the twin rivers kopje zambia stratigraphy fauna and artefact assemblages from the 1954 and 1956 excavations abstract earlier lupemban assemblages from brecciated fissure sediments on twin rivers kopje are of great interest in view of the appreciably greater antiquity recently suggested for the earlier middle stone age the twin rivers assemblages are compared with those from kalambo falls the congo basin and zimbabwe the assemblages combine components from both the forested grasslands of equatoria and the savanna woodlands of east and south central africa faunal remains suggest that the early middle stone age sequence reflects several episodes of climatic change between 130 000 years bp and bp

tectono sedimentary evolution and geochronology of the middle miocene altinapa basin and implications for the late cenozoic uplift history of the taurides southern turkey abstract the tauride range in southern turkey is flanked and overlain by neogene sedimentary basins to the south and on top of the high range these basins are mainly marine whereas poorly studied intramontane basins dominated by continental deposits are exposed to the north in this paper we study the stratigraphy and structure of the continental altinapa basin and provide 40ar 39ar geochronology for volcanic deposits in the stratigraphy the stratigraphy can be subdivided into a lower group displaying 400 m of fining upward fluvio lacustrine sediments unconformably overlain by an upper group with 500 m of lacustrine deposits andesitic lavas and volcaniclastic sediments 40ar 39ar dating of three volcaniclastic samples across the upper group provide 11 8 11 6 ma ages the altinapa basin is an extensional basin which formed predominantly due to n s to ne sw directed stretching the main basin forming phase occurred during deposition of the lower group prior to 11 8 ma paleostress inversion analyses demonstrate uniaxial stress with highly variable extension directions that are consistent with currently observed seismicity patterns the middle miocene extension history of the altinapa basin is consistent with a regional pattern of middle miocene ne sw to nw se extension north of the cyprus subduction zone this suggests that the cyprus subduction zone has been in retreat relative to central anatolia since at least middle miocene time the continental altinapa basin is currently at an elevation of 1 km whereas partly contemporaneous marine sediments in the mut basin that lies on top of the tauride range are elevated to 2 km this shows strong late cenozoic differential uplift in southern turkey with at least 1 km more uplift of the tauride range than of the intramontane basins to the north we conclude that the current high elevation of the taurides is related to late neogene extension and does not result from the late cretaceous to perhaps oligocene folding and thrusting that deformed the rocks in the range

palinspastic reconstruction versus cross section balancing how complete is the central taurides fold thrust belt turkey in many fold thrust belts cross section derived shortening estimates are significantly lower than predicted based on plate convergence this has led to controversial hypotheses that shortening may be largely underestimated due to wholesale underthrusting convergence without shortening below far traveled continent or ocean derived nappes the late cretaceous eocene taurides fold thrust belt southern turkey may contain a highly incomplete shortening record of convergence likely caused by wholesale underthrusting to estimate this underthrusting we calculate convergence across the belt using a map view palinspastic reconstruction that takes into account major rotations of tectonic units during their accretion we use paleomagnetic and fault kinematic analysis timing of accretion and africa eurasia convergence to constrain our reconstruction our paleomagnetic results confirm an 40 clockwise vertical axis rotation of the geyikdagi nappe that forms the core of the belt which we interpret is accommodated by a lateral gradient in underthrusting on faults structurally above and below the geyikdagi nappe we reconstruct 400 450 km of convergence across the taurides during their accretion we compare this predicted convergence to shortening calculated from balanced cross sections in which we reconstruct a minimum of 154 km shortening 57 km within far traveled nappes 70 km thrusting of far traveled nappes over the geyikdagi nappe and 27 km shortening within the geyikdagi nappe shortening in the taurides created a significant nappe stack but the majority of convergence was accommodated by wholesale underthrusting with barely a trace at the surface including 160 km of convergence by rotation of the belt and 90 130 km related to missing africa eurasia convergence

tectono stratigraphy of the cankiri basin late cretaceous to early miocene evolution of the neotethyan suture zone in turkey the cankoro basin straddles the izmir ankara erzincan suture zone which demar cates the former position of the northern branch of the neotethys it includes more than 3 km of pre middle miocene in fill related to late cretaceous to pre middle miocene evolution of the region the basin has developed on the upper cretaceous subduction complex and arc related basins of the neotethys ocean the basin fill includes an upper cretaceous forearc sequence over lain by paleocene with a local unconformity the upper cretaceous configuration of the cankoro basin is interpreted as a part of a forearc basin the paleocene and younger history is interpreted as a foreland sequence dominated by progressively southwards migrated depocenters in front of southward migrating thrust faults upon which a series of piggy back basins were developed ter mination of the forearc setting and beginning of foreland basin conditions indicates complete sub duction of the neotethyan oceanic crust and onset of collision between the pontides laurasia and the taurides gondwana in the paleocene thrusting and related sedimentation continued until the aquitanian early miocene

