effects of h2o on elastic wave velocities in ultrabasic rocks at 900 c under 1 gpa simultaneous measurements of compressional and shear wave velocities vp and vs in five ultrabasic rocks with hydrous minerals were carried out from room temperature to 900 c under 1gpa in a closed system both vp and vs in all five rocks decreased markedly near 600 c and or 800 c following the dehydration of hydrous minerals in the rocks considering velocities only in the anhydrous matrix which were estimated from the volumetric ratio of forsterite and enstatite in each sample the effects of water produced by the dehydration reactions were estimated the ratio of v at 900 c under 1gpa is represented by the following equation v 1 0 0027 w to both p and s wave where v is the velocity in the rock including the extricated water w kg m 3 and is the velocity in the sample excluding the extricated water the low velocity layer lies between the descending lithosphere and the overlying asthenosphere beneath the japanese island arcs and the ratio of vp drop for the low velocity layer to that of the underlying descending lithosphere is approximately 5 if the observed velocity drop is wholly attributed to the free water produced by dehydration of serpentine minerals in the descending slab the required volumetric ratio of serpentine minerals in the descending slab would be 5 10

leakage of clogged channels that partially penetrate surficial aquifers a theoretical formulation describing leakage from clogged channels that partially penetrate surficial aquifers is reported in this paper leakage characteristics are parameterized by a reach transmissivity which is defined as the volume flow rate out of the channel per unit length of the channel per unit drawdown an expression is developed to relate the reach transmissivity to the transmissivity of the formation mean channel width distance of drawdown measurement from the channel centerline ratio of drawdowns on both sides of the channel and local reach transmissivity associated with clogging this theoretical expression and associated limitations are verified using a fine scale numerical model the proposed formulation was field tested at two channels the measurements of reach transmissivity were found to vary linearly with the drawdown ratio as predicted by the theory furthermore the aquifer transmissivity obtained by fitting the theoretical formulation to the measurements is in close agreem

confined deep water system development on the accretionary wedge miocene kahramanmaras foreland basin s turkey abstract according to theoretical studies the foreland basin consists of accretionary wedge including wedge top or piggyback basin foredeep forebulge and backbulge depozones all of them are parallel to the orogenic belts of the overlying and underlying plates the closure of the southern branch of the neotethys during the late cretaceous led to an oblique collision of the arabian plate and the anatolide taurides platform leading to the development of the miocene kahramanmaras foreland basin kfb thus the promontory shape of the arabian plate prevented the development of an accretionary wedge parallel to the orogenic belt the accretionary wedge of the kfb includes blocks of various sizes and age mainly mesozoic limestone scattered within an early tertiary matrix mass wasting deposits and shallow to deep marine sediments at the beginning of the miocene transtensional tectonism led to the development of half graben basins on top of the accretionary wedge these basins namely the tekir and cukurhisar also cut the foredeep of the kfb obliquely in contrast with the theoretical study this paper focuses on the evolution and fillings of those basins initially claystone and basin margin reef deposits filled the half graben basins as a consequence of the lower miocene sea invasion then long and narrow conglomeratic channels starting from the northern edge of the basins fan delta progressed southwards passing into sandy lobes then into claystones an activation of the boundary faults of the wedge top basin stopped the progression of the lower middle miocene sediments and led to their deformation then the sedimentation of the kfb shifted towards the basin centre during the middle miocene

stratigraphic and tectonic settings of early paleolithic of north west armenia the quaternary stratigraphy and tectonic development of the southern javakheti upland and the adjacent upper akhurian and lori uplifted basins in nw armenia lesser caucasus and geological position of the early and middle acheulian lithic industries were studied using a multi method approach studies of sedimentary sections petrological and geochemical correlation of lavas and tuffs k ar dating of volcanic rocks and sims 238u 206pb dating of tuffs examination of obtained fossils and pollen analysis and determination of remanent magnetic polarity of volcanic rocks and clastic sediments have been used to compile the stratigraphic scheme and to estimate the age of units the low mountain topography was differentiated to ridges and basins to the beginning of quaternary the eruptions of basalts and basaltic andesites evened topography of the upper akhurian and lori basins in the gelasian the lava flows spread along big river valleys at tens of kilometers at the late gelasian the eruptions of basaltic trachyandesites trachyandesites and dacites replaced the basaltic eruptions the latter dammed the akhurian river flowing to the south and the upper akhurian river found the flowing to the east via the valley like depression of the karakhach pass to the dzoraghet debed valley the course grained tuffaceous clastic karakhach unit was deposited during the olduvai subchron not earlier than 1 9 1 85 ma and the earliest calabrian the water transit between the upper akhurian and lori basins was interrupted later because of rise of the karakhach pass volcanic activity renewed for a short time in the early calabrian 1 7 and 1 5 1 4 ma the end calabrian and earliest middle pleistocene sedimentation 1 0 5 ma occurred in stagnant water partly lacustrine conditions this was expressed by formation of the relatively fine grained kurtan unit during the last 0 5 ma the region underwent flexure fault deformation and tectonic uplift at 350 800 m the epoch of formation of the karakhach unit was characterized by middle mountain topography and humid climate not later than 1 85 ma the region was occupied by the earliest hominines producing lithic industries of the early acheulian aspect they contained crude hand axes and other macro tools made of local dacite and basalt sites of karakhach muradovo and agvorik early appearance of these industries might be caused by natural parting of dacite and basalt to tabulated fragments that gave a possibility to make such macro tools the middle acheulian artifacts were found in the kurtan i section of the kurtan unit

structure and elasticity of serpentine at high pressure abstract serpentines occur in the subduction zone settings both along the slab and within the mantle wedge they are candidates for transporting water in to the deep earth their presence is manifested by serpentine mud volcanoes high electrical conductivities magnetic and seismic anomalies using theoretical methods we predict a pressure induced structural transformations in serpentine the transformations are related to the behavior of the silicate framework and misfit between octahedral and tetrahedral layers as the structure is compressed the octahedral layer and tetrahedral layers are compressed at different rates at 7 gpa the misfit between the layers vanishes this causes non linear pressure dependence of tetrahedral rotational angle this is also manifested by the onset of anomalous pressure dependence of the elastic constants c 11 c 33 c 12 c 13 beyond 7 gpa the misfit between the layers grows again reaching extremum at 22 gpa this is also manifested by discontinuity in average si o bond length volume of tetrahedron and re orientation of hydroxyl vector the symmetry of the crystal structure however remains unaffected evidence of pressure induced hydrogen bonding is absent in serpentine as evident from reduction of o h bond length upon compression results of compression for the low pressure regime p k 0 79 gpa k 0 12 and k 0 2 where k is the bulk modulus prime indicates pressure derivatives and o refers to zero pressure our best estimates of k 0 k 0 and the gruneisen parameter at 300 k and zero pressure based on our results are 61 gpa 17 and 0 77 respectively at low pressures serpentine structure is anisotropic with c 11 2 4 c 33 the pressure derivative of elastic constants c ij p are such that around 22 gpa c 11 c 33 an elastic instability c 66 50 gpa is also noted the elastic constant tensor reveals large acoustic anisotropy 41 in v p and seismic wave velocities that are significantly higher than those inferred from experiments on serpentinites

the berit transect of the tauride thrust belt s turkey late cretaceous early cenozoic accretionary collisional processes related to closure of the southern neotethys abstract we report on an integrated study of a critical segment of the tauride thrust belt in se turkey berit area units related to two sutures are exposed in the northerly and southerly parts of the area studied in the north the upper cretaceous binboga melange reflects the closure of a northerly mesozoic oceanic basin in the south contrasting units document the closure of the southern neotethys in the south the berit or goksun ophiolite formed as an incipient oceanic arc within the southern neotethys during the late cretaceous c 90 ma intercalated amphibolite granulite facies rocks may record a dismembered metamorphic sole an underlying meta sedimentary meta volcanic unit is interpreted as accreted continental rift and oceanic seamount lithologies the berit ophiolite was accreted to the tauride active continental margin to the north around 85 ma and was then intruded by calc alkaline granites c 70 85 ma northerly margin units were exhumed and covered by shelf carbonate sediments during latest cretaceous early cenozoic time northward subduction during the mid cenozoic c 45 ma resulted in back arc extension along the tauride active margin and subduction influenced volcanism possibly controlled by slab roll back during oligocene early miocene time the southern neotethys closed and the tauride active margin was telescoped to create the present south vergent thrust stack this was accompanied by mass wasting of the advancing allochthon to form sub aqueous frontal olistostromes the arabian platform was over ridden by mid miocene time followed by left lateral strike slip along the east anatolian fault zone as anatolia began to escape westwards towards the aegean sea

eocene development of the northerly active continental margin of the southern neotethys in the kyrenia range north cyprus we focus on an active continental margin related to northwards subduction during the eocene in which sedimentary melange olistostromes forms a key component maastrichtian early eocene deep marine carbonates and volcanic rocks pass gradationally upwards into a thick succession 800 m of gravity deposits exposed in several thrust sheets the lowest levels are mainly siliciclastic turbidites and debris flow deposits interbedded marls contain middle eocene planktonic benthic foraminifera and calcareous nannofossils sandstones include abundant ophiolite derived grains the higher levels are chaotic debris flow deposits that include exotic blocks of late palaeozoic mesozoic neritic limestone and dismembered ophiolite related rocks a thinner sequence 200 m in one area contains abundant redeposited paleogene pelagic limestone and basalt chemical analysis of basaltic clasts shows that some are subduction influenced basaltic clasts from unconformably overlying alluvial conglomerates late eocene oligocene indicate derivation from a supra subduction zone ophiolite including boninites taking account of regional comparisons the sedimentary melange is interpreted to have formed within a flexurally controlled foredeep floored by continental crust gravity flows including large limestone blocks multiple debris flows and turbidites were emplaced followed by southwards thrust imbrication the emplacement was possibly triggered by the final closure of an oceanic basin to the north alanya ocean further convergence between the african and eurasian plates was accommodated by northwards subduction beneath the kyrenia active continental margin subduction zone rollback may have triggered collapse of the active continental margin non marine to shallow marine alluvial fans prograded southwards during late eocene oligocene time marking the base of a renewed depositional cycle that lasted until latest miocene time

