and isotropic sheeted dykes and basic volcanic rocks the extrusive rocks are mainly pillow lavas sheet flows and lava breccias geochemical evidence of immobile major and trace elements and pyroxene chemistry indicate mid ocean ridge mor and volcanic arc basalt vab compositions and suggest that the kure ophiolite was generated above a subduction zone chrome spine1 analysis also supports this interpretation in some thrust sheets the extrusives are depositionally overlain by hemi pelagic shales passing up into terrigenous turbidites and shales which are up to several hundred metres thick in intact successions cyprus type massive sulphides interpreted as precipitates from black smokers are located along the lava sediment contact individual intact sediment units up to several kilometres thick within the kure complex are separated by narrow up to 10 m wide zones of intense shearing layer parallel extension and melange formation asymmetrical folds reverse faults thrusts and duplex structures throughout the kure complex indicate mainly northwards emplacement the kure complex is thought to have opened in the late palaeozoic as a marginal basin above a northward dipping palaeotethyan subduction zone located along the southern margin of eurasia the kure marginal basin later closed in response to inferred southward subduction leading to development of an accretionary prism prior to late jurassic time the kure complex is unlikely to represent the main palaeotethyan suture as has been suggested in some earlier tectonic reconstructions regional comparisons with dobrogea crimea and caucasus suggest the kure basin opened then closed along a south eurasia active margin

late palaeozoic early cenozoic tectonic development of the eastern pontides artvin area turkey stages of closure of tethys along the southern margin of eurasia

the margins of laurussia in central and southeast europe and southwest asia the continuation of the laurussian margin into central and southeast europe and southwest asia is defined by the rheic suture which becomes harder to trace to the southeast because of complex post variscan strike slip displacements and tectonic stacking linked to the cimmerian and alpine cycles the uncertain extent of the neoproterozoic baikalian orogeny fringing baltica ambiguous early paleozoic paleobiogeographic data and strike slip activity complicate the distinction of the tornquist suture from the transeuropean suture zone there is growing evidence for the incorporation of the brunovistulian malopolska and west moesian terranes into the late neoproterozoic cambrian baltican margin the istanbul zonguldak terrane along with the bitesh and east moesia terranes may have been part of the avalonian terrane assemblage although an arabian nubian shield or baltica provenance cannot be excluded the terranes of the armorica terrane assemblage bordering the rheic suture include the outer carpathian tatra getic and balkan terranes in southeast europe and sakarya and the anatolide tauride terrane in turkey further east the rheic suture may be present in the caucasus in all probability between the greater caucasus and the scythian platform or alternatively between the greater caucasus and transcaucasia alborz in northern iran is interpreted as a distal part of transcaucasia the location of the rheic suture in the southeast part of the turan domain of central asia is poorly constrained

palaeozoic early tertiary tethyan evolution of melanges rift and passive margin units in the karaburun peninsula western turkey and chios island greece

the ophiolite related mersin melange southern turkey its role in the tectonic sedimentary setting of tethys in the eastern mediterranean region the mersin melange underlies the intact mersin ophiolite and its metamorphic sole to the south of the mesozoic tauride carbonate platform in southern turkey the melange varies from chaotic melange to broken formation in which some stratigraphic continuity can be recognized based on study of the broken formation four lithological associations are recognized 1 shallow water platform association dominated by upper palaeozoic lower cretaceous neritic carbonates 2 rift related volcanogenic terrigenous pelagic association mainly upper triassic andesitic acidic volcanogenic rocks siliciclastic gravity flows basinal carbonates and radiolarites 3 within plate type basalt radiolarite pelagic limestone association interpreted as upper jurassic lower cretaceous seamounts with associated radiolarian sediments and upper cretaceous pelagic carbonates 4 ophiolite derived association including fragments of the upper cretaceous mersin ophiolite and its metamorphic sole locally the ophiolitic melange includes granite that yielded a k ar radiometric age of 375 7 10 5 ma late devonian this granite appears to be subduction influenced based on immobile element composition the mersin melange documents the following history 1 triassic rifting of the tauride continent 2 jurassic cretaceous passive margin subsidence 3 oceanic seamount genesis 4 cretaceous supra subduction zone ophiolite genesis 5 late cretaceous intra oceanic convergence metamorphic sole formation and 6 latest cretaceous emplacement onto the tauride microcontinent and related backthrusting regional comparisons show that the restored mersin melange is similar to the beysehir hoyran nappes further northwest and a northerly origin best fits the regional geological picture these remnants of a north neotethys inner tauride ocean were formed and emplaced to the north of the tauride carbonate platform they are dissimilar to melanges and related units in northern syria western cyprus and southwestern turkey which are interpreted as remnants of a south neotethys early high temperature ductile transport lineations within amphibolites of the metamorphic sole of the mersin ophiolite are generally orientated e w possibly resulting from vertical axis rotation of the ophiolite while still in an oceanic setting by contrast the commonly northward facing later stage brittle structures are explained by backthrusting of the ophiolite and melange related to exhumation of the partially subducted northern leading edge of the tauride continent