age and paleoenvironmental reconstruction of partially remagnetized lacustrine sedimentary rocks oligocene aktoprak basin central anatolia turkey the age and paleoenvironmental record of lacustrine deposits in the aktoprak basin of south central turkey provides information about the evolution of topography including the timing of development of an orographic rain shadow caused by uplift of the mountain ranges fringing the central anatolian plateau new magnetostratigraphy based age estimates in combination with existing biostratigraphic ages suggest that the partially remagnetized kurtulmus tepe section of the basin is chattian upper oligocene the mean carbon and oxygen stable isotope ratios 18o 24 6 2 0 13c 4 9 1 1 are largely constant through the section and indicative of a subtropical open freshwater lake these isotopic values are also similar to those of the chattian mut basin to the south on the mediterranean side of the modern orographic barrier tauride mountains and indicate absence of an orographic barrier during late oligocene basin deposition post depositional partial remagnetization occurred after tilting of the basin sequence and was mineralogically controlled affecting grey carbonate rich rocks average caco3 82 whereas interlayered pink carbonate poor rocks average caco3 38 carry a primary pretilt magnetization the pink rocks are rich in clay minerals that may have reduced the permeability of these rocks that carry a primary magnetization concentrating basinal fluid flow in the carbonate rich grey layers and leading to the removal and reprecipitation of magnetic minerals the normal and reverse polarities recorded by the remagnetized rocks suggest that remagnetization occurred over a protracted period of time

stratigraphic correlation of the neogene basins in southwestern anatolia regional palaeogeographical palaeoclimatic and tectonic implications abstract the extensional intramontane grabens that formed in southwestern anatolia in the late cenozoic bear the unique tectono sedimentary palaeontological and palynological record of a region that underwent rapid transition from the last compressional pulses of the alpine orogeny to the tectonic phase of orogen collapse and the onset of neotectonic regime the change in tectonic regime was accompanied by regional climatic changes recorded by the sedimentary environments of the basins and evidenced by palaeontological and palynological data the late early to mid middle miocene was characterized by a warm and humid subtropical climate with densely forested wetlands the late middle to late miocene witnessed a change to arid climatic conditions with grass dominated steppe ecosystems the pliocene climate was warm and humid with savannah type open habitats in terms of their stratigraphic development the southwestern anatolian basins form two distinct groups one group is represented by the denizli soke and yatagan basins which commenced their development in the early burdigalian and underwent similar phases of environmental change 1 the burdigalian phase of alluvial environment and redbed deposition 2 the late burdigalian langhian phase of alluvial sedimentation accompanied by the formation of terminal lakes 3 the serravallian middle tortonian phase of the formation of shallow perennial lakes 4 the middle tortonian messinian phase of lake expansion and deepening followed by shrinking and shallowing 5 the pliocene phase of lake expansion and deepening and 6 the erosional quaternary phase of two stage alluvial sedimentation separated by a high relief erosional unconformity the other younger group of tectonic grabens is represented by the karacasu bozdogan cameli and esen basins which commenced their development in the earliest tortonian and underwent common environmental changes 1 the tortonian phase of alluvial environment and redbed deposition coeval with the phase of lake drying in the denizli soke and yatagan basins 2 the messinian phase of the formation of terminal lakes coeval with the re establishment of shallow lakes in the three other basins 3 the zanclean phase of shallow perennial lakes coeval with the expansion and deepening of lakes in the other basins 4 the piacenzian phase of deep lacustrine environments 5 the gelasian phase of shallow lacustrine environments and 6 the erosional quaternary phase of two stage alluvial sedimentation similar as in the other basins in spite of the time offset in their development the two basin groups have been strongly modulated by climate and hence show correlative responses to regional climatic changes despite the time offset in their tectonic development the two basin groups showed correlative environmental changes imposed by regional climatic conditions the basins were environmentally unified by the quaternary alluvial phase of their development in the late cenozoic anatolia was at the crossroads of fauna migration routes between africa asia and europe and the palaeontological data from the southwestern anatolian basins shed more light on this phenomenon the study as a whole contributes to a better understanding of the late cenozoic environmental climatical and biogeographical changes in the eastern mediterranean

morphotectonic evolution of mavibogaz canyon and sugla polje sw central anatolia turkey abstract this study focuses on the morphotectonic evolutionary history of two significant geomorphic features sugla structural border polje and mavibogaz canyon located within the sugla seydisehir akoren kavakkoy and bozkir grabens in the central taurides data were obtained by detailed field mapping of faults rocks and geomorphic features three phases of tectonic deformation were determined the three erosional surfaces developed especially in the form of tectonically controlled steps during oligocene early miocene middle miocene and late miocene early pliocene sequentially southwest to northeast trending karstified hanging paleovalleys are present on the high erosional surfaces which have been attributed to the end of early miocene and late miocene faulting induced tectonic movements enabled the formation of sugla seydisehir paleograben in early miocene we suggest that the mavibogaz canyon was formed by captures at the beginning of late miocene and late pliocene and by incision in late pliocene quaternary depending on the headward erosion of carsamba river starting from the beginning of quaternary a tensional neotectonic regime became prominent and then a series of modern graben horst structures formed along the reactivated older grabens one of these is the sugla seydisehir reactivated graben sugla structural border polje developed within the graben total visible tectonic subsidence of the polje is 134 m underground capture of surface water occurred on the southern slopes of the graben waters of sugla polje are transported intermittently into konya basin on the surface and into the mediterranean basin via natural swallow holes beach deposits water marks cliffs and notches marking the late pleistocene lake level 10 m and two perched corrosion surfaces 50 and 22 m were detected around the polje