new data on the late cenozoic basaltic volcanism in syria applied to its origin abstract new data on geology and 21 k ar dates of the late oligocene quaternary basalts in syria combined with analysis of the new and previous data are used to reconstruct the volcanic history and relations between it and tectonic events volcanism began at the end of oligocene 26 24 ma and was concentrated in the late oligocene early miocene along a n trending band which stretches from the jebel arab harrat ash shaam up to kurd dagh and southern turkey activity waned in the middle miocene 17 12 ma but was resumed in the same band in the tortonian and increased in the messinian and early pliocene 6 3 4 ma when volcanism spread to the shin plateau and its coastal extension after a brief hiatus 4 3 5 ma volcanism became still more intensive and spread from the n trending band to the east into the northern margin of the mesopotamian foredeep and to the west into the dead sea transform zone additional eruptions continued into the holocene volcanism lasted 25 million years in the jebel arab highland and 15 million years in the aleppo plateau the long duration of volcanism in the same parts of the moving arabian plate and absence of records of one way migration of the activity mean that the magmatic sources moved together with the plate i e they were situated within the lithosphere mantle coincidence of the tectonic and volcanic stages of the arabian plate development proves that volcanic activity depended on the geodynamic situation caused by the plate motion situated within the lithosphere magmatic sources within this transverse band were possibly caused by thermal and deforming influences of the asthenospheric lateral flow moved laterally from the ethiopia afar deep superplume

rupture kinematics of 2020 january 24 mw 6 7 doganyol sivrice turkey earthquake on the east anatolian fault zone imaged by space geodesy

the misis andirin complex a mid tertiary melange related to late stage subduction of the southern neotethys in s turkey abstract the mid tertiary mid eocene to earliest miocene misis andirin complex documents tectonic sedimentary processes affecting the northerly active margin of the south tethys neotethys in the easternmost mediterranean region each of three orogenic segments misis in the sw andirin central and engizek in the ne represent parts of an originally continuous active continental margin a structurally lower volcanic sedimentary unit includes late cretaceous arc related extrusives and their lower tertiary pelagic cover this unit is interpreted as an early tertiary remnant of the mesozoic south tethys the overlying melange unit is dominated by tectonically brecciated blocks 100 m across of mesozoic neritic limestone that were derived from the tauride carbonate platform to the north together with accreted ophiolitic material the melange matrix comprises polymict debris flows high to low density turbidites and minor hemipelagic sediments the misis andirin complex is interpreted as an accretionary prism related to the latest stages of northward subduction of the south tethys and diachronous continental collision of the tauride eurasian and arabian african plates during mid eocene to earliest miocene time slivers of upper cretaceous oceanic crust and its early tertiary pelagic cover were accreted while blocks of mesozoic platform carbonates slid from the overriding plate tectonic mixing and sedimentary recycling took place within a trench subduction culminated in large scale collapse of the overriding northern margin and foundering of vast blocks of neritic carbonate into the trench a possible cause was rapid roll back of dense downgoing mesozoic oceanic crust such that the accretionary wedge taper was extended leading to gravity collapse melange formation was terminated by underthrusting of the arabian plate from the south during earliest miocene time collision was diachronous in the east engizek range and se anatolia collision generated a lower miocene flexural basin infilled with turbidites and a flexural bulge to the south miocene turbiditic sediments also covered the former accretionary prism further west misis range the easternmost mediterranean remained in a pre collisional setting with northward underthrusting incipient subduction along the cyprus arc the lower miocene basins to the north misis and adana indicate an extensional to transtensional setting the ne sw linking segment andirin probably originated as a mesozoic palaeogeographic offset of the tauride margin this was reactivated by strike slip and transtension during later tertiary diachronous collision related to on going plate convergence the former accretionary wedge upper plate was thrust over the lower miocene turbiditic basins in mid late miocene time the plio quaternary was dominated by left lateral strike slip along the east anatolian transform fault and also along fault strands cutting the misis andirin complex

faunal remains from the oldowan site of muhkai ii in the north caucasus potential for dating and palaeolandscape reconstruction abstract the results of study of faunal materials unique for the north eastern caucasus are published deriving from layer 80 of the oldowan site of muhkai ii twenty six specimens of four species of carnivorous mammal and six species of herbivorous mammal were identified in this material in addition the remains of small mammals reptiles and amphibians were identified which are indicators for the dating of the assemblage and the establishment of the specific characteristics of the natural environment at the time of usage of the oldowan site while in the modern day the investigated region consists of a belt of medium high mountains during the chronological period under study open landscapes of savannah type with small areas of forest vegetation dominated based on a combination of data from palaeomagnetic analysis and faunal determinations the time of existence of the complex is established as no later than the lower limit of the olduvai episode during the matuyama palaeomagnetic epoch

late cretaceous miocene sedimentary development of the arabian continental margin in se turkey adiyaman region implications for regional palaeogeography and the closure history of southern neotethys abstract the middle cretaceous late miocene sedimentary successions that are exposed on the arabian continental margin near adiyaman provide valuable insights into sedimentary tectonic and climatic processes that affected the southern neotethys and its continental margins deposition in the region began with aptian early campanian shelf carbonates followed by deepening during the mid campanian lithoclastic bioclastic turbidites accumulated along the downfaulted northern margin of the arabian platform during the campanian a flexurally controlled foredeep developed in advance of the emplacement of mesozoic allochthonous continental margin and oceanic rocks during the latest campanian early maastrichtian e g supra subduction zone kocali ophiolite alluvial detritus was shed from the emplaced allochthon in non marine to shallow marine deltaic settings during latest campanian early maastrichtian a marine transgression resulted in the establishment of a shallow marine shelf during the mid maastrichtian during the latest maastrichtian the platform submerged initiating deeper water hemipelagic sedimentation uplift took place during the palaeocene resulting in sediment instability slumping and formation of high density subaqueous gravity flows in response to regional faulting and tilting some areas in the north and the southwest emerged during the early middle eocene generating alluvial fans in a warm humid climate that favoured oxidation and reddening the likely control of the tectonic instability was far field compression related to the latest stages of subduction of the southern neotethys or the initial stages of collision of the arabian and tauride continents an oligocene hiatus is likely to reflect the formation of a collision related forebulge followed by flexural subsidence to form an early miocene foreland basin this was finally over ridden by the northerly active continental margin of the southern neotethys during early mid miocene regional suture tightening mid late miocene and related non marine coarse clastic sedimentation was followed by westward tectonic escape of the anatolian microplate towards the aegean region during plio quaternary time

modification of canal flow due to stream aquifer interaction unsteady canal flow in an integrated canal flow groundwater flow system is analyzed by solving the coupled equations governing canal flow groundwater flow and the seepage between them analytical solu tions are obtained for the coupled system for small water level disturbances using fourier analysis methods and complex variables dimensionless parameter groups characterizing the aquifer the canal and the sediment layer are identified using the governing equations and the solution the influence in the aquifer and the semipermeable bottom sediment layer due to disturbances in canal flow is studied the analytical solutions are compared to numerical solutions obtained using the modflow model and the hydrologic simulation engine of the south florida regional simulation model results of the analysis are useful in determining the range of aquifer sediment and canal characteristics for which stream aquifer interaction is important the results can be used to determine the conditions for which the canal is hydraulically disconnected from the aquifer because of the sediment layer the analytical solution is useful to understand the propagation characteristics of small amplitude water level disturbances in the canal and the aquifer the characteristics studied include the amplitude decay constant and the speed the solution can be used to design benchmark problems that can be used to evaluate integrated canal flow groundwater flow models the results of the study can be used to estimate the space and time steps needed in the canal and the aquifer when simulating stream aquifer interaction as part of the overall effort to restore the everglades eco system in south florida and to meet its regional water man agement responsibilities the south florida water management district sfwmd sfwmd 1999 and other organizations have developed a number of mathematical models to simulate the water management system one important requirement of these models is the capability to simulate stream aquifer in teraction or stream wetland interaction a significant part of the south florida landscape is covered with a network of ca nals that extends for thousands of miles through wetlands ag ricultural areas and urban areas the behavior of water levels in the canals when areas adjacent to canals are subjected to water level changes is not completely understood the influ ences of the highly conductive surface aquifer and the less conductive bottom sediment layer of the canal on the overall hydrology are also not completely known these behaviors influence a significant part of south florida hydrology the current study provides a method to understand the basic pa rameters that govern the problem and to obtain an analytical solution stream aquifer and stream wetland interactions have previ ously been studied by a number of researchers the study by pinder and sauer 1971 was conducted by using a coupled numerical model for canal flow and 2d groundwater flow the objective was to study the influence of bank storage on the modification of flood waves the example used by pinder and sauer 1971 served as a benchmark test for integrated mod els such as modbranch swain and wexler 1996 and modnet walton et al 1999 these models consist of a modflow model mcdonald and harbaugh 1988 coupled with either the branch model schaffranek 1987 or the unet model hec 1996 the comparison between the so lution obtained by pinder and sauer 1971 and the solutions obtained using modbranch or modnet was not perfect 1

stochastic analysis of stream groundwater interaction subject to temporally correlated recharge summary in this article the coupled equations describing the transient groundwater flow and stream flow fluctuations are solved based on the fourier stieltjes integral representation where the lateral inflow term in the stream flow perturbation equation connects the process of groundwater flow to that of stream flow the closed form solutions describing the variability in groundwater flow specific discharge and stream flow discharge are developed to quantify the influence of the variability in temporally correlated recharge in an unconfined aquifer on the stream flow discharge we found from the closed form solutions that the temporal correlation scale and the variance of recharge fields influence the variability in groundwater flow specific discharge and the stream flow discharge positively in addition the hydraulic diffusivity coefficient takes the role of reducing the variability in stream flow discharge

pliocene early pleistocene history of the euphrates valley applied to late cenozoic environment of the northern arabian plate and its surrounding eastern turkey abstract the pliocene quaternary paleogeography of the euphrates river valley changed due to sinistral movements on the east anatolian fault zone eafz and the taurus ridge rise by movements on the south taurus thrust evidence of these changes is based on studies of the pliocene quaternary deposits of the euphrates river basin to the north and to the south of the taurus ridge and the late cenozoic deformation including offsets on the eafz combination of methods was used to date the pliocene quaternary deposits it includes geological and geomorphic analysis and correlation of sections determination of remanent magnetization paleontological and archaeological finds pollen analysis and k ar dating of volcanic rocks to the north of the taurus ridge the late miocene tectonic depressions were filled by lakes connected by braided streams in the early pliocene the euphrates and murat river valleys formed and the euphrates flew to the south westwards of its recent position via the graben like trough of the sultan suyu river valley and farther to the erikdere that are recent euphrates tributaries the flow was interrupted later because of some desiccation and rise of the taurus ridge the flow recommenced in the end gelasian early calabrian via the goksu cayi and erikdere valleys consecutively and was interrupted again at the end of calabrian 0 8 0 9 ma the euphrates waters found the recent way via the taurus ridge and the former upstream bottoms of the euphrates and its tributaries valleys became a vast upper terrace after this the taurus ridge rose by more than 330 m lower terraces were formed because of the tectonic uplift that was more intense to the north of the taurus ridge 0 13 0 16 mm year than to the south of it 0 1 mm year the new formed segment of the euphrates valley was offset on the eafz at 12 km that gives the slip rate of 13 15 mm year