paleomagnetic results along the bitlis zagros suture zone in se anatolia turkey implications for the activation of the dead sea fault zone abstract the tectonic evolution of se anatolia is associated with the collision between the taurides and the arabian platform in the early cenozoic after the final closure of the southern branch of the neotethys ocean during late cretaceous to early eocene times the ongoing deformation was characterized by northward movement of arabia followed by westward extrusion of anatolia having been displaced along the northern and eastern anatolian transform faults the neotectonic deformation history between the anatolian plate and the arabian platform since the closure of the southern neotethyan oceanic basin from late cretaceous to present has not been studied in detail paleomagnetically therefore we carried out a paleomagnetic study of mesozoic and cenozoic rocks at 34 localities along the bitlis zagros suture zone in se anatolia located in the boundary region between the taurides and the arabian platform and delimited by the dead sea fault paleomagnetic results from the area show clockwise rotations of 35 6 14 1 and 26 7 8 0 with respect to the african plate from upper jurassic lower cretaceous and upper cretaceous limestones respectively the paleomagnetic results indicate also an earlier deformation opening due to the dead sea fault zone dsfz farther north on the tauride block counterclockwise rotation of 34 5 12 5 is recorded by upper cretaceous limestones in the se of the study area on the northern margin of arabia however smaller counterclockwise rotations of 12 3 8 3 and 2 5 10 0 in late cretaceous and 12 7 13 6 in middle eocene rocks show relative tectonic stability middle miocene rocks close to the suture zone show counterclockwise rotation by about 39 4 10 9 while farther away from the suture zone counterclockwise rotations of 21 9 9 9 and 7 5 5 8 are observed paleolatitudinal motion from south to north from the late jurassic to the present is in concordance with the apparent polar wander path of eurasia and africa

facies independent reservoir characterization of the micropore dominated word field edwards formation lavaca county texas micropore dominated carbonate reservoirs remain challenging for accurate hydrocarbon evaluation and production as conventional reservoir models using depositional textures and petrophysical properties to distribute porosity and permeability cannot be applied nevertheless understanding the distribution of pore systems and predicting the fluid flow behavior of microporous reservoirs is fundamental as micropores constitute a significant percentage of the total porosity and storage capacity we present the results from an integrated study on the producing micropore dominated word field characterized by a facies independent diagenetically controlled pore system that approaches 100 microporosity four cored wells through the albian edwards formation were described and correlated using stacking patterns and vertical facies trends pore type characterization was done through thin section petrography routine core analyses sem and micp data this study is an example of a permeable reservoir in which intergrain pores are cemented during burial diagenesis and micropores being more resistant to cementation remain open to depths greater than 4000 m 13 000 ft a unique relationship exists between porosity permeability median pore throat size and microcrystalline textures independent of facies and fabrics cumulative gas production data show there is a correlation between the total porosity and the structural position of the wells wells high on the structure have the highest production we demonstrate that an equally well connected micropore network exists in mud dominated rocks via the matrix and via grain to grain contacts in grain dominated rocks the here described intragrain micropore network through grain to grain contacts in cemented grainstones is a new carbonate flow path that will likely become more important as more unconventional carbonate reservoirs are explored

subduction complex of pre jurassic age northern anatolia turkey in northern anatolia a zone of pre liassic orogenic deformation is located mainly between the internal anatolian massifs and the north anatolian fault this belt consists of metamorphic rocks in blueschist greenschist and amphibolite facies and an ophiolitic dynamometa morphic melange the metamorphic rocks represent deformed and metamorphosed oceanic crust and upper mantle whereas the melange rocks originated in diverse environments in abyssal plain trench arc trench gap and forearc environments the evolution of these assemblages is interpreted as a product of subduction probably associated with the closure of the tethys subduction related deformation and meta morphism terminated diachronously from pre late triassic in the west to pre late liassic in the east probably as a result of the diachronous closure of the tethys