inversion of field data in fault tectonics to obtain the regional stress iii a new rapid direct inversion method by analytical means summary a new method for determining the reduced stress tensor with four degrees of freedom the orientations of the three principal stress axes as well as the ratio of principal stress differences using fault slip data or focal mechanisms of earthquakes is presented from a computational point of view the inversion of fault slip data is made in a direct way by purely analytical means as a result the determination process is extremely fast and adaptable on small microcomputers from a physical point of view the method aims at simultaneously i minimizing the angles between theoretical shear stress and actual slip vector and ii having relative magnitudes of shear stress large enough to induce slip despite rock cohesion and friction examples of application to actual fault slip data sets with good or poor variety of fault slip orientations are shown the double significance of the basic criterion adopted results in a more realistic solution of the inverse problem than the single minimization of the shear stria angle

segmented african lithosphere beneath the anatolian region inferred from teleseismic p wave tomography summary lithospheric deformation throughout anatolia a part of the alpine himalayan orogenic belt is controlled mainly by collision related tectonic escape of the anatolian plate and subduction roll back along the aegean subduction zone we study the deeper lithosphere and mantle structure of anatolia using teleseismic finite frequency p wave traveltime tomography we use data from several temporary and permanent seismic networks deployed in the region approximately 34 000 p wave relative traveltime residuals measured in multiple frequency bands are inverted using approximate finite frequency sensitivity kernels our tomograms reveal segmented fast seismic anomalies beneath anatolia that corresponds to the subducted portion of the african lithosphere along the cyprean and the aegean trenches we identify these anomalies as the subducted aegean and the cyprus slabs that are separated from each other by a gap as wide as 300 km beneath western anatolia this gap is occupied by slow velocity perturbations that we interpret as hot upwelling asthenosphere the eastern termination of the subducting african lithosphere is located near the transition from central anatolia to the eastern anatolian plateau or arabian eurasian collision front that is underlain by large volumes of hot underplating asthenosphere marked by slow velocity perturbations our tomograms also show fast velocity perturbations at shallow depths beneath northwestern anatolia that sharply terminates towards the south at the north anatolian fault zone nafz the associated velocity contrast across the nafz persists down to a depth of 100 150 km hence our study is the first to investigate and interpret the vertical extent of deformation along this nascent transform plate boundary overall the resolved upper mantle structure of anatolia is directly related with the geology and tectonic features observed at the surface of the anatolian plate and suggest that the segmented nature of the subducted african lithosphere plays an important role in the evolution of anatolia and distribution of its tectonic provinces

petrological and geochemical characteristics of cenozoic high k calc alkaline volcanism in konya central anatolia turkey abstract late miocene to pliocene volcanic rocks outcrop west northwest and southwest of the konya area in central anatolia turkey volcanic products are lava domes nuee ardentes and ignimbrite deposits predominantly andesitic to dasitic in composition together with rare basalt basaltic andesite basaltic trachyandesite and trachyandesite 50 35 69 39 sio2 the serie exhibits high k calc alkaline affinities fractional crystallization of pyroxene plagioclase and fe ti oxides is the main process in the magmatic evolution of konya volcanic rocks volcanic units exhibit typical high k calc alkaline character their geochemical characteristics e g enrichments in lil elements such as k rb ba sr depletion in hfse such as ti nb and high ba nb and low nb y ratios are consistent with those of active continental margin regions high 87 sr 86 sr 0 704841 0 707340 and low 143 nd 144 nd 0 512390 0 512618 ratios suggest crustal involvement in their petrogenesis correlations between 86 sr 87 sr isotope with rb rb nb rb ba and rb sr also emphasize the effect of crustal contamination on the andesitic and dacitic magmas as a consequence konya volcanic rocks are products of assimilation and fractional crystallization afc processes of a magma which seems to be linked to the subduction of the african plate underneath the anatolian plate during miocene

