late pleistocene uplift history along the southwestern marmara sea determined from raised coastal deposits and global sea level variations pleistocene raised coastal deposits characterized by locally abundant shells aragonite cemented beachrock and associated nearshore deposits border the western marmara sea at elevations of 0 50 m field observations confirm that these deposits formed during a series of transgressive and regressive events u th dates in 16 in situ shells from four localities show that the peak of the transgressions occurred during the highstands of oxygen isotopic stages 7 and 5 between 53 and 210 ka the elevations of these dated deposits can be used to quantify their post depositional uplift and indicate that the entire western marmara shelf including the strait of canakkale dardanelles has been rising at an average rate of 0 40 mm yr 1 since 225 ka the primary cause of uplift is the local compression associated with a restraining bend in the western segment of the north anatolian fault paleogeographic maps constructed using the average rate of tectonic uplift and detailed topographic and bathymetric maps reveal that prior to glacial oxygen isotopic stage 8 the marmara sea was never isolated from the aegean sea even when global sea level was low because the floor of the strait of canakkale was too deep early in its uplift history the dominance of mytilus edulis in raised coastal terraces dating from the lowstand of glacial oxygen isotopic stage 8 suggests that the degree of communication between the aegean sea and marmara sea was comparable to that of the present during the peak of glacial oxygen isotopic stage 6 the floor of the strait was subaerially exposed isolating the marmara sea for the first time in the pleistocene from the higher salinity mediterranean water inflow and possibly causing it to become a blackish water lake during interglacial isotopic stages 9 7 and 5 the strait of canakkale was very wide and deep 100 125 m and there were two subsidiary channels bolayir and eceabat channels providing additional links between the aegean sea the marmara sea further promoting significant water exchange between these basins the dominance of ostrea edulis in the raised terraces dating from isotopic stages 5 and 7 confirms an enhanced penetration of the mediterranean water mass into the marmara sea the history of communication between the black sea fed by central and northern european drainage systems and the low latitude mediterranean sea is of fundamental importance in understanding the genesis of organic rich sapropel deposits throughout the region the results presented in this paper caution against the simple assumption that sea level change alone controlled the degree of connection across this oceanographic gateway instead the physiography and paleoceanography of the region were controlled both by variations in global sea level and the rate of uplift in an area of active transpression

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

westward propagation of north anatolian fault into the northern aegean timing and kinematics comment and reply based on stratigraphical and structural evidence armijo et al 1999 1 considered that the north anatolian fault has 70 85 km total offset in the marmara region of northwest turkey they also suggested that the fault reached the marmara region 7 5 ma their main stratigraphic evidence is a

assessment of mineralogical and petrographic factors affecting petro physical properties strength and cracking processes of volcanic rocks abstract microtextural features influence the petrophysical and mechanical properties of rocks including the elastic properties and cracking processes under axial loads volcanic rocks with varying microtextural characteristics and compositions were evaluated to assess the effect of the main constituents mineralogical petrographic and micro structural features on the petrophysical properties elastic properties and strength furthermore detailed analyses were also used to understand the cracking processes under axial loads the analyses of the cracking processes were completed on thin sections obtained from the mechanically tested specimens the results from the quantitative mineralogical and petrographic studies and observations from thin sections revealed that the mineral mass fractions have an effect on the specific gravity and loss on ignition loi values on the other hand unconfined compressive strength ucs and elastic properties are mostly affected by petrographic variables e g mineral content the ucs values tend to decrease with a relative increase in the groundmass with respect to the phenocryst content and vice versa biotite is the only mineral that influences the ucs individually geometric features e g feret s diameter and perimeter of opaque minerals and biotite are determined to be important constituents influencing the young s modulus under axial loads crack propagation is strongly dependent on the proportional distribution of the phenocryst and groundmass it was observed that increasing groundmass content leads to predominantly axial cracks the cracks tend to bend or propagate as a boundary crack when they reach the boundary of an unaltered phenocryst thus axial and shear cracks co exist with increasing amounts of phenocrysts which hinders crack propagation occasionally cracks can penetrate the altered or opaque phenocrysts depending on the degrees of orientation with respect to applied load of the same minerals furthermore the synthesis of the measurements obtained from ucs tests and thin section observations reveals that an increase in the amount of phenocrysts which promote the formation of more shear cracks in addition to axial cracks causes an increase in the radial strain and poisson s ratio the other factors investigated had minor effects on physical and mechanical properties of studied rocks