apatite fission track data for the miocene arabia eurasia collision the collision between the eurasian and arabian plates along the 2400 km long bitliszagros thrust zone isolated the mediterranean from the indian ocean and has been linked to extension of the aegean rifting of the red sea and the formation of the north and east anatolian fault systems however the timing of the collision is poorly constrained and estimates range from late cretaceous to late miocene here we report the fi rst apatite fi ssiontrack aft ages from the bitlis zagros thrust zone the aft samples are distributed over the 450 km length of the bitlis thrust zone in southeast turkey and include metamorphic rocks and eocene sandstones despite the disparate lithology and large distance the aft ages point consistently to exhumation between 18 and 13 ma the aft ages along with a critical appraisal of regional stratigraphy indicate that the last oceanic lithosphere between the arabian and eurasian plates was consumed by the early miocene ca 20 ma the results imply that aegean extension predated the arabia eurasia collision

age of the earliest paleolithic sites in the northern part of the armenian highland by shrimp ii u pb geochronology of zircons from volcanic ashes abstract understanding the earliest period of hominid dispersal from africa to eurasia requires reliable ages since artifacts are not suitable for direct dating geochronology of an artifact host rock matrix is the only robust approach possible matrix contamination limits the application of bulk mineral analysis but the spatially selective secondary ionization mass spectrometry sims technique allows screening of contaminants in two recently discovered early paleolithic sites in the northern armenian highland the stratigraphic sequence includes ash bearing volcanic layers with zircon autocrysts suitable for sims u pb dating at the karakhach site zircons from the ash bearing volcanic layers yielded single age populations this suggests that the layers were formed during multiple eruptions and were not reworked zircon crystallization ages of 1 942 0 046 ma 1 804 0 030 ma and 1 750 0 020 ma are close to eruptions and therefore date the enclosed early acheulian lithic artifacts for artifacts underneath the oldest ash layer the zircon age indicates the minimum age of artifacts these results identify the karakhach as the oldest early acheulian site in eurasia at the kurtan site the dated ash layer underlies palaeosols containing early middle acheulian artifacts the stratigraphic succession at this site implies that the u pb zircon age of 1 432 0 028 ma from the ash is nearly coeval with the beginning of human occupation at the site

an ephemeral stream aquifer interaction model the boundary integral equation method is applied to the interaction between an ephemeral stream and an unconfined aquifer through a semipervious streambed the resulting two dimensional vertical slice model describes groundwater flow when the stream and aquifer are hydraulically disconnected or connected as well as the transition between these two states it incorporates the green ampt equation with the hydraulically disconnected boundary conditions the model was successfully calibrated using stream discharge and bore hydrograph data from the little para river recharge study south australia it predicts with sufficient accuracy the inflow and outflow from the stream to the aquifer during fluctuating water levels in the stream

record of cenozoic sedimentation from the amanos mountains southern turkey implications for the inception and evolution of the arabia eurasia continental collision abstract the sedimentary succession of the southern amanos mountains bordering the eastern margin of the karasu rift in south central turkey provides a record of environmental change from the eocene lutetian to the upper miocene tortonian that charts the final evolution of the northern margin of the arabian plate prior to and during continental collision eocene shallow marine carbonates hacidagi formation are interpreted as the youngest unit of the arabian passive margin succession deposited on a northwards facing carbonate ramp subsequent deformation and uplift took place during the oligocene represented by folding of the eocene and older strata this is interpreted to be the result of initial continental collision between arabia and eurasia unconformably overlying the eocene limestone are lower miocene conglomerates sandstones and palaeosols up to 150 m thick kici formation these were deposited in a range of marginal marine settings consisting of alluvial fan fan delta facies flood plain as well as basinal facies subsequently during the middle miocene local patch reefs developed in restricted areas kepez formation followed by upper miocene sediments gokdere formation composed of relatively deep water hemipelagic marl with clastic interbeds which represent a transgression during this period the upper miocene becomes sandier upwards this records the regression from the relatively deep water facies to coastal sediments water depth gradually became shallower until during pliocene time the area became continental in nature by the quaternary rifting had resulted in the development of the karasu rift with active alluvial fans along the margins and braided rivers depositing coarse conglomerates in the axial zone these conglomerates are interbedded with basaltic lava flows that resulted from the region extension across the area this research shows that initial continental collision occurred in this area after the lutetian 40 4 ma and before the aquitanian 23 03 ma supporting the hypothesis that the southern neotethys ocean closed during the late eocene to oligocene this was a time of climatic change including the onset of southern hemisphere glaciation in which the closure of the southern neotethys may have had played an important role

late cretaceous cenozoic subduction collision history of the southern neotethys new evidence from the caglayancerit area se turkey evidence of the subduction collision history of the s neotethys is well exposed in the frontal part of the se anatolian thrust belt and the adjacent arabian continental margin the foreland succession in the study area begins with eocene shelf carbonates ranging from shallow marine to deeper marine without sedimentary input from the tauride continent to the north after a regional hiatus oligocene sedimentation resumed during the early miocene with terrigenous gravity flow deposition in the north lice formation and shallow marine carbonates further south clastic detritus was derived from the tauride continent and oceanic accretionary material the base of the overriding tauride allochthon comprises ophiolite derived debris flows ophiolite related melange and dismembered ophiolitic rocks above this the regional scale bulgurkaya sedimentary melange an olistostrome includes blocks and dismembered thrust sheets of metamorphic rocks limestone and sandstone which include late cretaceous and eocene foraminifera the matrix is mainly strongly deformed eocene oligocene mudrocks hemipelagic marl and sandstone turbidites the thrust stack is topped by a regionally extensive thrust sheet malatya metamorphic unit which includes greenschist facies marble calcschist schist and phyllite representing tauride continental crust beginning during the late mesozoic the s neotethys subducted northwards beneath a backstop represented by the tauride microcontinent malatya metamorphic unit ophiolites formed within the s neotethys and accreted to the tauride active margin large scale sedimentary melange developed along the tauride active margin during eocene oligocene on the arabian margin a sedimentary hiatus and tilting oligocene is interpreted to record initial continental collision the early miocene terrigenous gravity flows represent a collision related flexural foreland basin southward overthrusting of the tauride allochthon took place during early middle miocene associated regional uplift triggered large scale alluvial deposition the foreland folded and faulted in response to suture zone tightening late miocene left lateral strike slip characterised the plio pleistocene

late cenozoic surface uplift revealed by incision by the river euphrates at birecik southeast turkey incision by the river euphrates has created a dramatic erosional landscape in the northern arabian platform in se turkey we obtain accurate heights of its terrace deposits in the birecik area using differential gps and summarise evidence regarding heights of late miocene basalt flows and low altitude wetland sediments we thus estimate 600 m of uplift since the early late miocene 9 ma represented by 270 m of fluvial incision the difference reflecting downstream channel lengthening as the coastline has retreated to the persian gulf 1400 km away the oldest recognised sediments inset below this level form a thick aggradation between 100 and 130 m above the present level of the euphrates we estimate that this accumulated during 5 3 ma when uplift rates were low such that aggradation was necessary to maintain a downstream channel gradient in response to the coastal retreat palaeolithic artefacts have been reported locally in euphrates deposits up to 80 m above present river level which we tentatively date to 1 8 ma the euphrates subsequently incised to within 10 m of its present level before aggrading 45 m higher in the late early pleistocene the final 55 m of incision reflects the increase in uplift rates observed worldwide in the early middle pleistocene following the mid pleistocene revolution

ar ar dating of late cenozoic basaltic volcanism in northern syria implications for the history of incision by the river euphrates and uplift of the northern arabian platform 1 ar ar dating of basalt flows capping terrace deposits of the river euphrates in northern syria has provided a new quantitative chronology for the late cenozoic evolution of this important river system and for the associated history of surface uplift of the northern arabian platform through which it flows a region of relatively strong crust that has experienced only slow deformation notably fluvial deposits 65 m above the euphrates are overlain by basalt dated to 2717 20 ka those 45 m above the river are overlain by basalt dated to 2116 39 ka and those 8 9 m above the river are overlain by basalt dated to 402 11 ka these new dates require the previous dating scheme based on paleolithic archaeology to be revised the euphrates terrace deposits and the associated incised valley are much older than was previously thought rates of incision by the euphrates providing a proxy for regional surface uplift that is inferred to be the isostatic response to regional erosion have varied significantly over the past 3 ma with indications that between 1 2 and 0 9 ma there was regional subsidence which gave rise to fluvial aggradation this unusual pattern involving reversals in the sense of vertical crustal motions is interpreted to be a consequence of a relatively cold and thin mobile lower crustal layer no more than 5 km thick evidently due to the presence of a much thicker underlying layer of mafic underplating at the base of the crust this study thus indicates previously unsuspected complexity in the isostatic response to regional erosion in an area of high crustal stability

dating and correlation of the quaternary fluvial terraces in syria applied to tectonic deformation in the region abstract new data on location height and composition of terraces of the el kabir and orontes rivers in syria are represented by combined use of paleontological archaeological paleomagnetic and radio isotopic methods ages of these river terraces are estimated and they are correlated with the euphrates river terraces the age of the terraces is defined more precisely by evidence of synchronism of the el kabir alluvial terraces and the marine terraces of the mediterranean coast the average rates of incision during different time intervals were estimated in the studied valleys and their segments using relative height of the terraces this gives the possibility of approximately estimating a rate of the quaternary uplift in different tectonic provinces of syria as well as rates of vertical movements on the lattaqieh the el kabir valley hama the orontes valley and euphrates the euphrates valley faults the rates of incision were usually small in the earlier stages of the valley formation and increased later the middle and late pleistocene rates of the valley incision reach 220 280 mm ky in the el kabir valley the coastal range anticline 80 130 mm ky in the orontes valley and the euphrates upstream of the assad reservoir the mobile platformal aleppo block and 25 30 mm ky in the euphrates valley downstream of the assad reservoir southwestern side of the mesopotamian foredeep

aquifer response to stream stage and recharge variations i analytical step response functions abstract laplace transform step response functions are presented for various homogeneous confined and leaky aquifer types and for anisotropic homogeneous unconfined aquifers interacting with perennial streams flow is one dimensional perpendicular to the stream in the confined and leaky aquifers and two dimensional in a plane perpendicular to the stream in the water table aquifers the stream is assumed to penetrate the full thickness of the aquifer the aquifers may be semi infinite or finite in width and may or may not be bounded at the stream by a semipervious streambank the solutions are presented in a unified manner so that mathematical relations among the various aquifer configurations are clearly demonstrated the laplace transform solutions are inverted numerically to obtain the real time step response functions for use in the convolution or superposition integral to maintain linearity in the case of unconfined aquifers fluctuations in the elevation of the water table are assumed to be small relative to the saturated thickness and vertical flow into or out of the zone above the water table is assumed to occur instantaneously effects of hysteresis in the moisture distribution above the water table are therefore neglected graphical comparisons of the new solutions are made with known closed form solutions

