paleoclimatology and paleoecology across the eocene oligocene boundary thrace basin northeast aegean sea greece abstract the detailed biostratigraphic and ichnological analysis of the upper eocene lower oligocene forearc sedimentary sequence in the southern greek part of the thrace basin on lemnos island reveals a relationship between eco sedimentary factors and the base level dynamics influencing calcareous nannofossils and trace fossil assemblages the lower part of the 350 m thick succession was deposited in a sand rich submarine fan system and upper part in a shelf environment it contains nannofossil assemblages and distributions typical of the np19 np21 biozones the eocene oligocene e o boundary top of np20 biozone is clearly distinguished within the upper parts of the turbidite system where a decrease in water temperature salinity nutrient supply and oxygenation level is also revealed additionally 19 ichnospecies mostly graphoglyptids typical of deep sea fan deposits have been distinguished the trace fossil diversity and abundance decrease upward reflecting the impact of the changing depositional environments from basin floor fans to slope systems and then shelfal environments the regional basin fill history rather than global climatic changes was probably the fundamental controlling factor on the distribution of graphoglyptids and other trace fossils across the e o boundary

the south marmara fault we use about 800 km of multichannel exploration seismic reflection profiles of the seventies as well as the results of three drill holes that penetrated the sedimentary cover down to the upper cretaceous basement to describe a continuous gently curvilinear south concave zone of deformation about 10 km wide that extended over the whole southern shelf of the sea of marmara from the gulf of gemlik to the dardanelles straits in lower pliocene time about 4 ma we call this zone of deformation the south marmara fault smf system and propose that the smf was then a branch of the dextral north anatolian fault this branch passed to the north of the marmara island eocene block and thus had a south facing concavity this curvature resulted in a significant component of shortening in the western part of the fault the smf was deactivated at the end of lower pliocene about 3 5 ma except for its easternmost branch between the gulf of gemlik and imrali island where about 5 mm year of dextral motion is still occurring today

timing kinematics and cause of aegean extension a scenario based on a comparison with simple analogue experiments abstract since the early 1970s most geodynamic models proposed for the eastern mediterranean consider that the initiation of extension in the aegean during the late middle miocene or later was a direct consequence of the westward extrusion of anatolia away from the arabia eurasia collision front in the late 1990s a few models have taken into account the increasing evidence for an earlier initiation of aegean extension arising mostly from the analysis of deformation within the various alpine metamorphic complexes of the area based largely on our own investigations we first present a review of the data that reliably constrain the minimum age for the initiation of extension in these complexes it shows that regional scale extension with a pattern of stretching orientations similar to that of the pliocene pleistocene was already strongly active in the aegean before the onset of arabian indentation into eurasia lower miocene vs middle or upper miocene this implies that the initiation of aegean extension did not result from the lateral extrusion of anatolia instead extension may have started owing to a process of gravity spreading of the continental lithosphere that had previously been thickened during alpine collision the main arguments favouring this interpretation are presented and a preliminary scenario is proposed for the neogene evolution of the eastern mediterranean in which lateral extrusion of anatolia occurred lately during southward spreading of the aegean lithosphere in order to test this hypothesis further physical experiments simulating the horizontal spreading of a continental lithosphere toward a free boundary have been carried out the analysis of various elements of the deformation field displacements strain rotations fault pattern and kinematics both in the experiments and in the aegean domain reveals an excellent agreement between the two not only do early stages of aegean extension appear to fit the gravity spreading hypothesis but so does the recent to present internal deformation of the aegean transverse e w active shortening observed in the northern aegean is commonly taken as one of the most striking pieces of evidence that aegean extension results from the lateral extrusion of anatolia the experiments indicate that such transverse shortening may equally develop as a result of pure gravity spreading associated with a pattern of faults and rotations that compares well with that of the northern aegean pure dextral shearing along some strands of the north aegean trough fault system and the related development of an asymmetric pattern of faults in the northern aegean are eventually the only features that evidently arise from the extrusion of anatolia since less than 3 ma finally we argue that during the early stages of aegean extension since at least 21 ma and until ca 11 ma the distribution of extensional strain on a regional scale has been controlled by the distribution of earlier thickening post thickening thermal weakening through partial melting of deep levels of the crust probably accounts for the localization of extensional strain within the areas of thick crust restoring the aegean in its most likely configuration at the onset of bulk crustal extension suggests that 1 the extensional strain rate remained roughly constant or has eventually decreased since the onset of aegean extension and 2 the amounts of extension before and after 16 ma have been roughly equal

an active deep marine strike slip basin along the north anatolian fault in turkey the tekirdag depression within the marmara sea in the mediterranean region is an active rhomb shaped strike slip basin along the north anatolian fault with a basin floor at a water depth of 1150 m new multichannel seismic reflection data and on land geological studies indicate that the basin is forming along a releasing bend of the strike slip fault and is filled with syntransform sediments of pliocene quaternary age the basin is bounded on one side by the north anatolian fault and on the other side by a subparallel normal fault which forms the steep submarine slope in cross section the basin is strongly asymmetric with the thickness of the syntransform strata increasing from a few tens of meters on the submarine slope to over 2 5 km adjacent to the north anatolian fault seismic sections also show that the slope forming normal fault connects at depth to the north anatolian fault implying that the basin is completely detached from its substratum the whole structure can be envisaged as a huge rather flat negative flower structure the releasing bend of the north anatolian fault responsible for the formation of the basin is flanked by a constraining bend along the constraining bend the syntransform strata are being underthrust implying a recent change in the direction of the regional displacement vector this thrusting is responsible for the uplift of the submarine slope to a height of 924 m possibly by a mechanism of elastic rebound regional geology suggests that most of the syntransform strata are lacustrine with only the topmost few hundred meters consisting of deep marine clays the anomalous present depth of the tekirdag depression is due to reduced quaternary sedimentation coupled with high rates of displacement along the north anatolian fault which amounts to 20 mm yr in the marmara sea region

comparative petroleum systems analysis of the interior basins of turkey implications for petroleum potential abstract the interior basins of turkey remain effectively unexplored and their petroleum systems are poorly understood this paper presents a comparative summary of the geological evolution petroleum potential and prospectivity of the central tuz golu sivas and cankiri and east anatolian mus hinis pasinler horasan and tercan askale basins using geological seismic geochemical and petrophysical data and a series of quantitative basin models the studied basins are ranked on the basis of source effectiveness reservoir quality seal efficiency and the timing of hydrocarbon expulsion and migration relative to trap formation a qualitative risk assessment based on the elements of the petroleum system is used to evaluate the likelihood of hydrocarbon discovery in each of the basins this study shows that the chance of hydrocarbon discovery in the east anatolian basins is unlikely very unlikely and tuz golu sivas and cankiri basins are equally likely unlikely unlikely likely and unlikely respectively heavy oil and minor gas associated with two mature petroleum systems were discovered in the tuz golu basin various trap forming mechanisms such as salt tectonics and middle eocene compression accompanied by the effective sealing capacity of the eocene evaporites favor the hydrocarbon exploration potential of the tuz golu basin the highest exploration risk in the tuz golu basin arises from the poor quality sandstone reservoirs the biggest risk factor in the eastern anatolian basins is insufficient thermal maturity despite the presence of good quality source rocks the sivas basin is one of the most promising interior basins of turkey due to the presence of multiple mature petroleum systems and high quality reservoirs there is a high chance of accumulation of multi phase hydrocarbons in the eocene and miocene traps the major problem in the sivas basin is the lack of an efficient seal rock the cankiri basin contains all of the necessary elements of an ideal petroleum system except the presence of an organic rich source rock thus the chance of hydrocarbon discovery in the cankiri basin is low

from transpression to transtension changes in morphology and structure around a bend on the north anatolian fault in the marmara region abstract the east west trending north anatolian fault makes a 17 bend in the western marmara region from a mildly transpressional segment to a strongly transtensional one we have studied the changes in the morphology and structure around this fault bend using digital elevation models field structural geology and multi channel seismic reflection profiles the transpression is reflected in the morphology as the ganos mountain a major zone of uplift 10 km wide and 35 km long elongated parallel to the transpressional ganos fault segment west of this bend flat lying eocene turbidites of the thrace basin are folded upwards against this ganos fault forming a monocline with the ganos mountain at its steep southern limb and the flat lying hinterland farther north at the flat limb the sharp northern margin of the ganos mountain coincides closely with the monoclinal axis the strike of the bedding and the minor and regional fold axes in the eocene turbidites in ganos mountain are parallel to the trace of the ganos fault indicating that these structures as well as the morphology have formed by shortening perpendicular to the north anatolian fault the monoclinal structure of ganos mountain implies that the north anatolian fault dips under this mountain at 50 and this ramp terminates at a decollement at a calculated depth of 8 km east of this fault bend the northward dip of the north anatolian fault is maintained but it has a normal dip slip component this has led to the formation of an asymmetric half graben the tekirdag basin in the western sea of marmara containing a thickness of up to 2 5 km of pliocene to recent syn transform sediments as the ganos uplift is translated eastwards from the transpressional to the transtensional zone it undergoes subsidence by southward tilting however a morphological relic of the ganos uplift is maintained as the steep northern submarine slope of the tekirdag basin the minimum of 3 5 km of fault normal shortening in the ganos mountain and the minimum of 40 km eastward translation of the ganos uplift indicate that the present fault geometry has existed for at least the last 2 million years