exhumation with a twist paleomagnetic constraints on the evolution of the menderes metamorphic core complex western turkey 1 much remains to be understood about the links between regional vertical axis rotations continental extension and shortening in western turkey miocene vertical axis rotations have been reported that occur simultaneously with the extensional exhumation of the menderes metamorphic core complex which has been related to back arc extension in the eastern part of the aegean back arc in this paper we explore the spatial and temporal relationships between vertical axis rotations in southwestern turkey and extensional unroofing of the menderes massif to this end we provide a large set of new paleomagnetic data from western turkey and integrate these with the regional structural evolution to test the causes and consequences of oroclinal bending in the aegean region the lycian nappes and bey daglari are shown to rotate 20 between 16 and 5 ma defining the eastern limb of the aegean orocline this occurred contemporaneously with the exhumation of the central menderes massif along extensional detachments and after the latest oligocene to early miocene exhumation of the northern and southern menderes massifs exhumation of the latter two was not associated with vertical axis rotations the lower miocene volcanics in the region from lesbos to usak to the north of the central menderes massif underwent a small clockwise rotation insignificant with respect to eurasia this shows that exhumation of the central menderes massif was associated with a vertical axis rotation difference between the northern and southern menderes massifs of 25 30 this result is in excellent agreement with the angle defined by the trends of buyuk menderes and alasehir detachments as well as the angle defined by the regionally curving stretching lineation pattern across the central menderes massif these structures define a pivot point rotation pole for the west anatolian rotations the rotation of the southern domain including the southern menderes massif the lycian nappes and bey daglari must have led to n s contraction east of this pole the eastern limit of the rotating domain is formed by the transpressional couple of the aksu thrust and kirkkavak fault in the center of the isparta angle previously reported clockwise rotations in the volcanic fields near afyon may be the result of distributed n s shortening east of the pivot point the precise accommodation of this shortening history remains open for investigation late oligocene to early miocene extension in the eastern part of the aegean back arc was ne sw oriented and likely bounded by a discrete transform this transform may be associated with an early evolution of the eastern aegean subduction transform edge propagator fault oroclinal bending in the west anatolian region is likely related to a reconnection of the eastern part of the aegean orocline with the african northward moving plate in tandem with roll back in the aegean back arc comparable to a recently postulated scenario for western greece

age and kinematics of the burdur basin inferences for the existence of the fethiye burdur fault zone in sw anatolia turkey abstract the burdur basin is a late miocene to pliocene fluvio lacustrine basin in sw anatolia it is developed within the postulated fethiye burdur fault zone which was argued to be a sinistral strike slip fault zone developed in response to propagation of the pliny strabo step fault into sw anatolia turkey in order to assess the presence and tectonic characteristics of the fault zone we conducted a paleomagnetic study in the burdur basin that involved rock magnetic experiments anisotropy of magnetic susceptibility ams measurements and developing a magnetostratigraphy for dating purposes the obtained age model constrains most part of the tectonic evolution of the basin the well exposed 270 m thick burdur section revealed 3 normal and 2 reverse polarity magnetozones we propose that the burdur formation spans most of the gauss chron 3 4 2 5 ma which implies a sedimentation rate of 18 cm kyr the ams results in the section indicate nw se directed extension in addition we have also conducted kinematic analyses from 1790 fault slip data collected at 44 sites distributed within the supposed fethiye burdur fault zone in the region the results indicate that the region has been developed under a nw se directed extensional deformation regime and was dominated by ne sw striking normal faults from late miocene to recent few nw se striking normal faults with strike slip components are categorized as transfer faults which accommodated differential stretching between the burdur and cameli basins stretching amounts increase southwards demonstrating a dextral transtensional character of the transfer faults we have not observed any significant strike slip motion along the ne sw striking faults which challenges the presence and sinistral transcurrent nature of the supposed fethiye burdur fault zone

late cenozoic stress distribution along the misis range in the anatolian arabian and african plate intersection region se turkey 1 this study defines the mio pliocene to present day stress regime acting at the northeastern mediterranean along the se border of the neogene adana basin along the misis range the inversion of earthquake focal mechanisms shows that the present day state of stress is dominantly a transtension combined the strike slip and extension with a consistent ene n83 e trending hmin 3 axis the inversion slip vectors measured on fault planes and chronologies between striations indicate a consistent strike slip stress regime that varied from transpressional initially to transtensional during pleistocene time with the latter continuing into recent times as indicated by earthquake focal mechanism inversions both states have consistent nnw n15 w trending compatible with nnw arabian drift direction and ene n75 e trending hmax 1 and hmin 3 axes respectively but have significantly different mean arithmetic stress ratio rm values rm 0 75 indicating transpression for the old regional stress regime and rm of 0 20 denoting transtensional for the younger regional stress regime the crosscutting of striations confirms also the change within the strike slip stress regime both stress regimes induce sinistral displacement along the major strike slip fault systems i e east anatolian fault karatas osmaniye fault the temporal stress regime change probably occurred during quaternary time and resulted from coeval influence of the superimposed forces owing to subduction processes in the southwest along the cyprus arc continental collision in the east and westward escape of the anatolian block in the north and west

