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

validation of the ice 3g model of wurm wisconsin deglaciation using a global data base of relative sea level histories a global data base consisting of radiocarbon controlled relative sea level rsl histories from 392 different geographic locations has been compiled for use in analyses of the glacial isostatic adjustment process these data may be employed to constrain both the spatiotemporal characteristics of the last deglaciation event of the current ice age and the rheological structure of the planetary interior in a previous paper in this series tushingham and peltier 1991 we employed the rsl data in this set from sites that were once ice covered to refine the apriori model of deglaciation that had been delivered by past research in the area of pleistocene geomorphology peltier and andrews 1976 wu and peltier 1983 to produce a new global model of this event that we have called ice 3g in the present paper following a description of the full data base and of the methods used to compile it we employ data from the sites that were not ice covered 200 time series to verify the plausibility of this refined model of deglaciation and to test the extent to which the totality of the observations constrain the radial viscoelastic structure of the planet the analysis of solutions to the forward problem presented here reinforce previous inferences of a preference for a thick lithosphere by rsl data from sites along the u s east coast and a preference by data from most near field sites for an increase in viscosity across the 670 km discontinuity in the mantle by a factor of approximately 2 when the viscosity of the upper mantle is fixed to the value of 1021 pa s originally deduced by haskel 1935 on the basis of his analysis of the data from fennoscandia

wave dispersion study for tsunami propagation in the sea of marmara in this paper the aim is to investigate whether there are differences between the dispersion and non dispersion solutions on tsunami propagation for this purpose two numerical models of tsunami propagation are compared one of these numerical models is a nondispersive model that uses saint venant equations and the other is a dispersive model that uses boussinesq equations the tsunamis resulting from a submarine mass failure smf which is settled at the bottom of the north eastern sea of marmara are examined an analytical solution considering wave dispersion is developed for obtaining near field tsunami amplitudes above the submarine mass failure numerical modeling is used at the sea surface from the common boundary called as liquid boundary with incident waves up to the coastal regions to get the tsunami amplitudes the output of the analytical model is taken as the disturbances for the numerical method in the numerical solutions telemac 2d software system is used for both dispersive and nondispersive modeling the results of the dispersive and nondispersive models are compared to each other both temporal and spatial differences in the amplitudes and wave shapes are examined the obtained results demonstrate that there are no noticeable differences between the dispersion and non dispersion solutions except some special cases and some special landslide velocities

progradation of the late quaternary gediz delta turkey abstract detailed 3 5 khz seismic reflection profiling and coring have shown that the continental shelf break and slope off izmir bay turkey are formed by prograding deltaic silty mud sequences the muds contain shallow brackish water benthic and cold water planktonic foraminifera they were deposited when sea level was about 110 m below its present position during the last pleistocene glaciation slumping took place on the prodelta slope leaving rotational slump scars and imbricate slump blocks downslope delta top truncation took place in shallow water by erosive coastline retreat after distributary abandonment there has been little or no sedimentation since that time outer izmir bay is thus floored by relict sands following rapid post glacial transgression the gediz delta was reestablished in izmir bay archaeological evidence shows it has prograded during the last 3000 yrs at least six shifts in the position of the gediz mouth are distinguished during this time and abandoned delta top channels can be correlated with submarine delta lobe sequences

pleistocene holocene calcareous nannofossil biostratigraphy of core samples from the northeastern sea of marmara fenerbahce pendik nw turkey abstract pseudoemiliana lacunosa gephyrocapsa oceanica and emiliania huxleyi ionian pleistocene holocene calcareous nannoplankton zones were identified from 82 samples of 14 cores taken from 8 locations in the northeastern sea of marmara the investigation indicates that the identified biozones have been alternated by tectonic activity in the 1 5 and 6 core locations the study area has been affected three times by tectonic activity during the pleistocene holocene time interval the first activity occured during the early pleistocene and the others during holocene

late pleistocene holocene evolution of the northern shelf of the sea of marmara abstract chirp sub bottom profiling multibeam bathymetric mapping and a combination of faunal and isotopic analysis of molluscs and foraminifera in sediment cores on the northern shelf of the sea of marmara som provide evidence of sea level excursions water exchanges between the adjacent mediterranean and black seas and oscillating salinity over the last 160 ka bp during the marine isotope stages mis 2 mis 3 mis 4 and mis 6 the som disconnected from the mediterranean sea and evolved into a lake during mis 1 mis 5 and mis 7 the som reconnected and became salty once again sapropels formed shortly after each invasion of mediterranean saltwater observed in our cores concurrent suboxic dysoxic conditions prevailed over quite shallow substrates on the shelf ancient shorelines are pervasive at 85 m on the northern shelf and in the region of prince islands coincident with the elevation of the modern bedrock sill in the canakkale dardanelles strait at times when global eustatic sea level dropped below this sill the surface of the som stabilized at its outlet and freshened thus this particular shoreline is interpreted as the edge of the most recent som lake that existed from about 75 ka bp to 12 ka bp the freshening is observed in very light 6 values of 18 o measured on freshwater molluscs and the complete absence of foraminifera two brief lacustrine episodes during mis 5 suggest that the level of the canakkale outlet might have been as shallow as 50 m in the past a likelihood supported by submerged terraces along its margins bounding the modern central channel and the presence of an euryhaline biofacies in unit l4 1 corresponding to mis 5b 18 o profiles and carbon 14 dating show that salinification of the som and the blossoming of bioherms evolved rapidly after the latest connection with the mediterranean at 12 ka bp however freshening proceeded more slowly once the connection was severed

seismic imaging of the three dimensional architecture of the cinarcik basin along the north anatolian fault the cinarcik basin is a transtensional basin located along the northern branch of the northern north anatolian fault naf in the sea of marmara the eastern half of which has been identified as a seismic gap during the seismarmara 2001 experiment a dense grid of multichannel seismic reflection profiles was shot covering the whole cinarcik basin and its margins the new seismic images provide a nearly three dimensional view of the architecture of the basin fault system at depth and sedimentary infill and provide insight into its tectonic evolution along both northern and southern margins of the basin seismic reflection data show deep penetrating faults hence long lived features which have accommodated a large amount of extension there is no indication in the data for a single throughgoing strike slip fault neither a cross basin fault nor a pure strike slip fault running along the northern margin faster opening is presently observed in the eastern part of the basin the cinarcik basin seems to have developed as a transtensional basin across strike slip segments of the northern naf for the last few million years

distribution of surficial shelf sediments in the northeastern and southwestern parts of the sea of marmara strait and canyon regimes of the dardanelles and bosporus surficial sediment samples collected from the northeastern and southwestern shelf regions of the sea of marmara together with data available from other sources indicate marked variations in sediment compositions resulting from differences in topographical hydrological and biological conditions in the strait channels of the dardanelles and bosporus where strong undercurrents prevail the floor was covered mostly by coarse grained sediments rich in sand and gravel however in areas of relatively low energy conditions sediments contained appreciable amounts of mud with a tendency towards an increase in the amount of clay towards the open sea the effects of the strong undercurrents on the bedforms was also apparent in the southern strait of bosporus where sidescan sonar surveys revealed the presence of asymmetrical sand ripples although terrigenous mud is the principal sediment type in the two canyons dardanelles and south bosporus the sediments in particular on the floor of south bosporus canyon show a distinct contrast between the inner n s and outer e w trending parts along its axis where depths are greatest the outer part of the canyon appears to contain much more coarse sediment in part derived from the benthic communities than the inner canyon in general both the topography related current regimes and the biological activities in the study areas mostly determine the types and modes of sediment distribution among the biogenic components the calcareous corraline algae rhodophycae chiefly lithothamnium calcareum and l fruticolusum and the molusc families galeommatacae and cerithiospidae are associated with the prevailing mediterranean undercurrents especially in the shallower waters of the junction of the sea of marmara and strait of bosporus the relatively abundant mollusc species mytilus galloprovincialis and modiolus barbatus and the trochidae in the strait of bosporus are largely affected by black sea waters the wide range of carbonate concentrations in the sediments generally reflects the relative abundances of biogenic admixtures in the samples high carbonate percentages in the sediments are usually associated with low mud contents and vice versa interestingly the organic carbon contents of the sediments generally increase with proximity to the black sea suggesting influxes of appreciable amounts of organic matter from the black sea

neotectonics of the southeast marmara region nw anatolia turkey the north anatolian fault zone nafz bifurcates into three branches in the marmara region which is a transition zone between the strike slip tectonics manifested by the nafz and the n s directed extensional regime of western anatolia the southern marmara region is characterized by the middle and the southern branches while the northern branch controls the north marmara region the south marmara region is characterized by approximately e w trending rhomb like horst and graben complexes bounded by strike slip faults with normal component striking mainly in e w direction this study documents the geometry and the structural characteristics of the nafz in the southeast marmara region and discusses the commencement age of the strike slip tectonics using deformation patterns of neogene units and information available in the literature q 2002 elsevier science ltd all rights reserved