tectonostratigraphic models of the alpine terranes and subduction history of the hellenides abstract the tectonostratigraphy of the hellenic terranes is related to their paleogeodynamic and paleogeographic evolution which comprises three major stages i continental rifting in the northern margin of gondwana characterised by volcanosedimentary complexes of late paleozoic triassic ii continental drifting and contemporaneous oceanic opening of tethyan basins in between the continental terranes during triassic paleogene with shallow water carbonate platforms on the continental terranes and ophiolite suites interlayered with pelagic sediments within the tethyan basins iii accretion of the tectonostratigraphic terranes with docking along the active european margin characterised by flysch melange sedimentation along the trenches from early jurassic to neogene two tectonostratigraphic models can be distinguished one for the continental terranes carbonate platforms and another for the oceanic basins the duration of each geodynamic stage for each terrane is obtained from the chronology of the tectonostratigraphic facies change the general trend is younger ages observed in the southern terranes and older ages towards the northern terranes the two alternative tectonostratigraphic models are applied in the two groups of terranes and the chronology of the geodynamic paleogeographic stages is estimated the hellenic subducted slab as shown in the seismic tomographic images is correlated to the terrane paleogeography using the estimated widths and the average subduction rates the upper 1700 km of the slab correspond to the three southern more external terranes whereas the remainingpart of the slab may represent the other more internal terranes a palinspastic model of the hellenides is presented taking into account the chronology of each stage for every terrane obduction of ophiolites over the southern platforms is observed in all four oceanic basins blueschist exhumation formation of core complexes and tectonic windows through extensional detachments occur after micro collision of continental terranes platforms and their isostatic uplift within the upper plate after their detachment from the subducting slab

faulting of lemnos island a mirror of faulting of the north aegean trough northern greece abstract a detailed analysis of the faulting on lemnos island since the miocene was achieved by grouping the recorded meso scale faults and their slickenlines into different groups replacing them with mean representative fault planes mrfp and lineations mrfl and finding the stress tensors driven to the activation of the different mrfp mrfl pairs the oldest recognized fault activity followed the late oligocene n s contraction and uplift d1 event as the latter is implied by e w to ene wsw buckle folds in the upper eocene lower oligocene molasse type sediments it was an early middle miocene strike slip to transpression deformation d2 event associated with n s contraction that also affected the lower miocene volcanogenic rocks the next fault activity was dated in middle late miocene and caused a wnw ese extension d3 event this deformation suggests that a during the late eocene oligocene the north aegean trough was developed as a fore arc basin between the rhodopian magmatic arc and its subduction accretion complex to the south and b during the late oligocene middle miocene the north aegean trough as the whole hellenic hinterland was subjected to the transpression s l deformation and lateral extrusion because of the late collisional processes between apulia and eurasia plates and the retreating of the hellenic orogen from late miocene to pliocene a ne sw extension to right lateral transtension d4 event dominated the north aegean trough indicating that the retreating of the hellenic orogen was completely balanced by a back arc extension the deformation facilitates the westward propagation of the north anatolian fault into the north aegean sea since the early pleistocene the deformation of the north aegean trough is related to a nne ssw back arc extension d5 of the present day hellenic subduction zone and the dominant ene wsw to e w faults along the north aegean trough function as normal to oblique right lateral normal faults

the thrace basin in the rhodope province of ne greece a tertiary supradetachment basin and its geodynamic implications abstract detailed tectonic analysis and geological mapping on the tertiary molassic and volcanosedimentary rocks of the thrace basin in northeastern greece allowed us to reconstruct the structural evolution of the basin and its geotectonic setting as well as the orientation of the regional paleostress field sedimentation was linked with a calc alkaline and locally shoshonitic magmatism associated with the tertiary syn to late orogenic extension in the rhodope province we interpret the molassic tertiary greek part of the thrace basin as a supradetachment basin associated with sedimentary and volcanic infilling five 5 deformational events t1 to t5 have been distinguished during basin evolution from eocene to quaternary time t1 is related to a low angle normal detachment fault zone with a top to the sw to ssw sense of movement and initial basin subsidence during middle late eocene to oligocene time simultaneously with uplift and exhumation of the footwall rhodope metamorphic rocks stacking and crustal thickening in the more external parts of the hellenic orogenic belt have taken place during the same time t2 evolved during oligocene miocene time it was characterized by transpressional tectonics and formation of large strike slip faults and extensional fractures as well as conjugate thrust faults and folds with n nw or s se sense of movement during miocene pliocene time the third t3 event took place it was responsible for the high angle normal faults dismembering the eocene oligocene molassic basin into neogene grabens the t4 event affected the neogene sediments of the basin with minor reverse strike slip faults as well as normal faults the following t5 event is related to large normal active faults they coincided with the active tectonics of the study area defined by the earthquake focal mechanisms

low temperature constraints on the cenozoic thermal evolution of the southern rhodope core complex northern greece the south rhodope core complex srcc of northern greece is probably the most studied metamorphic core complex of the rhodope massif and yet its geological evolution has not yet been fully unravelled especially the later stages of its thermotectonic evolution we applied the fission track method on apatite and zircon and the u th sm he method on apatite in order to reconstruct the low temperature thermal history the main detachments responsible for the unroofing of the core complex are the kerdilion and the strymon valley detachments the kerdilion detachment initiated the exhumation of the srcc at the latest at 42 ma and controlled it until about 24 ma between 24 and 12 ma the strymon valley detachment accommodated the exhumation since 12 ma brittle normal faults some of them cutting the strymon valley detachment were responsible for the final cooling of the basement rocks in the studied area and the formation of syn tectonic sedimentary basins activity along these brittle normal faults lasted until 6 ma or probably even until today as indicated by recent seismic activity in the area

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

late miocene transcurrent tectonics in nw turkey evidence from palaeomagnetism and 40ar 39ar dating of alkaline volcanic rocks a number of intra continental alkaline volcanic sequences in nw turkey were emplaced along localized extensional gaps within dextral strike slip fault zones prior to the initiation of the north anatolian fault zone this study presents new palaeomagnetic and 40 ar 39 ar geochronological results from the lava flows of nw turkey as a contribution towards understanding the neogene quaternary tectonic evolution of the region and possible roles of block rotations in the kinematic history of the region 40 ar 39 ar analyses of basalt groundmass indicate that the major volume of alkaline lavas of nw turkey spans about 4 million years of episodic volcanic activity palaeomagnetic results reveal clockwise rotations as high as 73 in thrace and 33 anticlockwise rotations in the biga peninsula movement of some of the faults delimiting the areas of lava flows and the timing of volcanic eruptions are both older than the initiation age of the north anatolian fault zone implying that the region experienced transcurrent tectonics during late miocene to pliocene times and that some of the presently active faults in the region are reactivated pre existing structures

the two stage aegean extension from localized to distributed a result of slab rollback acceleration back arc extension in the aegean which was driven by slab rollback since 45 ma is described here for the first time in two stages from middle eocene to middle miocene deformation was localized leading to i the exhumation of high pressure metamorphic rocks to crustal depths ii the exhumation of high temperature metamorphic rocks in core complexes and iii the deposition of sedimentary basins since middle miocene extension distributed over the whole aegean domain controlled the deposition of onshore and offshore neogene sedimentary basins we reconstructed this two stage evolution in 3d and four steps at aegean scale by using available ages of metamorphic and sedimentary processes geometry and kinematics of ductile deformation paleomagnetic data and available tomographic models the restoration model shows that the rate of trench retreat was around 0 6 cm year during the first 30 my and then accelerated up to 3 2 cm year during the last 15 my the sharp transition observed in the mode of ex