geometry and seismic properties of the subducting cocos plate in central mexico the geometry and properties of the interface of the cocos plate beneath central mexico are determined from the receiver functions rfs utilizing data from the meso america subduction experiment mase the rf image shows that the subducting oceanic crust is shallowly dipping to the north at 15 for 80 km from acapulco and then horizontally underplates the continental crust for approximately 200 km to the trans mexican volcanic belt tmvb the crustal image also shows that there is no continental root associated with the tmvb the migrated image of the rfs shows that the slab is steeply dipping into the mantle at about 75 beneath the tmvb both the continental and oceanic moho are clearly seen in both images and modeling of the rf conversion amplitudes and timings of the underplated features reveals a thin low velocity zone between the plate and the continental crust that appears to absorb nearly all of the strain between the upper plate and the slab by inverting rf amplitudes of the converted phases and their time separations we produce detailed maps of the seismic properties of the upper and lower oceanic crust of the subducting cocos plate and its thickness high poisson s and vp vs ratios due to anomalously low s wave velocity at the upper oceanic crust in the flat slab region may indicate the presence of water and hydrous minerals or high pore pressure the evidence of high water content within the oceanic crust explains the flat subduction geometry without strong coupling of two plates this may also explain the nonvolcanic tremor activity and slow slip events occurring in the subducting plate and the overlying crust

discovery of the late triassic middle carnian rhaetian radiolarians in the volcano sedimentary sequences of the kocali complex se turkey correlation with the other tauride units abstract the kocali complex in se turkey includes pelagic sediments pelagic limestones cherts etc basic volcanic rocks of oceanic crust origin together with platform derived sediments its depositional age was previously assigned as late jurassic early cretaceous in order to study the radiolarian contents of volcano sedimentary sequences in this complex six stratigraphic sections have been measured mainly at the ne and nw adiyaman city radiolarian faunas from these stratigraphic sections reveal that the age of these sequences ranges from middle carnian to rhaetian based on these data the depositional age of the complex is older than the previously assigned lithological characteristics widespread triassic basic volcanic rocks associated with pelagic sediments and radiolarian contents of these sequences have close similarities with the sequences of the alakircay nappe of the antalya nappes in western and central taurides based on taxonomic studies 99 taxa have been determined of which one genus adiyamanium and four species monocapnuchosphaera kocaliensis paronaella speciosa ferresium okuyucui and adiyamanium crassum are described as new

stream water infiltration bank storage and storage zone changes due to stream stage fluctuations abstract during a flood period stream stage increases induce infiltration of stream water into an aquifer subsequent declines in stream stage cause a reverse motion of the infiltrated water this paper presents the results of the water exchange rate between a stream and aquifer the storage volume of the infiltrated stream water in the surrounding aquifer bank storage and the storage zone the storage zone is the part of aquifer where groundwater is replaced by stream water during the flood modflow was used to simulate stream aquifer interactions and to quantify rates of stream infiltration and return flow modpath was used to trace the pathlines of the infiltrated stream water and to determine the size of the storage zone simulations were focused on the analyses of the effects of the stream stage fluctuation aquifer properties the hydraulic conductivity of streambed sediments regional hydraulic gradients and recharge and evapotranspiration et rates on stream aquifer interactions generally for a given stream aquifer system larger flow rates result from larger stream stage fluctuations larger storage volumes and storage zones are produced by larger and longer lasting fluctuations for a given stream stage hydrograph a lower permeable streambed an aquitard or an anisotropic aquifer of low vertical hydraulic conductivity can significantly reduce the rate of infiltration and limit the size of the storage zone the bank storage solely caused by the stage fluctuation differs slightly between gaining and losing streams short term rainfall recharge and et loss in the shallow groundwater slightly influence on the flow rate but their effects on bank storage in a larger area for a longer period can be considerable

variability of stream flow discharge in response to self similar random fields of temporal fluctuations in lateral inflow rate summary this article presents the use of stochastic methodology for quantitative analysis of variability in stream flow discharge in response to fluctuations in lateral inflow rate where the lateral inflow rate is considered to be the difference between rainfall and infiltration rates in this work we focus on the case where the temporal correlation structure of the fluctuations in the lateral inflow rate can be characterized by the statistics of random fractals a closed form expression quantifying the stream flow variability is therefore developed to investigate the influence of the fractal dimension of lateral inflow process and the size of time domain it is found that the stream flow discharge variability increases with the time domain size while the fractal dimension of lateral inflow process plays a role in the smoothness of fluctuations in stream flow discharge around the mean

early palaeolithic sites on the taman peninsula southern azov sea region russia bogatyri sinyaya balka and rodniki new archaic early palaeolithic sites bogatyri sinyaya balka and rodniki are reported from the taman peninsula in southern russia the geological setting of the sites as well as the mammal fauna palynological data and palaeomagnetic data clearly indicate mid early pleistocene early biharian age of the deposits in many of its typological and technological characteristics the archaeological assemblages of bogatyri sinyaya balka and rodniki are similar to the oldowan industry although they show specific local features

experimental and theoretical studies of the stabilities of talc antigorite and phase a at high pressures with applications to subduction processes we have experimentally determined the equilibrium talc enstatite quartz coesite h2o to 40 kbar in the system mgosio2h2o msh using both synthetic and nearly pure mg end member natural talc and other synthetic starting materials for the other solid phases at 40 kbar the equilibrium dehydration boundary lies 150 c higher than that calculated using data from the existing internally consistent thermochemical data bases the reason for this discrepancy lies in the erroneous compressibility data of talc in the data bases we have retrieved the compressibility of talc from the experimental phase equilibrium data and have also calculated sereral other equilibria in the msh system involving talc antigorite and the dense hydrous magnesium silicate dhms commonly referred to as phase a comparison of these equilibria with selected thermal profiles at the leading edge of young and old subducting oceanic slabs along with the dehydration condition of basaltic amphibole and solidus of mantle peridotite provides an explanation for the observed heights of the volcanic fronts above subducting oceanic lithosphere further it is found that in cold oceanic slabs 50 ma with subduction velocity of 10 cm y antigorite will transform to the dhms phase a through a vapor conserved reaction at a depth of 200 km phase a will then serve as a carrier of water into the deeper mantle

dispersion of regional body waves at 100 150 km depth beneath alaska in situ constraints on metamorphism of subducted crust phase delays at high frequencies are observed in body waves that travel in the alaska slab along its strike at 100 150 km depth the delays between 2 6 hz energy and the direct 0 5 1 hz arrival are 0 5 1 5 s for p waves and 1 5 4 s for s waves such dispersion suggests a waveguide structure that parallels the slab perhaps near its top a channel that is 2 6 km thick and 2 5 5 slower than surrounding mantle can explain the observations the thickness of the layer is comparable to that of subducted oceanic crust or somewhat thinner the layer may be crust that is slow at these depths the required velocity anomaly is too small to be due to a continuous layer of metastable gabbro yet too large to represent an eclogite layer it may indicate a mixture of the two or persistence of hydrated mineral assemblages to depth

new evidence and model on the evolution of the southeast anatolian orogen this paper describes the orogenic evolution of the southeast anatolian orogenic belt based mostly on new geologic data collected from its constituent tectonic units in the course of new mapping programs of the past decade the southeast anatolian orogenic segment of the alpides may be divided into three approximately east west trending zones from south to north they are the arabian platform followed by a zone of imbrication and then a zone of nappes the arabian platform includes a mostly marine sedimentary succession deposited from early cambrian to middle miocene time the zone of imbrication is a narrow belt sandwiched between the arabian platform and the zone of nappes it consists of imbricated thrust slices emplaced onto a late cretaceous to early miocene sequence the zone of nappes is the highest tectonic unit consisting of two stacks of nappes simply designated the lower and upper nappes the lower nappe is represented by the slices of a polyphase metamorpbic ophiolitic assemblage and the maden group the upper nappe rests on the lower nappe and is represented by the bitlis and poturge metamorphic massifs southeastern anatolia underwent two major episodes of alpide deformation the first occurred during the late cretaceous period when ophiolite was emplaced on the arabian platform this event was not the consequence of a continental collision the ophiolite obduction onto the arabian platform was followed by a regionwide extension and a new marine transgression over the platform immediately after the ophiolite obduction the second episode of deformation occurred during middle eocene miocene time in two distinct stages as a result of the progressive elimination and complete closure of the ocean s which led to the collision between the zone of nappes located to the north being a part of eurasia and the arabian plate the maden marginal basin formed north of the subduction zone that eliminated the ocean between eurasia and arabia along the southern margin of the taurus belt and abutted the arabian plate much later during the final collision the second episode of deformation formed the present orogenic segment leading to the amalgamation of different tectonic units these amalgamated nappes collided with the arabian plate and welded onto it at the latest stage of the orogenic evolution during the miocene epoch

upper mantle velocity structure estimated from ps converted wave beneath the north eastern japan arc summary the upper boundary of the descending oceanic plate is located by using ps waves converted from p to s at the boundary in the tohoku district the north eastern part of honshu japan the observed ps p time data are well explained by a two layered oceanic plate model composed of a thin low velocity upper layer whose thickness is less than 10 km and a thick high velocity lower layer the upper and lower layers respectively have 6 per cent lower and 6 per cent higher velocity than the overriding mantle the estimated location of the upper boundary is just above the upper seismic plane of the double planed deep seismic zone this result indicates that events in the upper seismic plane at least in the depth range from 60 to 150 km occur within the thin low velocity layer on the surface of the oceanic plate