reassessment of probabilistic seismic hazard in the marmara region abstract in 1999 the eastern coastline of the marmara region turkey witnessed increased seismic activity on the north anatolian fault naf system with two damaging earthquakes m 7 4 kocaeli and m 7 2 duzce that occurred almost three months apart these events have reduced stress on the western segment of the naf where it continues under the marmara sea the undersea fault segments have been recently explored using bathymetric and reflection surveys these recent findings helped scientists to understand the seismotectonic environment of the marmara basin which has remained a perplexing tectonic domain on the basis of collected new data seismic hazard of the marmara region is reassessed using a probabilistic approach two different earthquake source models 1 the smoothed gridded seismicity model and 2 fault model and alternate magnitude frequency relations gutenberg richter and characteristic were used with local and imported ground motion prediction equations regional exposure is computed and quantified on a set of hazard maps that provide peak horizontal ground acceleration pga and spectral acceleration at 0 2 and 1 0 sec on uniform firm rock site condition 760 m sec average shear wave velocity in the upper 30 m these acceleration levels were computed for ground motions having 2 and 10 probabilities of exceedance in 50 yr corresponding to return periods of about 2475 and 475 yr respectively the maximum pga computed at rock site is 1 5 g along the fault segments of the naf zone extending into the marmara sea the new maps generally show 10 to 15 increase for pga 0 2 and 1 0 sec spectral acceleration values across much of marmara compared to previous regional hazard maps hazard curves and smooth design spectra for three site conditions rock soil and soft soil are provided for the istanbul metropolitan area as possible tools in future risk estimates

morphotectonic evidence from the southern branch of the north anatolian fault naf and basins of the south marmara sub region nw turkey this study investigated the morphotectonic evidence from the southern branch of the north anatolian fault naf and the south marmara sub region nw turkey the south marmara sub region has two uplifts located in the south and north and a depression between these uplifts the uplifts are bounded by the southern branch of the naf the southern branch is divided into the yenice gonen ygfz manyas mustafakemalpasa mmf uluabat ufz and bursa bfz faults the relation between the active tectonics and recent morphology were evaluated by using the geomorphic indices gis af asymmetry factor t topographic symmetry factor sl river length gradient index smf mountain front sinuosity gis were used to define the effects of tectonism on morphology and were used to calculate the relative tectonic activity index iat the values obtained through the gis indicate a young tectonism in the study area the study area morphometrically presented two iat classes class 1 high relative tectonic activity and class 2 moderate relative tectonic activity the present gps data and iat classes of the southern branch faults of the nafz were correlated all of the calculations and field data reveal that the southern branch of the naf is the main tectonic element forming the geomorphology of the south marmara sub region

uplift and subsidence from oblique slip the ganos marmara bend of the north anatolian transform western turkey abstract bends that locally violate plate motion parallel geometry are common structural elements of continental transform faults we relate the vertical component of crustal motion in the western marmara sea region to the nnw pointing 18 bend on the northern branch of the north anatolian fault naf n between the ganos segment which ruptured in 1912 and the central marmara segment a seismic gap crustal shortening and uplift on the transpressive west side of the bend results in the ganos mountain crustal extension and subsidence on the transtensional east side produce the tekirdag basin we propose that this vertical component of deformation is controlled by oblique slip on the non vertical north dipping ganos and tekirdag segments of the north anatolian fault we compare holocene with quaternary structure across the bend using new and recently published data and conclude the following first bend related vertical motion is occurring primarily north of the naf n this suggests that this bend is fixed to the anatolian side of the fault second current deformation is consistent with an antisymmetric pattern centered at the bend up on the west and down on the east accumulated deformation is shifted to the east along the right lateral naf n however leading to locally opposite vertical components of long and short term motion uplift has started as far west as the landward extension of the saros trough current subsidence is most intense close to the bend and to the ganos mountain while the basin deepens gradually from the bend eastward for 28 km along the fault the pattern of deformation is time transgressive if referenced to the material but is stable if referenced to the bend the lag between motion and structure implies a 1 1 1 4 ma age for the basin at current dextral slip rate 2 0 2 5 cm year third the tekirdag is an asymmetric basin progressively tilted down toward the naf n which serves as the border fault progressive tilt suggests that the steep northward dip of the fault decreases with depth in a listric geometry at the scale of the upper crust and is consistent with reactivation of paleogene suture related thrust faults fourth similar thrust fault geometry west of the bend can account for the ganos mountain anticline monocline as hanging wall block folding and back tilting oblique slip on a non vertical master fault may accommodate transtension and transpression associated with other bends along the naf and other continental transforms

long term seismicity of istanbul and of the marmara sea region we examine the long term seismicity of the marmara sea region in turkey over a period of twenty centuries to attempt to answer two questions 1 how well recorded in history is the earthquake activity of this region and 2 does seismicity over this long period of time differ from that over the present century we study this densely populated and fast developing region because it is one of the most tectonically active regions on the continents that appears today to be relatively quiescent

oxygen isotopes and sea level from the time that detailed oxygen isotope records derived from foraminifera living in the constant temperature environment of the abyssal ocean became available there has been a discrepancy between the ice volume record that these records imply and that derived from the altitude of dated coral terraces around the world here we re examine the data and conclude that the temperature of the abyssal ocean has been an actively varying component of the climate system

distribution of seismic velocities and attenuation in the crust beneath the north anatolian fault turkey from local earthquake tomography we investigate the crustal structure beneath the western part of the north anatolian fault zone nafz an area where at least five damaging earthquakes occurred during the twentieth century this study is based on local earthquake tomography using the data from aftershocks of the izmit event 17 august 1999 m 7 4 recorded by stations of permanent and temporary networks we derive the distribution of v p v s and the v p v s ratio based on the iterative inversion for both v p v s and v p v p v s using the lotos code innovatively in this study we perform an inversion for frequency dependent s wave attenuation 1 q s the reliability of the results is assessed through synthetic tests the distributions of the resulting seismic parameters v p v s v p v s and q s highlight important geodynamical features in the study area the low velocity and high attenuation patterns mostly correlate with the fracturing zones of the nafz low velocities are also observed beneath the main sedimentary basins e g adapazari duzce and kuzuluk high velocity and low attenuation patterns correlate with blocks presumed to be rigid kocaeli armutlu and almacik blocks the rupture traces of the largest earthquakes in this area pass generally in the transition areas between high and low velocities while moderate and weak seismicity is mostly concentrated in low velocity areas based on these results we propose and discuss the role that the almacik block could have played in producing the largest earthquakes in the study area in the twentieth century

evidence for a minimum 52 1 km of total offset along the northern branch of the north anatolian fault in northwest turkey abstract the north anatolian fault naf splits into two major branches in northwestern turkey with most of the present strain accumulation and holocene displacement being along the northern branch naf n estimates of total offset along the naf n range between 4 km and 70 km in the marmara sea region these different estimates lead to different interpretations on the formation of marmara sea basins in this study we use cretaceous faults sub perpendicular to the naf n as precise offset markers based on these faults as well as the offset of the middle eocene volcanic belt we report a minimum 52 1 km cumulative dextral displacement along the naf n east of marmara sea near 31 e longitude the displacement of the middle eocene volcanic belt shows that the offset is post middle eocene if we assume an additional 15 km dextral displacement on the second strand of the naf n duzce fault the total offset along the naf n can be estimated as 67 km in the eastern marmara region adding the published offsets that range from 16 to 26 km on the southern branch of the naf give a total offset estimate of whole naf zone as 88 5 km in the eastern marmara region the gps velocity estimate indicates 23 mm yr 1 of total plate motion across and near eastern marmara sea that would take 3 9 million years to accumulate 88 km of displacement on the naf additionally the anatolian plate would not have instantaneously accelerated to its modern rate of motion thus initiation of transform displacement must somewhat pre date 3 9 ma