detrital supply from subduction accretion complexes to the eocene oligocene post collisional southern thrace basin nw turkey and ne greece abstract the thrace basin is a large mostly eocene oligocene post collisional sedimentary basin which developed following the closure of the vardar izmir ankara oceanic domain latest cretaceous paleocene sandstone petrologic data framework and heavy mineral analyses and the synthesis of preexisting and new sedimentological observations along representative stratigraphic sections show that the basin fill of the southern thrace basin was mostly derived from the izmir ankara and biga intra pontide subduction accretion complexes to the south proximal facies consistently show northward paleocurrents whereas most paleocurrent indicators measured downcurrent point to an eastward paleoflow likely the result of the deflection of primary gravity flows originated along the southern margin of the basin detrital contributions from the rhodopian basement complex to the west are virtually absent within the southern thrace basin fill conversely rhodopes derived eocene proximal facies in northeastern greece are characterized by a series of coarse grained fan deltas prograding eastward and likely feeding the basin plain turbidites of the depocentral portion of the thrace basin now concealed in the subsurface to the north of our study area arenites of the southern thrace basin are mostly lithic arkoses and arkosic litharenites provenance from the izmir ankara and biga suture zones to the south is characterized by ophiolitic granitoid gneissic low grade metamorphic and extrabasinal carbonate rock fragments as well as by picotite and glaucophane the application of detailed petrographic observations for discriminating paleo vs neovolcanic and penecontemporaneous vs noncoeval terrigenous sands lead to a substantial revision of the geodynamic interpretation of the thrace basin formerly considered a forearc basin a significant penecontemporaneous volcanic component is common in the upper eocene lower oligocene section and can be related to extensive post collisional volcanism following the closure of the vardar izmir ankara ocean the coexistence of pure neovolcanic layers crystal tuffs and cinerites and hybrid arenites rich in penecontemporaneous carbonate grains with sands derived from a continental basement and ophiolitic suites indicates the presence of episutural basins where shallow water carbonates were deposited on top of the exhuming subduction accretion prism these carbonates were mixed with penecontemporaneous neovolcanic and terrigeneous components and redeposited in deeper marine environments

active tectonics of the north and central aegean sea summary in this paper we examine the connection between the westward motion of turkey relative to europe and the extension in and around the aegean sea the principal new data available since the last attempt to synthesize the tectonics of this region by mckenzie 1978 are much improved focal mechanisms of earthquakes constrained by p and sh body wave modelling as well as by first motions these mechanisms show that the faulting in the western part of the aegean region is mostly extensional in nature on normal faults with a nw to wnw strike and with slip vectors directed nnw to nne there is evidence from palaeomagnetism that this western region rotates clockwise relative to stable europe in the central and eastern aegean and in nw turkey distributed right lateral strike slip is more prevalent on faults trending ne to ene and with slip vectors directed ne palaeomagnetic data in this eastern region is more ambiguous but consistent with very small or no rotations in the northern part and possibly anticlockwise rotations relative to europe in the south the strike slip faulting that enters the central aegean from the east appears to end abruptly in the sw against the nw trending normal faults of greece the kinematics of the deformation is controlled by three factors the westward motion of turkey relative to europe the continental collision between nw greece albania and the apulia adriatic platform in the west and the presence of the hellenic subduction zone to the south as the right lateral slip on the north anatolian fault enters the aegean region it splays out becoming distributed on several parallel faults the continental shortening in nw greece and albania does not allow the rotation of the western margin of the region to be rapid enough to accommodate this distributed e w right lateral shear and thus leads to e w shortening in the northern aegean which is compensated by n s extension as the southern aegean margin can move easily over the hellenic subduction zone the dynamics of the system once initiated is self sustaining being driven by the high topography in eastern turkey and by the roll back of the subducted slab beneath the southern aegean the geometry of the deformation resembles the behaviour of a system of broken slats attached to margins that rotate in spite of its extreme simplicity a simple model of such broken slats is able to reproduce quantitatively most of the features of the instantaneous velocity field in the aegean region including the slip vectors and nature of the faulting in the eastern and western parts the senses and approximate rates of rotation the overall extensional velocity across the aegean and the distribution of strain rates as seen in the seismicity and topography or bathymetry and using geodetic measurements as part of this study we re examined the relation between the surface faulting and the focal parameters determined seismologically for the three large 1981 gulf of corinth earthquakes and reassessed the evidence for associating particular earthquakes in the sequence with observed surface faulting an important result is that in one of the events there is a resolvable discrepancy between the slip vector measured at the surface and that determined from the seismic body waves

tectonics of the buried kirklareli fault thrace region nw turkey abstract the study investigated the geometry seismicity and kinematics of the kirklareli fault kf by using drilling seismic reflection and field data the kf located in the thrace region nw turkey is a buried fault that forms a morphological boundary between the strandzha mountains and the ergene basin it has lithological and morphological importance in the region although there were some destructive earthquakes in the basin historically the magnitude of the largest earthquake measured instrumentally was only 4 6 earthquake data obtained from the kandilli observatory and earthquake research institute indicate that the epicentres are concentrated along the kf deep borehole data show a total vertical displacement of 223 m over the last 2 ma displacement calculations indicated that the kf moves with a normal displacement of at least 0 1 mm year the seismic profile verified the existence of the kf kinematic analysis of measurements on bedding planes of a formation near the kf demonstrates n105 direction the activeness and existence of the hangingwall and footwall of the kf are discussed on the basis of morphometric analyses and geomorphic indices the two geomorphic indices sl and vf show that tectonism effects the morphology the kf has normal fault geometry according to drilling seismological and gps data geomorphic indices and field observations

late cenozoic tectonics and stratigraphy of northwestern anatolia the effects of the north anatolian fault to the region in northwest anatolia there is a mosaic of different morpho tectonic fragments within the western part of the right lateral strike slip north anatolian fault naf zone these were developed from compressional and extensional tectonic regimes during the paleo and neo tectonic periods of turkish orogenic history a ne sw trending left lateral strike slip fault system adapazari karasu fault extends through the northern part of the sakarya river valley and began to develop within a n s compressional tectonic regime which involved all of northern anatolia during middle eocene to early middle miocene times since the end of middle miocene times this fault system forms a border between a compressional tectonic regime in the eastern area eastwards from the northern part of the sakarya river valley and an extensional tectonic regime in the marmara region to the west the extension caused the development of basins and ridges and the incursions of the mediterranean sea into the site of the future sea of marmara since late miocene times following the initiation in late middle miocene times and the eastward propagation of extension along the western part of the naf a block north anatolian block began to form in the northern anatolia region since the end of pliocene times the adapazari karasu fault constitutes the western boundary of this block which is bounded by the naf in the south the northeast anatolian fault in the east and the south black sea thrust fault in the north the northeastward movement of the north anatolian block caused the formation of a marine connection between the black sea and the aegean mediterranean sea during the pleistocene

the cele mafic complex evidence for triassic collision between the sakarya and istanbul zones nw turkey abstract the lowest structural levels of the istanbul zone are exposed in the sunnice massif north of bolu they comprise the greenschist facies ediacaran calc alkaline bimodal yellice metavolcanics which are intruded by the dirgine granitoid amphibolite facies mafic and subordinate ultramafic rocks of the cele mafic complex hitherto termed the cele meta ophiolite include hornblende gneisses of island arc meta tholeiitic and transitional to calc alkaline metagabbroic compositions and were previously thought to be part of the istanbul zone basement together with minor serpentinized troctolite and harzburgite lenses they are exposed in a broadly antiformal structure beneath the yellice metavolcanics although these rocks structurally underlie and on account of their higher metamorphic grade were previously thought to be older than the ediacaran cambrian rocks of the istanbul zone basement their oldest isotopic dates are permian indicating that they are instead much younger than the overlying rocks from which they must be divided by an inferred istanbul zone basal thrust instead these mafic rocks may be linked to the almacik complex and hence interpreted as the underthrust crustal base to a permo triassic active continental margin attached to the gondwana derived sakarya zone now located south of the istanbul zone triassic and jurassic metamorphic ages record compressional events marking a cimmerian event closing the palaeotethys ocean

fission track evidence for late oligocene and mid miocene activity along the north anatolian fault in south western thrace apatite fission track ft analyses of sandstone samples collected across the trace of the ganos segment of the north anatolian fault naf in south western thrace turkey indicate that a significant structural discontinuity was in existence at least by the latest oligocene such discontinuity had a complex kinematic history as exhumation south of it occurred during the latest oligocene and north of it during the mid miocene our data imply that early pliocene westward propagation of the naf in the marmara region followed a pre existing structural discontinuity such discontinuity could be related to the development of the intra pontide suture marking the terminal closure of the intra pontide ocean during the oligocene