kinematic consistency between the dead sea fault zone and the neogene and quaternary left lateral faulting in se turkey a revised quantitative kinematic model has been determined for the dead sea fault zone dsfz and the left lateral fault zones in se turkey the relative motions of the african and arabian plates across the dsfz are represented by relative rotation about 31 1 n 26 7 e at 0 40 0 02 ma 1 the northern dsfz in syria and southern turkey is interpreted for the first time as a series of transpressional stepovers along which the left lateral slip rate is substantially less than the rate of relative plate motion because this slip is oblique to the plate motion the slip rate on the east anatolian fault zone eafz is estimated as 8 mm a 1 restoring its observed slip thus requires its age to be 4 ma the previous phase of deformation which involved slip on the malatya ovacik fault zone mofz before the eafz came into being is thus dated to 7 4 ma suggesting initiation of the north anatolian fault zone nafz at 7 ma not 5 ma as previously thought the total left lateral slip on the northern dsfz in southernmost turkey is estimated as at least 65 km partitioned with 45 km on the amanos fault 10 km on the east hatay fault and a further 10 km on the kirkpinar fault farther east much of this slip is inferred to have occurred during the miocene before the modern geometry of this plate boundary zone developed when it first formed the af ar plate boundary was relatively complex it initially reactivated preexisting structures in the palmyra foldbelt in syria and in the gaziantep region of southern turkey which were significantly misaligned relative to the plate motion requiring major components of shortening as well as left lateral slip the transition from this initial rather diffuse geometry to the present localised geometry of the dsfz across western syria occurred within the miocene the predicted rate of relative motion between the stable interiors of the turkish and african plates in the vicinity of their common boundary onshore of iskenderun gulf in southern turkey is estimated as westward at 9 mm a 1 however this promontory of the african plate is itself moving westward relative to the stable interior of this plate at 7 8 mm a 1 the rate of localised left lateral slip on the onshore part of this boundary the ne trending yakapinar goksun fault is thus estimated as only 2 mm a 1 this locality can also be regarded as within the distributed boundary zone between the turkish and arabian plates the estimated relative motion between these plates is at 8 7 mm a 1 towards the ssw partitioned between localised left lateral slip at 2 mm a 1 on the yakapinar goksun fault and at least 1 mm a 1 on the amanos fault and 2 5 mm a 1 on east hatay fault with at most distributed left lateral simple shear at 3 2 mm a 1 across the amanos mountains in between however the combined slip on left lateral faults east of the amanos mountains may be as high as 6 mm a 1 with slip at 1 7 mm a 1 on the amanos fault and at 4 3 mm a 1 on the east hatay fault and any active faults farther east this requires no more than 0 7 mm a 1 of distributed simple shear across the amanos mountains raising the possibility that this component of deformation may in fact be zero this small nonzero estimate possibly indicating a closure error arising from minor errors in predicted values of other relative motion vectors it is proposed that this boundary between the turkish and african plates first developed at the same time as the mofz and nafz but its original geometry involving left lateral slip on the karatas osmaniye fault has since become locked by the presence of relatively strong ophiolitic crust within this fault zone this quantitative kinematic model demonstrates for the first time how it is possible for the left lateral faulting accommodating the nnw sse relative motion between the arabian and african plates in nw syria to dovetail into the left lateral faulting accommodating the wsw ene relative motion between the turkish and arabian plates in se turkey

equilibrium profile development in graded deep water slopes eocene eastern turkey recently published models for deep marine slopes provide a framework for understanding the sedimentary architecture and geometries of major correlative surfaces in this environment these models use concepts which include i the development of erosional and unconformable onlapping relationships in a slope to basin setting by processes other than changes in relative sea level e g earthquake induced gravity flows ii the definition of genetic facies associations and iii the development of base of slope systems by repeated mass wasting in order to establish an equilibrium slope profile these models are based primarily on seismic data from present day slopes or numerical simulation and have not been tested in the field an example from turkey of a progradational eocene basin to slope transition is presented to test these models we found that most mass wasting occurs at the top and not base of the slope that this is likely to be earthquake induced rather than related to changes in relative sea level and that seafloor topography continues to control sand transportation pathways and mass wasting throughout slope apron deposition

late palaeogene neogene evolution of the triple junction region near maras south central turkey the marao region of turkey includes the anatolian arabian african triple junction the african arabian margin is marked by left lateral transtension along the dead sea kara su rift motion on the anatolian arabian boundary is partitioned between the left lateral east anatolian fault and a fold thrust belt termed the engizek zone equivalent to the bitlis suture further east the african anatolian boundary lies along the cyprus misis andirin trend and is expressed near the triple junction as the aslantao iskenderun zone now undergoing slow left lateral transtension the neogene evolution of these boundaries is largely recorded in the stratigraphy and structure of the basins that lie along the anatolian arabian lice basin and anatolian african aslantao iskenderun basin boundaries these basins appear to have developed in the early miocene along major strike slip zones large half graben in the pre neogene 9basement9 of the western misis andirin block developed contemporaneously with motion on the anatolian african boundary these extensional features evolved subsequent to the intense shattering of the mesozoic carbonate sequence in the misis andirin block and its mixing with panels of deep water palaeogene strata to form an extensionally disrupted assemblage transpression and conversion of both anatolian african and anatolian arabian boundaries to fold thrust belts occurred in the late miocene transpression continues along the anatolian arabian boundary but transtension has recurred along the anatolian african boundary since the pliocene

experimental determination of elastic properties of talc to 800 c 0 5 gpa calculations of the effect on hydrated peridotite and implications for cold subduction zones abstract we have measured compressional wave velocity v p in talc as a function of temperature at 0 5 gpa v p falls from 5 27 0 23 km s 1 at 25 c to 4 35 0 15 km s 1 at 800 c combining these results with a previously published bulk modulus k and k p gives a poisson s ratio of 0 268 and a shear modulus g of 22 6 gpa under atmospheric conditions assuming that is independent of temperature gives a k t value of 19 3 0 64 mpa k 1 at 0 5 gpa we used the experimental data in combination with published data to calculate bounds on the elastic moduli of a peridotite hydrated with talc just above cold subducting lithosphere we find that an assemblage hydrated by only 0 9 wt h 2 o has elastic wave velocities calculated from the voigt reuss hill average lower than the anhydrous rock by an average of 7 6 for v p and 9 7 for shear waves v s at 700 c these results are consistent with observations of converted phase behavior in the vicinity of the surface of a cold subducting slab and may place the low velocity layer observed in the lowermost mantle wedge not the uppermost slab as has previously been suggested

influence of pressure and mineralogy on seismic velocities in oceanic gabbros implications for the composition and state of the lower oceanic crust 1 we have analyzed the relationship between p wave velocities measured at pressures of 40 100 and 200 mpa and modal mineralogy in oceanic gabbro samples from ocean drilling program holes 735b 894g and 923a at all pressures increasing velocities correspond to increasing pyroxene contents and decreasing alteration phyllosilicate and amphibole content but indicate little or no variation of olivine content in part because the olivine compositions are in the range fo65 to fo73 a voigt reuss hill inverse model reveals that the effective bulk density and elastic moduli of olivine in the gabbros are low even relative to fo73 possibly because the olivine grains contain ubiquitous networks of cracks even if the cracks are not present in situ on average gabbros with velocities typical of seismic layer 3 6 7 7 0 km s 1 contain 5 15 alteration products including 5 15 amphibole and 0 5 phyllosilicates these results suggest that the lower crust is on average slightly to moderately altered

dating the homo erectus bearing travertine from kocabas denizli turkey at at least 1 1 ma abstract since its discovery within a travertine quarry the fragmentary cranium of the only known turkish homo erectus the kocabas hominid has led to conflicting biochronological estimations first estimated to be 500 ka old the partial skull presents a combination of archaic and evolved features that puts it as an intermediate specimen between the dmanisi fossils homo georgicus and the chinese zhoukoudian skulls homo erectus respectively dated to 1 8 to 0 8 ma here we present a multidisciplinary study combining sedimentological paleontological and paleoanthropological observations together with cosmogenic nuclide concentration and paleomagnetic measurements to provide an absolute chronological framework for the upper fossiliferous travertine unit where the kocabas hominid and fauna were discovered the 26 al 10 be burial ages determined on pebbles from conglomeratic levels framing the upper fossiliferous travertine unit which exhibits an inverse polarity constrains its deposition to before the cobb mountain sub chron that is between 1 22 and 1 5 ma the alternative match of the normal polarity recorded above the travertine with the jaramillo subchron lower limit 1 07 ma may also be marginally compatible with cosmogenic nuclides interpretation thus the proposed minimum age of 1 1 ma for the end of massive travertine deposition the actual age of the fossils is likely to be in the 1 1 1 3 ma range this absolute date is in close agreement with the paleoanthropological conclusions based on morphometric comparisons implying that kocabas hominid belongs to the homo erectus s l group that includes chinese and african fossils and is different from middle and upper pleistocene specimens furthermore this date is confirmed by the large mammal assemblage typical of the late villafranchian because it attests to the antiquity of human occupation of the anatolian peninsula and one of the waves of settlements out of africa this work challenges the current knowledge of the homo erectus dispersal over eurasia

retrodeforming the arabia eurasia collision zone age of collision versus magnitude of continental subduction the arabia eurasia collision has been linked to global cooling the slowing of africa mediterranean extension the rifting of the red sea an increase in exhumation and sedimentation on the eurasian plate and the slowing and deformation of the arabian plate collision age estimates range from the late cretaceous to pliocene with most estimates between 35 and 20 ma we assess the consequences of these collision ages on the magnitude and location of continental consumption by compiling all documented shortening within the region and integrating this with plate kinematic reconstructions shortening estimates across the orogen allow for 350 km of neogene upper crustal contraction necessitating collision by 20 ma a 35 ma collision requires additional subduction of 400 600 km of arabian continental crust using the oman ophiolite as an analogue ophiolitic fragments preserved along the zagros suture zone permit 180 km of subduction of the arabian continental margin plus overlying ophiolites wholesale subduction of this more dense continental margin plus ophiolites would reconstruct 400 500 km of postcollisional arabia eurasia convergence consistent with a ca 27 ma initial collision age this younger arabia eurasia collision suggests a noncollisional mechanism for the slowing of africa and associated extension

ophiolitic and metamorphic assemblages of southeast anatolia and their significance in the geological evolution of the orogenic belt the southeast anatolian orogen may be divided into three roughly east west trending structural zones formed as a result of continental collision between the taurus platform and the arabian continent along the orogenic belt metamorphic and ophiolitic rocks occur widely the ophiolites represent remnants of the ocean or oceans which were totally consumed between these converging continental blocks during late cretaceous to miocene period metamorphic rocks formed from the oceanic as well as the continental rocks which were incorporated into a nappe stack during the consumption of the oceanic lithosphere and the progressive southward advance of the nappes toward the arabian continent the metamorphic units together with the ophiolite associations provide stratigraphic and petrologic evidence indicating time place and environment of formation of these units the metamorphic units also provide evidence of nappe transportation stages which are complementary to the data derived from the sedimentary successions in the evaluation of the orogenic evolution of southeast anatolian orogen