tectonic evolution of the marmara sea and its surroundings abstract the basins in the marmara sea are the products of a superimposed evolutionary history defined by two different aged fault systems the early miocene early pliocene thrace eskisehir fault zone and its branches and the late pliocene recent north anatolian fault and its branches the thrace eskisehir fault and its westward branching secondary fault systems define the early neotectonic signature in the region the late neotectonic period started at the end of the early pliocene when the north anatolian fault divided the thrace eskisehir fault into four parts during the late neotectonic period the north anatolian fault extended westward as a number of splays by joining with the ganos bandirma behramkale and manyas edremit fault zones the branches of the north anatolian fault zone nafz caused the evolution of a number of basins which differ in character depending on the trend and past characteristics of the older branches that became connected since the northern branch of the north anatolian fault is connected to the n80 e trending ganos fault zone gfz in the west a single buried fault has developed in the marmara sea causing the well known troughs and ridges superimposed onto the negative flower structure formed by the gfz in the early neotectonic period the middle strand which extends from iznik lake to bandirma is oriented east west up to the n60 e trending bandirma behramkale fault zone then turns southward in the vicinity of bandirma forming a region dominated by compressional tectonics this bending caused n30 e trending tension in addition to the strike slip motion between the eastern part of gemlik bay and bandirma bay the southern branch of the nafz on the other hand produced three pull apart basins with different characteristics along the yenisehir bursa and manyas segments the southern branch of the nafz connected to the manyas edremit fault zone which is oriented n45 e to the south of manyas and the associated bending and rotation caused a n15 e trending extension in addition to the strike slip regime between manyas and uluabat the branches of north anatolian fault cut through the thrace eskisehir fault at three places the east marmara sea region in gemlik bay and to the east of bursa giving lateral offsets of 58 59 7 8 and 10 11 km respectively the cumulative motion is 75 78 km corresponding to the total lateral offset of the north anatolian fault in the region the correlation of these offsets with global positioning system slip vectors and with stratigraphic results implies that the north anatolian fault reached into the marmara sea region about 3 5 million yr ago tectonic processes forming the marmara sea and its environs were initiated by the thrace eskisehir fault and its splays have been most recently controlled by the north anatolian fault and its splays during the last 3 5 million yr

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

morphologic features of the marmara sea from multi beam data abstract the bathymetrical image of the marmara sea nw of turkey was prepared using data from mainly multi beam surveys and from various other sources the marmara sea presents a unique and complicated morphological system which is mainly controlled by the active tectonic regime of the north anatolian fault zone nafz the sub bottom morphology of the marmara sea consists of a wide shelf area 55 of the total area and the marmara trough which includes the slopes ridges and deep basins the four basins separated by ridges constitute the e w trending marmara trough in an elliptical form submarine canyons and landslides constitute the secondary morphological units of the marmara sea the angle and the shape of the slopes are variable in different parts of the marmara sea the linear shaped slopes bounding the cinarcik basin eastern extremity of the marmara sea and off the ganos mountain system west of marmara sea are characteristic with their high gradient and resulted from strike slip fault the curve shaped slopes with low angles are considered to be associated with normal fault e w aligned lineaments are morphological expressions of strike slip faults and can be traced from the ganos mountain system through cinarcik basin cutting through the basins and ridges in the western marmara trough and bounding the cinarcik basin at the slope basin transitions these lineaments reflect a new rupture of nafz and must have occurred after the formation of the marmara trough

palynology of sapropelic layers from the marmara sea palynological records of the sediments from the deep basins of the marmara sea revealed four palynological zones indicating the changing climatic conditions during late glacial to holocene the lower two zones were defined by the high abundance of artemisia and chenopodiaceae that suggest the climate of the source area was cold and arid however the establishment of mediterranean warm and wet climate and corresponding regression of continental aridity were shown by the decreasing chenopodiaceae and increasing pollen grains of humid type vegetation in zone c the highest total pollen with the dominance of quercus identifies the deglaciation and coincides with the formation of sapropelic layers in the marmara sea the warmer and humid condition of deglaciation was indicated with diversified moisture demanding deciduous and coniferous pollen grains in zone b these pollen assemblages and their distribution pattern indicate that the source area was warm and wet during the deposition of sapropelic layers in the marmara sea and also reflect signals of black sea origin

the sea of marmara a two dimensional seismic reflection profile data archive 1 in 1997 1500 km of high resolution two dimensional 2 d reflection seismic data were acquired in the sea of marmara region western turkey an archive of the 40 profiles of processed seismic data in segy format together with the differential global positioning system dgps locations and acquisition parameters for each profile are available for download from iris

high resolution seismic reflection profiles for the reconstruction of postglacial transgressive shorelines an example from greece abstract in 1982 we carried out a shallow penetration high resolution seismic profiling study on the shelf of the southern argolid peloponnesos greece to identify and map the shores of the late pleistocene and holocene and to establish their coastal environments portable equipment and a local boat were used the lowest glacial shore occurs at 115 to 118 m within the range of global values the subsequent rise across the distinct old land surface left behind many shore features scaps beaches and beach ridges channels and lagoons now buried under a few meters of post transgressive deposits these features cluster at a small number of depths below present sea level suggesting that the rise of the sea usually too fast to leave an imprint was episodically interrupted by brief stillstands or even temporary reversals of climatic or tectonic origin the clusters can be roughly dated with reference to a global sea level rise curve after 6000 yr b p sparse archaeological data establish a local curve the seismic profiling technique convenient and not costly holds promise for the identification of postglacial shores elsewhere prior to sampling for dating it has wide application for environmental reconstructions of vanished coastal zones as a basis for prehistoric resource assessments these applications are illustrated with examples from this study

the seismotectonics of the marmara region turkey results from a microseismic experiment the marmara region is an active tectonic zone characterised by the transition between the dextral strike slip regime of the north anatolian fault naf and the extension regime of the aegean sea strong historical earthquakes m 7 and the presence of known seismic gaps imply a high level of seismic hazard a synthesis of recent studies of active tectonics in the region is presented including inland and underwater observations the branching of the naf is explained in terms of increasing influence of the extension historical information and instrumental seismicity are reinterpreted in order to have a critical appraisal of the existence of large seismic gaps in the central and eastern marmara sea focal mechanisms of strong earthquakes are used to obtain orientation and shape factor of the deviator of the stress tensor the resulting tensor is in shear regime s 2 vertical but close to extension r 0 93 with s 1 oriented n145 0 a microseismic experiment with 48 stations distributed around the marmara sea was carried out in october december 1995 a total of 137 microearthquakes were located and 23 of those were selected to obtain focal mechanism solutions the epicentral distribution indicates activity along the system of pull apart basins north of the marmara sea the segment between marmara sea and the saros bay activated in 1912 and the gulf of izmit site of the 1754 earthquake are now silent seismic activity is very linear along the northern branch of the naf but it is more divused on the bursa and iznik branches southeast of the marmara sea the stress tensor obtained from the focal mechanisms of the micro earthquakes is compared to the one inverted from teleseismic data the microseismic stress is compatible with a shear intermediate regime like the one obtained from strong earthquakes though not as well constrained one of the acceptable solutions having the same orientation but diverent shape r 0 5 2000 elsevier science b v all rights reserved

high resolution seismic profiling in the sea of marmara northwest turkey late quaternary sedimentation and sea level changes high resolution sparker seismic profiling was carried out in the sea of marmara northwest turkey to study the late quaternary tectonics and sedimentation of this important active basin at the western end of the north anatolian fault zone a sedimentary unit interpreted as the clinoforms of a prograding delta was observed in places along the outer part of the southern shelf the topset foreset transitions of the latest clinoforms cluster around 100 m below present sea level they were probably deposited during the last glacial maximum and early phase of deglaciation between 25 and 13 k y b p when the level of the aegean was below that of the dardanelles sill 60 70 m below sea level at present therefore the sea of marmara was isolated from the aegean during the last glacial maximum but it is possible that a fluvial overflow existed across the dardanelles during this time stabilizing the level of the marmara lake and allowing the delta progradation rivers that drain into the sea of marmara from the south have a much greater combined drainage basin area and sediment flux than those draining the region to the north this may explain the much broader shelf to the south half graben bounded by north dipping normal faults observed within the southern shelf would tend to trap sediment sourced from the south and subdue any sea bed morphology on the shelf

quaternary paleoclimatic paleoceanographic and tectonic evolution of the marmara sea and environs strabo 63 bc 21 ad book 1 3 4 jones 1954 themarmarasea fig 1 hasalwaysattractedinterestasagreatgatewaylinkingtheblackseato the eastern mediterranean sea through a net work of narrow straits with shallow sills straitsof bosphorus istanbul and dardanelles c anakkale forthepast2500 3000yr informa tion about surface and bottom currents depthsoundings and sea level variation were crucialforsafenavigationacrossthesestraitsbysea far ingpeopleandexplorers thusconstitutingama jorstrategicassetandyieldingenormouseconom icandpoliticaladvantages throughoutantiquity sailors knew that the bottom waters across thestraits of dardanelles and bosphorus owednorthward and utilized this knowledge to sailintothemarmaraseaandblackseabyloweringlargebasketswithweightsintothenorth owingmediterranean water to counteract the strongsouth directed surface out ow from the blacksea systematic scienti c investigations in the mar marasearegionstartedinthelate19thcentury the rstbathymetricsurveyrevealedthepresenceof three deep basins and their intervening ridges andrussow 1901 p nar 1943 subsequentlyproposedthatasinglefaulttransectedthesethreebasins extending from the izmit bay in the eastto the gulf of saros in the west pfannensteil 1944 noted the rhombohedric shape of thedeepmarmaraseabasinsandproposedthattheridgesseparatingthebasinsrepresenthorstblocksbounded by normal faults healsosuggested inadditiontothestraitofbosphorus thepresenceofasecondchannel thesakaryabosphorus fig 1 which connected the black sea to the mar mara sea during the quaternary in 1948 ketinpublished his renowned paper revealing the truenatureofthenorthanatolianfaultasoneoftheworld slargest active intra continental strike slipfaults ketin 1948 pavoni 1961 and kopp etal 1969 proposedthataseriesofsyntheticand