tectonic significance of mafic volcanic rocks in a mesozoic sequence of the menderes massif west turkey the mesozoic platform sequence of the menderes massif consists of thick succession of detrital and carbonate rocks in this sequence there are mafic metavolcanic rocks at two different levels the first level of mafic metavolcanic intercalations is in the late triassic detrital rich series located in the caltasi formation which is the lowermost unit of the mesozoic platform the second level of the mafic metavolcanic rocks is located in the late cretaceous paleocene selcuk formation laying on top of the platform sequence the caltasi formation which is composed of mica schists thinly bedded cherts calc schist and mafic volcanic intercalations unconformably overlie the bayindir formation which consists of mica schists phyllites and white quartzites of palaeozoic or probably older age the mafic volcanic rocks in the caltasi formation are alkaline basalts with within plate characteristics and are formed during an intraplate extension the caltasi formation is conformably overlain by the kayaalti formation represented by calc schists dolomitic marbles and rudist and emery bearing massive marbles in ascending order the selcuk formation overlies the kayaalti formation and consists of a mica schist matrix with allochthonous blocks of mafic volcanic rocks metaperidotites metagabbros and massive marbles the mafic volcanic rocks in the selcuk formation are tholeiitic basalts and are petrologically similar to mid oceanic basalts the geological and geochemical characteristics of the mafic metavolcanic rocks in the caltasi formation indicate that during the late triassic the menderes platform was segmented probably by the opening of a branch of the neotethyan ocean between the late triassic and the late cretaceous the menderes carbonate platform was built up during the latest cretaceous early paleocene a slab of oceanic crust obducted on this platform and provided slices of mafic metavolcanic rocks into the selcuk formation

biochronology of jurassic and early cretaceous radiolarites from the lycian melange sw turkey and implications for the evolution of the northern neotethyan ocean new radiolarian ages for blocks of radiolarian cherts associated with other blocks of distal pelagic facies and ophiolitic lithologies within the lycian melange sw turkey indicate deposition during mid jurassic to early cretaceous time radiolarites overlying pink pelagic limestones of an allochthonous carbonate unit accumulated during the midto late jurassic on the basis of structural evidence the lycian melange is inferred to have been rooted within the northern neotethys to the north of the tauride anatolide microcontinent the lycian radiolarites can be compared with other dated radiolarites from the izmir ankara suture the root zone of the northern neotethyan ocean based on all the available radiolarian data it is inferred that radiolarites accumulated within the northern neotethys in western turkey from late triassic mid carnian to late norian to midcretaceous cenomanian time the radiolarites were later detached from their inferred oceanic basement and accreted within a subduction complex during the late cretaceous turonian maastrichtian and emplaced over the northern margin of the tauride anatolide continent together with slices of continental margin and ophiolitic lithologies following the development of mesozoic radiolarian biostratigraphical schemes during the last 25 years radiolarian biochronology has become invaluable for reconstructing the palaeogeography palaeoceanography and tectonic evolution of tethyan oceanic basins and margins de wever 1989 robertson et al 1991 de wever et al 1994 danelian robertson 1997 2001 radiolarites in the tethyan realm commonly occur within melanges that are interpreted as parts of accretionary prisms related to subduction of ocean crust robertson 2002 2004 radiolarian ages from such melanges provide valuable age constraints on related geological processes including spreading intra plate volcanism and tectonic accretion e g al riyami et al 2001 beccaletto et al 2005 here we will present the first radiolarian evidence from the lycian melange an east west trending late mesozoic accretionary complex in sw turkey collins robertson 1997 fig 1 this melange forms part of the wellknown lycian nappes in sw turkey de graciancky 1972 poisson 1977 1984 collins robertson 1998 the root zone of the melange is considered to lie to the north of the regional basement represented by the tauride anatolide platform collins robertson 1998 2003 and is inferred to lie within the izmir ankara suture zone to the north of the menderes massif robertson pickett 2000 robertson et al 2004 we will also review the limited available data for radiolarites from comparable tectonic units within the izmir ankara suture zone and the bey daglari we conclude by considering the implications of the available radiolarian evidence for the evolution of the mesozoic tethyan ocean

gondwana derived microcontinents the constituents of the variscan and alpine collisional orogens abstract the european variscan and alpine mountain chains are collisional orogens and are built up of pre variscan building blocks which in most cases originated at the gondwana margin such pre variscan elements were part of a pre ordovician archipelago like continental ribbon in the former eastern prolongation of avalonia and their present day distribution resulted from juxtaposition through variscan and or alpine tectonic evolution the well known nomenclatures applied to these mountain chains are the mirror of variscan resp alpine organization it is the aim of this paper to present a terminology taking into account their pre variscan evolution at the gondwana margin they may contain relics of volcanic islands with pieces of cadomian crust relics of volcanic arc settings and accretionary wedges which were separated from gondwana by initial stages of rheic ocean opening after a short lived ordovician orogenic event and amalgamation of these elements at the gondwanan margin the still continuing gondwana directed subduction triggered the formation of ordovician al rich granitoids and the latest ordovician opening of palaeo tethys an example from the alps external massifs illustrates the gradual reworking of gondwana derived pre variscan elements during the variscan and alpine tertiary orogenic cycles

