a lower pleistocene to holocene terrestrial record from the eskisehir graben central anatolia paleoclimatic and morphotectonic implications abstract as one of the rare terrestrial archive with continuous sedimentation back to almost 1 ma in anatolia the eskisehir graben was investigated in outcrops and cores by multi proxy analysis regarding chronology and paleoclimatology the present study comprises significant implications for both the impact of climate changes on fluvial systems in the timescales of the milankovitch band and the controversial age and rate of the crustal extension in western anatolia our findings indicate that loi950 and 18ocarb which are indicators for the amount of soil carbonate and paleo temperature respectively are collectively capable of distinguishing between glacial and interglacial periods in the predominantly floodplain deposits of the graben infill secondarily loi550 and 13ccarb values further help this discrimination via primary production and composition of vegetation cover respectively pollen data albeit highly discontinuous due to poor preservation under subaerial conditions point out a steppe like vegetation cover where the forest components expand particularly in the wet interglacial periods in the other hand the chronological frame provided by astronomical calibration of certain proxy records strongly suggest that the eskisehir fault zone initiated as a boundary fault of a half graben some 900 ka the rate of vertical movement on its southern branch since the last 70 ka is unexpectedly high 2 3 mm a a phenomenon that requires urgent risk assessment analysis in the vicinity of the eskisehir city

a case study of compression to escape tectonic transition tectonic evolution of the nallihan wedge and comparison with the tercan wedge eastern mediterranean turkey abstract the nallihan and cayirhan regions in western anatolia host the stratigraphically and tectonically important features of nallihan wedge the stratigraphic relationships and structural architecture of the wedge are not well understood which are essential for better understanding of the timing and tectonic evolution of western anatolia today the nallihan wedge is bounded by the north anatolian fault and the thrace eskisehir fault in the northwest and southwest respectively the existence of dagkuplu melange within the wedge represents the closure of the izmir ankara ocean the occurrence of the lower jurassic shelf slope reef and deep sea successions transitioning upward into the cretaceous shelf and slope successions represent the opening and closing cycles of the intra pontide ocean the tight and asymmetric folds steep in the west gentle in the east within this stratigraphic sequence and the development of the eocene units reflect the closure of the intra pontide and izmir ankara oceans the geometric structure and evolution of the nallihan wedge is directly related to the final continental collision w e and sw ne striking large scale oblique thrusts also exhibit notable strike slip components within the study area the principal direction of the fold axes are w e and wnw ese oriented for the eocene and neogene units during the eocene the depositional environment of the study area was a ramp basin mainly dominated by a braided river when a portion of the intra pontide ocean was situated on the northern side of the study area the compressional tectonic regime continued to the end of the oligocene which is followed by a new tectonic regime during the miocene when the triangular shape region between the thrace eskisehir fault and the north anatolian fault developed as an intermontane basin the evolution of this basin can be compared with the tercan wedge bordered by the north eastern anatolian fault and the north anatolian fault in the nallihan and cayirhan regions the n s trending compressional regime started during the upper cretaceous and continued until the final continental collisional during the upper eocene the compressional structures in the area became reactivated during the post collisional escape tectonic phase in western anatolia leading to the development of the prominent isparta angle during the miocene during this period the thrace eskisehir fault and burdur fethiye shear zone also formed as intracontinental transform fault zones in western anatolia the nallihan wedge started to form in a wedge shaped area between the thrace eskisehir fault and the zone of strike slip faults with thrust component that later developed into the north anatolian fault thus eocene and pre eocene structures obtain strike slip component by an inversion during the miocene during and post pliocene the thrace eskisehir fault lost its tectonic activity as the north anatolian fault propagated westward into the region previously controlled by the thrace eskisehir fault during this interval the nallihan wedge entered a new stage of deformation which is also observed today

episodic graben formation and extensional neotectonic regime in west central anatolia and the isparta angle a case study in the aksehir afyon graben turkey