global positioning system measurements of present day crustal movements in the arabia africa eurasia plate collision zone we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1994 at 54 sites extending east west from the caucasus mountains of southern russia georgia and armenia to the aegean coast of turkey and north south from the southern edge of the eurasian plate pontus block to the northern edge of the arabian platform viewed from a eurasia fixed reference frame sites on the northern arabian platform move n38 13 w at 20 3 mm yr roughly consistent with the velocity implied by nuvel 1a circuit closure n23 7 w at 24 2 mm yr the motion of arabia appears to be transferred directly to the region of turkey north of the suture however eastern turkey is characterized by distributed deformation while central western turkey is characterized by coherent plate motion involving westward displacement and counterclockwise rotation of the anatolian plate internal deformation within the central part of the anatolian plate is less than 2 mm yr the anatolian plate is decoupled from eurasia along the right lateral strike slip north anatolian fault naf this different response in eastern and western turkey to the collision of arabia may result from the different boundary conditions the hellenic arc forming a free boundary to the west and the asian continent and oceanic lithosphere of the black and caspian seas forming a resistant boundary to the north and east we derive a best fitting euler vector for anatolia eurasia motion of 29 2 0 8 n 32 9 0 4 1 3 0 1 m y the mapped surface trace of the naf corresponds well to a small circle about this pole the new euler vector implies an upper bound for naf slip rate of 30 2 mm yr i e assuming all relative motion is accommodated along the naf using the nuvel 1a euler vector for arabia eurasia and the gps euler vector for anatolia eurasia we determine an arabia anatolia euler vector of 31 2 n 45 2 e 0 9 0 1 m y and an upper bound on the east anatolian fault slip rate of 15 3 mm yr the aegean trough region of western turkey deviates significantly from coherent plate rotation in addition to rotating with anatolia this region shows roughly n s extension at a rate of 14 5 mm yr taken together with satellite laser ranging results along the hellenic arc the contemporary pattern of deformation indicates increasing motions toward the arc suggesting that the westward displacement and counterclockwise rotation of anatolia is driven both by pushing from the arabian plate and by pulling or basal drag associated with the foundering african plate along the hellenic subduction zone

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

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

geology of the saros graben and its implications for the evolution of the north anatolian fault in the ganos saros region northwestern turkey abstract palaeo and neo tectonic evolutions of the gulf of saros northwestern turkey were investigated based on geological mapping geomorphology seismicity and gps measurements in this area three overlapping basins were differentiated the thrace enez and saros basins the thrace basin opened during the middle eocene on the continental strandja massif as a post collisional fault controlled extensional basin after the closing of the intra pontide ocean to the south this basin reached its greatest extent during the late eocene early oligocene and then turned into an intramontane terrestrial basin from the middle miocene onwards the enez basin opened along the southern margin of the former thrace basin as an e w trending half graben during the middle miocene the age and geometry of this basin corresponds to the extensional basins of the aegean graben system to the south stratigraphy and structures related to the north anatolian fault indicate that the fault started to be active since pliocene and modified older structures the fault zone evolved in two stages in and around the gulf of saros during the initial stage the fault was trending as a single segment with a transpressional nature and without any stepping and caused thrusting and folding subparallel to the main trace of the fault since the late pliocene the fault was left stepping in the saros area giving rise to the saros pull apart basin we modelled these two stages by using boundary element method and found that there is a good correlation between the modelling results and geology and geomorphology

investigating the effects of micro texture and geo mechanical properties on the abrasiveness of volcanic rocks abstract the abrasiveness of rocks is a fundamental rock property that affects sawing and cutting performance wear of tunnel boring machine tbm heads the cerchar abrasiveness index cai test is a commonly used procedure to define rock abrasivity this paper investigates the relationship between quantitative mineralogical and petrographic data and cai values for some selected volcanic rocks in addition the research examines the relationship between physical e g effective porosity and p wave velocities and mechanical e g uniaxial compressive strength ucs brazilian tensile strength bts young s modulus e properties including brittleness values and cai values quantitative mineralogical and petrographic analyses reveal the variations in micro textural properties as defined by different groundmass phenocryst ratios analyses also suggest that the dimensions of opaque minerals and plagioclase feldspar apparently have individual effects on cai values additionally the combined effects of grain size and primary types of constituent minerals have a significant on cai values additionally results of physical and mechanical tests indicate that as p wave velocities increase cai values increase the increasing values of ucs bts and e cause cai values to increase significantly however only one of three brittleness values was found to have a considerable relationship with cai values this research demonstrates the importance of evaluating the micro textural variations and the combined effects of micro texture physical properties and mechanical properties on the cai values of volcanic rocks