the temporal evolution of the active margin along the southeast anatolian orogenic belt se turkey evidence from u pb ar ar and fission track chronology abstract the southeast anatolian orogenic belt saob resulted from the north dipping subduction of the southern neotethyan oceanic lithosphere in late mesozoic and early cenozoic however the timing and the rate of the continental collision are still under debate here we present new u pb ar ar and fission track ages from the i type calc alkaline granitoids esence dogansehir and baskil cutting the goksun ispendere and komurhan ophiolites and also the malatya keban metamorphics representing the tauride active continental margin along the saob in this study high to low temperature thermochronological methods applied to the granitoids are used to understand the temporal and geodynamic evolution of the tauride active continental margin and continental collision between tauride and arabian platforms in the frame of the neotethyan convergence during cretaceous and miocene the u pb zircon ages range from 83 to 88 ma for the baskil and from 81 to 83 ma for the esence granitoids the 39 ar 40 ar ages indicate that these late cretaceous granitoids cooled below 300 c in 6 10 ma the formation ages and the timing of the gradual cooling of the late cretaceous granitoids are similar to metamorphism age and the timing of the exhumation of the hp lt bitlis metamorphics during this stage the combined field geochemistry and geo thermochronological data suggest that the first continental collision event occurred between bitlis puturge micro continents to the south and tauride platform to the north in an oblique subduction zone between 84 and 74 ma the granitoids continued uplifting during early middle eocene together with the exhumation of hp uht berit metaophiolite in an extensional regime related to the opening of the maden back arc basin this period also let the intrusion of the dogansehir arc magmatism intruding the puturge and malatya keban metamorphics berit metaophiolite and maden complex the eocene dogansehir granitoid has similar u pb and 39 ar 40 ar ages suggesting a fast cooling the apatite fission track aft ages for all granitoid bodies suggest that they were mainly cooled or uplifted in two episodes where the first one is in the eocene in an extensional setting the aft data marked the final continental collision between the taurides and the arabian platform first in oligocene and the break off of the subducted slab and the delamination process caused fast uplift of the eastern anatolia during middle to late miocene

formation of the late palaeozoic konya complex and comparable units in southern turkey by subduction accretion processes implications for the tectonic development of tethys in the eastern mediterranean region abstract the southern margin of eurasia from the balkan region eastwards is widely envisaged as an active continental margin related to northward subduction at least during late carboniferous early cenozoic time by contrast the late palaeozoic setting of the southern gondwana margin was previously interpreted as an intra continental marginal basin related to southward subduction beneath the northern margin of gondwana or as part of a forearc complex e g forearc basin related to northward subduction beneath eurasia palaeotethyan evolution is recorded in the konya complex new name an assemblage of palaeozoic silurian carboniferous meta sedimentary and meta igneous rocks that is exposed beneath metamorphosed upper permian mesozoic shelf type sediments in central southern turkey to the north of the tauride mountains the konya complex is dominated by large thrust slices of mainly devonian shallow water platform carbonates bozdag unit there is also a melange that is made up of lenticular sheets and blocks of mainly lower carboniferous shallow water limestones silurian devonian black chert lydite pelagic limestones and rare blocks of mid ocean ridge type and within plate type basaltic rocks the blocks are set in a mainly terrigenous derived siliciclastic matrix locally including siliceous tuff the matrix is interpreted as mainly deep water turbidites and debris flow deposits an overlying intact volcanic sedimentary sequence includes chemically enriched extrusives e g trachyandesites that also exhibit a negative nb anomaly suggesting a subduction influence dykes crosscutting the carbonate platform units are relatively depleted and also show a subduction influence shallow marine carbonates and terrigenous quartzose sediments of mainly late permian age are exposed above the konya complex in the west of the area in contrast triassic non marine to shallow marine clastic sediments unconformably overlie the konya complex in the east of the area both the permian and the triassic sediments pass upwards without a break into a middle triassic upper cretaceous platform carbonate succession which was overthrust by accretionary melange and ophiolites during latest cretaceous time the mesozoic carbonate platform and the underlying konya complex experienced polyphase deformation and partial high temperature low pressure metamorphism related to alpine late cretaceous early cenozoic closure of tethys comparison of tauride and pontide units suggests the deformed konya complex upper palaeozoic carbonate platform has gondwanan affinities we also compare the complex with other upper palaeozoic units in southern turkey including the tekedere unit lycian nappes and the karaburun and chios melanges all of these units are interpreted to have formed by subduction accretion processes alternative possible settings involve northward subduction southward subduction or terrane displacement strike slip northward subduction beneath eurasia requires collisional assembly with gondwana possibly during the latest triassic cimmerian orogeny for which there is little evidence a southward dipping subduction zone would need to be located some distance outboard of the gondwana margin as there is little evidence of upper palaeozoic arc magmatism in the tauride platform emplacement as an exotic terrane probably derived from further west in the balkan region is also possible