long wavelength undulations of the seismic moho beneath the strongly stretched western anatolia summary western turkey provides spectacular examples of the two end member models of deformation of the continental lithosphere with strain localization along the north anatolian fault and distributed north south extension along the aegean coast to provide constraints on the mechanisms of continental deformation we present a new high resolution image of lithospheric structurealonga 650kmtransectcrossingwesternanatoliaat28 elongitudefromtheblack sea to the mediterranean more than 2600 receiver functions are computed from records of teleseismic earthquakes at 40 broadband seismic stations with an average spacing of 15km lateral variations of crustal thickness and vp vs ratio are inferred from both h k and common conversion point stacks we observe long wavelength variations of moho depth from 31km in the thrace basin to 25km beneath the marmara sea 32km beneath the izmir ankara suture 25km beneath the menderes massif and 20km on the coast of the mediterranean no mid or lower crustal interface is visible in the migrated depth section and seismic discontinuities are confined to the shallow crust the small amplitude and long wavelength lateral variations of the moho topography suggest that viscous flow in a hot lower crust has smoothed out the lateral variations of crustal thickness induced by cenozoic continent continent collision thecrust mantleboundaryisflatbeneaththecentralandsouthernmenderesmassif the rougher moho topography and more heterogeneous crust of the marmara region likely result from transtension in the north anatolian fault zone superimposed onto aegean extension the moho of the subducted african lithosphere is observed dipping northward between 40 and 60km depth at the southern end of the profile the abrupt termination of the subducted slab only 50km to the north of the mediterranean coast confirms the slab tear inferred from previous tomographic studies

a review of tectonics and sedimentation in a forearc setting hellenic thrace basin north aegean sea and northern greece abstract exposure of the forearc region of the north aegean sea greece offers insight into evolving convergent margins the sedimentary fill of the thrace basin during the late eocene to oligocene time provides a record of subduction driven processes such as growth of magmatic arcs and construction of accretionary complexes this large sediment repository received sediment from two sources the southern outboard basin margin reflects the active influence of the exhumed accretionary prism e g pindic cordillera or biga peninsula while the northern inboard margin records the effect of the magmatic arc in the rhodope region the forearc basin sedimentary fills shoal upward into shallow marine strata but are dominated mainly by deep marine facies the depositional trend and stacking pattern are dominated by progradational patterns this trend which is observed in both basin margins is related to tectonic deformation rather than sea level fluctuations additional evidence for this tectonic uplift comes from the backstripping analysis the accretionary complex provided material into the forearc basin this material was transported northeast and formed a sand rich turbidity system that evolved upslope into shallow marine deposits stratigraphic data indicate that this turbidity system exhibits a successive landward inboard migration of the depocenter provenance data utilizing sandstone petrography conglomerate clast composition and bulk rock geochemistry suggest that this system reflects an increased influx of mafic material into the basin volcanic arc derived material was transported south and east and accumulated in deep marine settings both stratigraphic and provenance data indicate a seaward outboard migration of the basin depocenter and a significant increase in felsic detritus into the forearc

pore fluid chemistry of the north anatolian fault zone in the sea of marmara a diversity of sources and processes as part of the 2007 marnaut cruise in the sea of marmara an investigation of the pore fluid chemistry of sites along the main marmara fault zone was conducted the goal was to define the spatial relationship between active faults and fluid outlets and to determine the sources and evolution of the fluids sites included basin bounding transtensional faults and strike slip faults cutting through the topographic highs the basin pore fluids are dominated by simple mixing of bottom water with a brackish low density pleistocene lake marmara end member that is advecting buoyantly and or diffusing from a relatively shallow depth this mix is overprinted by shallow redox reactions and carbonate precipitation the ridge sites are more complex with evidence for deep sourced fluids including thermogenic gas and evidence for both silicate and carbonate diagenetic processes one site on the western high displayed two mound structures that appear to be chemoherms atop a deep seated fluid conduit the fluids being expelled are brines of up to twice seawater salinity with an exotic fluid chemistry extremely high in li sr and ba oil globules were observed both at the surface and in cores and type ii gas hydrates of thermogenic origin were recovered hydrate formation near the seafloor contributes to increase brine concentration but cannot explain their chemical composition which appears to be influenced by diagenetic reactions at temperatures of 75 c 150 c hence a potential source for fluids at this site is the water associated with the reservoir from which the gas and oil is seeping which has been shown to be related to the thrace basin hydrocarbon system our work shows that submerged continental transform plate boundaries can be hydrologically active and exhibit a diversity of sources and processes

a fore arc origin for the thrace basin nw turkey hydrocarbon bearing thrace basin occupies much of the european part of turkey the middle eocene to oligocene sequence in the centre of the basin exceeds 9 km in thickness based on the stratigraphy structure and the regional context of this basin we propose that it developed as a fore arc basin between the medial eocene and the oligocene above the northward subducting intra pontide ocean its post miocene history has been dominated mainly by wrench tectonics resulting from the activity of the now deactivated northwestern strand of the present day north anatolian fault zone

possible strand of the north anatolian fault in the thrace basin turkey an interpretation the north anatolian fault is a 1200 km long major transform fault bounding the anatolian plate on its north side the fault formed during the late middle miocene as a broad shear zone with a number of strands splaying westward in a horsetail pattern later movement became localized along a central strand and the southerly and northerly splays became inactive the west northwest striking thrace strike slip fault system is one of these right lateral presently inactive splays it consists of three subparallel strike slip faults from north to south these are the kirklareli luleburgaz and babaeski fault zones which extend for about 130 km through the thrace basin the thrace fault zone probably connected to the southeast with the presently active northern strand of the north anatolian fault in the marmara sea to the northwest the zone may have extended to the plovdiv graben zone in bulgaria the cenozoic thrace basin contains middle eocene to pliocene sedimentary rocks the thrace right lateral wrench fault system formed prior to the pliocene and had become inactive by the pliocene strike slip fault zones with normal and reverse separation are detected by seismic reflection profiles and subsurface data as the system became inactive the motion on the north anatolian fault zone began to be accommodated in the marmara sea region thus the thrace fault system represents the oldest strand of the north anatolian fault to the west of istanbul releasing bend extensional structures and restraining bend compressional structures are abundant along the fault zones several hydrocarbon producing anticlines lie en echelon to the luleburgaz fault zone regionally the thrace fault ystem has a horsetail shape with the various strands becoming younger southward

the rhodope zone as a primary sediment source of the southern thrace basin ne greece and nw turkey evidence from detrital heavy minerals and implications for central eastern mediterranean palaeogeography detrital heavy mineral analysis coupled with a regional geological review provide key elements to re evaluate the distribution of the rhodope metamorphic zone se europe in the region and its role in determining the evolution of the thrace basin we focus on the eocene oligocene sedimentary successions exposed in the southern thrace basin margin to determine the dispersal pathways of eroded crustal elements of both oceanic and continental origins as well as their different contributions through time lithological aspects and tectonic data coupled with geochemistry and geochronology of metamorphic terranes exposed in the area point to a common origin of tectonic units exposed in nw turkey biga peninsula with those of ne greece and se bulgaria rhodope region the entire region displays 1 common extensional signatures consisting of comparable granitoid intrusion ages and a ne sw sense of shear 2 matching zircon age populations between the metapelitic and metamafic rocks of the circum rhodope belt ne greece and those of the camlica kemer complex and cetmi melange exposed in nw turkey detrital heavy mineral abundances from eocene oligocene sandstones of the southern thrace basin demonstrate the influence of two main sediment sources mostly of ultramafic ophiolitic and low to medium grade metamorphic lithologies plus a third volcanic source limited to the late eocene oligocene detrital cr spinel chemistry is used to understand the origin of the ultramafic material and to discriminate the numerous ultramafic sources exposed in the region compositional and stratigraphic data indicate a major influence of the metapelitic source in the eastern part gallipoli peninsula during the initial stages of sedimentation with increasing contributions from metamafic sources through time on the other hand the western and more external part of the southern thrace margin gokceada samothraki and limnos displays compositional signatures according to a mixed provenance from the metapelitic and metamafic sources of the circum rhodope belt camlica kemer complex and cetmi melange tectonic restoration and compositional signatures provide constraints on the palaeogene palaeogeography of this sector of the central eastern mediterranean region