using mechanical modeling to constrain fault geometries proposed for the northern marmara sea 1 in recognition of potential seismic hazard along the north anatolian fault within the marmara sea geophysical surveys have recently been conducted to collect high resolution bathymetry and seismic reflection data despite the high quality of the data fault interpretations by different authors are varied and a conclusive fault geometry within the marmara sea remains elusive this paper presents a mechanical modeling method for constraining proposed fault geometry interpretations in the model crustal faults within the marmara sea slip in accordance with gps constrained slip rates along deep plate boundary dislocations we test three fault models proposed by others and show that an interpretation with a series of pull apart basins along a master strike slip fault best produces the observed deformation pattern within the marmara sea the locations and relative subsidence of the basins along the northern marmara trough are well matched the computed slip vectors on the faults in the best fitting model indicate that except for small faults bounding the tekirdag basin the faults have dominantly right lateral slip with rakes within 15 of horizontal on the local scale this suggests that interaction between the segmented strike slip faults is the dominant mechanism producing the observed vertical deformation in the marmara sea on the regional scale if the marmara sea faults behaved in this manner over geologic timescales then right lateral plate boundary motion without an additional component of north south extension associated with the aegean sea is sufficient to produce the marmara sea pull apart basin morphology

a study of microearthquake seismicity and focal mechanisms within the sea of marmara nw turkey using ocean bottom seismometers obss we have carried out seismological observations within the sea of marmara nw turkey in order to investigate the seismicity induced after gflcqk iuzmit kocaeli earthquake mw 7 4 of august 17 1999 using ocean bottom seismometers obss high resolution hypocenters and focal mechanisms of microearthquakes have been investigated during this marmara sea obs project involving deployment of 10 obss within the cvnarcvk eastern marmara sea and central tekirdagu western marmara sea basins during april july 2000 little was known about microearthquake activity and their source mechanisms in the marmara sea we have detected numerous microearthquakes within the main basins of the sea of marmara along the imaged strands of the north anatolian fault naf we obtained more than 350 well constrained hypocenters and nine composite focal mechanisms during 70 days of observation microseismicity mainly occurred along the main marmara fault mmf in the marmara sea there are a few events along the southern shelf seismic activity along the main marmara fault is quite high and focal depth distribution was shallower than 20 km along the western part of this fault and shallower than 15 km along its eastern part from high resolution relative relocation studies of some of the microearthquake clusters we suggest that the western main marmara fault is subvertical and the eastern main marmara fault dips to south at 458 composite focal mechanisms show a strike slip regime on the western main marmara fault and complex faulting strike slip and normal faulting on the eastern main marmara fault d 2004 elsevier b v all rights reserved

late quaternary depositional history of the north evvoikos gulf aegean sea greece a high resolution seismic reflection survey was carried out in the north evvoikos gulf a deep 450 m semi enclosed basin in east central greece connected to the aegean sea via a 45 m sill to the north and a 30 m wide 10 m deep straight to the south this active extensional basin is bound by major normal faults that switch polarity along strike thereby controlling the asymmetric shape of the basin the survey records show a continuous upper unit in the marine strata deposited since the post glacial transgression on an erosion surface generated during the last glacial the upper unit can be traced downslope into the basin plain where it merges into a unit of laterally continuous interbedded turbidites and hemipelagic deposits the buried erosion surface has many terraces distributed over several depth zones between 65 m and 165 m below present sea level that are evidence for a fluctuating water level when in the last glacial interval the sill depth in the north was about 55 m below today s sealevel and the gulf became isolated from the aegean sea thus during the last 70 kyr the water level of the lowstand lakes fluctuated in correspondence with the oxygen isotope stages ois and the climatic conditions in the dryer stages ois 4 2 the lake water level was lower in the wetter stages ois 1 3 the lake water level was higher these events are also correlated with sediment budgets input from the surrounding land to the basin researches carried out in many other gulfs of variable depth in the ionian and aegean seas indicated presence of sills at today s depths between 50 and 70 m the generation of these features is postulated as sedimentary as many sea level fluctuations ranged in this depth interval

the north anatolian fault a new look dedicated to the memory of three pioneers ihsan ketin sirri erinc and melih tokay and a recent student aykut barka who burnt himself out in pursuit of the mysteries of the north anatolian fault abstract the north anatolian fault naf is a 1200 km long dextral strike slip fault zone that formed by progressive strain localization in a generally westerly widening right lateral keirogen in northern turkey mostly along an interface juxtaposing subduction accretion material to its south and older and stiffer continental basements to its north the naf formed approximately 13 to 11 ma ago in the east and propagated westward it reached the sea of marmara no earlier than 200 ka ago although shear related deformation in a broad zone there had already commenced in the late miocene the fault zone has a very distinct morphological expression and is seismically active since the seventeenth century it has shown cyclical seismic behavior with century long cycles beginning in the east and progressing westwa

modelling tectonic deformation along the north anatolian fault in the sea of marmara abstract using analogue techniques we attempted to model the complex tectonic deformation pattern observed along the north anatolian fault in the sea of marmara from morpho bathymetry and seismic reflection images in particular this paper focuses on the so called cinarcik segment of the fault connecting the eastern izmit segment which entirely ruptured during the mw 7 4 1999 earthquake to the western segment of the central high the cinarcik segment potentially loaded after the izmit earthquake is expected to rupture during an earthquake occurring in the near future possibly the next decades with a high potential to affect the istanbul metropolitan area our analysis suggests that the development of the observed structures accommodating strike slip transtensional and transpressional deformations could be explained by changes in the geometry of fault segments within a right lateral strike slip tectonic regime tectonic deformations were reproduced in the analogue model by imposing a small about 10 and sharp difference in the relative orientations of the strike slip segments at the edges of a major releasing bend in the model slower strain accumulation occurs along the analogue of the cinarcik segment than along the analogue of the izmit segment of the fault this would predict a delay for earthquakes triggered by stress transfer between the izmit and cinarcik segments the model further predicts that most of the deformation in the cinarcik basin is controlled by the sharp changes in the geometry of the fault itself

tectonic evolution of the north sea basin crustal stretching and subsidence summary the lithospheric stretching model for the formation of sedimentary basins was tested in the central north sea by a combined study of crustal thinning and basement subsidence patterns a profile of crustal structure was obtained by shooting a long range seismic experiment across the central graben the main axis of subsidence a seabed array of 12 seismometers in the graben was used to record shots fired in a line 530 km long across the basin the data collected during the experiment were interpreted by modelling synthetic seismograms from a laterally varying structure and the final model showed substantial crustal thinning beneath the graben subsidence data from 19 exploration wells were analysed to obtain subsidence patterns in the central north sea since jurassic times changes in water depth were quantified using foraminiferal assemblages where possible and observed basement subsidence paths were corrected for sediment loading compaction and changes in water depth through time the seismic model is shown to be compatible with the observed gravity field and the small size of observed gravity anomalies is used to argue that the basin is in local isostatic equilibrium both crustal thinning and basement subsidence studies indicate about 70 km of stretching across the central graben during the mid jurassic to early cretaceous extensional event this extension appears to have occurred over crust already slightly thinned beneath the graben and the seismic data suggest that total extension since the early permian may have been more than 100km the data presented here may all be explained using a simple model of uniform extension of the lithosphere

origin of the strait of canakkale dardanelles regional tectonics and the mediterranean marmara incursion abstract the regional tectonics and the mid to late quaternary seismic stratigraphy of the strait of canakkale dardanelles and its opening towards the aegean sea were interpreted by using shallow seismic profiles this strait is a narrow valley that resulted from regional uplift of the gelibolu and biga peninsulas in the pliocene as a consequence of compressional events generated by strike slip faulting activity of the ganos fault a northern strand of the north anatolian fault a nne ssw trending fault system between eceabat and canakkale believed to result from the left lateral displacement of the ganos fault on the gelibolu peninsula cut this valley into different segments the connection between the marmara basin and the aegean sea has been achieved after flooding of the connected valleys during the mid to late pleistocene three major sea level lowstands 130 150 m during this period 600 kyear bp interrupted the sea water connection at least twice three main seismic unconformities detected in the sediments of the strait of canakkale represent these lowstands minor sea level lowstands could have induced narrowing of the strait and erosion of depositional units the recent geological history of the strait of canakkale appears as deduced from the gelibolu peninsula and its western regions strongly related to escape tectonics influenced by the compressional forcing of the anatolian block in addition it also shows a morphological evolution which carries the effects of the global sea level variations