late devonian late triassic sedimentary development of the central taurides s turkey implications for the northern margin of gondwana the sedimentary rocks that constitute the northern margin of gondwana stretching from morocco around north africa to oman help to document regional to global sea level change and the evolution of the tethyan ocean to the north such continental margin sediments provide sensitive indicators of eustatic sea level change local to regionalscale tectonics and climatic change the late palaeozoic to triassic period encompasses rifting and sea floor spreading of one or more tethyan oceans some areas particularly morocco and algeria in the west show evidence of compressional deformation related to closure of a hercynian ocean during early carboniferous time late palaeozoic deformation is also documented in oman further southeast in contrast the levant region and egypt both lack evidence of late carboniferous early mesozoic compressional deformation although vertical tectonic movements are evident in the eastern mediterranean region relatively proximal i e southerly areas of the autochthonous gondwana margin are well exposed in north africa however more distal parts of the margin are beneath the mediterranean sea or are exposed in sutured continental terranes within the tethyan orogen however such outcrops provide a unique window into late palaeozoic early mesozoic palaeoenvironments along the northern margin of gondwana

self subduction of the pangaean global plate one of the most striking and rare occurrences in the earth s history is the amalgamation of most of the continental lithosphere into one supercontinent the most recent supercontinent pangaea lasted from 320 to 200 million years ago here we show that after the continental collisions that led to the formation of pangaea plate convergence continued in a large wedge shaped oceanic tract we suggest that plate strain at the periphery of the supercontinent eventually resulted in self subduction of the pangaean global plate when the ocean margin of the continent subducted beneath the continental edge at the other end of the same plate our scenario results in a stress regime within pangaea that explains the development of a large fold structure near the apex of the palaeotethys ocean extensive lower crustal heating and continental magmatism at the core of the continent as well as the development of radially arranged continental rifts in more peripheral regions of the plate

the cretaceous tertiary deformation of the lhasa block and its implications for crustal thickening in tibet the strong tertiary deformation of the northern margin of the indian plate and of the tsangpo suture zone is not matched by comparable deformation within the lhasa block yet the southern margin of the block was the site of large scale intrusive activity the gangdese or transhimalayan batholith throughout the late cretaceous and was therefore presumably weaker than its surroundings this poses a problem for any approach that interprets the deformation of tibet in terms of diffuse crustal thickening however there is evidence that the lhasa block was in elevation as well as in magma type an andean margin by the end of the cretaceous and we suggest that the buoyancy force associated with the elevated crust was sufficient to inhibit compressional deformation within the southern lhasa block this suggestion is tested quantitatively by treating the continental lithosphere as a thin viscous sheet containing an isostatically compensated elevation contrast when subjected to boundary conditions representing the collision between india and asia the sheet accommodates convergence by diffuse deformation over a region comparable in size with the tibetan plateau in the absence of an elevation contrast this deformation consists of approximately 100 thickening strain over the region a precollision elevation contrast of 3000 m in the lhasa block would have resulted in its experiencing roughly 40 rather than 100 postcollisional thickening smaller elevation contrasts would have resulted in greater thickening and vice versa these calculations have implications for the mode of crustal thickening in northern tibet as the available evidence suggests that the topographic expression of the earlier mesozoic tectonic activity in southern asia was erased before the india asia collision we expect that there has been widespread and relatively homogeneous crustal shortening migrating northward from the lhasa block during the tertiary

obduction subduction and collision as reflected in the upper cretaceous lower eocene sedimentary record of western turkey late cretaceous early eocene tethyan evolution of western turkey is characterized by ophiolite obduction high pressure low temperature metamorphism subduction arc magmatism and continent continent collision the imprints of these events in the upper cretaceous lower eocene sedimentary record of western anatolia are studied in thirty eight well described stratigraphic sections during the late cretaceous period western turkey consisted of two continents the pontides in the north and the anatolide taurides in the south these continental masses were separated by the izmir ankara neo tethyan ocean during the convergence the pontides formed the upper plate the anatolide taurides the lower plate the arc magmatism in the pontides along the black sea coast is biostratigraphically tightly constrained in time between the late turonian and latest campanian ophiolite obduction over the passive margin of the anatolide tauride block started in the santonian soon after the inception of subduction in the turonian as a result large areas of the anatolide tauride block subsided and became a region of pelagic carbonate sedimentation during the campanian the leading margin of the anatolide tauride block was buried deeply and was deformed and metamorphosed to blueschist facies during campanian times the campanian arc volcanic rocks in the pontides are conformably overlain by shaley limestone of maastrichtian palaeocene age however maastrichtian sedimentary sequences north of the tethyan suture are of fore arc type suggesting that although arc magmatism ceased by the end of the campanian age continent continent collision was delayed until palaeocene time when there was a change from marine to continental sedimentation in the fore arc basins the interval between the end of the arc magmatism and continent continent collision may have been related to a northward jump of the subduction zone at the end of campanian time or to continued obduction during the maastrichtian