late miocene surface uplift of the southern margin of the central anatolian plateau central taurides turkey the timing and pattern of surface uplift of miocene marine sediments capping the southern margin of the central anatolian plateau in southern turkey provide a first order constraint on possible mechanisms of regional uplift nannofossil ostracod and planktic foraminifera biostratigraphy of the basyayla section mut ermenek basin within the mut and koselerli formations suggests a tortonian age for marine sediments unconformably capping basement rocks at 2 km elevation the identification of biozone mmi 12a 7 81 8 35 ma from planktic foraminifera in the upper part of the section provides the tightest constraint on the age which is further limited to 8 35 8 108 ma as a result of the reverse polarity of the collected samples chron 4r 1r or 4r 2r this provides a limiting age for the onset of surface uplift at the margin of one of the world s major orogenic plateaus from which an average uplift rate of 0 24 0 25 mm yr can be calculated subhorizontal beds of the uppermost marine sediments exposed throughout the mut ermenek basin suggest minimal localized deformation with just minor faulting at the basin margin and broad antiformal deformation across the basin this implies that the post 8 ma uplift mechanism must be rooted deep within the crust or in the upper mantle published pn wave velocity data for the region are compatible with topography compensated by asthenosphere across the southern margin of the plateau showing a close match to the highest topography when elevations are filtered with a 100 km wide smoothing window uplift along the southern margin of the central anatolian plateau is also reflected by the pattern of miocene marine sediments capping the margin which form an asymmetric drape fold over the topography these observations together with tomographic evidence for slab steepening and break off beneath the eastern anatolian plateau suggest that at least some of the 2 km of post 8 ma uplift of the southern central anatolian plateau margin is compensated by low density asthenospheric mantle that upwelled following slab break off

new insights on the neogene tectonic evolution of the aksu basin se turkey from the anisotropy of magnetic susceptibility ams and paleostress data abstract the junction between the aegean and cyprus arc in the southern turkey forms a triangular shaped morphological structure so called isparta angle ia in neogene time the inner part of the isparta angle became overlain by sedimentary basins including manavgat koprucay and aksu characterized by marine clastics and carbonates aksu basin one of these marine basins provides geological records about the neogene crustal deformation and stress field in the eastern mediterranean region therefore we kinematically assess if and when tectonic stress fields affected the aksu basin in early miocene to recent times for this purpose anisotropy of magnetic susceptibility ams data ams of cored samples and fault slip data from the brittle mesoscopic faults were collected the 490 oriented samples for anisotropy of magnetic susceptibility measurements were analyzed and two different maximum magnetic lineation s directions are recognized 1 n s magnetic lineation in pliocene and 2 from n s to nw se magnetic lineation in the miocene the results inferred from more than 1000 fault slip data collected from 83 different sites combined with ams results demonstrate that the aksu basin developed under four different tectonic phases 1 e w extensional phase related to basin formation 2 n s compressional lycian phase 3 n e s w compressional aksu phase and 4 n s extensional recent phase

seismic stratigraphy and structural evolution of the adana basin eastern mediterranean abstract detailed interpretation and mapping of multi channel seismic reflection profiles from the adana basin show that a south verging linked imbricate thrust stack existed across the northern portion of the adana basin prior to the deposition of early miocene sedimentary successions following the development of the basement cored fold thrust belt the region was irregularly denuded paleohighs and lows delineate the axis of hanging wall culminations and intervening structural depressions between forelimbs and backlimbs of the stacked sheets with residual topographic relief locally reaching 1500 m the stratigraphic and structural architecture of the early to middle miocene successions in the adana basin records a significant phase of tectonic subsidence that initiated in the early miocene followed by deposition of a thick deep water succession in an underfilled basin then relatively rapid uplift gave rise to basin inversion and erosion prior to or during the early tortonian the upper miocene global eustatic sea level fall initiated in the tortonian the transition from deep water to fluvio deltaic sedimentation in the early tortonian recorded the combined effects of a global eustatic sea level fall and regional tectonic uplift presumably related to renewed activity in the tauride orogen to the north it led to widespread erosion giving rise to a smooth unconformity surface in most of the adana basin the stratigraphic and structural relationships suggest that the onset of east directed thrusting in the trailing portion of the misis fold thrust belt occurred sometime during the lower tortonian coinciding with the switch from marine to terrestrial sedimentation the truncation by this unconformity of the folded thrusted successions of both miocene successions across the trailing thrust sheets marks the effect of progressive erosion as the thrust sheets are uplifted above base level a prominent progressive syntectonic unconformity is developed extending from the region of main thrust culminations westward into the depocentre situated on the backlimb of the leading thrust of the misis fold thrust belt much of the tortonian deposition took place within this trailing piggy back basin and the easterly onlap and the westerly tilt of this succession mark the progressive uplift of the fold thrust belt during the remainder of the tortonian terrestrial and fluvio deltaic deposition in the tortonian was succeeded in the messinian by the deposition of mixed evaporite carbonate clastic succession in the adana basin the base of this succession is a local unconformity across the tortonian succession that marks the cessation of the fold thrust activity in the east and ensuing erosion across the fill of the tortonian piggy back basin the subcrop of the messinian succession marks the edge of deposition in a paleotopographic depression situated between the tortonian misis fold thrust belt in the east and the paleoslope over the front of the reactivated tauride fold thrust belt in the north the western margin of deposition of the messinian succession was probably controlled by the development of the kozan fault zone plio quaternary subsidence created the accommodation space that allowed rapid delta progradation