morphotectonic development of the marmara region abstract the marmara region of northwest turkey covers the marmara sea basin and the surrounding lands in the region morphologically different areas may be distinguished the marmara sea basin is a structural depression the land to the north is known as the thrace kocaeli peneplain a flatland elevated above a horst this may be referred to as the istanbul horst bounded by two strike slip fault zones which define the structural boundaries of two sea basins the black sea in the north and the marmara sea in the south the southern boundary fault is part of the north anatolian transform fault zone nafz which cuts through the region in the e w direction and extends to the aegean sea region the land to the south of the marmara sea is a plateau about 300 to 800 m high known as the bursa balikesir plateau it has a rather rugged topography represented by nw and ne trending ridges separated by depressions the ridges and the depressions correspond to horsts and grabens respectively the data reveal that the marmara region has passed through the following morphotectonic evolution together with the surrounding region it suffered a long period of denudation between the oligocene and the end of the late miocene which formed a regionwide peneplain the n s extensional regime followed this phase and began to produce a horst graben system and thus fragmented the peneplain the flat lying erosional surfaces have been elevated above the horsts later the nafz reached the marmara region in the initial stage it affected nw anatolia extensively as a wide right lateral shear regime this has evolved and through time the present narrow fault zone has developed the major morphological difference between the regions to the north and the south of the marmara sea basin is mainly related to the nafz as a plate boundary it formed a barrier to the n s extension saving the northern sector from the effect of the extension the southern region has gradually elevated to much higher altitudes

holocene sedimentation in the tectonically active tekirdag basin western marmara sea turkey abstract the effects of various depositional conditions and active tectonics on the late holocene sedimentation in the tekirdag basin west of the marmara sea were investigated in 11 gravity cores and on 3 seismic profiles representing shelf to slope to deep basin floor environments except for the two coarser grained avg 60 sand and gravel and calcareous avg 25 caco 3 shelf cores sediments in the slope and basin floor cores constitute low calcareous avg 12 caco 3 and terrigenous mud 90 silt and clay the occurrences of relatively higher total organic carbon contents in sediments from the southern slope 1 14 1 38 compared to that from the northern slope 0 37 1 2 indicate significant input from the southern rivers the presence of silty sandy laminations within the mud matrix of the cores and chaotic and mounded reflection configurations on the seismic profiles from the slope and basin floor environments all suggest the effects of gravity mass movements of sediments slides slumps turbidites most likely due to seismotectonic events earthquakes however it was difficult to establish a basin wide correlation between the historical earthquake events in the region and the positions of silty sandy laminations in dated deep sea sediment cores due to complicated other events such as repeated river run off and floods increased sediment load and slope failure the water contents of sediments from the basin floor avg 10 30 are significantly lower than those from the slope sediments avg 32 46 the former can be explained by the influences of synsedimentation with tectonics and compaction between the north and south boundary sub faults of the naf system whereas the latter shows fluidization of slope sediments during sliding and slumping radiocarbon dated base sections from three cores revealed that sediment deposition at these sites commenced about 4700 bp when the late holocene depositional conditions changed from the formation of upper sapropels to the present state the increases of organic carbon contents at or near the base sections of the cores support this contention

geochemistry of the lunar highlands as revealed by measurements of thermal neutrons thermal neutron emissions from the lunar surface provide a direct measure of bulk elemental composition that can be used to constrain the chemical properties of near surface depth 85 are generally associated with large impact basins and are colocated with clusters of nearly pure plagioclase identified with spectral reflectance data

seismicity of the sea of marmara turkey since 1500 summary we use the earthquake history of the last 500 years to help evaluate the tectonic and hazard contexts of the1999 earthquakes at izmit and dzce in westernturkey the 20th century has been unusually active but over the 500 year period the seismic moment release can account for the known right lateral shear velocity across the marmara region observed by gps two areas of known late quaternary faulting stand out as unusually quiet over this period the northwest shore of the sea of marmara and the southern branch of the north anatolian fault system between bursa and mudurnu

modes rates and geomorphological consequences of active tectonics in the marmara region nw turkey a critical overview based on seismotectonic field observations abstract the marmara region is a tectonically active belt in northwestern turkey where field evidence of the collusion escape and strike slip tectonics is manifested the effect of tectonics on the modification of coastal and morphological features of nw turkey is although extensive relatively unknown and rarely appreciated active tectonics in the region has normal and reverse forms of dip slip namely uplift and subsidence and strike slip as is plainly demonstrated by the 1999 marmara earthquake sequence along the north anatolian fault naf these tectonic effects are presently related to the geometry of the naf the mode of lateral movement along it and proximity to the fault the 1999 earthquakes provided data indicating that over a return period of about 250 years seismotectonic strike slip movements recur up to 5 m and dip slip movements up to 2 6 m suggesting the rate of tectonics along the naf in the marmara region is on the order of 20 mm a for strike slip and 10 mm a for dip slip movements these rates are sufficiently large to form during the late quaternary prominent features of the landscape in the marmara region

calibration of the c 14 timescale over the past 30 000 years using mass spectrometric u th ages from barbados corals uranium thorium ages obtained by mass spectrometry from corals raised off the island of barbados confirm the high precision of this technique over at least the past 30 000 years comparison of the u th ages with 14c ages obtained on the holocene samples shows that the u th ages are accurate because they accord with the dendrochronological calibration before 9 000 yr bp the 14c ages are systematically younger than the u th ages with a maximum difference of 3 500 yr at 20 000 yrbp the u th technique thus provides a way of calibrating the radiocarbon timescale beyond the range of dendrochronological calibration

active tectonics of the izmit gulf ne marmara sea from high resolution seismic and multi beam bathymetry data abstract several active faults were determined in the gulf of izmit using high resolution shallow seismic and multi beam bathymetry data one of them is a buried fault fault 2 following central axis of the gulf which forms the current morphology within its releasing and restraining bends releasing bends control the current morphology of the sub basins also restraining bends form folds in the central basin and a thrust in the western basin a left step over between two strike slip faults faults 2 and 11 creates a transpressional area therefore hersek and catal deltas are uplifted it is determined that fault 2 could not be related to the origination of the gulf because it cuts all basins and ridges thus present geometry of the fault 2 is not suitable for the initial formation of the gulf from this point of view the fault 2 is initiated recently compared to the whole north anatolian fault zone nafz in the marmara sea therefore fault 2 is recognised as a new rupture of the nafz probably active since the end of the last glacial ice period

oscillating quaternary water levels of the marmara sea and vigorous outflow into the aegean sea from the marmara sea black sea drainage corridor abstract detailed interpretation of single channel air gun and deep tow boomer profiles demonstrates that the marmara sea turkey experienced small amplitude 70 m fluctuations in sea level during the later quaternary limited in magnitude by the sill depth of the strait of dardanelles moderate subsidence along the southern shelf and quaternary glacio eustatic sea level variations created several stacked deltaic successions separated by major shelf crossing unconformities which developed during the transitions from global glacial to interglacial periods near the strait of dardanelles a series of sand prone deposits are identified beneath an uppermost holocene transparent mud drape the sandy deposits thicken into mounds with the morphology and cross sectional geometries of barrier islands sand waves and current generated marine bars all cross stratification indicates unidirectional flow towards the dardanelles prior to the deposition of the transparent drape which began 7000 years bp in strong support of the notion that the marmara sea flowed westwards into the aegean sea through the dardanelles at times of deglaciation in northern europe the global sea level curve shows that at 11 000 and 9500 years bp sea level rose to the sill depths of the straits of dardanelles and bosphorus respectively the effect from 11 000 to 9500 years bp was seawater incursion into the marmara sea drowning and formation of algal serpulid bioherms atop lowstand barrier islands and transgression of shelves and lowstand deltas at 9500 years bp glacial meltwater temporarily stored in the black sea lake developed into a vigorous southward flow toward the aegean sea forming west directed sandy bedforms in the western marmara sea and initiating deposition of sapropel s1 in the aegean sea this strong outflow persisted until 7000 years bp after which a mud drape began to accumulate in the marmara sea and euryhaline mediterranean mollusks successfully migrated into a progressively more saline black sea where sapropel deposition began most eastern mediterranean sapropels from s1 to s11 appear to correlate with periods of rising sea level and breaching or near breaching of the bosphorus sill these events are believed to coincide with times of vigorous outflow of low salinity fresh surface waters transiting the black sea marmara sea corridor and ultimately derived from melting of northern european ice sheets