processes of late cretaceous to late miocene episodic thrust sheet translation in the lycian taurides sw turkey the lycian taurides of sw turkey consist of an allochthonous mesozoic passive margin succession that was episodically detached from its autochthon and translated southeastwards between latest cretaceous to late miocene times a combination of structural analysis sedimentology palaeontology and geochemistry allows subdivision of this orogenic event into 1 latest cretaceous trench passive margin collision causing ophiolite obduction and detachment of the koycegyiz thrust sheet 2 mid late eocene continent continent collision renewing southeastwards thrusting and causing detachment of the teke dere thrust sheet and yavus thrust sheets 3 miocene extensional collapse of the orogen with southeastwards translation of the allochthon coeval with rift basin formation in the hinterland

the beysehir hoyran hadim nappes genesis and emplacement of mesozoic marginal and oceanic units of the northern neotethys in southern turkey the beysehir hoyran hadim nappes crop out over 700 km from nw to se above a regionally autochthonous tauride carbonate platform the beysehir hoyran nappes begin with a thrust sheet c 400 m of mainly redeposited carbonates quartzose sandstones and mudstones of mid late triassic age interpreted as a proximal slope base of slope succession above is a thrust sheet c 1 km of middle upper triassic intermediate acidic extrusive rocks volcaniclastic rocks and minor pelagic carbonates interpreted as a continental rift thin

development of concepts concerning the genesis and emplacement of tethyan ophiolites in the eastern mediterranean and oman regions this article uses evidence mainly from the eastern mediterranean and oman to help understand the origin and emplacement of ophiolites field studies in these regions emphasize the diversity of ophiolite related sedimentary and tectonic processes topics to be discussed here include the sedimentary covers of ophiolites their metamorphic soles related melanges and emplaced continental margin slope rise units modes of ophiolite emplacement will also be considered and tectonic reconstructions that have a direct bearing on the origin and emplacement of ophiolites the writer argues that there is compelling evidence that many ophiolites formed by spreading above intraoceanic subduction zones evidence from their intact sedimentary covers however indicates that such subduction was only incipient in most cases as directly associated volcanic arcs or back arc basins are rare metamorphic soles record fragments of oceanic lithosphere derived from settings ranging from open ocean to continental slope rise settings underlying melanges record the subduction of most of the ocean lithosphere formed at spreading ridges continental margin units beneath ophiolites demonstrate that these ophiolites were formed in ocean basins that were mainly initiated by continental rifting in the eastern mediterranean and oman regions ophiolite emplacement was commonly achieved by trench margin collision although strike slip transpression and large scale accretion along subducting margins played a role in some cases taking account of the mesozoic palaeotectonic setting of the eastern mediterranean region it is widely believed that ophiolites of two main ages mid jurassic and late cretaceous were formed in several small oceanic basins separated by rifted microcontinents the history of tethys in pre mesozoic time remains more open to question lastly giant subduction related ophiolites as in oman cyprus or the balkans may not be forming anywhere in the world ocean today but may instead relate to rare events in earth history when regional to global plate boundaries were drastically reorganised

formation of the late palaeozoic early mesozoic karakaya complex and related ophiolites in nw turkey by palaeotethyan subduction accretion several pre jurassic tectonic units in nw turkey are crucial to the current debate regarding the timing and direction of subduction of palaeotethys a major ocean that separated eurasia and gondwana in late palaeozoic early mesozoic times the most critical unit is the karakaya complex a deformed low grade assemblage of oceanic origin which comprises a nw verging se dipping stack of tectonostratigraphic units here interpreted as a palaeotethyan accretionary complex the units display lithologies consistent with origins in seamount trench abyssal and rifted carbonate platform settings clastic basin sequences developed on top of the complex other relevant tectonostratigraphic units in the area include ultrabasic rocks of supra subduction zone affinity which tectonically overlie permian carbonate platform units with intervening metamorphic soles and melanges restored structural trends suggest the presence of a southward dipping palaeotethyan subduction zone bordering gondwana related units during the late permian triassic this was probably additional to more important regional northward subduction along the southern margin of eurasia from the eastern mediterranean to the himalayas

lycian melange southwestern turkey an emplaced late cretaceous accretionary complex the lycian thrust belt is an important part of the tethyan orogenic belt in the eastern mediterranean region it includes a unit of internally disrupted thin skinned thrust sheets layered tectonic melange and a melange rich in ophiolitic material ophiolitic melange the layered tectonic melange is dominated by mesozoic distal deep water sedimentary rocks and the ophiolitic melange includes disrupted thrust sheets of early mesozoic shallow water limestone and blocks of basalt of both mid ocean ridge and within plate geochemical affinities a complete record of closure of a tethyan oceanic basin began with late cretaceous intraoceanic subduction followed by latest cretaceous trench continental collision and ended with mid tertiary continental collision and orogenic collapse