spatial distribution of sea level markers on lesvos island ne aegean sea evidence of differential relative sea level changes and the neotectonic implications article i nfo the aim of this study is to provide new data on relative sea level changes and neotectonics of the northeast ern aegean sea region eastern mediterranean through the analysis of the coastal geomorphology of lesvos the third largest greek island there is a paucity of presently available data in this sector of the aegean sea which is a tectonically active area strongly controlled by the north anatolian fault in this paper morpholog ical biological and sedimentary records of paleo sea levels have been used to reconstruct relative sea level changes to identify variations in the tectonic regimes as well as to assess the paleoseismicity in the studied areas according to the results late quaternary relative sea level changes at lesvos were not homogenous and variations in the tectonic setting played a crucial role in the coastal evolution the nw se trending faults on the southern shore of the island control a significant uplift affecting about 30 km of coastline this uplift trend is controlled by the footwall of the lesvos fault a major offshore normal fault that has been subject to relatively little quantitative investigation radiocarbon dating indicated that the last co seismic uplift took place at 3365 3963 cal yr bp and resulted in about 0 75 m of vertical displacement in contrast all the paleo sea level markers mapped in the northeastern sector were presently underwater and despite the high seismicity of the area no evidence of coastal uplift was observed in this part of the island thus the paper provides the first field evidence of a differential late quaternary evolution of lesvos island in addition results represent the first quantitative information on the activity of the lesvos fault suggesting a reconsid eration of its importance in the neotectonics of the area

morphology displacement and slip rates along the north anatolian fault turkey 1 geological and geomorphological offsets at different scales are used to constrain the localization of deformation total displacement and slip rates over various timescales along the central and eastern north anatolian fault naf in turkey the naf total displacement is reevaluated using large rivers valleys 80 15 km and structural markers pontide suture 85 25 km tosya vezirkopru basins 80 10 km these suggest a neogene slip rate of 6 5 mm yr over 13 myr the river network morphology shows offsets at a range of scales 20 m to 14 km across the main fault trace and is also used to estimate the degree to which deformation is localized at a smaller scale the morphology associated with small rivers is offset by 200 m along the naf the age of these features can be correlated with the holocene deglaciation and a slip rate of 18 3 5 mm yr is determined this is consistent with a rate of 18 5 mm yr deduced independently from the 14c dating of stream terrace offsets over the short term gps data gives a similar rate of 22 3 mm yr all our results tend to show that most of the deformation between the anatolian and eurasian lithospheric plates has been accommodated along or very close to the active trace of the naf the difference between the neogene and the holocene slip rate may be due to the recent establishment of the current plate geometry after the creation of the naf

the active main marmara fault abstract this paper presents selections from and a synthesis of a high resolution bathymetric sparker and deep towed seismic reflection data set recently acquired by the french ifremer r v le suroit in an e w deep trough that forms the northern half of the sea of marmara in nw turkey it includes the first high resolution complete bathymetric map of this area a single throughgoing dextral strike slip fault system which is the western continuation of the northern branch of the north anatolian fault cuts this trough lengthwise and joins the 1999 8 17 kocaeli earthquake fault with the 1912 8 09 arkoy murefte earthquake fault both of which display strike slip offset in its eastern one fourth the structure follows closely the northern margin of the deep trough whereas in the west it hugs its southern margin the eastern one fourth of the structure has a minor component of its displacement distributed across the deep trough owing to a possible original bend in the course of the dextral structure the present course of the north anatolian fault in the sea of marmara originated some 2 105 a ago by cutting across the older basin fabric generated by a dominant nne ssw extension before it began taking up major motion in the pliocene

vertical displacement trends in the aegean coastal zone ne mediterranean during the holocene assessed by geo archaeological data trends in the vertical displacement i e uplift or subsidence of the aegean sea coastal zone have been assessed by comparing observational data with those derived from the predictive glacio hydro isostatic model of lambeck and purcell 2005 for a period spanning from the mesolithic to the late roman times the data base comprises published studies that use both geomorphological with associated biological material and archaeological sea level indicators markers localities demonstrating uplift of high amplitude were detected in front of the hellenic arc antikythira crete rhodes nisyros and in the northeast aegean region thrace whilst areas experiencing tectonic subsidence were mainly observed in the central aegean region which is characterized by an extensional tectonic domain however regional scale tectonic particularities have caused uplift in parts of the west and east coast of central aegean tectonically stable sites can be found in the cyclades plateau however this is due to a bala