pollen evidence for late pliocene early pleistocene vegetation and climate change in the north caucasus north western caspian region abstract pollen and spores have been analysed in deposits of the akchagylian apsheronian in the north western caspian sea region providing a picture of past vegetation and climate change for the late pliocene to early pleistocene on the basis of pollen assemblages in sediment cores and outcrops from the north caucasus the caucasus mineral nyye vody region the tersko sunzhensky area and the foothills of dagestan climatic fluctuations and related changes in vegetation can be recognized for the time from 3 6 to 0 8 ma the lower akchagylian is characterized at first by an open landscape dominated by steppe vegetation in the middle of the lower akchagylian the transgression of the palaeo caspian spread and the treeless landscapes of the earliest akchagylian were replaced by forests with thermophilic relicts during the middle upper akchagylian and apsheronian periods the vegetation cover of the north caucasus gradually changed forests were replaced with steppe and semi desert vegetation in response to episodes of aridification and changes were evident in the structure of the dendroflora the vegetation of the north caucasus shows changes consistent with climatic warming at around 3 2 ma which coincides with a period of warming in the mediterranean and probable represents the mid pliocene warm period

recent volcanism tectonics and plate kinematics near the junction of the african arabian and anatolian plates in the eastern mediterranean abstract in the eastern mediterranean plate convergence occurs between africa arabia and anatolia the africa arabia motion is a strike slip displacement along the dead sea fault the africa anatolia motion is taken up by subduction south of cyprus the convergence between arabia and anatolia is taken up along the east anatolian fault the analysis of the regional fault surfaces reveals the presence of two major tectonic phases that affected southeastern turkey near the junction of these three plates the older deformations are related to a n s compression the more recent movements are directed mainly westward and associated with strike slip and extension tectonics near the triple junction since 2 ma a fissure volcanism produced tholeiite followed by alkali basalt along the amanos fault the northern end segment of the dead sea fault in addition reconstruction of rigid plate kinematics between arabia africa and anatolia using recent plate motion parameters and space geodesy data suggest for the east anatolian fault a slip rate of 7 8 9 mm year the maximum finite displacement recognised for this structure being around 15 km we have obtained 1 9 ma as the maximum age for the fault formation the volcanic tectonic and kinematic data converge to propose a ca 2 ma age for the change of local tectonic regime in the junction area the structural mapping the geometry of the fractures used by the magma to reach the surface and the presence of alkali basalt of mantle source suggest that the deformation along the northern end of the dead sea transform i e the amanos fault was modified by the formation of the east anatolian fault zone in this region apparition of the east anatolian fault accommodating westward motion of the anatolian plate resulted in oblique slip tension along the amanos segment of the dead sea transform giving rise to a fissure fed mantle derived alkaline volcanism at ca 2 ma which lasted until recent times 0 4 ma

experimentally based water budgets for dehydrating slabs and consequences for arc magma generation phase diagrams of hydrous mid ocean ridge mor basalts to 330 km depth and of hydrous peridotites to 250 km depth are compiled for conditions characteristic for subduction zones a synthesis of our experimentally determined phase relations of chlorite lawsonite epidote zoisite amphibole paragonite chloritoid talc and phengite in basalts and of phase relations from the literature of serpentine talc chlorite amphibole and phase a in ultramafics permits calculation of h2o contents in hydrous phase assemblages that occur in natural compositions this yields the information necessary to calculate water budgets for descending slabs starting from low grade blueschist conditions 10 20 km depth with h2o contents between 5 and 6 wt for hydrated oceanic crust complete dehydration is achieved between 70 and 300 km depth as a function of individual slab geotherms hydrous phases which decompose at depth below volcanic arcs are lawsonite zoisite chloritoid and talc phengite in mafic compositions and chlorite and serpentine in peridotite approximately 15 35 of the initially subducted h2o are released below volcanic arcs the contribution of amphibole dehydration to the water budget is small 5 20 and occurs at relatively shallow depth 65 90 km in any predicted thermal structure dehydration is a combination of a stepwise and a continuous process through many different reactions which occur simultaneously in the different portions of the descending slab such a dehydration characteristic is incompatible with single phase dehydration models which focus fluid flow through a unique major dehydration event in order to explain volcanic fronts as a consequence of continuously progressing dehydration water ascending from the slab will be generally available to depth of ca 150 200 km the fluid rising from the subducting lithosphere will cause partial melting in the hot portion of the mantle wedge we propose that the volcanic front simply forms above the mantle wedge isotherm where the extent of melting is sufficient to allow for the mechanical extraction of parental arc magmas thermal models show that such an isotherm ca 1300oc locates below volcanic fronts slab surface depths below such an isotherm are compatible with the observed depths of the slab surface below volcanic fronts 1998 elsevier science b v all rights reserved

provenance of the northern part of the kahramanmaras peripheral foreland basin miocene s turkey abstract the miocene kahramanmaras peripheral foreland basin kpfb resemble to classic foreland basin model with small differences in the classic model both the accretionary wedge and foredeep extend lengthways parallel to the plate margin in addition accretionary wedge includes wedge top basin or piggy back basin that extends parallel to foredeep however the accretionary wedge of the kpfb contains small half graben type basins that obliquely intersect the plate margin between the arabian plate and the anatolide taurides platform due to the irregular shape of the plate boundary tectonic lineaments controlled the shape and orientation of these basins and larger main depocentre of the kfpb which were predominantly filled with deep sea sediments this paper focuses on the provenance of features of the kfpb predominantly was fed from the northern basin margin while also aiming to resolve the complex basin evolution that occurred during the miocene clasts of palaeozoic and mesozoic limestone and ophiolites are common components of the confined deep water clastic systems which evolved as elongated trenches in the north western sector of the kpfb during the early middle miocene during the middle miocene continuous thrusting of the northern basin margin to south caused depocentre migration to south east through the basin interior at that time the north east and central depocentres of the kpfb were filled primarily by clasts of ophiolite and metamorphic units the tectonic control on basin fill architecture can be observed anywhere in the kfpb the principal tectonic features controlled the geometry and orientation of the canyon the channel geometry of the deep water slope on the northern basin margin the frequency and distribution of slump slide debris flows and the overall pattern of sedimentation cycles in the stratigraphy of the slope and the central basin floor some basin sectors have continuously reactivated and as a result different sediment entry points with substantial local accumulation of sediment and deformation have evolved on the slope and basin floor three scales of provenance were used to investigate the source rock a field based observation and analysis of conglomerate clasts b modal analysis of sandstone facies and c geochemical analysis all of which were in agreement

sedimentology of a late cenozoic collisional sequence the misis complex adana southern turkey abstract this study is concerned with miocene sequences formed within part of the cukurova basin of southern turkey a major downwarp created during the early stages of collision between the afro arabian plate and the tauride anatolian microplate assemblage we report here the results of a combined stratigraphical sedimentological structure and geochemical study of the misis complex a structurally elevated segment of cukurova basin fill this analysis has demonstrated the structurally imbricated nature of the misis sequences and the tectonic juxtaposition of originally well separated coeval facies the initial discernible phase of basin filling pre burdigalian was marked by deep marine conditions and marginal tectonic instability probably related to a late phase of tauride nappe advance the subsequent phase of crustal extension burdigalian early tortonian produced expansion of the cukurova basin limits and an upwards shoaling succession in which sediment transport towards the southwest gradually became dominant as a result of earlier suturing and uplift in northeasterly sectors of the collision zone the miocene arenites of the misis complex are petrographically diverse with common siliciclastic and carbonate detrital admixtures and mineralogically immature and their position in petrotectonic fields indicates a compound provenance from both recycled orogen and magmatic arc sources a noteworthy petrographic feature is the compositional similarity of arenites from both shallow and deep marine facies the general succession of neogene facies observed in the cukurova basin and misis complex is consistent with their evolution within a perisutural foreland basin but this interpretation is complicated by petrographic and geochemical features attributed to remnants of an older magmatic arc later stages of basin filling are also marked by the local occurrence of anomalous palaeoenvironmental associations including olistostromic units attributed to contemporaneous intra basinal tectonism

development and verification of a 3 d integrated surface water groundwater model summary coupled modelling of surface and subsurface systems is a valuable tool for quantifying surface water groundwater interactions in the present paper the 3 d non steady state navier stokes equations after reynolds averaging and with the assumption of a hydrostatic pressure distribution are for the first time coupled to the 3 d saturated groundwater flow equations in an integrated surface water groundwater model irene a finite difference method is used for the solution of the governing equations of irene a semi implicit scheme is used for the discretisation of the surface water flow equations and a fully implicit scheme for the discretisation of the groundwater flow equations the two sets of equations are coupled at the common interface of the surface water and groundwater bodies where water exchange takes place using darcy s law a new approach is proposed for the solution of the coupled surface water and groundwater equations in a simultaneous manner in such a fashion that gives computational efficiency at low computational cost irene is verified against three analytical solutions of surface water groundwater interaction which are chosen so that different components of the model can be tested the model closely reproduces the results of the analytical solutions and can therefore be used for analysing and predicting surface water groundwater interactions in real world cases

slab low velocity layer in the eastern aleutian subduction zone summary local earthquakes in the vicinity of the alaskan peninsula s shumagin islands often produce arrivals between the main p and s arrivals not predicted by standard traveltime tables based on traveltime and polarization these anomalous arrivals appear to be from p to s conversions at the surface of the subducted pacific plate beneath the recording stations the p to s conversion occurs at the top of a low velocity layer which extends to at least 150 km depth and is 8 f 2 per cent slower than the overlying mantle the slab is 7 per cent faster than the mantle the low velocity layer contains the foci of the earthquakes in the upper plane of the double seismic zone and confines ps ray paths to lie within it these observations indicate that layered structures persist to positions well past the surface location of the volcanic front reactions forming high pressure minerals do not yield slab like velocities until beyond the point that subduction zone magma genesis occurs if the subducted oceanic crust forms the layer it is subducted essentially intact

oligocene miocene basin evolution in se anatolia turkey constraints on the closure of the eastern tethys gateway the oligocene miocene was a time characterized by major climate changes as well as changing plate configurations the middle miocene climate transition 17 to 11 ma may even have been triggered by a plate tectonic event the closure of the eastern tethys gateway the marine connection between the mediterranean and indian ocean to address this idea we focus on the evolution of oligocene and miocene foreland basins in the southernmost part of turkey the most likely candidates to have formed this gateway in addition we take the geodynamic evol ution of the arabian eurasian collision into account the musand elazog u basins located to the north of the bitlis zagros suture zone were most likely connected during the oligocene the deepening of both basins is biostratigraphically dated by us to occur during the rupelian early oligocene deep marine conditions between 350 and 750 m prevailed until the chattian late oligocene when the basins shoaled rapidly to subtidal intertidal environment in tropical to subtropical conditions as indicated by the macro fossil assemblages we conclude that the emergence of this basin during the chattian severely restricted the marine connection between an eastern indian ocean and western mediterranean marine domain if a connection persisted it was likely located south of the bitlis zagros suture zone the kahramanmarasbasin located on the northern arabian promontory south of the bitlis zagros suture zone was a foreland basin during the middle and late miocene possibly linked to the hatay basin to the west and the lice basin to the east our data indicates that this fore land basin experienced shallow marine conditions during the langhian followed by a rapid dee pening during langhian serravallian and prevailing deep marine conditions between 350 and 750 m until the early tortonian we have dated the youngest sediments underneath a subduc tion related thrust at c 11 ma and suggest that this corresponds to the end of underthrusting in the kahramanmarasregion i e the end of subduction of arabia this age coincides in time with the onset of eastern anatolian volcanism uplift of the east anatolian accretionary complex and the onset of the north and east anatolian fault zones accommodating westward escape tec tonics of anatolia after c 11 ma the foreland basin south of the bitlis formed not or no longer a deep marine connection along the northern margin of arabia between the mediterranean sea and the indian ocean we finally conclude that a causal link between gateway closure and global climate change to a cooler mode recorded in the mi3b event d 18 o increase dated at 13 82 ma cannot be supported