a new classification of the turkish terranes and sutures and its implication for the paleotectonic history of the region abstract the turkish part of the tethyan realm is represented by a series of terranes juxtaposed through alpine convergent movements and separated by complex suture zones different terranes can be defined and characterized by their dominant geological background the pontides domain represents a segment of the former active margin of eurasia where back arc basins opened in the triassic and separated the sakarya terrane from neighbouring regions sakarya was re accreted to laurasia through the balkanic mid cretaceous orogenic event that also affected the rhodope and strandja zones the whole region from the balkans to the caucasus was then affected by a reversal of subduction and creation of a late cretaceous arc before collision with the anatolian domain in the eocene if the anatolian terrane underwent an evolution similar to sakarya during the late paleozoic and early triassic times both terranes had a diverging history during and after the eo cimmerian collision north of sakarya the kure back arc was closed during the jurassic whereas north of the anatolian domain the back arc type oceans did not close before the late cretaceous during the cretaceous both domains were affected by ophiolite obduction but in very different ways north directed diachronous middle to late cretaceous melange obduction on the jurassic sakarya passive margin senonian synchronous southward obduction on the triassic passive margin of anatolia from this it appears that the izmir ankara suture currently separating both terranes is composite and that the passive margin of sakarya is not the conjugate margin of anatolia to the south the cimmerian taurus domain together with the beydaglari domain part of the larger greater apulian terrane were detached from north gondwana in the permian during the opening of the neotethys east mediterranean basin the drifting cimmerian blocks entered into a soft collision with the anatolian and related terranes in the eo cimmerian orogenic phase late triassic thus suturing the paleotethys at that time the taurus plate developed foreland type basins filled with flysch molasse deposits that locally overstepped the lower plate taurus terrane and were deposited in the opening neotethys to the south these olistostromal deposits are characterized by pelagic carboniferous and permian material from the paleotethys suture zone found in the mersin melange the latter as well as the antalya and mamonia domains are represented by a series of exotic units now found south of the main taurus range part of the mersin exotic material was clearly derived from the former north anatolian passive margin huglu type series and re displaced during the paleogene this led us to propose a plate tectonic model where the anatolian ophiolitic front is linked up with the samail baer bassit obduction front found along the arabian margin the obduction front was indented by the anatolian promontory whose eastern end was partially subducted continued slab roll back of the neotethys allowed anatolian exotics to continue their course southwestward until their emplacement along the taurus southern margin mersin and up to the beydaglari promontory antaya mamonia in the latest cretaceous paleocene the supra subduction ocean opening at the back of the obduction front troodos type ocean was finally closed by eocene north south shortening between africa and eurasia this brought close to each other cretaceous ophiolites derived from the north of anatolia and those obducted on the arabian promontory the latter were sealed by a maastrichtian platform and locally never affected by alpine tectonism whereas those located on the eastern anatolian plate are strongly deformed and metamorphosed and affected by eocene arc magmatism these observations help to reconstruct the larger frame of the central tethyan realm geodynamic evolution

genesis of the wolverine volcanic sediment hosted massive sulfide deposit finlayson lake district yukon canada mineralogical mineral chemical fluid inclusion and sulfur isotope evidence the wolverine deposit is a high grade 6 2 mt at 12 7 zn 1 3 cu 1 6 pb 370 9 g t ag and 1 8 g t au volcanic and sedimentary rock hosted massive sulfide deposit in the finlayson lake area yukon territory the area has the potential to become an important mining camp and currently contains more than 30 million tons mt of massive sulfide ore in five deposits a succession of metamorphosed early mississippian felsic volcanic and sedimentary rocks that are interpreted to have formed on the margin of an ensialic back arc ocean basin between the yukon tanana terrane and the ancestral north american craton hosts the wolverine deposit the massive sulfide ore occurs at a single horizon that marks a significant change in the character of the volcanism from quartz and feldspar phyric rhyolite of the footwall to aphyric rhyolite and chemical sedimentary exhalative rock of the hanging wall the deposit consists of two discrete zn pb ag massive sulfide lenses situated at the same stratigraphic level connected by strata bound semimassive replacement style zn pb ag mineralization copper rich massive sulfide commonly replaces the zn pb ag massive sulfide at the base of the lenses and in the footwall replacement zones beneath the massive mineralization several zones of sulfide stringer veins and chlorite sericite carbonate alteration occur within permeable footwall volcaniclastic rocks alteration minerals preferentially associated with massive sulfide mineralization include ba rich phengitic mica biotite mg rich chlorite and siderite microthermometric measurements of fluid inclusions in the massive sulfide bodies and accompanying stringer zones indicate formation at temperatures of 235 to 353 c primary aqueous liquid rich fluid inclusions in hydrothermal quartz from quartz sulfide stringer veins contain low salinity fluids 2 1 8 5 wt nacl equiv mean 6 0 there is no evidence of fluid boiling in the inclusions and based on the average fluid salinity and temperature of homogenization mineralization took place under a minimum water depth of 1 000 m in situ analyses of 34sv cdt in sulfide minerals from massive sulfide lenses means 0 8 and sulfide stringer veins mean 12 0 display a bimodal distribution lower 34s values characterize sulfides near the top of the lenses versus higher more positive values in underlying veins may reflect different processes of reduction of seawater sulfate sulfur in sulfides from the tops of the lenses was likely derived mainly from bacterial reduction of seawater sulfate whereas sulfur in the stringer veins and at the base of the lenses was mainly from inorganic reduction of seawater sulfate sulfide minerals precipitated both on the sea floor and in the subsea floor from hydrothermal fluids that vented from multiple mounds the presence of black shales and the strongly positive sulfur isotope compositions of the sulfides provide evidence that the ambient bottom water in the basin in which the wolverine deposit formed was likely anoxic this environment may have contributed to the preservation of the sulfide mounds based on its tectonic setting host rock types local geologic setting metal grades age and source s of sulfur the wolverine deposit best exemplifies the volcanic sediment hosted massive sulfide vshms class of syngenetic massive sulfide deposits in the district

rapid early middle miocene exhumation of the kazdag massif western anatolia apatite fission track analyses indicate that the kazdag massif in northwestern anatolia was exhumed above the apatite partial annealing zone between 20 and 10 ma i e early middle miocene with a cluster of ages at 17 14 ma the structural analysis of low angle shear zones high angle normal faults and strike slip faults as well as stratigraphic analysis of upper plate sedimentary successions and previous radiometric ages point to a two stage structural evolution of the massif the first stage encompassing much of the rapid thermal evolution of the massif comprised late oligocene early miocene low angle detachment faulting and the associated development of small supradetachment grabens filled with a mixture of epiclastic volcaniclastic and volcanic rocks kucukkuyu fm the second stage plio quaternary has been dominated by i strike slip faulting related to the westward propagation of the north anatolian fault system and ii normal faulting associated with present day extension this later stage affected the distribution of fission track ages but did not have a component of vertical normal movement large enough to exhume a new partial annealing zone the thermochronological data presented here support the notion that neogene extensional tectonism in the northern aegean region has been episodic with accelerated pulses in the early middle miocene and plio quaternary

seafloor authigenic carbonate crusts along the submerged part of the north anatolian fault in the sea of marmara mineralogy geochemistry textures and genesis abstract extensive seafloor authigenic carbonate crusts occur as pavements mounds and chimneys along the north anatolian fault system nafs in the sea of marmara they are often covered or surrounded by patches of black fe sulphide rich sediments and associated with hydrocarbon rich gas and brackish water emissions in the 1250 m deep deep basins and with deep saline formation waters and hydrocarbons emissions from mud volcanoes and anticlines on the 350 650 m deep compressional highs the authigenic carbonate crusts are commonly porous with sinter like botryoidal and sugary granular textures and constructed from cementation of framework elements consisting mainly of bivalve shells and shell fragments serpulid tubes fibrous microbial organic matter and rarely pebbles the authigenic cements consist mainly of aragonite in most sites but high mg calcite occurs as a major carbonate cement at some basinal sites where the brackish former marmara lake waters emerge the buoyant emission of brackish waters in the deep marmara basins and deeply sourced fluids from the tertiary thrace basin at the compressional highs are supported by relatively low 18o values 0 5 to 3 8 v pdb average 2 1 v pdb n 24 of carbonates in the former and high values 2 6 to 3 4 v pdb average 3 0 n 9 in the latter areas low 13c values 47 6 to 13 7 v pdb average 34 9 v pdb n 33 and close association with black reduced sediments indicate that the seafloor authigenic carbonates are formed by the anaerobic oxidation of methane aom at or near the seafloor as result of high methane flux possibly during periods of high seismic activity authigenic carbonates from the western and central highs are relatively less depleted in 13c than those of the deep basin sites suggesting both microbial and thermogenic methane source for the deep basins carbonates and mainly thermogenic hydrocarbon with some contribution from the biodegradation of heavy hydrocarbons and gas hydrate dissociation for carbonates from the compressional highs u th ages of the authigenic carbonates range from less than 1 ka bp to 9 6 ka bp the age distribution together with the geochemical and mineralogical data suggests that different processes such as seismo tectonics and gas hydrates destabilization might have played important role in the authigenic carbonate formation in the sea of marmara over the last 10 ka