miocene remagnetisation of carbonate platform and antalya complex units within the isparta angle sw turkey abstract a palaeomagnetic study has been carried out within the mesozoic and tertiary units of the relatively autochthonous carbonate platforms and the allochthonous deep sea volcanics and sediments of the antalya complex exposed around the isparta angle sw turkey the antalya complex is interpreted as a mosaic of carbonate platforms basinal sediments volcanic and ophiolitic rocks which formed within a southerly strand of the neotethyan ocean adjacent to gondwana the results indicate a widespread remagnetisation event negative fold tests show that the remanence at most sites is of secondary origin e g within the cirali lavas the magnetisation is carried by magnetite of presumed authigenic origin the remagnetisation event is believed to have occurred in the early middle miocene burdigalian langhian it was possibly triggered by the migration of orogenic fluids ahead of the advancing lycian nappes during their emplacement onto the carbonate platforms subsequent to remagnetisation a large segment of the isparta angle underwent an anticlockwise rotation of 30 this rotation is attributed to the overall convergence and bending of the hellenic arc and the final stages of emplacement of the lycian nappes during the late miocene in agreement with previous studies previously southerly palaeolatitudes were inferred from late triassic extrusives of the godene zone calbali dag unit the post folding magnetisation identified here within the cirali lavas of the godene zone to the south implies that these low palaeolatitudes result from the inappropriate application of structural tilt corrections the available data cannot be used to substantiate an origin for the antalya units south of the equator in the early mesozoic instead a position close to the northern margin of gondwana is indicated

phytoliths from archaeological sites in the tropical forest of ituri democratic republic of congo abstract phytoliths record late quaternary vegetation at three archaeological sites in the ituri rain forest the oldest deposits dated to ca 19 000 to 10 000 14c yr b p contain abundant phytoliths of grasses but also enough arboreal forms to show that the landscape was forested the late glacial forests may have had a more open canopy than today s younger phytolith assemblages show that the northeast congo basin was densely forested throughout the holocene archaeological materials among the phytoliths show that people lived in this region during the pleistocene therefore pleistocene and holocene prehistoric foragers probably inhabited tropical forests of the northeast congo basin many millennia before farming appeared in the region

miocene recent evolution of the western antalya basin and its linkage with the isparta angle eastern mediterranean abstract interpretation of 9500 km of multichannel seismic reflection profiles showed the presence of two major tectonic histories in western antalya basin spanning from the miocene or older to the pliocene quaternary a prominent fold thrust belt affects the miocene succession in the offshore the thrusts swing from a nw se strike with sw vergence in the northeast of the mapped area to a more northerly strike with westerly vergence at the western shelf edge of the deep basin the miocene deformation appears to continue offshore from the westerly directed thrusting seen onshore that characterizes the eastern edge of the isparta angle the contraction is consistent with the counterclockwise miocene rotation of the western side of the isparta angle determined from paleomagnetic studies the thrust belt forms the western extremity of the wider regional aksu kyrenia misis oroclinal culmination the tectonic activity experienced a period of relative quiescence across the western antalya basin during the messinian a major kinematic change occurred in the pliocene when the regional strain was partitioned into three spatially localized tectonic domains an extensional domain confined to the pliocene quaternary unit 1 occupied the northeastern portion of the study area a predominantly extensional domain with a few re activated pre existing miocene contractional structures occupied the southern and central portion of the study area and an extensional and or transtensional domain occupied the continental shelf and slope in the westernmost antalya basin these complexities relate to strike slip motions as the crustal block within the isparta angle moved northwards relative to the blocks to the north

magma generation by slab steepening and breakoff beneath a subduction accretion complex an alternative model for collision related volcanism in eastern anatolia turkey 1 eastern anatolia is regarded as one of the best examples of continental collision represented by a 2 km high plateau it displays shallow and diffuse seismicity indicating that the crust is still being actively deformed perhaps the most striking aspect of eastern anatolia is the volume and compositional variability of collision related volcanic products erupted during the neogene and quaternary time a number of models have been proposed for the genesis of this volcanism in the region however recent geophysical studies have revealed that a mantle lithosphere is almost completely absent beneath a greater portion of the region which makes us question the validity of the previous models in this paper we propose a new model for magma genesis slab steepening and breakoff beneath a large subduction accretion complex this model holds that a northward subducting oceanic lithosphere beneath the eastern anatolia accretionary prism gets steepened and eventually detached from the continental lithosphere of the bitlis poturge massif following the continent accretionary complex collision this brings the asthenospheric mantle in contact with the accretionary complex at shallow depths e g around 50 km resulting in rapid regional uplift and extensive melting which leads to collisional volcanism

rotations of normal fault blocks quantify extension in the central tauride intramontane basins sw turkey quantifying the amount of stretching in extensional basin systems is often challenging in the absence of seismic profiles or boreholes however when fault spacing and orientation as well as vertical axis rotation patterns are known map view restoration may provide a good estimate of total extension this integrated structural and paleomagnetic approach provides a relatively straightforward tool in extensional basin restoration and fault zone kinematic analysis here we provide results of an extensive paleomagnetic survey of the neogene central tauride intramontane basins sw turkey where previous work revealed a complex array of basin bounding normal faults and relay ramps in total 437 oriented cores were sampled at 43 sites distributed within miocene pliocene continental sedimentary rocks from the ilgin altinapa yalvac and beysehir basins despite the more or less coherent overall strike of the mountain belt and basins rotations vary from 42 clockwise yalvac to 10 beysehir 21 ilgin and 30 altinapa counterclockwise we show that the rotation pattern is related to normal faults and lateral variations in fault displacement superimposed on regional rotation patterns we restore these to estimate a minimum ne sw horizontal extension of 30 35 km across the basin system as a consequence of our reconstruction it appears that the sultandaglari range that exposes low grade metamorphic paleozoic and mesozoic rocks of the geyikdagi and bolkardag nappes of the taurides represents a miocene extensional core complex