the effect of dissolved magnesium on creep of calcite ii transition from diffusion creep to dislocation creep we extended a previous study on the influence of mg solute impurity on diffusion creep in calcite to include deformation under a broader range of stress conditions and over a wider range of mg contents synthetic marbles were produced by hot isostatic pressing hip mixtures of calcite and dolomite powders for different intervals 2 30 h at 850 c and 300 mpa confining pressure the hip treatment resulted in high magnesian calcite aggregates with mg content ranging from 0 5 to 17 mol both back scattered electron images and chemical analysis suggested that the dolomite phase was completely dissolved and that mg distribution was homogeneous throughout the samples at the scale of about two micrometers the grain size after hip varied from 8 to 31 m increased with time at temperature and decreased with increasing mg content 3 0 mol grain size and time were consistent with a normal grain growth equation with exponents from 2 4 to 4 7 for samples containing 0 5 17 0 mol mg respectively we deformed samples after hip at the same confining pressure with differential stresses between 20 and 200 mpa using either constant strain rate or stepping intervals of loading at constant stresses in a paterson gas medium deformation apparatus the deformation tests took place at between 700 and 800 c and at strain rates between 10 6 and 10 3 s 1 after deformation to strains of about 25 a bimodal distribution of large protoblasts and small recrystallized neoblasts coexisted in some samples loaded at higher stresses the deformation data indicated a transition in mechanism from diffusion creep to dislocation creep at stresses below 40 mpa the strength was directly proportional to grain size and decreased with increasing mg content due to the reductions in grain size at about 40 mpa the sensitivity of log strain rate to log stress n became greater than 1 and eventually exceeded 3 for stresses above 80 mpa at a given strain rate and temperature the stress at which that transition occurred was larger for samples with higher mg content and smaller grain size at given strain rates constant temperature and fixed grain size the strength of calcite in the dislocation creep regime increased with solute content while the strength in the diffusion creep regime was independent of mg content the results suggest that chemical composition will be an important element to consider when solid substitution can occur during natural deformation

present day kinematics of the middle east and eastern mediterranean the middle east and eastern mediterranean regions contain three major strike slip fault zones the dead sea fault zone dsfz and the north and east anatolian fault zones nafz and eafz these accommodate northward motion of the african and arabian plates relative to eurasia and westward motion of the small turkish plate this study deduces an internally consistent solution for the present day kinematics of these plates which is accurate to better than 20 and applicable throughout time since 5 ma by constraining the slip senses and rates on these strike slip fault zones the 7 0 5 mm yr 1 left lateral slip rate on the dsfz is associated with counterclockwise rotation of arabia relative to africa at 0 33 m y 1 around an eulcr pole near 33 n 23 e the nafz takes up counterclockwise rotation of the turkish plate relative to eurasia at 0 83 m y 1 13 around a pole at 31 n 35 5 e with right lateral slip rate 15 mm yr 1 the resulting prediction for the eafz involves 14 mm yr 1 left lateral motion and 2 mm yr 1 of shortening between arabia and turkey the triple junction of africa arabia and turkey is near the city of kahramanmaras this locality contains a narrow promontory bounded by ssw trending left lateral faults at the edges of the arabian and turkish plates which is loosely attached to the african plate moving westward relative to its interior at 4 mm yr 1

microfabric study on the deformational and thermal history of the alpi apuane marbles carrara marbles italy marbles from different geometrical and structural positions within the alpi apuane metamorphic complex show a large variability in microfabric types as indicated by microstructure c axis orientation and temperature analysis statically recrystallized samples showing a granoblastic microstructure and polygonal grain boundaries are characterized by a grain size variation from east to west from 80 100 m to 250 300 m this is correlated with an equilibration calcite dolomite temperature from 360 380 c to 420 430 c two kinds of dynamically recrystallized microstructures have been investigated a first one exhibiting coarse grains 150 200 m with lobate grain boundaries and a strong shape preferred orientation and a second one characterized by a smaller grain size 40 50 m and predominantly straight grain boundaries these microstructural types associated with localized post thermal peak shear zones and meter to kilometer scale folds are interpreted as related to high strain and high temperature crystal plastic deformation mechanisms dislocation creep associated with predominant grain boundary migration type b1 or subgrain rotation recrystallization type b2 these differences in dynamically recrystallized microstructures are related to equilibration temperatures higher in type b1 390 c than in type b2 370 340 c we have been able to relate the development of the different microfabric types to the successive stages of deformation of the alpi apuane metamorphic complex