reply to comment by caracciolo et al on maravelis et al 2015 accretionary prism forearc interactions as reflected in the sedimentary fill of southern thrace basin lemnos island ne greece

cenozoic thermal evolution of the central rhodope metamorphic complex southern bulgaria we have combined new titanite zircon and apatite fission track and apatite u th sm he analyses with previously published u pb rb sr and 40ar 39ar thermochronological data to reconstruct the cenozoic thermal evolution of the central rhodope metamorphic complex crmc exposed mainly in southern bulgaria and to a lesser extent in northern greece results reveal two phases of cooling during the first phase between 37 and 33 ma the crmc experienced rapid cooling from partial melting at 650 c to ca 60 c multiple generations of low angle ductile to brittle fault zones accommodated the exhumation of the migmatitic core together with parts of its high grade periphery oligocene volcanism and associated local elevation of the geothermal gradient is responsible for the resetting of some fission track ages in the crmc the second cooling phase to temperatures of about 40 c between 24 and 13 ma is related to exhumation along high angle normal faults in the southern part of the crmc

a precursor of the north anatolian fault in the marmara sea region abstract apatite u th he and fission track analyses of both basement and sedimentary cover samples collected around the marmara sea point to the existence of a system of major e w trending structural discontinuities active at least from the late oligocene in the early pliocene inception of the present day north anatolian fault naf system in the marmara region occurred by reactivation of these older tectonic structures this is particularly evident across the ganos fault in southern thrace as exhumation south of it occurred during the latest oligocene and north of it during the mid miocene in this area large tectonic structures long interpreted as the results of plio quaternary naf related transpressional deformation i e the ganos monocline the korudag anticline and the gelibolu folds were in fact produced during the late oligocene early miocene the overall lack of significant u th he age differences across the naf indicates that the early pliocene inception of strike slip motion in the marmara region represents a relatively minor episode at the scale of the entire marmara region the geographic pattern of exhumation ages shown in this study results instead from the complex superposition of older tectonic events including i the amalgamation of sakarya and anatolide tauride terranes and ii aegean related extension

the korudag anticlinorium in the south thrace basin northwest turkey a super giant petroleum trap complex the sedimentary sequence of the south thrace basin northwest turkey comprises upper cretaceous holocene sediments in this basin the korudag anticlinorium which is the subject of this study is located between the aegean sea in the west and the sea of marmara to the east the anticlinorium which is approximately 300 km 186 mi long and 40 km 25 mi wide was formed by effects of the neotethys subduction accretion complex and istranca massif collision during the late early miocene the korudag anticlinorium was deformed to its present day structure by the oldest splay of the north anatolian fault upper middle miocene and the northern branch of the north anatolian fault naf n not earlier than 200 ka organic geochemical analysis oil and gas to source rock correlation and basin modeling studies suggest that the korudag anticlinorium should be charged by hydrocarbons generated from the karaagac ceylan regionally and mezardere formations gas and oil are being produced from the korudag anticlinorium and its subparallel anticlines in the north marmara degirmenkoy seymen cayirdere karacali yulafli tekirdag sevindik and vakiflar gas plus oil fields mapping done as part of this study indicates that the korudag anticlinorium has not yet been tested and explored comprehensively

basement types of the thrace basin and a new approach to the pre eocene tectonic evolution of the northeastern aegean and northwestern anatolia a review of data and concepts in northwestern turkey the pre eocene basement of the thrace basin consists of the strandja rhodope metamorphics in the north northwest the istanbul zonguldak paleozoic sequence in the northeast a tectonic mixture of the fragments from the sakarya continent and pre upper cretaceous ophiolites in the southeast and the uppermost cretaceous paleocene transgressive sediments the ophiolites belong to a dogger early cretaceous oceanic basin the northeastern vardar ocean between the rhodope and sakarya continents the ne trending oceanic branch closed diachronously during the early late malm to the northeast but during latest early cretaceous to late cretaceous time toward the main vardar ocean in the southwest during the final closure the suture zone acted as a strike slip fault zone the latest cretaceous paleocene transpressional to transtensional activities caused the juxtaposition of different basement types and the development of a tectonic mixed zone the biga armutlu ovacik zone between the rhodope and sakarya continents under the regional n s compression on the plate overlying the north northeastward dipping vardar subduction zone the southwestward escape of an area of crust bounding by the wnw trending balkan thrace dextral fault zone to the north and the ne trending biga armutlu ovacik sinistral zone to the southeast caused a triangular shaped and isolated depression area for the deposition of the uppermost cretaceous paleocene transgressive sediments in a transtensional setting the tectonically bounded depression area constitutes also a necessary accommodation space for the deposition of the initial deposits of early eocene age in the thrace basin

interplay between geochemistry and magma dynamics during magma interaction an example from the sithonia plutonic complex ne greece orogenic granitoids often display mineralogical and geochemical features suggesting that open system magmatic processes played a key role in their evolution this is testified by the presence of enclaves of more mafic magmas dispersed into the granitoid mass the occurrence of strong disequilibrium textures in mineralogical phases and or extreme geochemical and isotopic variability in this contribution intrusive rocks constituting the sithonia plutonic complex northern greece are studied on the basis of mineral chemistry whole rock major trace element geochemistry and sr and nd isotopic composition sithonia rocks can be divided into a basic group bearing macroscopic mafic enclaves microscopic disequilibrium textures geochemical and isotopic evidence of magma interaction and an acid group in which most geochemical and isotopic features are consistent with a magma mixing process but macroscopic and microscopic features are lacking a two step mixing plus fractional crystallization mfc process is considered responsible for the evolution of the basic group the firststepexplainsthechemicalvariationinthemaficenclavegroup abasicmagma representedbytheleastevolvedenclaves interacted

from tethys to eastern paratethys oligocene depositional environments paleoecology and paleobiogeography of the thrace basin nw turkey the oligocene depositional history of the thrace basin documents a unique paleogeographic position at a junction between the western tethys and the eastern paratethys as part of the tethys shallow marine carbonate platforms prevailed during the eocene subsequently a three staged process of isolation started with the oligocene during the early rupelian the thrace basin was still part of the western tethys indicated by typical western tethyan marine assemblages the isolation from the tethys during the early oligocene is reflected by oolite formation and endemic eastern paratethyan faunas of the solenovian stage the third phase reflects an increasing continentalisation of the thrace basin with widespread coastal swamps during the late solenovian the mollusc assemblages are predominated by mangrove dwelling taxa and the mangrove plant avicennia is recorded in the pollen spectra the final continentalisation is indicated by the replacement of the coastal swamps by pure freshwater swamps and fluvial plains during the late oligocene mammal zone mp 26 this paleogeographic affiliation of the thrace basin with the eastern paratethys after 32 ma contrasts all currently used reconstructions which treat the basin as embayment of the eastern mediterranean basin

accretionary prism forearc interactions as reflected in the sedimentary fill of southern thrace basin lemnos island ne greece architecture of the well exposed ancient forearc basin successions of northeast aegean sea greece provides useful insights into the interplay between arc magmatism accretionary prism exhumation and sedimentary deposition in forearc basins the upper eocene lower oligocene basin fill of the southern thrace forearc basin reflects the active influence of the uplifted accretionary prism deep marine sediments predominate the basin fill that eventually shoals upwards into shallow marine sediments this trend is related to tectonically driven uplift and compression field stratigraphic sedimentological petrographic geochemical and provenance data on the lower oligocene shallow marine deposits revealed the accretionary prism i e pindic cordillera or biga peninsula as the major contributor of sediments into the forearc region field investigations in these shallow marine deposits revealed the occurrence of conglomerates with 1 mafic and ultramafic igneous rock clasts 2 low grade metamorphic rock fragments and 3 sedimentary rocks the absence of felsic volcanic fragments rules out influence of a felsic source rock geochemical analysis indicates that the studied rocks were accumulated in an active tectonic setting with a sediment source of mainly mafic composition and palaeodispersal analysis revealed a ne nne palaeocurrent trend towards the rhodopian magmatic arc thus these combined provenance results make the accretionary prism the most suitable candidate for the detritus forming these shallow marine deposits

discussion unraveling the provenance of eocene oligocene sandstones of the thrace basin north east greece by caracciolo et al 2011 sedimentology 58 1988 2011