alkaline series related to early middle miocene intra continental rifting in a collision zone an example from polatli central anatolia turkey abstract a large volcanic area 7600 km2 the galatean volcanic province gvp developed in northwest central anatolia during the miocene along the neo tethys ocean suture zone possibly by post collisional processes the gvp mainly comprises 20 14 my old acid to intermediate volcanites with a geochemical signature indicating a mantle source modified by earlier late cretaceous subduction related events 100 km south of the gvp near polatli ankara basaltic rocks that cover large areas are intercalated with the miocene deposits of the beypazari basin an intra continental subsidence zone at the southwest of the gvp field observations geochemistry and k ar age dating of the polatli volcanites show that they are early 19 9 ma to mid 14 1 ma miocene in age covering an area as large as 215 km2 variations in lava thickness and the thickness of the underlying silicified baked zones suggest that the basaltic lavas erupted from a southern source possibly from the eskisehir fault zone and flowed northwards most polatli samples have chemical compositions that indicate derivation from a mantle source with crustal contamination during ascent they do not display any characteristic to suggest a subductional component although the gvp and polatli lavas formed close in time and space they were derived from different mantle sources considering the positions of these two magmatic regions with regard to the tethyan suture zone we propose that the mantle beneath the gvp and near the suture zone memorised the earlier subduction while the mantle beneath polatli that is located about 100 km further from the suture zone remained apparently unchanged after a significant volume of magma was consumed in the gvp a later 10 my and last activity guvem activity has produced quantitatively much less basaltic rocks where this subductional signature seems to completely disappear considering that the western anatolian crust is proposed to undergo extension since the late oligocene early miocene times the early miocene intra plate polatli activity may have developed within this extensional tectonic regime combined with regional data polatli data also provide broad estimations on how long a subductional event continues to modify the mantle after the subduction ceased at least 20 my how long the subductional signature is preserved during significant magmatism between 6 and 10 my and how far the subductional effect disappears laterally on the mantle with respect to the collision zone

the nw scotland earthquake swarm of 1974 summary a swarm of earthquakes occurred in the kintail area of nw scotland in 1974 august with magnitudes up to ml 4 6 and reported intensities up to vi mm one earthquake of the series was recorded by about 60 temporary stations of the lispb refraction experiment in addition to the permanent lownet network this allowed the determination of an accurate epicentre for that event which was then used as a control event to locate other earthquakes of the kintail series the events of that swarm had a strikeslip focal mechanism and seemed to be associated with the strathconon fault

a re evaluation of the eskisehir fault zone as a recent extensional structure in nw turkey abstract the eskisehir fault zone efz one of the major active structures within the anatolian platelet is investigated in a 100 km long sector between bozuyuk and alpu in vicinity of eskisehir the morphotectonic observations indicate that throughout the studied area the efz extends wnwwards as a ca 15 km wide belt and is composed of some 21 fault segments 5 25 km long these segments form a north dipping southern set and two south dipping northern sets all together working both sides of the eskisehir graben the faults are dominantly normal in character with a slight right lateral component in the westernmost areas the estimated total vertical displacement on certain northern and southern fault segments exceeds 450 m in order to estimate the initiation age of the efz a brief stratigraphic review is given the generally horizontal pliocene terrestrial deposits are separated from the miocene succession by a low angular unconformity and are cut in turn by the efz sedimentological data show that neither the distribution of the pliocene depositional environments and their paleocurrent directions nor the preserved pliocene basal unconformity surface have a genetic relation to the efz these data strongly suggest that the efz is a younger post pliocene active normal fault zone with low rates of deformation

neotectonics and long term seismicity in europe and the mediterranean region we present a neotectonic model of ongoing lithosphere deformation and a corresponding estimate of long term shallow seismicity across the africa eurasia plate boundary including the eastern atlantic mediterranean region and continental europe gps and stress data are absent or inadequate for the part of the study area covered by water thus we opt for a dynamic model based on the stress equilibrium equation this approach allows us to estimate the long term behavior of the lithosphere given certain assumptions about its structure and physics for both land and sea areas we first update the existing plate model by adding five quasirigid plates the ionian sea adria northern greece central greece and marmara to constrain the deformation pattern of the study area we use the most recent data sets to estimate the lithospheric structure the models are evaluated in comparison with updated data sets of geodetic velocities and the most compressive horizontal principal stress azimuths we find that the side and basal strengths drive the present day motion of the adria and aegean sea plates whereas lithostatic pressure plays a key role in driving anatolia these findings provide new insights into the neotectonics of the greater mediterranean region finally the preferred model is used to estimate long term shallow seismicity which we retrospectively test against historical seismicity as an alternative to reliance on incomplete geologic data or historical seismic catalogs these neotectonic models help to forecast long term seismicity although requiring additional tuning before seismicity rates are used for seismic hazard purposes