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

beachrock formation on the coast of gokceada island and its relation to the active tectonics of the region northern aegean sea turkey abstract there are beachrock formations in 5 different sections of the south coast of gokceada turkey s largest aegean island these beachrocks form two different groups in terms of layering characteristics 18o and 13c stable isotope compositions consecutive cementation structures and 14c dating the west group beachrocks to the west were dated to 4010 5830 bp while the east group beachrocks were dated to 620 2390 bp the beachrock formations in both groups are separated by the ne sw trending ugurlu fault the ugurlu fault is a right lateral strike slip with reverse component oblique fault and is an active fault within the north anatolian fault zone in the period between the formation of the two beachrock groups 2390 4010 bp an earthquake was responsible for the destruction of gokceada yenibademli mound and the development of two generations of beachrock

westward propagation of the north anatolian fault into the northern aegean timing and kinematics we present new evidence for the propagation processes of the north anatolian fault folding in the dardanelles straits region allows us to document the timing of the deformation preceding and the finite displacement after the passage of the propagating tip of the fault the accuracy of the observations is due to interplay between deformation and the sea level changes in the mediterranean the well known messinian regression followed by the pliocene transgression the long term kinematics around the sea of marmara pull apart total displacement of about 85 km over the past 5 m y is similar to the present day kinematics deduced from space geodesy at a larger scale westward propagation of the north anatolian fault over nearly 2000 km in the past 10 m y appears to be associated with strain recovery suggesting that the continental lithosphere retains long term elasticity

asymmetric slip partitioning in the sea of marmara pull apart a clue to propagation processes of the north anatolian fault between 1939 and 1999 the north anatolian fault naf experienced a westward progression of eight large earthquakes over 800 km of its morphological trace the 2000 km long north anatolian transform fault has also grown by westward propagation through continental lithosphere over a much longer timescale 10 myr the sea of marmara is a large pull apart that appears to have been a geometrical mechanical obstacle encountered by the naf during its propagation the present paper focuses on new high resolution data on the submarine fault system that forms a smaller pull apart beneath the northern sea of marmara between two well known strike slip faults on land izmit and ganos faults the outstandingly clear submarine morphology reveals a segmented fault system including pull apart features at a range of scales which indicate a dominant transtensional tectonic regime there is no evidence for a single continuous purely strike slip fault this result is critical to understanding of the seismic behaviour of this region of the naf close to istanbul additionally morphological and geological evidence is found for a stable kinematics consistent both with the long term displacement field determined for the past 5 myr and with present day anatolia eurasia motion determined with gps however within the sea of marmara region the fault kinematics involves asymmetric slip partitioning that appears to have extended throughout the evolution of the pull apart the loading associated with the westward propagation process of the naf may have provided a favourable initial geometry for such a slip separation

tectonic elements controlling the evolution of the gulf of saros northeastern aegean sea turkey abstract tectonic elements controlling the evolution of the gulf of saros have been studied based upon the high resolution shallow seismic data integrated with the geological field observations evolution of the gulf of saros started in the middle to late miocene due to the nw se compression caused by the counterclockwise movement of the thrace and biga peninsulas along the thrace fault zone hence the north anatolian fault zone is not an active structural element responsible for the starting of the evolution of the gulf of saros the compression caused by the rotational movement was compensated by tectonic escape along the pre existing ganos fault system two most significant controllers of this deformation are the sinistral ganos fault and the dextral northern saros fault zone both extending along the gulf of saros the most important evidences of this movement are the left and right oriented shear deformations which are correlated with structural elements observed on the land and on the high resolution shallow seismic records at the sea another important line of evidence supporting the evolution of this deformation is that the transgression started in the early late miocene and turned as a result of regional uplift into a regression on the gelibolu peninsula during the turolian and in the north of the saros trough during the early pliocene the deformation on the gelibolu peninsula continued effectively until the pleistocene taking into account the fact that this deformation affected the late pleistocene units of the marmara formation the graben formation of the gulf of saros is interpreted as a recent event however at least a small amount of compression on the gelibolu peninsula is observed it is also evident that compression ceased at the northern shelf area of the gulf of saros