new paleomagnetic results from upper cretaceous arc type rocks from the northern and southern branches of the neotethys ocean in anatolia a paleomagnetic study of cretaceous arc type rocks in the central eastern pontides and in the southeastern taurides investigates the tectonic and paleolatitudinal evolution of three volcanic belts in anatolia namely the northern and southern volcanic belts in the pontides and the se taurides volcanic belt the paleomagnetic data indicate that magnetizations were acquired prior to folding at most sampling localities sites except for those in the erzincan area in the eastern pontides the southern volcanic belt was magnetized at a paleolatitude between 23 8 3 8 4 2 n and 20 2 1 2 1 3 n hisarli j geodyn 52 114 128 2011 reported a more northerly paleolatitude 26 6 4 6 5 1 n for the northern volcanic belt the comparison of the new paleomagnetic results with previous ones in anatolia allows to conclude that the southern volcanic belt in the central eastern pontides was emplaced after the northern volcanic belt as a result of slab roll back of the northern neotethys ocean in the late cretaceous in the southeast taurides upper cretaceous arc related sandstones were at a paleolatitude of 16 8 3 8 4 2 the late cretaceous paleomagnetic rotations in the central pontides exhibit a counterclockwise rotation of r pm delta r 37 1 circ pm 5 8 circ group 1 cankiri yaylacayi formation while maastrichtian arc type rocks in the yozgat area group 2 show clockwise rotations r r 33 7 8 4 and r r 29 3 6 0 in the se taurides counterclockwise and clockwise rotations of r pm delta r 48 6 text circ text pm 5 2 text circ text and r pm delta r 34 1 text circ text pm 15 1 text circ text are obtained group 4 elazig magmatic complex the late cretaceous paleomagnetic rotations in the pontides follow a general trend in concordance with the shape of the suture zone after the collision between the pontides and the kirsehir block the affect of the westwards excursion of the anatolian plate and the associated fault bounded block rotations in miocene are observed in the east of the study area and the se taurides

tectonic evolution of the intra pontide suture zone in the armutlu peninsula nw turkey abstract the armutlu peninsula and adjacent areas in nw turkey play a critical role in tectonic reconstructions of the southern margin of eurasia in nw turkey this region includes an inferred intra pontide oceanic basin that rifted from eurasia in early mesozoic time and closed by late cretaceous time the armutlu peninsula is divisible into two metamorphic units the first the armutlu metamorphics comprises a precambrian high grade metamorphic basement unconformably overlain by a palaeozoic low grade mixed siliciclastic carbonate volcanogenic succession including bimodal volcanics of inferred extensional origin with a possibly inherited subduction signature the second unit the low grade iznik metamorphics is interpreted as a triassic rift infilled with terrigenous calcareous and volcanogenic lithologies including basalts of within plate type the triassic rift was unconformably overlain by a subsiding jurassic late cretaceous cenomanian passive margin including siliciclastic carbonate turbidites radiolarian cherts and manganese deposits the margin later collapsed to form a flexural foredeep associated with the emplacement of ophiolitic rocks in turonian time geochemical evidence from meta basalt blocks within ophiolite derived melange suggests a supra subduction zone origin for the ophiolite the above major tectonic units of the armutlu peninsula were sealed by a maastrichtian unconformity comparative evidence comes from the separate almacik flake further east considering alternatives it is concluded that a mesozoic intra pontide oceanic basin separated eurasia from a sakarya microcontinent with a wider northern neotethys to the south lateral displacement of exotic terranes along the south eurasian continental margin probably also played a role e g during late cretaceous suturing in addition to overthrusting

middle permian early triassic magmatism in the western pontides nw turkey geodynamic significance for the evolution of the paleo tethys abstract permian triassic magmatic rocks are widely exposed in different tectonic terranes and continental blocks in the aegean region this study is focussed on the istanbul zone and the istranca strandja massif which are located in the western pontides of nw turkey the kirklareli and the tepecik plutons intruded into the metamorphic basement rocks of the istranca massif and the sancaktepe pluton is emplaced into the istanbul paleozoic sedimentary sequences we present new geochemical data for these plutons in order to interpret their petrogenesis and time of emplacement and use this information for geodynamic interpretation the zircon u pb crystallization ages are 268 3 2 1 ma for the kirklareli pluton 249 4 1 5 ma for the tepecik pluton and 257 3 1 5 ma and 253 7 1 75 ma for the the sancaktepe pluton they are high k calc alkaline to shoshonitic granitoids with aluminum saturation index asi values between 0 9 and 1 3 which define them as peraluminous and slightly metaluminous 87sr 86sr i values for the studied plutons range between 0 701123 and 0 707704 143nd 144nd i ratios calculated for crystallization ages are between 0 512052 and 0 512431 and end i values vary from 4 71 to 2 22 tdm model ages range between 0 83 and 1 41 ga these plutons are enriched in liles and lree and depleted in hfses with negative eu anomalies indicating that the melts were derived from mafic crustal sources our new data suggest that the kirklareli pluton was generated in a subduction related magmatic arc and the highly fractionated sancaktepe and tepecik plutons were formed in a back arc setting in response to the northward subduction of the paleo tethys ocean during the mid permian early triassic