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

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

from palaeotectonics to neotectonics in the neotethys realm the importance of kinematic decoupling and inherited structural grain in sw anatolia turkey abstract in order to asses young i e neotectonic fault kinematics and the relation with plate tectonic processes in sw turkey we focused on the questions 1 what produced the structural grain i e how and when are faults generated 2 what was is the kinematic behaviour of these faults and 3 during which period s were these faults active firstly the distribution of faults has been investigated using a lineament analysis performed on satellite imagery and digital elevation models we define five main tectonic domains in sw turkey 1 and 2 the northern and southern western anatolian extensional provinces 3 the eastern hellenic arc including rhodes island and the submarine anaximander mountains 4 the lycian taurides and 5 the western limb of the isparta angle lineament analysis reveals dominance of three lineament groups i e nne ene and wnw trending in all identified domains variations in the relative importance of lineament groups exist and are attributed to the specific tectonic evolution of each domain a synthesis of recently published field data shows that the onset of activity of related fault groups is neither synchronous nor uniform the structural grain for the neotectonic deformation in sw turkey is formed during the last stage of palaeotectonic deformation stage 1 which is dominated by the onset of the menderes massif exhumation along a top n major detachment the datca break away fault seyitoglu g isik v and cemen i 2004 complete tertiary exhumation history of the menderes massif western turkey an alternative working hypothesis terra nova 16 358 364 and related se ward sliding of the lycian nappes in the footwall of this fault this stage is characterized by spatially variable types of deformation that are delineated by from nw to se the datca fault around the menderes lycian contact zone and the lycian frontal thrust zone respectively the kinematic decoupling along these structures explains the co existence of top n detachment type extension in the western anatolian extensional province and ongoing nappe emplacement and piggy back development in the lycian taurides the decoupling also explains the lateral complexity of deformation associated with later neotectonic deformation from late miocene onward stage 2 nne ssw extension dominated the western anatolian extensional province influenced by combined anatolian extrusion and hellenic subduction roll back contemporaneously bidirectional ese wnw and nne ssw extension controls the lycian taurides due to the effects of hellenic arc expansion superposed on extrusion roll back extension the zone of kinematic decoupling is characterized by structural complexity with local transpressional features during stage 3 post late pliocene the same types of extension prevail in the western anatolian extensional province and the lycian taurides although a third tectonic regime becomes gradually more important this regime is associated with a tectonic escape in the hellenic arc that induced forearc slivers to be sheared of the expanding arc along mostly sinistrally displacing ene trending strike slip zones several of these zones have been identified in the coastal zones of sw turkey either through recent seismicity or field observations and are especially focused in the lycian taurides domain here they form what is classically referred to as the fethiye burdur fault zone which becomes gradually penetrated from the sw by oblique or strike slip zones exemplifying the time transgressive nature of the tectonic escape mechanism zones of kinematic decoupling remain persistent throughout the entire early miocene recent tectonic evolution of sw turkey and explain the existence of differently deforming tectonic domains

evidence from the gediz graben for episodic two stage extension in western turkey western turkey falls within a wide belt of nne ssw directed active continental extension generally similar to the basin and range province of the usa it comprises a zone of wnw ese trending major grabens detailed study of the gediz graben reveals two contrasting infills that represent two distinct extensional stages separated by a short phase of compression the older infill consists of an 800 m thick folded and exhumed continental sedimentary sequence with intercalated calc alkaline volcanics it accumulated in a basin formed in the northern hanging wall of a detachment fault during miocene early pliocene times the younger infill rests on the older infill with angular unconformity and consists of about 170 m of undeformed terraced continental sediments and basaltic lavas it accumulated during plio quaternary times in an asymmetric graben bounded by step like normal faults this later extension was probably triggered by the commencement of sea floor spreading along the red sea in early pliocene times and has persisted to the present almost all the grabens in western turkey are best explained by this episodic two stage graben model with an intervening phase of short term compression which differs from the progressive evolution inferred for the basin and range province of the usa