moment tensor inversion of recent small to moderate sized earthquakes implications for seismic hazard and active tectonics beneath the sea of marmara summary we retrieve the moment tensors of 64 small to moderate sized events that occurred mostly beneath the sea of marmara using near field data recorded at strong motion and broad band seismic stations the near field displacement records are inverted to their sources utilizing kuge s method where the best fit between the synthetic and observed seismograms is achieved through searching a centroid moment tensor cmt point in a grid scheme we also analyse the stress fields acting in the eastern and western parts of the sea of marmara by inverting the p and t axes of the focal mechanisms obtained significant biases in the stress tensors are obtained the nearly horizontal maximum compressive axis 1 in the western part is rotated 16 counter clockwise compared with 1 in the eastern part the 2 axis is close to vertical shear tectonic regime in the east and the plunge of 2 axis in the west is 36 transpressive tectonic regime changes in the 3 axis are also observed that is it is close to horizontal in the east and dips 49 in the west the spatial distribution of the focal mechanisms suggests that the stress field in the eastern part of the sea of marmara is homogenous compared with the western part and we identify five distinct subsidiary faults 1 a wnw ese striking right lateral strike slip fault located a few kilometres sw of the princes islands 2 a wsw ene striking right lateral strike slip fault named the yalova hersek fault 3 an e w striking normal fault located onshore between

the 1999 izmit earthquake sequence in turkey seismological and tectonic aspects the izmit duzce earthquake sequence is the largest sequence recorded by modern digital networks in the history of turkish earthquakes the m w 7 4 izmit mainshock occurred at 29 967 e and 40 729 n and 13 km depth at 00 hr 01 min 38 7 sec utc on 17 august 1999 and was preceded by at least eight immediate foreshocks of magnitude m l 3 0 aftershock locations show that a large region has become seismically very energetic following the mainshock and that most of the aftershock zone developed quickly in the first 3 days the distribution of the aftershocks illuminates numerous seismotectonic structures associated with the various branches of the north anatolian fault naf in the aftershock zone the seismicity pattern defines a rupture plane that extends about 80 km east and 75 km west of the mainshock epicenter confirming bilateral rupture during the mainshock the western aftershock activity is almost entirely located offshore extending along the axis of the izmit bay we show that the westernmost extent of the mainshock rupture reached the offshore region just 10 km south of the princes islands the dominance of strike slip motion is one of the main characteristics of the izmit sequence a number of significant aftershock clusters occur off the inferred mainshock rupture plane the spatial and temporal occurrence of these clusters show that they are triggered by the complex redistribution of stresses and dynamic strains imposed by the dislocation of the mainshock the focal mechanisms of the events located in the western end of the rupture zone show both strike slip and normal faulting mechanisms we infer that the yalova cluster was triggered by the mainshock the dominance of the normal faulting mechanisms supports the notion that dynamic extensional strains played a major role in triggering this cluster four events located off the princes islands indicate similar source mechanisms characterized by right lateral strike slip motion parallel to the strike of the northern boundary fault nbf and local trend of aftershock distribution this observation leads to a first order seismotectonic evidence that the nature of the nbf which is known to be a transtensional feature at the surface is dominated by strike slip motion at depth the coexistence of strike slip and extensional seismotectonic features in the sea of marmara highlights the importance of strain partitioning amongst shallow transtentional structures accommodating north south extension and deeper structures associated with the naf accommodating east west right lateral shear manuscript received 22 september 2000

seismic activity triggered by the 1999 izmit earthquake and its implications for the assessment of future seismic risk summary a serious question has remained as to the location of the western end of the main rupture zone associated with the 1999 izmit turkey earthquake a clear answer to this question is extremely important for the assessment of future seismic risk in the eastern marmara sea region turkey in this paper we show an effective approach to answering this important question unifying different kinds of information such as seismic activity focal mechanism solutions and stress changes caused by the main shock into a clear image we first point out that the major moment release is 1 6r10 20 n m and covered the area between 29 7ue and 30 5ue and we then claim that the enhanced seismic activity after the main shock in the eastern marmara sea region should be regarded as activity triggered by the increase of stress rather than as aftershock activity along the ruptured zone we propose three fault segments with an average stress increase on each in the western extension of the main shock rupture zone as potential sites for future large earthquakes namely i the 50 km long yalova hersek segment 0 45 mpa ii the nw setrending right lateral strike slip fault known as the princes islands segment 0 18 mpa

seismicity and source parameters for small scale earthquakes along the splays of the north anatolian fault naf in the marmara sea summary major discrepancy between present day fault models in the marmara sea is closely related to structural development of depression areas beneath the sea therefore in this study the marmara sea and especially its major basins are investigated by means of recent seismological observations consisting of microseismicity 1 2 md 3 6 2002 may 2006 may focal mechanisms 2 4 md 5 0 1999 2006 and stress analysis based on the focal mechanisms in the cinarcik basin where either pull apart model or negative flower structure is proposed northeastern margin is represented by strike slip sources having a nw alignment probably corresponding to a cross basin strike slip fault developing in a matured pull apart basin this suggestion is directly relevant to experiments of sand box analogue models these experiments indicate that such a cross basin strike slip fault is produced after the pull apart basins attain their mature stage eventually resulting in less vertical displacements attributed to normal faults bounding the basin this experimental decline may be corroborated by the paucity of normal mechanisms in the basin extensional motion in this region is more influential outside of the basin especially to the area where an onshore seismic activity is monitored on the land on the other hand another strike slip activity in the cinarcik basin is distributed on a possible strand parallel to the northern coastline of the marmara sea in the armutlu peninsula this may indicate that one or more short strands of the northern splay extend to the west by bounding the basin from the south in the central basin the existence of a right lateral strike slip faulting on an east west trending fault is supported by similar strike slip focal mechanisms located at both extremities of the basin to the west dominant style of deformation gradually shifts from strike slip faulting to transpression along the western coastline of the marmara sea where the northern splay joins with the offshore continuation of the ganos fault finally focal mechanisms in the marmara sea are inverted for the best fitting stress tensor characterized by a subvertical 2 axis and two subhorizontal stress axes of 1 and 3 oriented nw se and ne sw respectively conclusively this study infers that the current tectonics of the marmara sea is mainly governed by a strike slip regime ascribed to both submarine splays of the naf and partly dominated by extensional and compressional features indicating shallow processes at local scales

mediterranean vegetation lake levels and palaeoclimate at the last glacial maximum the apparent conflict between pollen evidence for widespread artemisia steppe1 6 implying semi arid conditions and geomorphological evidence for high lake levels4 7 11 has produced controversy about the ice age palaeoclimate of the mediterranean region here we use a water balance model12 to predict catchment runoff and a biome model13 to predict vegetation type to reconstruct the palaeoenvironment around lake loannina a type locality for the northern mediterranean region we show that both sets of evidence are compatible with a summer dry winter wet regime with seasonal temperature anomalies similar to those predicted by atmospheric model simulations of the last glacial maximum14 18 the drying effect of the cold north atlantic ocean may have been counteracted in winter by increased storm frequency under a southward shifted jet stream as shown by several atmospheric models16 18

last glacial holocene paleoceanography of the black sea and marmara sea stable isotopic foraminiferal and coccolith evidence multi proxy data and radiocarbon dates from several key cores from the black sea and marmara sea document a complex paleoceanographic history for the last v30 000 yr the marmara sea was isolated from both the black sea and the aegean sea during glacial periods when global sea level lowering subaerially exposed the shallow sills at the straits of bosphorus and dardanelles i e lake stage and reconnected through both straits during interglacial periods when rise of global sea level breached the shallow sills i e gateway stage micropaleontological data show that during the lake stage the surface water masses in both the marmara sea and black sea became notably brackish however during the gateway stages there was a low salinity surface layer and normal marine water mass beneath two sapropel layers are identified in the marmara sea cores sapropels m2 and m1 were deposited between v29 5 and 23 5 ka and v10 5 and 6 0 ka respectively micropaleontological and stable isotopic data show that the surface water salinities were reduced considerably during the deposition of both sapropel layers m2 and m1 and calculation using planktonic foraminiferal transfer functions shows that sea surface temperatures were notably lower during these intervals the presence of fauna and flora with black sea affinities and the absence of mediterranean fauna and flora in sapropels m1 and m2 strongly suggest that communication existed with the black sea during these times a benthic foraminiferal oxygen index shows that the onset of suboxic conditions in the marmara sea rapidly followed the establishment of fully marine conditions at v11 10 5 ka and are attributed to black sea outflow into the marmara sea since 10 5 ka these suboxic conditions have persisted to the present the data discussed in this paper are completely at odds with the flood hypothesis of ryan et al 1997 and ryan and pitman 1999 crown copyright 2002 elsevier science b v all rights reserved