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

early miocene climate and biomes of turkey evidence from leaf fossils dispersed pollen and petrified wood abstract the early miocene was a period of major palaeogeographic reorganization in the eastern mediterranean region during which time the anatolian plateau became subaerial and several intracontinental basins intermittently became connected to the paratethys and mediterranean seas in this paper we analyse early miocene vegetation and climate using leaf records palynological assemblages and fossil wood at 36 localities from western and central turkey most of which have precise age control based on radiometric dating and mammal faunal ages using the leaf flora of guvem bes konak kesekoy climate leaf analysis multivariate program clamp analyses and koppen signatures were employed to infer a palaeoclimate typical of modern laurel forest regions based on the palynological records abundance of various pollen taxa was used as a measure of openness of vegetation and regional presence of major tree taxa most pollen floras are dominated by tree pollen ranging from 85 to 98 and indicated widespread afforestation in the pollen diagrams shifts in dominance from swamp forest elements taxodioideae to well drained forests pinaceae indicate changes in lake levels or phases of basin development such shifts may have been associated with the development of more xeric forest vegetation wood anatomical features such as false tree rings further may indicate seasonal climate pollen diagrams and macrofossils reflect zonal and azonal broadleaf and needleleaf forest and extrazonal open vegetation the latter occurred in areas with shallow soils on volcanic rocks or limestone e g cycads dracaena or coastal areas herb dominance taxonomic composition and biogeographic affinities suggest laurel forest as a major forest biome on well drained soils and ecotones between laurel forest and broadleaf deciduous forest biomes a comparison with younger floras shows that these are neither more diverse nor more warmth loving despite an increase in global temperature mid miocene climatic optimum suggesting bottlenecks during previous oligocene cooler times for warmth loving taxa

on the relationship between the formation of shear zones and the form of the flow law for rocks undergoing dynamic recrystallization abstract the formation and maintenance of shear zones in rocks at high temperatures when viscous flow takes place at constant volume requires strain weakening several processes can lead to a strain weakening characteristic in the flow of such rocks to high strains but conventional experimental rock mechanics techniques cannot normally provide high quality mechanical data to high strains recent experimental data for calcite marble have demonstrated strain weakening accompanied by dynamic recrystallization a power law with strain exponent r can be used to describe the dependence of the flow stress on strain together with the conventional description of the dependence of strain rate on stress described by a stress exponent n the stable localization of strain into shear zones is favoured by more negative values of r e g r 0 8 and more positive values of n e g n 5 to 7 a further important factor is the critical strain e0 for the onset of recrystallization and hence strain weakening shear zone formation is favoured by smaller values for e0 shear zone formation weakens the crustal section in which they occur but the amount of weakening may not be great perhaps no more than 50 of the previous steady state flow stress certain rock types such as mafic igneous rocks may through their mechanical properties be more susceptible to shear zone formation than others such as mica schists it is emphasized that the analysis presented is based upon a strain dependent flow law that describes single phase dynamic recrystallization by grain boundary migration that leads to enhanced recovery without any change in deformation mechanism no consideration is given to possibly important effects arising from the activation of grain size sensitive flow or to potential weakening effects arising from syntectonic metamorphic reactions

an updated database of holocene relative sea level changes in ne aegean sea abstract the reconstruction of holocene relative sea levels has several implications ranging from the investigation of coastal vertical movements to the calibration of earth rheology models and ice sheet reconstructions the north eastern aegean sea is among the tectonically complex sectors of the eastern mediterranean mainly influenced by the activity of the north anatolian fault in this paper we created a relative sea level rsl database by expanding upon the previous compilation with recently published geological and archaeological data we reconstruct the rsl history in those aegean coastal sectors located within the south marmara microplate a broad shear zone located between western anatolia and central greece and affected by dominant strike slip faulting at times combined with a normal component then we compared it with the rsl histories obtained for the surrounding coastal sectors the analysis of the database indicated that it is not possible to define a common holocene rsl curve for the entire ne aegean as rsl history here is majorly influenced by changes in deformation patterns in addition data in our database are consistent with a continuous rsl rise in the last 6 0 ka bp in the whole ne aegean sea and cannot support the hypothesis of a mid holocene rsl highstand in the area finally we present our best estimates of late holocene rates of rsl prior to any possible acceleration during the twentieth century in the broad area of ne aegean here we identified the fastest rising rate 0 9 mm a 1 in that sector whose active tectonic deformation is mainly controlled by the north anatolian fault activity

a determination of the three dimensional seismic properties of anorthosite comparison between values calculated from the petrofabric and direct laboratory measurements bernard eront and david mainprice zaboratoire de tectonophysique i h iversit montpe lier ii montpe lier france nikolas i christensen department of earth and atmospheric sciences purdue unh ersity west lafayette btdiana we have undertaken a coinparative study of the seisnfic properties of an anorthosite the seisnfic properties have been calculated froin the lattice preferred orientation lpo of plagioclase 90 by volume and olivine 10 by voluine and the elastic constants of these minerals laboratory measurements of vp 24 directions and vs 6 directions have been made on the same sample at room temperature and pressures up to 1 0 gpa the twe techniques agree with 0 1 km s for all orientations studied when the voigt averaging method is used hill and reuss averaging methods give calculated velocities significantly lower than the experimental ones a study of the difference between the velocity values given by the two methods reveals a systematically larger departure in orientations normal to the foliation the orientation dependent difference between the two tedmiques can be explained if there are small errors in the elastic constants for single crystal plagioclase used in the initial calculations the axial lpo symmetry of the plagioclase with all the crystallographic b axes parallel to the specimen symmetry axis allowed us to calculate c22 norinal to 010 directly from the laboratory measurement of vp some constraints can be put on c22 c44 c66 c12 and c23 on average our data require 10 modification of the single crystal constants reported by ryzhova 1964