biostratigraphic data from the cetmi melange northwest turkey palaeogeographic and tectonic implications abstract the cetmi accretionary melange is cropping out in the biga peninsula of northwest turkey it is characterised by an isolated position relatively far from the accretion complexes of the nearest suture zones which raises the question of its lateral correlations a detailed biostratigraphic investigation of the limestone and radiolarite blocks and the matrix of the cetmi melange allowed to propose a solution for this palaeogeographic problem scarce red nodular limestones in the han bulog facies represent the oldest lithology in the melange their late scythian ladinian age is based on chiosella gondolleloides the co occurrence of gladigondolella sp and nicoraella cf kockeli and paragondolella fuelopi light grey limestone blocks are a characteristic feature of the cetmi melange they occur in two distinct facies facies a consists of packstone to grainstone and is characterised by unsorted and poorly washed pelbiosparites facies b consists of wackestone to packstone and is characterised by poorly washed biopelmicrites to biopelsparites the foraminiferal assemblage of facies a containing triasina hantkeni is of late norian to rhaetian age the foraminiferal assemblage of facies b never contains t hantkeni and is characteristic of a late triassic carnian to norian rhaetian age radiolarian cherts are widely distributed in the cetmi melange they record fully pelagic sedimentation from the upper bajocian to the aptian the matrix of the cetmi melange consists of brown to black shales sometimes silty or siliceous intercalated with dark grey greywackes palynomorphs of one sample of brownish silty shale yielded an early to middle albian age based on the co occurrence of several dinoflagellate cysts the age of the matrix representing the youngest lithology within the melange and of the unconformable overlaying section latest albian cenomanian indicate that the melange forming process stopped between the early albian and the latest albian cenomanian at a regional scale the cetmi melange has little in common with the melanges from the izmir ankara and intra pontide sutures of northwestern turkey precluding a direct correlation on the other hand the cetmi melange shares several characteristics with the melange like units of the eastern rhodope zone bulgaria and greece like a major cenomanian transgression the reworking of triassic limestones and middle jurassic lower cretaceous radiolarians and the absence of jurassic cretaceous passive margin lithologies the occurrence of rhodopian units on the biga peninsula suggests that the studied units represent an isolated fragment of the rhodope zone in nw turkey

a first deep seismic survey in the sea of marmara deep basins and whole crust architecture and evolution abstract increased source strength streamer length and dense spatial coverage of seismic reflection profiles of the seismarmara leg 1 allow to image the deep structure of the marine north marmara trough nmt on the strike slip north anatolian fault naf west of the destructive izmit 1999 earthquake a reflective lower crust and the moho boundary are detected they appear upwarped on an e w profile from the southern central basin eastwards towards more internal parts of the deformed region thinning of the upper crust could use a detachment suggested from an imaged dipping intracrustal reflector that would allow upper crustal material to be dragged from beneath it and above the lower crust accounting for the extensional component but also southwest motion of the southern margin of the nmt sections across the eastern half of the nmt crossing the cinarcik and imrali basins reveal several faults that are active reaching into the basement and have varying strike and proportions of normal and strike slip displacement they might be viewed as petals of a large scale negative flower structure that spreads over a width of 30 km at surface and is rooted deeper in the lithosphere under the central basin a very thick sediment infill is revealed and its extensional bounding faults are active and imaged as much as 8 km apart down to 6 km depth we interpret them as two deep rooted faults encompassing a foundering basement block rather than being merely pulled apart from a jog in a strike slip above a decollement the deep basin lengthening would account for only a modest part of the proposed 60 km finite motion since 4 myr along the same direction oblique to the nmt that sidesteps the shear motion from its two ends thus differential motion occurred much beyond the deep basins like subsidence involving the nmt bounding faults and the intracrustal detachments the complex partitioned motion localized on active faults with diverse natures and orientations is suggested to represent the overburden deformation induced from horizontal plane simple shear occurring in depth at lithospheric scale and in front of the north anatolian fault when it propagated through the region

moho crustal architecture and deep deformation under the north marmara trough from the seismarmara leg 1 offshore onshore reflection refraction survey abstract understanding further the nature and evolution at lithospheric scale of the sea of marmara on the north anatolian fault needs constraints on the deep crustal and moho spatial variation this has been probed here with offshore onshore and obs ocean bottom seismometer refraction seismics in addition to coincident mcs marine multichannel reflection seismic profiles over the whole north marmara trough the diverse strikes of mcs profiles in a dense grid allow to avoid misinterpretation of late echoes in the deep basin as moho reflections and attribute them to sidesweeps moho is instead positively identified from reversed observations of first arrival head and refracted waves at the top of the mantle obtained at large offset by land stations a significant and sharp reduction in its depth on the order of 5 km occurs beneath both the eastern and western rims of the north marmara trough with a more progressive crustal thinning from the south the wide angle reflections on obs and land stations document in addition to moho the top of a lower crustal reflective layer which is also sampled by mcs profiles and appears to follow moho topography the dense grid of mcs profiles along the southwestern margin of the north marmara trough reveals a dipping reflector through the upper crust with tilted basement blocks on top this low angle fault is suggested as a normal sense detachment extending in depth towards the reflective lower crust the upwarp of the moho and lower crustal layer towards the north marmara trough suggests that crustal thinning occurs mostly in the upper crustal part with lateral transport of the material towards wsw in the footwall of the detachment and possibly other features to the south in the motion of anatolia with respect to stable eurasia oblique to the north marmara trough thinning can be accommodated in an asymmetric partitioning of the displacement on several branching faults at lithospheric scale

eocene oligocene stratigraphy and structural history of the karaburun area southwestern black sea coast turkey transition from extension to compression the stratigraphic succession exposed in the karaburun area southern black sea coast nw turkey records multiple changes in depositional and tectonic settings during cenozoic times it starts with the middle upper eocene sogucak formation of reef limestone that across a normal fault omitting the lower part of the lower oligocene ceylan formation deep marine shale unit abuts the upper part of the ceylan formation that is made up of two facies 1 shallow marine sandstone and 2 shallow marine limestone units containing horizons of submarine slumps both facies are unconformably overlain by the fluvial upper miocene cukurcesme formation the tectonic record includes 1 latest eocene early oligocene ne sw extension 2 early oligocene ne sw shortening and 3 late miocene nw ne extension the earliest normal faults cutting the sogucak and the lower part of the ceylan formations are associated with clastic dykes injected into the deep marine shale these structures suggest a disruption of the eocene carbonate platform and are also known in the neighbouring thrace basin the following ne sw shortening created the ne vergent karaburun thrust that is synchronous with the shallowing and inversion of the ceylan basin rotation of the stress field is recorded by changes in clastic dyke orientation and their deformation compression caused multiple westerly directed submarines slides from uplifts in easterly located regions this event is not recorded in the thrace basin finally the miocene tectonic activity formed nw and ne striking normal faults the outlined tectonic history includes early oligocene extensional and compressional episodes recorded in the southern margin of the black sea that had hitherto not been known

molecular and isotopic composition of gas occurrences in the thrace basin turkey origin of the gases and characteristics of possible source rocks abstract molecular and isotopic compositions of nine gas samples from seven fields in the thrace basin northwest turkey are determined in order to define the characteristics of the respective possible source rocks according to previous organic geochemical studies the hamitabat ceylan and mezardere formations are considered as potential source rocks a first evaluation of the 13 c values of methane ethane propane and the d isotope value of methane indicated in general a thermogenic origin however a further evaluation which considers the isotopic composition of 13 c from methane ethane and propane vs 1 n where n is the respective number of carbon atoms in each gas molecule showed mixing of gases of different origin in most of the analysed gas samples consequently three gas groups are distinguished group a a thermogenic gas from a single source rock group b a mixture of thermogenic and microbial gases group c a mixture of thermogenic gases at least from two different source rocks a modelling approach which predicts the isotopic composition of a thermogenic gas from a marine or terrestrial organic matter as a function of isotopic composition and maturity of the respective source rock enabled definition of source rock properties a mature 1 3 1 6 vitrinite reflectance source rock with a mixed terrestrial marine type of organic matter and an early mature 0 7 0 8 vitrinite reflectance source rock with marine organic matter were identified as precursors of thermogenic gases in the basin furthermore microbial gas also contributed to the formation of some gas fields in all natural gas samples investigated the mature source rock of mixed type organic matter contributed the major part of thermally generated gas in this way it has to be considered as the main gas producing source in the thrace basin however a final gas source rock correlation was not performed since all the three possible source rocks have gained the predicted maturity ranges in the kitchen areas of the gas fields and the spatial distribution of organo facies of the potential source rocks is unknown this study in thrace basin has shown that determination of source rock properties by isotopic modelling contributes to gas source rock correlation which is problematic in basins with more than one possible source rock