sea level changes and tectonics in the quaternary extensional basin of the south evvoikos gulf greece the tectonically active south evvoikos gulf forms the submerged part of a young basin produced by neogene fragmentation of the hellenides so furnishing an opportunity to study the earliest stages of an extensional rift reflection profiles show three seismo stratigraphic units a thin holocene unit a a thick late and middle pleistocene unit b and a deformed mesozoic cenozoic basal unit c in the eastern gulf at least seven alternatingly stratified and acoustically transparent subunits are related to pleistocene sea level changes that episodically isolated the gulf correlation with the global eustatic sea level curve indicates that deposition in the gulf formed by southeastward divergence of its northern and southern boundary faults began during the last million years subsequent glacio eustatic sea level changes superimposed major variations in depositional conditions on long term subsidence lack of pleistocene marine beds on the adjacent land implies that a high rate of subsidence confined lacustrine and marine deposition to the basin itself

north anatolian fault in the gulf of izmit turkey rapid vertical motion in response to minor bends of a nonvertical continental transform 1 the catastrophic rupture of the north anatolian fault east of the marmara sea on 17 august 1999 highlighted a need for mapping the underwater extension of that continental transform a new bathymetric map of izmit gulf indicates that the fault follows the axis of the gulf with a few minor bends submerged shorelines and shelf breaks that formed during the last glacial maximum provide markers to quantify vertical deformation variable tilting of these horizons reveals that vertical deformation is highest just south of the fault a correlation between vertical deformation of the southern fault block and distance to fault bends can be accounted for by a fault dipping steeply to the south hence subsidence uplift of the southern hanging wall block would be expected where the fault strikes at a slightly transtensional transpressional orientation to relative plate motion subsidence reaches about 8 mm yr west of the town of golcuk and might be accommodated in 1 2 m subsidence events during large earthquakes that scenario is compatible with the tsunami runups and the coseismic subsidence of the southern shore that occurred in 1999 seafloor morphology also suggests that earthquakes are accompanied by widespread gas and fluid release the periphery of the deepest basin displays a hummocky texture diagnostic of sediment fluidization and mud volcanoes occur west of hersek peninsula that might be activated by earthquakes finally the backscatter imagery reveals a series of lineaments midway through the gulf that are interpreted as products of the 1999 surface rupture the seafloor is undisturbed farther west suggesting that surface slip decreased to an insignificant level beyond hersek possibly the stress shadow from the 10 july 1894 earthquake which was felt strongly along the western izmit gulf contributed to arrest the 1999 surface rupture

black sea marmara sea quaternary connections new data from the bosphorus istanbul turkey abstract previous studies concluded that the bosphorus strait was formed during the quaternary by fluvial incision of a valley between the black sea to the north and the marmara sea in the south hitherto however few details of the evolution of this connection have been elucidated from the sediments deposited within the bosphorus itself we report here details of sedimentological and palaeontological evidence relating to this history obtained from five boreholes drilled into the unconsolidated sediment fill in the north central sector of the bosphorus together with nearby geophysical profiles the quaternary fill of this part of the bosphorus comprises two major facies associations yellow arkosic sands dominate the lower facies association a these are assigned a middle to late pleistocene age and the contained faunas have a lagoonal to lacustrine character and a black sea provenance paratethyan affinities the abruptly succeeding units of facies association b comprise fining and coarsening upwards units of coarse to fine shelly and clayey sands that alternate with shell bearing green clays these sediments were formed in a range of marine and coastal settings and biostratigraphic evidence and absolute dating demonstrate the mid late holocene age of this upper unit initially brackish faunal assemblages in this upper unit show an upward increase in marine and mediterranean affinities integrating these new data with previously published observations from coeval deposits in the southern bosphorus and izmit bay ne marmara sea we conclude that during the late pleistocene and early holocene a topographic barrier existed in the south central sector of the bosphorus on both sides of which estuarine and lagoonal sediments accumulated with distinctive black sea and mediterranean faunas during a significant rise in sea level between 7000 and 5300 years ago this barrier was finally submerged permitting interchange of marine waters between the mediterranean and the black sea and creating the present oceanographic situation this evolution conflicts with the cataclysmic role of the bosphorus in the early holocene as postulated in the catastrophic flood hypothesis of ryan et al mar geol 138 1997 119 126 annu rev earth planet sci 31 2003 525 554 it also contrasts with the history recorded from the gulf of izmit where intermittent connection between these two bodies of water throughout much of the quaternary is evident

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

boron content of lake ulubat sediment a key to interpret the morphological history of nw anatolia turkey abstract freshwater lake ulubat c 1 5 m deep and c 138 km2 receives sediment from a 10 414 km2 area in the seismically active susurluk drainage basin sdb of nw turkey the b and trace element contents of the lake infill seem to be a link between the fresh landforms of the sdb and the lacustrine sediment deposition in lake ulubat has been 1 60 cm a 1 for the last 50 a according to radionucleides however the sedimentation rate over the last millennium was 0 37 cm a 1 based on 14c dating the b content of the lacustrine infill displays a slight increase at 0 50 m and a drastic increase at 4 m depth occurring c 31 a and c 1070 a ago respectively probably the topmost change corresponds to the start of open mining in the sdb and the second one to the natural trenching of borate ore deposits these dates also show indirectly a 1 4 cm a 1 erosion rate during the last millennium as the borate beds were trenched up to 15 m by extrapolation it is possible to establish that the formation of some of the present morphological features of the southern marmara region especially river incision began in the late pleistocene and developed especially over the last 75 ka

tectonically induced quaternary drainage diversion in the northeastern aegean the maritsa river in the balkans over 500 km long flows at present into the northern aegean sea geological and geomorphological data indicate that it was flowing into the marmara sea until about 1 5 ma and was diverted into the aegean sea following coseismic uplift along the north anatolian fault seismic reflection sections in the marmara sea indicate the presence of up to 2 5 km thick fluviatile to limnic upper miocene quaternary sediments probably supplied by a palaeo maritsa river the drainage diversion cut off the sediment supply with the result that the terrigeneous sediments of the marmara sea were depressed to a water depth of 1150 m

catastrophic flooding of the black sea abstract decades of seabed mapping reflection profiling and seabed sampling reveal that throughout the past two million years the black sea was predominantly a freshwater lake interrupted only briefly by saltwater invasions coincident with global sea level highstand when the exterior ocean lay below the relatively shallow sill of the bosporus outlet the black sea operated in two modes as in the neighboring caspian sea a cold climate mode corresponded with an expanded lake and a warm climate mode with a shrunken lake thus during much of the cold glacial quaternary the expanded black sea s lake spilled into to the marmara sea and from there to the mediterranean however in the warm climate mode after receiving a vast volume of ice sheet meltwater the shoreline of the shrinking lake contracted to the outer shelf and on a few occasions even beyond the shelf edge if the confluence of a falling interior lake and a rising global ocean persisted to the moment when the rising ocean penetrated across

the effects of the north anatolian fault zone on the latest connection between black sea and sea of marmara abstract the development of the strait of istanbul is also one of the principal results of the tectonics which led to the evolution of the north anatolian fault zone nafz in the marmara region 3 7 ma ago high resolution seismic profiles from the marmara entrance of the strait of istanbul show a folding which occurred after the deposition of the parallel reflected tyrrhenian sediments over the tyrrhenian strata a fondoform zone of a deltaic sequence and marine sediments of the latest sea level rising are present these sediments also display syn depositional folding this situation implies that a local compressional stress field was created over the area probably since the wurm glacial age this recent variation of the tectonic regime in the northern shelf of the sea of marmara may indicate a significant change in the development of the nafz through the sea of marmara this variation of evolution of the nafz affected the latest development of the strait of istanbul via clockwise rotation of the istanbul and kocaeli peninsulas by right lateral shearing between two zone bounding faults this rotation has led to the development of nne ssw left lateral faults in the strait of istanbul and local compressional and tensional areas explaining the compressional structures seen in the southern entrance of the strait of istanbul therefore the latest mediterranean black sea connection was established by means of the sufficient deepening of the bosphorus channel by a variation in the evolution of nafz through the sea of marmara