tectonically induced coastal uplift mechanism of gokceada island northern aegean sea turkey abstract this paper presents evidence of coastal uplift on gokceada formerly imbros island situated in the northern aegean sea in proximity to a deep trough along the seismically active north anatolian fault naf the island comprises 2 km thick sedimentary strata underlain by metamorphic rocks which are similar to those observed 170 km to the north in the strandzha rhodope mountains the sedimentary strata begin at the bottom with eocene turbidites and limestones continue upward with oligocene lower miocene detritial rocks and andesitic volcanoclastics and end with loosely consolidated sandstones of the upper miocene pliocene at the top the island at its extreme eastern coast has a peneplain form however at its northern part it is mountainous and has steeply inclined coastal cliffs uplifted paleo shore notches hanging valleys springs waterfalls uncemented slope deposits travertine formations and exposed fault scarps field evidence of many coastal morphological geological and tectonic features together with corresponding seismic reflection data suggest that the island has experienced a rapid uplift i e vertical displacement with respect to the saros trough along the naf total uplift is on the order of a few kilometers since the initiation of the naf during pliocene or late pleistocene as suggested by some studies and the yearly rate varies from a few millimeters to a centimeter according to the age assumed for this major fault

character of active faulting in the north aegean sea abstract a re evaluation of the reprocessed seismic reflection data was made for the investigation of the presumed western continuation of the north anatolian fault naf in the aegean and mapping geometries of active faults in the aegean sea seismic data collected and processed by various national and international companies were selected from the data archives and they were reprocessed after stacking to bring them to the same processing and signal to noise ratio standards the total length of the selected lines is 8000 km we investigated the character of active faulting in the north aegean sea using seismic reflection data moreover the relations of active faults with earthquakes were examined using earthquake fault plane solutions fps we show that the active faults are dominantly normal in character in the nne aegean where fps for earthquakes with m 5 indicate strike slip movements along these faults we propose a simple mechanism that potentially explains this inconsistency active normal faults are oriented in a ne sw direction in alignment with the sw escape motion of the anatolian block in this region and this orientation facilitates instantaneously strike slip movements along these otherwise normal faults

exhumation of blueschists along a tethyan suture in northwest turkey a blueschist belt formed during the mid cretaceous 88 ma high pressure metamorphism of a passive continental margin sequence of shale siltstone quartzite and limestone occurs immediately south of the tethyan suture in northwest turkey a transect across the tethyan suture was mapped to constrain the exhumation of blueschist facies assemblages the presence of jadeite glaucophane and lawsonite in the blueschists indicates p t conditions of 20 kbar and 430 c the blueschists are tectonically overlain by a cretaceous oceanic accretionary complex showing an incipient blueschist metamorphism a peridotite slab with subvertical layering lies along a low angle fault contact over the blueschists and the accretionary complex isolated slices of early cretaceous 101 4 ma garnet amphibolites occur at the base of the peridotite the garnet amphibolites which show an incipient blueschist facies overprint have probably formed during the oceanic subduction in the foot wall of the subduction zone and later underplated the hanging wall blueschists and peridotites are abruptly truncated in the north by the steeply dipping suture fault that juxtaposes unmetamorphosed and slightly deformed triassic to jurassic sediments of the northern continent against the peridotite and the accretionary complex tectonic juxtaposition of the lower pressure accretionary complex and peridotites over the higher pressure blueschists implies the removal of a 45 km thick oceanic mantle sequence above the blueschists regional geological and geometric constraints suggest that the exhumation of the blueschists was achieved by a combination of two simultaneously acting mechanisms the first was the detachment of the upper crustal blueschist sequence from its basement in the subduction zone and its incorporation to the hanging wall followed by buoyant ascent the second mechanism is the progressive shallowing of the subducted continental lithosphere resulting in the thinning of the mantle wedge above the subducted slab the blueschists were partly exposed prior to the paleocene continent continent collision post collisional eocene 52 48 ma calc alkaline plutons that were emplaced in the blueschists and the overlying peridotite at 10 km depth are interpreted to have formed by crustal anatexis from advective heating by mantle melts these have probably been generated during the upwelling of the asthenosphere under the shallowing continental lithosphere