a magnetite rich cyprus type vms deposit in ortaklar a unique vms style in the tethyan metallogenic belt gaziantep turkey abstract the ortaklar vms deposit is hosted in the kocali complex consisting of basalts and deep sea pelagic sediments which formed by rifting and continental break up of the southern neotethyan in late triassic the basalts are of nmorb type without notable crustal contamination from the surface to depth the ortaklar deposit consists of a gossan zone a thick massive ore zone and a poorly developed stockwork zone primary mineralisation is characterised by distinctive facies including sulphide breccias proximal graded beds distal stockworks and chimney fragments ore mineral abundances decrease in the order of pyrite magnetite chalcopyrite and sphalerite two distinct phases of mineralisation massive magnetite and massive sulphide are present in the ortaklar deposit textural evidence e g magnetite replacing sulphides and the spatial relationships with the host rocks indicate that magnetite and sulphide minerals were generated in different stages the transition from sulphide to magnetite mineralisation is interpreted to relate to variation in h2s content of ore fluids the 1st stage massive sulphide ore might have formed by early hydrothermal fluids rich in fe and h2s the 2nd stage massive magnetite might have formed by later neutral hydrothermal fluids rich in fe but poor in h2s replacing the pre existing sulphide ore the alteration patterns mineral paragenesis lithological features massive ore stockwork ore gossan of the ortaklar deposit together with its trace elements cu pb zn au ag and ree signatures are all consistent with a cyprus type vms system the 34s values in pyrite and chalcopyrite samples range from 2 6 to 5 7 indicating that the hydrothermal fluids were associated with sub seafloor igneous activity typical of cyprus type vms deposits however magnetite formed later than sulphide minerals in the ortaklar deposit contrasting with typical cyprus type vms deposits where magnetite generally occurs in lower sections consequently although the ortaklar deposit generally conforms to cyprus type deposits it is distinguished from them by its late stage and high magnetite concentration thus the ortaklar deposit is thought to be an exceptional and perhaps unique cyprus type vms deposit

testing models of late palaeozoic early mesozoic orogeny in western turkey support for an evolving open tethys model field evidence from north south transects tests three tectonic models for tethys in western turkey for when a late palaeozoic ocean was closing and an early mesozoic ocean opening in model 1 a palaeozoic ocean subducted southwards rifting continental fragments from gondwana and opening a triassic neo tethys to the south closure and collision occurred by latest triassic time in model 2 a wide palaeozoic tethys subducted northwards with an active eurasian margin and a passive gondwana margin the northern gondwana margin rifted in the triassic fragments either remained nearby taurides or drifted northwards e g karakaya attached to a north subducting plate new oceanic crust replaced palaeo tethys with neotethys and back arc marginal basins opened along the south eurasian margin e g kure in model 3 a palaeozoic ocean also subducted northwards opening wide marginal basins a wide southern neotethys opened along the gondwana margin rifted eurasian anatolides and gondwana taurides fragments collided in mid tethys by latest triassic time field evidence from the pontides supports north dipping subduction models model 2 or 3 above key features are a south vergent hp lt accretionary prism magmatic arc and back arc basin system bordering the eurasian margin also evidence from the tauride mountains favours model 2 over model 3 critically the anatolides and taurides appear to have a common history and were unlikely to have been located on opposite sides of tethys as in model 3

constrains on the origin and history of the eastern mediterranean basin abstract the basin formed along the northern passive margin of gondwanaland as a relict of the mesozoic neotethys in early mesozoic time though direct information from the basin itself is meagre the geology of its passive margins and the regional framework of the tethys evolution constrain the formation and history of the basin the eastern mediterranean and its passive margins are interpreted to have formed as a result of several faulting and continental breakup phases from early permian to middle jurassic times before pangaea s complete disintegration this led to the detachment of the eratosthenes and tauride blocks from the margins of the levant and herodotus basins respectively the latter merged in the northeast with the cyprus basin that extended along arabia s northern margin the main rifting probably occurred in the triassic leading to seafloor spreading in the herodotus and cyprus basins while along the levant margin important rifting also occurred in the jurassic during the initial rifting stages extension perpendicular to the levant margin was important but subsequently the tauride block drifted mainly northward the existence of the passive margins and slopes of the eastern mediterranean is documented at least from the end of the middle jurassic until then the basin was probably narrow 200 300 km but during the main phase of the africa laurasia separation it grew to twice its present width or more this scenario depends critically on the interpretation that the tauride block was originally located next to northeastern africa on the western side of the eratosthenes block plate convergence and consumption of the northern portion of the basin have taken place since mid cretaceous times but the active convergent boundary on its northern side formed only in the neogene by modification of earlier structures some intra plate deformation also took place especially in the neogene but it hardly changed the original configuration of the remaining portion of the basin