active faults and evolving strike slip basins in the marmara sea northwest turkey a multichannel seismic reflection study abstract the north anatolian fault is a 1200 km long transform fault forming the boundary between the anatolian and eurasian plates near its western end it strikes through the marmara sea and is responsible for the creation of three deep marine depressions the north anatolian fault system and the linked basins in the eastern marmara sea were studied using newly acquired multi channel seismic reflection data in the marmara sea the north anatolian fault consists of a main strand and a few subsidiary branches the main strand is made up of the ganos 15 km long central marmara 105 km and north boundary 45 km fault segments the north boundary fault joins in the east to the izmit segment which was ruptured during the m s 7 4 earthquake on 17 8 1999 the north boundary fault is highly oblique to the regional displacement vector which results in the generation of a symmetrical fault wedge basin this cinarcik basin is a wedge shaped deep marine depression south of istanbul it is about 50 km long up to 20 km wide and 1250 m deep and is filled with pliocene to quaternary sediments over 3 km thick the north boundary fault joins in the west to the transpressional central marmara fault around the restraining segment boundary the syntransform sediments are being deformed into a large anticlinorium the cinarcik basin started to form when the westward propagating north anatolian fault intersected a northwest trending pre existing fault zone during the pliocene and bifurcated into nw and sw trending segments forming a transform transform transform type triple junction dextral strike slip movement along the arms of the triple junction led to the development of the cinarcik basin the present fault geometry in the marmara region was achieved later during the mid pliocene following the termination of the triple junction geometry south of the main north anatolian fault system there is a second active strike slip fault in the marmara sea made up of several segments a highly asymmetrical fault bend basin comprising pliocene quaternary sediments over 2 5 km thick is forming along a releasing fault segment of this south boundary fault system

late quaternary tectonic and sedimentary history of outer izmir and candarli bays western turkey abstract air gun and 3 5 khz seismic profiles from the eastern aegean sea off turkey show that the continental shelf of outer izmir and candarli bays is formed by several superimposed deltaic sequences during times of lowered sea level associated with late quaternary glaciations deltas prograded seaward more than 60 km from their present positions foreset progradation ceased with the rise of sea level in interglacial and post glacial times and deltas were reestablished far inland in drowned river valleys these major transgressions resulted in unconformities within the superimposed prograded delta sequences the most recent three unconformities are correlated with the beginning of oxygen isotope stages 5 3 and 1 and provide chronostratigraphic markers for a detailed analysis of sedimentation patterns in the late quaternary the coastal shelf and basins are subsiding at an average rate of about 1 m per 1000 years this tectonic subsidence manifests itself as widespread normal block faulting which can be related to the pre miocene structural framework of the region

strike slip fault geometry in turkey and its influence on earthquake activity the geometry of turkish strike slip faults has been reviewed and described from this data set it appears that fault geometry the distribution of discontinuities such as bends and stepovers along the main fault trace plays an important role in controlling the location of large earthquake rupture segments along the fault zones large earthquake ruptures generally do not propagate past individual stepovers that are wider than 5 km or bends that have angles greater than about 30 more important than the size of each discontinuity however is the total geometric pattern i e the distribution of adjacent bends and stepovers based not only on distance from one another but also on relative discontinuity size certain geometric patterns restraining single or double bends are particularly common and can be viewed as responsible for strain accumulation along portions of the fault zone fault geometry not only plays a role in the extent of earthquake rupture but also in characteristics of earthquake behavior for example large earthquake epicenters often occur near restraining bends or double bends furthermore aftershocks and swarm activity can often be associated with releasing areas areas along the strike slip fault that are undergoing a relatively large amount of extension

holocene glacial rebound and sea level change in nw europe summary observations of late pleistocene and holocene sea level change relative to the crust exhibit very considerable variations across nw europe in consequence of the response of the earth s crust to the deglaciation of fennoscandia and of the water added to the oceans from the melting of all late pleistocene ice sheets inversion of sea level observations from a site near the centre of the fennoscandian ice sheet and from three sites located beyond the margin of the ice sheet at the time of maximum glaciation yield a range of plausible models for the earth s response and for the ice models further constraints on this range of models is placed by a comparison of observed sea levels with predicted values at other sites near the former ice sheet margins the resulting mantle parameters are upper mantle viscosity 3 5 x 10 pa s lower mantle viscosity 2 7 x loz1 pa s lithospheric thickness 100150 km these values represent effective parameters that describe the response of the earth to surface loading of short to intermediate wavelengths on a time scale of 104yr the lower mantle viscosity is poorly constrained but the marked increase from upper to lower mantle is a characteristic of all plausible solutions the inversion places a constraint on the total volume of ice in the fennoscandian ice sheet such that the equivalent sea level rise from this contribution is about 13 14 m a less well determined constraint of about 10 m equivalent sea level rise is suggested for the barents kara ice sheet the inversion also indicates that a small amount of melt water from ice sheets far away from europe continued to be added into the oceans during late holocene time so as to raise the equivalent sea level by about 3 m during the past 6000 yr consistent with similar inversions of data from sites in the australian and pacific regions

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

submarine earthquake history of the cinarcik segment of the north anatolian fault in the marmara sea turkey the north anatolian fault naf in the marmara sea is a significant hazard for the city of istanbul the use of paleoseismological data to provide an accurate seismic risk assessment for the area is constrained by the fact that the naf system is submarine thus a history of paleoearthquakes can be inferred only by using marine sediment cores here a record of turbidites was obtained in two cores and used to reconstruct the earthquake history along the cinarcik segment a main branch of the naf klg04 was collected from a berm north of the fault and klg03 was positioned in the cinarcik basin south of the fault the cores were correlated using long term geo chemical variations in the sediment and turbidites deposited simultaneously at both sites were then identified radionuclide measurements suggest the most recent turbi dite was triggered by the 1894 c e m w 7 3 earthquake we conclude that the turbidites identified at both sites are earthquake generated based on their particular sedimento logical and geochemical signatures the correlation of turbidites at berm and basin sites and the match of the most recent turbidite with a nineteenth century historical earthquake to date older turbidites we used carbon 14 and paleomagnetic data to build an oxcal model with a local reservoir correction of 400 50 yr the cinarcik segment is found to have ruptured in 1509 c e sometime in the fourteenth century in 989 c e and in 740 c e with a mean recurrence interval in the range of 256 321 years finally we used the earthquake record obtained to review the rupture history of the adjacent segments over the past 1500 years

interaction between faulting and sedimentation in the sea of marmara western turkey 1 the aegean region is one of the most rapidly deforming continental areas in the world in the sea of marmara interaction between strike slip and extensional faulting has led to a complicated style of local deformation to the east the continental plate containing eastern and central turkey is moving westward with respect to eurasia with little internal deformation tectonic deformation is restricted to a narrow zone along the dominantly strike slip north anatolian fault however in the vicinity of the sea of marmara both surface mapping of faults and earthquake fault plane solutions indicate that extensional motions presumably related to back arc extension behind the hellenic subduction zone create a much wider zone of deformation which reaches hundreds of kilometers in width we use a regional grid of high resolution seismic reflection profiles to map the fault systems as they cross the sea of marmara and show how they divide the sea of marmara into separate deep basins with distinctive sediment sources and depositional styles in the southern sea of marmara these basins are half graben formed on north dipping fault planes which have trapped sediment coming into the sea of marmara from the south no evidence is found in the data set for the existence of a single strike slip fault through the sea of marmara or for the existence of a northern boundary fault along the tekirdag and central marmara basins we conclude that a single strike slip fault would be incapable of accommodating the relative motion and extension observed between western turkey and eurasia

clay mineral distribution in last glacial holocene sediment cores from the eastern marmara sea cinarcik basin izmit gulf transition nw turkey multisources and transport paths in a two way flow system abstract the regional variations in grain size xrd bulk and clay mineral distribution in 97 sediment samples from 6 gravity cores obtained from 20 to 300 m water depths have been investigated to reveal source and transportation patterns as well as the effects of climatic and sea level changes during the last 25 000 14 c bp in the eastern marmara sea ems nw turkey the major proportions of sediments in the ems consist of silt 20 83 and clay 17 90 whereas sand and gravel abundances rarely exceed 10 of the bulk minerals 10 a micas 23 55 and feldspars 17 55 dominate over quartz 10 21 and calcite 10 26 smectites 23 62 illite 18 36 chlorites 6 21 kaolinite 2 20 and 14s 14c mixed layer minerals 0 27 constitute the principal clay mineral assemblages both bulk and clay mineral assemblages in the ems are similar to those found in the izmit gulf on the southern marmara shelf at the marmara aegean approaches and the southern black sea this would suggest that there is no distinct source for mineral assemblages of the study area outside the marmara basin the concentrations of clay fractions and clay mineral assemblages tend to increase or decrease with depth in the cores but this is limited to some intervals and not to entire sections in the cores this distribution pattern therefore represents rather local sources of provenance and surrounding fluvial drainage basins together with dilution and distribution effects by current transport processes rather than the expected paleoclimatic features and sedimentary input by inflowing black sea and aegean sea water masses throughout the last glacial to holocene