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

slab detachment beneath eastern anatolia a possible cause for the formation of the north anatolian fault in this paper we discuss the possibility that the north anatolian fault naf results from the deep deformation of the slab beneath the bitlis hellenic subduction zone we described the tectonic evolution of the anatolia aegean area in three main steps before during and after the formation of the naf we remark that the tectonic conditions that are assumed to have triggered the formation of the naf i e collision to the east and extension to the west was already achieved before the onset of that strike slip fault system we also highlight that the formation of the naf was accompanied by the uplift of the turkish iranian plateau and by a surge of volcanism in the eastern anatolia collisional area and probably by the acceleration of the aegean trench retreat we show tomographic images from global p wave model of piromallo and morelli c piromallo a morelli p wave tomography of the mantle under the alpine mediterranean area j geophys res 108 2003 doi 10 1029 2002jb001757 showing that the slab beneath the bitlis collisional belt is not continuous and that its possible rupture pursues to the west at least up to cyprus and possibly up to the eastern end of the hellenic trench all these observations suggest that the plate tectonic re organization occurred in the late miocene early pliocene in the region results from slab break off in the bitlis area and from its lateral propagation to the west this idea is tested in analogue laboratory experiments which confirm that the break of the slab under the collisional belt may trigger 1 the acceleration of slab retreat to the west due to the increase in slab pull force 2 the indentation of the continent in the collisional area and 3 produce the conditions that permit the lateral escape of material towards the west and the formation of the naf

morphology and genesis of hillslope pediments in the febe area south cameroon summary the quaternary geomorphological evolution in africa is characterised by the occurrence of several pedimentation cycles in tropical climates with a short dry season and with highly and deeply weathered soils valley floor pedimentation is active valley flanks retreat and act as pedimentation scarps valley floor pedimentation results in the formation of a relief in half oranges and flat valley bottoms in a mountainous or a hilly relief so called hillslope pediments may be formed the pedimentation scarp retreats until it reaches the watershed the height of the pedimentation scarp decreases gradually from the river towards the hilltop close to the watershed the scarp disappears during the pedimentation process clay is transported as silt and sand sized micro aggregates these aggregates accumulate in the hillwash cover and constitute also the fine earth

an inverse problem in microtectonics for the determination of stress tensors from fault striation analysis abstract a method is proposed to compute some characteristics of a possible stress tensor related to striations measured in a given faulted area if several tectonic phases are responsible for the striations the method separates and determines the successive stress tensors the iterative algorithm consists of alternatively a sorting the data attributed to a tectonic phase and b computing the characteristics of the stress tensor of this phase the method is tested using an application to synthetic and actual data

micropaleontology and paleoecology of the neogene sediments in the adana basin south of turkey this paper analyses the stratigraphical features and fossil associations ostracod and planktonic foraminifer of the late miocene deposits in the adana basin in this research numerous samples were collected from the sediments both below and above the messinian evaporitic layers which cropped out in the western and middle part of the adana basin due to paleoenvironmental changes during the messinian salinity crisis the fine grained sediments below the gypsum layers surrounding topcu and karayayla villages located in the western part of the basin are sterile nodular anhydrite and enterolithic structures are well developed in these selenitic gypsum layers which are supposed to represent a sabkha environmental condition in the middle part of the adana basin some re sediment detritic gypsum deposits cropped out around semiramis village houses the lithological characteristics and faunal assemblages of the sediments both below and above these evaporites are more or less similar to each other fossil fauna ostracod and planktonic foraminifera demonstrate that these sediments are not older than latest tortonian as suggested by the presence of neogloboquadrina humerosa and not younger than earliest messinian as suggested by the last occurrence of globigerinoides bulloideus similar planktonic assemblages were found in the drill log bored east of the adana basin where there was no evaporitic occurrence both the planktonic species and the presence of globorotalia suterae from 7 81 ma to 7 24 ma point that also these fine granied sediments a late tortonian early messinian in age the quantity of kaolinite recorded is relatively higher in the tortonian early messinian than in the late messinian sediments all data show that during the latest tortonian earliest messinian time interval the area was characterised by shallow marine environments and humid climatic conditions