neotectonic deformation in the transition zone between the dead sea transform and the east anatolian fault zone southern turkey a palaeomagnetic study of the karasu rift volcanism in southern turkey ongoing differential impingement of arabia into the weak anatolian collisional collage resulting from subduction of the neotethyan ocean has produced one of the most complex crustal interactions along the alpine himalayan orogen several major transforms with disputed motions including the northward extension of the dead sea fault zone dsfz meet in this region to evaluate neotectonic motion on the amanos and east hatay fault zones considered to be northward extensions of the dsfz the palaeomagnetism of volcanic fields in the karasu rift between these faults has been studied remanence carriers are low ti magnetites and all except 5 of 51 basalt lavas have normal polarity morphological polarity and k ar evidence show that rift formation occurred largely during the brunhes chron with volcanism concentrated at 0 66 0 35 ma and a subsidiary episode at 0 25 0 05 forty four units of normal polarity yield a mean of d i 8 8 54 7 with inclination identical to the present day field and declination rotated clockwise by 8 8 4 0 within the 15 km wide hassa sector of the karasu rift the volcanic activity is concentrated between the amanos and east hatay faults both with left lateral motions which have rotated blocks bounded by nw se cross faults in a clockwise sense as the arabian block has moved northwestwards an average lava age of 0 5 ma yields a minimum cumulative slip rate on the system bounding faults of 0 46 cm year according with the rate deduced from the africa arabia euler vector and reduced rates of slip on the southern extension of the dsfz during plio quaternary times estimates deduced from offsets of dated lavas flows and morphological features on the amanos fault zone tectonophysics 344 2002 207 are lower 0 09 0 18 cm year probably because they are limited to surface fault breaks and do not embrace the seismogenic crust results of this study suggest that most strike slip on the dsfz is taken up by the amanos east hatay afrin fault array in southern turkey comparable estimates of quaternary slip rate are identified on other faults meeting at an unstable fff junction dsfz east anatolian fault zone karatas fault zone a deceleration in slip rate across the dsfz and its northward continuation during plio quaternary times correlates with reorganization of the tectonic regime during the last 1 3 ma including tectonic escape within anatolia establishment of the north and east anatolian fault zones bounding the anatolian collage in mid late pliocene times a contemporaneous transition from transpression to transtension and concentration of all basaltic magmatism in this region within the last 1 ma

late triassic rifting and jurassic cretaceous passive margin development of the southern neotethys evidence from the adiyaman area se turkey evidence of rifting and continental break up to form the s neotethys is found within the volcanic sedimentary kocali complex this is a folded thrust imbricated succession that includes lavas volcaniclastic sediments pelagic carbonates radiolarites and manganiferous deposits interbedded ribbon cherts contain radiolarians of late triassic to late jurassic age the lower part of the succession of mid late triassic age tarasa formation is dominated by enriched mid ocean ridge basalt e morb the overlying late triassic to mid jurassic interval konak formation is characterised by intercalations of ocean island basalt and e morb taking account of structural position the basalts erupted within the outer part of a continent ocean transition zone continental break up probably occurred during the late triassic carnian norian early to mid jurassic lavas and volcaniclastic sediments record volcanism probably after continental break up in addition the karadut complex is a broken formation that is located at a relatively low structural position just above the arabian foreland pelagic carbonates redeposited carbonates and radiolarites predominate radiolarians are dated as early to mid jurassic and late cretaceous in age the pelagic carbonates include planktic foraminifera of late cretaceous age the karadut complex resulted from the accumulation of calcareous gravity flows pelagic carbonate and radiolarites in a relatively proximal base of slope setting after continental break up morb and ophiolitic rocks formed within the s neotethys further north tectonic emplacement onto the arabian platform took place by earliest maastrichtian time regional interpretation is facilitated by comparisons with examples of triassic rifting and continental break up in the eastern mediterranean region and elsewhere

new developments in the upper pliocene pleistocene stratigraphic units of the dacian basin eastern paratethys romania abstract as a result of multidisciplinary investigations carried out in the last two decades the knowledge of the pliocene and quaternary stratigraphy from dacian basin has increased considerably new lithostratigraphic units were revealed for example trajkovo fm romanian vl deni fm v n tori fm pleistocene and other units have been reassessed izvoarele fm tulucesti fm romanian a new biozonation based on molluscan fauna from the late pliocene nsm11 nsm12 and pleistocene qm1 qm9 deposits made possible a more accurate subdivision and cronostratigraphical assignments and correlations many localities with romanian mammal associations lupoaia dr nic podari tetoiu leu etc were reviewed adding new taxa in the faunal list with implications for accurately establishing host deposit ages these studies together with bio magnetostratigraphic investigations led to revision of the romanian stage boundaries and subdivisions pelendavian valahian and to outline several new pleistocene chronostratigraphic units the argedavian dinogetian ilfovian stages and milcovian uzunian netindavian musaisian substages finally one major achievement consisted in the pliocene pleistocene boundary relocation in the dacian basin in agreement with its new position at 2 6 ma in the mediterranean realm

a 2 d tomographic model of the juan de fuca plate from accretion at axial seamount to subduction at the cascadia margin from an active source ocean bottom seismometer survey we report results from a wide angle controlled source seismic experiment across the juan de fuca plate designed to investigate the evolution of the plate from accretion at the juan de fuca ridge to subduction at the cascadia margin a two dimensional velocity model of the crust and upper mantle is derived from a joint reflection refraction travel time inversion to interpret our tomography results we first generate a plausible baseline velocity model assuming a plate cooling model and realistic oceanic lithologies we then use an effective medium theory to infer from our tomography results the extent of porosity alteration and water content that would be required to explain the departure from the baseline model in crust of ages 1 ma and away from propagator wakes and regions of faulting due to plate bending we obtain estimates of upper crustal hydration of 0 5 2 1 wt and find mostly dry lower crust and upper mantle in sections of the crust affected by propagator wakes we find upper estimates of upper crustal lower crustal and upper mantle hydration of 3 1 0 8 and 1 8 wt respectively at the cascadia deformation front we find that the amount of water stored at uppermost mantle levels in the downgoing jdf plate is very limited 0 3 wt with most of the water carried into the subduction zone being stored in the oceanic crust

qp melting temperature relation in peridotite at high pressure and temperature attenuation mechanism and implications for the mechanical properties of the upper mantle the anelastic properties of compressional waves in a peridotite have been determined in the laboratory at sufficiently high temperatures to 1280 c and pressures to 0 73 gpa to warrant comparison with seismic measurements of the earth a substantial decrease of qp is observed at temperatures well below the onset of partial melting qp systematically increases with increasing pressure over the entire temperature range of major significance is the finding that qp is dependent on the ratio of the temperatures to the melting solidus temperature i e qp depends on the homologous temperature the pressure dependence of qp appears through the pressure dependence of the solidus of the peridotite within the uncertainties of measurement of both qp and the phase diagram it appears that melting and high temperature anelastic properties have a common origin in peridotite the homologous temperature dependence of qp suggests that we may estimate the temperature and pressure dependence of qp for peridotites of different compositions and possibly even for hydrous peridotites if solidus temperatures are known as a function of pressure a far easier measurement than elastic and anelastic properties the activation volume of qp is greatly reduced at high pressure since the slope of solidus versus pressure rapidly decreases with increasing pressure pressure dependence of seismic velocity and melt fraction in peridotite also appears to be related to the homologous temperature the qp homologous temperature relation suggests a connection between qp and the properties of the grain boundaries that is the major loss of seismic energy occurs at the grain boundaries grain boundary relaxation or high temperature background attenuation is a possible mechanism for the grain boundary damping no frequency dependence of qp is resolved 0 0 2 in qp f over the pressure temperature and frequency ranges of the measurement the present results and the model of grain boundary relaxation suggest that an appropriate choice of grain size may give an ultrasonic q that is applicable to the earth experimentally determined anelastic properties of a peridotite are critical for modeling mechanical properties of the upper mantle implications of the results are as follows 1 seismic data commonly interpreted as indicating a partially molten asthenosphere may instead reflect a hot solid asthenosphere at 90 100 of the solidus temperature 2 partial melting may not produce any abrupt change of seismic velocity and q rather elastic and anelastic properties of the upper mantle will change gradually at the boundary where the geotherm crosses the solidus 3 there may be no sharp mechanical boundary between the lithosphere and the asthenosphere

anisotropic thermal properties of talc under high temperature and pressure abstract the anisotropic thermal conductivity and diffusivity of talc were simultaneously measured up to 5 3 gpa and 900 k using the pulse transient method although significant anisotropy was observed in the thermal conductivity of talc the average thermal conductivity is comparable to that of olivine and roughly three times greater than that of antigorite from the ratio of the thermal conductivity to the thermal diffusivity the heat capacity of talc was evaluated the pressure derivative of heat capacity was found to be positive which is related to the anomaly of thermal expansivity of talc above 50 c at atmospheric pressure