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

global positioning system constraints on plate kinematics and dynamics in the eastern mediterranean and caucasus we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1997 at 189 sites extending east west from the caucasus mountains to the adriatic sea and north south from the southern edge of the eurasian plate to the northern edge of the african plate sites on the northern arabian platform move 18 2 mm yr at n25 5 w relative to eurasia less than the nuvel 1a circuit closure rate 25 1 mm yr at n21 7 w preliminary motion estimates 1994 1997 for stations located in egypt on the northeastern part of africa show northward motion at 5 6 2 mm yr also slower than nuvel ia estimates 10 1 mm yr at n2 4 e eastern turkey is characterized by distributed deformation while central turkey is characterized by coherent plate motion internal deformation of 2 mm yr involving westward displacement and counterclockwise rotation of the anatolian plate the anatolian plate is de coupled from eurasia along the right lateral strike slip north anatolian fault naf we derive a best fitting euler vector for anatolia eurasia motion of 30 7 0 8 n 32 6 0 4 e 1 2 0 1 myr the euler vector gives an upper bound for naf slip rate of 24 1 mm yr we determine a preliminary gps arabia anatolia euler vector of 32 9 1 2 n 40 3 1 1 e 0 8 0 2 myr and an upper bound on left lateral slip on the east anatolian fault eaf of 9 1 mm yr the central and southern aegean is characterized by coherent motion internal deformation of 2 mm yr toward the sw at 30 1 mm yr relative to eurasia stations in the se aegean deviate significantly from the overall motion of the southern aegean showing increasing velocities toward the trench and reaching 10 1 mm yr relative to the southern aegean as a whole

the strain rate field in the eastern mediterranean region estimated by repeated gps measurements we use the combined gps velocity field of the eastern mediterranean for the period 1988 to 1996 to determine crustal deformation strain rates in a region comprising the hellenic arc the aegean sea and western anatolia we interpret the velocity field and determine the strain rate tensor by the spatial derivatives of the collocated motion vectors the region following the line marmara sea north aegean trough northern central greece and the central ionian islands is associated with strong right lateral shear motion with maximum shear strain rates of 180 nano strain a 180 10 9 a in the central aegean sea n s oriented extensional processes prevail reaching 100 nano strain a the southern aegean is characterized by relatively small strain rates maximum extensional components of the strain rate tensor reaching 150 nano strain a in a n s direction are found in central greece the hellenic arc is associated with moderate arc parallel extension and strong compression perpendicular to it projections of the strain rates parallel to the major fault zones reveal that the northern aegean is governed by the westward continuation of the north anatolian fault zone which is associated with strong dextral shearing maximum 220 nano strain a accompanied by numerous large earthquakes in this century

the aegean sea we summarize briefly the main features of a kinematic model of evolution of the aegean area since 13 ma the formation of the aegean sea by extensional tectonics is related to the subduction of the mediterranean floor below the hellenic arc we then make a quantitative estimate of vertical movements in the aegean area on the basis of geological data and demonstrate that the outer arc was built since the beginning of this episode of subduction by vertical uplift the easiest way to explain the uplift is by underplating finally we discuss briefly the dynamics of the subduction marginal sea formation processes in this continental collision framework

effect of iron content on the creep behavior of olivine 1 anhydrous conditions high temperature high pressure triaxial compressive creep experiments were carried out on polycrystalline samples of olivine fexmg1 x 2sio4 with x fe fe mg 1 0 0 75 0 5 and 0 3 to investigate the influence of fe content on rheological properties of olivine under anhydrous conditions samples with grain sizes of 50 m were deformed at differential stresses of 50 to 300 mpa primarily in the dislocation accommodated grain boundary sliding creep regime for temperatures between 1273 and 1473 k with a confining pressure of 300 mpa our results combined with published results on aggregates of fa10 demonstrate that samples of fa30 fa50 fa75 and fa100 creep 15 75 365 and 1480 times faster than samples of fa10 respectively under the same conditions our experimental results can be described by the flow law e e gbs0 ngbs bd 2xfapexp qgbso xfart with e gbs0 6 2 5 2 105s 1 ngbs 3 9 p 1 5 0 1 qgbs0 440 10 kj mol and 45 4 kj mol based on measured dependence of strain rate on iron concentration we conclude that at the same thermodynamic conditions the martian mantle which is more rich in fe than earth s mantle will be a factor of 10 less viscous than earth s mantle

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