palaeogeographical evolution of the thrace neogene basin and the tethys paratethys relations at northwestern turkey thrace abstract the thrace neogene basin situated in northwestern turkey was initiated by strike slip faulting that was active from the early miocene until the end of the pliocene during the early miocene it began to form under the control of the thrace eskisehir fault zone initiated by continental collision in northwestern anatolia late oligocene early miocene during the late early miocene the basin was a site of mainly fluviatile and limnic sedimentation to the west and marine sedimentation via the paratethyan transgression in the north with the onset of the middle miocene the thrace block started to rotate in a counterclockwise sense and escaped westward with respect to the strandja istanbul block owing to rejuvenation of fossil fault systems within it in this period warm marine conditions were also established around the gulf of saros through a mediterranean originated transgression during the middle late miocene fluviatile and limnic conditions were created over the western thrace by the westerly propagation of the thrace eskisehir fault zone one of the principal results of the early middle miocene tectonics is the tilting of the strandja istanbul block to the south severing the tethys and the paratethys during the latest miocene early pliocene period the thrace eskisehir fault zone was deactivated because of the evolution of the north anatolian fault zone to the south the resurrected ganos fault zone situated on the dissected fossil suture zone in the sea of marmara also joined the north anatolian fault zone uplifting the gelibolu peninsula and thus severing the connection that existed between the sea of marmara and the paratethys the sea of marmara eventually became an endemic basin by the activity of the north anatolian fault zone

a multistory gigantic subaerial debris flow in an active fault scarp in nw anatolia turkey anatomy mechanism and timing mass instability in the uplifting footwall blocks of normal faults involves a range of regional and local factors including among others climatic setting topography lithology and particularly ground shaking during earthquakes morphological and sedimentological investigations backed by 14c dating on a huge debris flow and its zone of depreciation provided favorable insights for dynamics and causative factors of this mass wasting our observations showed that ismetpasa debris flow with a volume of 96 km 3 involves three individual flows of decreasing significance in the late pleistocene holocene period the primary flow occurred in relation to a huge landslide developed on highly fractured and altered basaltic lavas near the crest of fault scarp c 18 7 ka bp and probably conditioned by high precipitation rates in the early interglacial although most of the blocky debris flow transferred into the neighboring graben to form a 2 km wide debris fan some remnant blocks and flow induced valley side slick

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

liquefaction potential assessment of a region using different techniques tepebasi eskisehir turkey abstract eskisehir is a city in turkey that is located primarily on the porsuk river alluvium deposits hence the probability of liquefaction is a geotechnical problem in this city in this study the liquefaction potential was investigated using a standard penetration test spt and downhole geophysical test menard pressuremeter tests were also performed in order to modify liquefaction analysis methods with this test laboratory tests were performed on standard penetration split sampler samples collected from the boreholes liquefaction analysis was performed considering different scenarios the first peak horizontal acceleration value was determined from the earthquake that occurred in 1956 which was 6 4 mw the second peak horizontal acceleration value was determined from cukurhisar sultandere fault which is approximately 40 km long and may create a 6 94 mw earthquake with a peak horizontal acceleration of amax 0 48 g there are some differences between spt n method and vs method but both the spt n method and the vs method are harmonious with each other in general for determination of the liquefable soils the vs method particularly results in a continuous profile for the liquefaction determination there is no regional liquefaction potential in the study region but locally liquefiable silty sand layers were determined the liquefable layer thickness increases with increasing peak horizontal acceleration a liquefaction analysis method using the menard pressuremeter test is suggested in this study both the cyclic resistance ratio crr chart and the equation are modified for liquefaction analysis using the menard pressuremeter test

was the 1899 menderes valley earthquake a double earthquake historical and paleosismological constraints abstract september 20 1899 menderes valley earthquake is the last destroying event in the buyuk menderes graben western turkey just proceeding the installation of the earliest seismograms in the world the previous geological studies revealed that this seismic event of estimated mw 6 5 6 7 caused a surface rupture of 50 km between aydin and kuyucak in the center of the graben based on the extremely different positioning of microseismic epicenter of this event in various historical documents we re evaluated the 1899 earthquake with a rather multidisciplinary perspective quantitative earthquake data including fatalities damage and various types of aids were gathered from daily journals and special commission reports of the time these data are corrected with the population statistics and georeferenced for exact determination of the position of the surface rupture we benefited the verbal description in historical documents and witnesses of elder local people furthermore morphological and palaeoseismological investigations were realized in the eastern part of the graben where surface deformations were made mention in historical documents different ground shake related indicators conformably revealed two distinct geographically separated damage zone one at yenipazar and the other at ortakci in the middle and east of the graben respectively trench studies in the west of the ortakci village indicated evidences of a seismic event presumably the 1899 earthquake with 180 cm vertical displacement bimodal distribution damage unrelated to basement lithology and building types and the incoherence between the total surface rupture length and the observed vertical offset and earthquake intensity lead us to conclude that the 1899 menderes valley earthquake was an earthquake doublet occurred in two neighboring segments in very close temporal proximity