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

dynamics of orogenic wedges and the uplift of high pressure metamorphic rocks subduction accretion complexes can be approximated as wedge shaped continua with a rigid buttress behind and a subducting litho spheric slab beneath thick wedges undergoing prograde metamorphism have a negligible long term yield strength and are likely to exhibit a complex nonlinear viscous rheology such a wedge will tend to deform internally until it reaches a stable configuration in which the gravitational forces generated by the wedge geometry balance the traction exerted on its underside by the subducting slab accretion of material at the wedge front will lengthen the wedge and cause it to shorten internally to regain the stable geometry this shortening will be expressed as late out of sequence thrusting backthrusting and folding conversely underplating of sediment or crustal slices will thicken the wedge which may need to extend internally to regain stability extension will cause listric normal faults that may merge downward into zones of ductile extension continued underplating at depth and compensating extension above provides a mechanism for bringing high p low t metamorphic rocks to upper levels in the rear of the wedge where they are commonly observed many major tectonic boundaries in convergent orogens such as the coast range thrust in the franciscan complex major nappe contacts in the alps and the contact between the nevado filabride and higher betic nappe complexes in the betic cordillera show abrupt increases in metamorphic grade downward across them this is consistent with their origin or reactivation as uplift related extensional structures

petrology of a supra subduction zone ophiolite elaz1g turkey the elazig region in eastern taurus turkey exposes paleozoic tertiary metamorphic magmatic and sedi mentary units contacts between the different units are mostly tectonic but there are also primary sedimentary and in trusive contacts the metamorphic rocks of the elazig region are the bitlis puturge and keban malatya massifs which are a single tectonostratigraphic unit that has been tectonically disrupted and fragmented during the upper cretaceous magmatic rocks in the region are represented by ophiolitic units magmatic arc products and young volcanic rocks the sedimentary units are represented by upper cretaceous tertiary marine and lacustrine sedimentary rocks in the study area the metamorphic units are represented by the paleozoic puturge metamorphic rocks composed of phyllite slate mica schist quartz muscovite schist calc schist and low grade metamorphite the ophiolite that is described in this paper is composed of wehrlite pyroxenite gabbro diabase dykes and dykes cutting gabbro these units are cut by the granitic rocks of the upper cretaceous elazig magmatic suite the lithological and geochemical data on the rocks of komurhan ophiolite indicate that these rocks were derived from crystallization of an enriched mid ocean ridge basalt morb type magma the komurhan ophiolite formed in a supra subduction spreading zone during the cretaceous re lated to this event is the north dipping subduction of the southern branch of neo tethys ocean which began spreading in the late triassic the crust was thickened by the development of an island arc and by the thrusting of the puturge metamorphic rocks onto this island arc in response to north south compression during the late cretaceous the magma formed by partial melting of the subducted slab giving rise to granitic rocks that cut the upper parts of the ophiolite the ophiolite and the elazig magmatic suite attained their present position after the middle eocene

the east anatolian fault geometry segmentation and jog characteristics a detailed account is given of the fault geometry and segment structure of the east anatolian fault zone as a whole based on mapping of active faults supported by available seismological and palaeoseismological data we divide the east anatolian fault into two main strands southern and northern the main southern strand is c 580 km long between karliova and antakya and connects with the dead sea fault zone and the cyprus arc via the amik triple junction the northern strand termed the surgu misis fault system is c 350 km long and connects with the kyrenia misis fault zone beneath the gulf of iskenderun we infer that slip partitioning between the main and northern strands of the east anatolian fault accommodates 2 3 and 1 3 of the slip rate of the lateral motion between the arabian and anatolian plates respectively in the celikhan adana antakya region taking account of the time elapsed from the latest events on the east anatolian fault we suggest that the pazarcik and amanos segments have the potential to produce destructive earthquakes in the near future

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

subduction zone thermal structure and mineralogy and their relationship to seismic wave reflections and conversions at the slab mantle interface seismological studies of the interface between downgoing slabs of subducted lithosphere and the overriding mantle provide constraints against which models of mantle and slab temperature and bulk composition can be tested these studies employing waves reflected and converted at the slab mantle interface suggest that a velocity contrast of 5 10 occurs over a distance of 10 20 km to depths of at least 350 km the authors have investigated whether such sharp contrasts can result form thermal structure compositional differences phase changes or other effects such as preferred mineral orientation using a mantle and slab temperature model a petrologic model of mantle and slab mineralogy and a data base of elastic properties of mantle and slab phrases theoretical seismic velocities were calculated and compared with the observed velocity contrast and boundary thickness constraints at 9 6 gpa and 1000c conditions modeled at the slab mantle interface at approximately 280 km depth cooler temperatures in the slab interior produce at constant composition only approximately a 1 75 v sub p increase into the slab in any of the peridotitic and eclogitic mineralogies investigated variation in v sub p among the different bulk compositions is only approximately 0 5 these contrasts are substantially lower than those obtained from the seismological studies andmore indicate that temperature and bulk compositional differences between mantle and slab are inadequate to cause the observed velocity contrasts they propose that phase transformations in mantle and slab mineralogies notably elevation of the olivine spinel phase change normally occurring at 400 km depth are important factors in these sharp contrasts other contributing effects may include preferential mineral orientation near the slab surface and at shallower depths the presence of partial melt or hydrous fluid evolved from dehydration reactions along the interface less

gps constraints on continental deformation in the africa arabia eurasia continental collision zone and implications for the dynamics of plate interactions 1 the gps derived velocity field 1988 2005 for the zone of interaction of the arabian african nubian somalian and eurasian plates indicates counterclockwise rotation of a broad area of the earth s surface including the arabian plate adjacent parts of the zagros and central iran turkey and the aegean peloponnesus relative to eurasia at rates in the range of 20 30 mm yr this relatively rapid motion occurs within the framework of the slow moving 5 mm yr relative motions eurasian nubian and somalian plates the circulatory pattern of motion increases in rate toward the hellenic trench system we develop an elastic block model to constrain present day plate motions relative euler vectors regional deformation within the interplate zone and slip rates for major faults substantial areas of continental lithosphere within the region of plate interaction show coherent motion with internal deformations below 1 2 mm yr including central and eastern anatolia turkey the southwestern aegean peloponnesus the lesser caucasus and central iran geodetic slip rates for major block bounding structures are mostly comparable to geologic rates estimated for the most recent geological period 3 5 myr we find that the convergence of arabia with eurasia is accommodated in large part by lateral transport within the interior part of the collision zone and lithospheric shortening along the caucasus and zagros mountain belts around the periphery of the collision zone in addition we find that the principal boundary between the westerly moving anatolian plate and arabia east anatolian fault is presently characterized by pure left lateral strike slip with no fault normal convergence this implies that extrusion is not presently inducing westward motion of anatolia on the basis of the observed kinematics we hypothesize that deformation in the africa arabia eurasia collision zone is driven in large part by rollback of the subducting african lithosphere beneath the hellenic and cyprus trenches aided by slab pull on the southeastern side of the subducting arabian plate along the makran subduction zone we further suggest that the separation of arabia from africa is a response to plate motions induced by active subduction

ab initio elastic properties of talc from 0 to 12 gpa interpretation of seismic velocities at mantle pressures and prediction of auxetic behaviour at low pressure talc is a hydrous magnesium rich layered silicate that is widely disseminated in the earth from the seafloor to over 100 km depth in ultra high pressure metamorphism of oceanic crust in this paper we determine the single crystal elastic constants at pressures from 0 to 12 gpa of talc triclinic c 1 and monoclinic c2 c polytypes using ab initio methods we find that talc has an extraordinarily high elastic anisotropy at zero pressure that reduces with increasing pressure the exceptional anisotropy is complemented by a negative poisson s ratio for many directions in crystal space calculations show that talc is not only one of very few common minerals to exhibit auxetic behaviour but the magnitude of this effect may be the largest reported so far for a mineral the compression vp and shear vs wave velocity anisotropy is 80 and 85 for the triclinic polytype at pressures where talc is known be stable in the earth up to 5 gpa the vp and vs anisotropy is reduced to about 40 for both velocities which is still a very high value vp is slow parallel to the c axis and fast perpendicular to it this remains unchanged with increasing pressure and is observed in both polytypes the shear wave splitting difference between fast and slow s wave velocities at low pressure has high values in the plane normal to the c axis with a maximum near the a axis in the triclinic and the b axis in the monoclinic polytype the c axis is the direction of minimum splitting the pattern of shear wave splitting does not change significantly with pressure the volume fraction of talc varies between 11 and 41 for hydrated mantle rocks but the lack of data on the crystallographic preferred orientation cpo precludes a detailed analysis of the impact of talc on seismic anisotropy in subduction zones however it is highly likely that cpo can easily develop in zones of deformation due to the platy habit of talc crystals for random aggregates of talc the isotropic vp vs and vp vs ratio have significantly lower values than those of antigorite and may explain low velocity regions in the mantle wedge vp vs ratios are more complex in anisotropic media because there are fast and slow s waves resulting in vp vs1 and vp vs2 ratios for every propagation direction making interpretation difficult in deformed polycrystalline talc with a cpo talc on the subduction plate boundary can strongly influence guided wave velocity as cpo would develop in this region of intense shearing the very low coefficient of friction 0 1 of talc above 100 c could also explain silent earthquakes at shallow depths ca 30 km along the subduction plate boundaries frequently responsible for tsunami

laboratory seismic measurements an aid in the interpretation of seismic field data this contribution reports data and evidence from laboratory measurements of compressional and shear wave velocities and mineralogical microstructural and chemical analyses in crustal rocks that may provide an aid to understanding and interpreting geophysical data it is shown that the correlation of laboratory seismic data with stratigraphic field data can provide the necessary data base for constructing a seismic model of the earth s crust in a particular geological area

seismic consequences of warm versus cool subduction metamorphism examples from southwest and northeast japan warm and cool subduction zones exhibit differences in seismicity seismic structure and arc magmatism which reflect differences in metamorphic reactions occurring in subducting oceanic crust in southwest japan arc volcanism is sparse and intraslab earthquakes extend to 65 kilometers depth in northeast japan arc volcanism is more common and intraslab earthquakes reach 200 kilometers depth thermal petrologic models predict that oceanic crust subducting beneath southwest japan is 300 to 500 c warmer than beneath northeast japan resulting in shallower eclogite transformation and slab dehydration reactions and possible slab melting

measurement of elastic wave velocities in granulite and amphibolite having identical h2o free bulk compositions up to 850 c at 1 gpa abstract simultaneous measurements of compressional and shear wave velocities v p and v s in two rocks with identical chemistry but with different mineral assemblages were carried out from room temperature to 850 c at 1 gpa one of the rocks is granulite and the other is amphibolite formed from the granulite by addition of h 2 o both v p and v s in the granulite and amphibolite decreased linearly with increasing temperature and there were obvious differences between the elastic wave velocities in the granulite and amphibolite for example the values of v p and v s at 700 c are respectively 7 75 km s 1 and 4 37 km s 1 for granulite and 7 40 km s 1 and 4 21 km s 1 for amphibolite the low velocity layer lies between the descending lithosphere and the overlying asthenosphere beneath the japanese island arc and the ratio of velocity drop for the low velocity layer compared to the surroundings is approximately 5 6 if the observed velocity drop were caused by a phase change i e granulite h 2 o amphibolite the 5 6 velocity drop could indeed be explained by an appropriate phase change e g anhydrous peridotite h 2 o amphibole peridotite