geochemical overview and undiscovered gas resources generated from hamitabat petroleum system in the thrace basin turkey abstract since the first drill in 1957 three oil 19 gas and condensate fields have been discovered in the thrace basin however any petroleum system with its essential elements and processes has not been assigned yet this study consists of two parts 1 geochemical overview of the previous work in order to get a necessary help to construct a petroleum system and 2 calculation of quantitative undiscovered hydrocarbon resources generated from this system an extensive overview study showed that the primary reservoir and source rocks in the thrace basin are the middle eocene hamitabat sandstones and shales respectively hence it appears that the most effective petroleum system of the thrace basin becomes the hamitabat petroleum system currently 18 5 billion m 3 of in place gas 2 0 million m 3 12 7 million bbl in place waxy oil as well as minor amount of associated condensate were discovered from this system this study showed that the regional distribution of the oil and gas fields almost overlapped with the previously constructed pod of active hamitabat shales implying that short and up dip vertical migration pathway of hydrocarbons from the source to trapping side was available thermal model demonstrated that hydrocarbon generation from the hamitabat shales commenced in the early miocene the amount of quantitative gas generation based on the mean original toc 0 94 wt mean original hi 217 hc g toc and the volume of the pod of active source rock 49 km 3 is approximately 110 billion m 3 of gaseous hydrocarbons that results in a high generation accumulation efficiency of 17 when 18 5 billion m 3 of already discovered hydrocarbons are considered

nature of a regional dogleg pattern in maturity profiles from thrace basin northwestern turkey a newly discovered unconformity or a thermal anomaly vitrinite reflectance ro profiles of the thrace basin are characterized by a regional dogleg pattern corresponding to the depths of ceylan and hamitabat formations we investigated the nature of this dogleg pattern using a one dimensional thermal maturity model by simulating three possible geological scenarios 1 two possible newly discovered unconformities one between the hamitabat and soucak or hamitabat and ceylan formations and the other within the hamitabat formation 2 an abnormal paleoheat flow regime paleothermal kick that developed in the oligocene and extended until the end of the early miocene and 3 a sharp thermal conductivity contrast in the stratigraphic column caused by thermally low conductive deposits of the ceylan formation which act as a regional thermal blanket the sensitivity of each suggested scenario within the model and their effect on the observed dogleg pattern have been examined a comparison of the measured and calculated modeled ro profiles from the proposed scenarios shows that the dogleg pattern can be best explained by a combination of the second paleoheat flow and third scenarios thermal conductivity instead of the unconformity scenario however the discovery of these two newly defined discordance surfaces with the help of well and seismic data requires a significant modification to the chronostratigraphy of the thrace basin the hamitabat karaaa ftepe and gaziky formations and the lower sections of the kean formation are suggested to be time correlative counterparts in a newly constructed chronostratigraphy thus the hamitabat formation can be evaluated as a part of the early middle eocene sequence similar to the gaziky formation in this article we suggest that the hamitabat formation be classified as a group instead of a formation

tectonic and sedimentary controls on widespread gas emissions in the sea of marmara results from systematic shipborne multibeam echo sounder water column imaging understanding of the evolution of fluid fault interactions during earthquake cycles is a challenge that acoustic gas emission studies can contribute a survey of the sea of marmara using a shipborne multibeam echo sounder with water column records provided an accurate spatial distribution of offshore seeps gas emissions are spatially controlled by a combination of factors including fault and fracture networks in connection to the main marmara fault system and inherited faults the nature and thickness of sediments e g occurrence of impermeable or gas bearing sediments and landslides and the connectivity between the seafloor and gas sources particularly in relation to the eocene thrace basin the relationship between seepage and fault activity is not linear as active faults do not necessarily conduct gas and scarps corresponding to deactivated fault strands may continue to channel fluids within sedimentary basins gas is not expelled at the seafloor unless faulting deformation or erosional processes affect the sediments on topographic highs gas flares occur along the main fault scarps but are also associated with sediment deformation the occurrence of gas emissions appears to be correlated with the distribution of microseismicity the relative absence of earthquake induced ground shaking along parts of the istanbul silivri and princes islands segments is likely the primary factor responsible for the comparative lack of gas emissions along these fault segments the spatiotemporal distribution of gas seeps may thus provide a complementary way to constrain earthquake geohazards by focusing the study on some key fault segments e g the northern part of the locked princes islands segment

imaging the basin and fault geometry from the multichannel seismic reflection data in the tekirda g basin marmara sea turkey summary determination of the fault geometry in the marmara sea has been a major problem for the researchers after the occurrence of the 1999 august 17 golcuk m 7 4 earthquake to shed a light to the problem we applied the pre stack kirchhoff depth migration technique to the multichannel seismic reflection data of three profiles to investigate the basin and fault geometry in the tekirda g basin in the western marmara sea the boundary of the basin and its sediments were revealed in n s and ne sw directions in depth sections we identify major fault types involving these structures at different locations in tekirdag basin showing that the basin is developed under their movement the north anatolian fault is imaged and interpreted as transtensional character at the centre of the tekirda g basin that is symmetrically divided with a large distributed zone the fault plane is imaged through the depth of 2 km dipping to the north with 90 in the upper 350 m and 82 in the lower part the basin thickness reaches about 2 5 km at that point syn transform sediments of the basin are disturbed by some normal faults dipping to the north these faults are represented by notable displacements of the reflections which prompted us to consider them as a potential tsunami source if they move during a large earthquake along the major fault another major fault is identified at the westernmost of the basin because it shows the same character as ganos fault it might be submarine part of it it has reverse component with the dip angle of 65 to the north and trending along the western flank of the basin a reverse fault is identified appearing in low angle 20 surrounding the edge of the submarine slide at southwest of the basin from its geometry it is interpreted as a local fault formed between two main faults from the sketch of the basin and the fault geometry obtained from the images we suggest that the basin should be formed by a pull apart system

how a mud dominated ramp changed to a carbonate clastic oil reservoir sea level fluctuations in cretaceous of the central persian gulf abstract mud dominated facies distribution of barremian turonian succession in the northeastern arabian plate in the central persian gulf represents a shallow ramp platform on the basis of petrographical studies core analysis data and gamma ray logs this succession has been studied for facies analysis defining depositional environment sequence stratigraphy and reservoir properties a total of 6 microfacies and 3 petrofacies types are recognized in this succession lagoonal environment was dominated during the deposition of dariyan kazhdumi and sarvak formations the lagoon rapidly changed to a sand shoal by falling sea level and increasing energy level of the depositional environment sequence stratigraphy of barremian turonian succession shows that mud dominated facies have been deposited in tsts and grain dominated facies in hsts of the sequences although grain dominated facies like packstone to grainstone and algal floatstone were spread during the hsts of sequences the changes in the texture and size of the grains had a negligible effect on reservoir quality during this period barremian turonian two major sea level falls caused considerable environmental changes such as platform emergence incised valley fills and clastic sediments influx into the carbonate platform meteoric diagenesis during the falling sea level had a major effect on the reservoir properties of the reservoirs under the sequence boundaries grains matrix and micrite dissolution and subsequent selective blocky and equant calcite cementation strongly modified the primary reservoir properties local dolomitization also enhance the porosity and permeability of the samples while large pores have been filled by cements microporosities remained unfilled until the late stages of diagenesis and burial

gas source rock correlation in thrace basin turkey abstract the tertiary thrace basin is the most productive gas province of turkey since exploration in the basin started almost 40 years before many elements of the petroleum system are now known however a gas source rock correlation is still not available as modern methods of correlation have still not been utilized yet a recent study on molecular and isotopic composition of gases could only show that gas accumulations have different origins accordingly a mature source rock with a mixed type of organic matter an early mature source rock with a mainly marine organic matter and a biogenic source have contributed in varying combinations to the formations of gas fields in the basin all of the three potential source rocks namely the lower eocene hamitabat formation upper eocene lower oligocene ceylan formation and the oligocene mezardere formation can fulfill the required maturity and organic matter type requirements in different parts of the basin furthermore the basin wide variation of these parameters is not known due to insufficient subsurface data and non representative distribution of data points therefore a new approach which considers the temporal development of maturation and gas generation in different source rocks within the drainage area of the gas fields and the presence of traps during this critical period was necessary in this study maturation and gas generation history of these three potential source rocks in the drainage areas of gas fields were determined by basin modelling comparing the presence of traps for a given gas field at these critical time periods of maturation and gas generation the most probable source rock could be determined the evaluation of the respective petroleum system in the drainage areas of the gas fields indicated that the hamitabat formation was the source for the pure thermogenic mature gases in the kuzey marmara hamitabat and karacaoglan fields it also contributed to the gas accumulations in several reservoir horizons in the degirmenkoy field the mezardere formation was the source rock for mature thermogenic gas in the karacali hayrabolu and tekirdag fields in these fields mixing with a biogenic gas also took place the mezardere formation was also the source of early mature thermogenic gas in the degirmenkoy field