late cretaceous to paleocene oroclinal bending in the central pontides turkey 1 the turkish pontide fold and thrust belt formed since the paleozoic and is an important element in the africa eurasia convergence and the resulting closure of the neo tethys ocean it has a peculiar arc shaped geometry in its central part along the black sea coast which may have resulted from oroclinal bending we have determined the vertical axis rotation history of this area using paleomagnetism on cretaceous to eocene rocks from 47 sites and critically analyzed previously published data we applied the same reliability criteria to all data our results show that late cretaceous sites have clockwise and counterclockwise rotations perpendicular to the structural trend in the central pontides in the eastern pontides they show only local rotations paleocene to eocene rocks in the central and eastern pontides show no rotation we conclude that the central pontide northward arc shaped geometry results from oroclinal bending in latest cretaceous to earliest paleocene times the timing and scale of geological processes that occurred in the region make it likely that orocline formation resulted from neo tethys closure between the pontides and the metamorphic promontory of the anatolide tauride block earlier studies on the southerly located cankiri basin reveal that clockwise and counterclockwise rotations occurred in eocene oligocene times this implies that the entire region underwent continuous deformation from late cretaceous to eocene caused by convergence of the pontides and the anatolide tauride block with a southward moving deformation front deformation was first localized in the northern part of the central pontides until the paleocene resulting in oroclinal bending and from at least eocene times it shifted toward the cankiri basin region

geogenesis pedogenesis and multiple causality in the formation of texture contrast soils abstract coarse over fine vertical texture contrasts vtc are common in soils and weathering profiles in a variety of environmental settings including many where inheritance or surficial processes alone cannot account for them a multiple causality model is presented here which shows that texture contrasts can form in response to a combination of ubiquitous phenomena there are six key elements downward translocation by water erosional winnowing soil mixing by bioturbation the tendency for surface clay additions to be mobilized while subsurface clays are more likely to remain in place and biological facilitation of moisture flux no element alone is sufficient to create a vtc but not all are necessary in any given regolith the model is illustrated by application to case studies in the ouachita mountains arkansas ridgetops in eastern kentucky the lower coastal plain of north carolina and the upper coastal plain of east texas the implications for interpretation of soils paleosols and weathering profiles is that the presence of a textural contrast by itself does not connote any particular set of geogenic or pedogenic processs or controls texture contrasts may be geogenic pedogenic or both given the widespread occurrence of the mechanisms of the multiple causality model vertical texture contrasts are inevitable

the formation of fire residues associated with hunter gatherers in humid tropical environments a geo ethnoarchaeological perspective this work was supported by the people programme marie curie actions of the european union s seventh framework programme fp7 2007 2013 under rea agreement n 623293 granted to d e f at the mcdonald institute for archaeological research university of cambridge radiocarbon dating was also funded by the exilarch s foundation for the dangoor research accelerator mass spectrometry laboratory d reams

significance of thick deposits of colluvium on hillslopes a case study involving the use of pollen analysis in the coastal mountains of northern california distinct bedrock hollows with a colluvial fill are common in soil mantled hillslopes it has been proposed that these hollows are sites of recurrent emptying by landsliding and subsequent slower refilling with colluvium on a hillslope in northern california we have quantified the time since emptying and the three dimensional configurations of the underlying bedrock surface correlation of the pollen record in the colluvium with a nearby pollen core from a lake with an accurate age control indicates that the oldest colluvium was deposited 11 000 to 13 500 years in the bedrock hollow since then deposition of colluvium in the hollow has been equivalent to 1 5 m of landscape lowering in the surrounding source area and to a local lowering rate of about 0 1 mm yr the longitudinal profile of the hollow is concave upward a form that causes the groundwater flow to rise toward the surface downslope leading to saturation and possibly to landsliding

tropical stone lines and podzolized sand plains as paleoclimatic indicators for weathered cratons abstract stone lines and podzolized white sand plains are characteristic features of the regolith in many low latitude cratonic landscapes but nevertheless often seem to be out of phase with the present pedogenic and geomorphic regimes of the humid tropics and subtropics consideration of contemporary environments where the genetic processes related to these features can be observed implies several conditions for prior events in landscape evolution 1 tropical stone lines may be interpreted as winnowed mudflows or lag deposits that reflect morphoclimatic events of brief duration torrential rains within an arid or semi arid phase of pronounced global cooling 2 within the present zone of the prevailing westerlies stone lines may reflect periglacial activity during brief interstade fluctuations 3 in lower latitudes the principal stone line which commonly truncates saprolites appears to be late wisconsinan wurmian in age coinciding more or less with the pleniglacial phase 4 the podzolized sands represent leached residuals and accordingly reflect extended intervals of leaching during the pleistocene and 5 the nature and distribution of podzolized sand plains indicates a pedogenic history of considerable variety and no brief episodicity as implied with stone lines

the nature of stone lines in the african quaternary record archaeological resolution at the rainforest site of mosumu equatorial guinea abstract stone lines are widespread quaternary features that appear in tropical and subtropical regions they have a diverse nature and genesis and are frequently associated with archaeological assemblages however archaeological deposition and stone line configuration may be unrelated geological events separated by thousands of years the energetics involved in stone line formation coarse and fine material translocation across space and in depth and overall assemblage integrity vary from one site to another this paper presents quantitative and spatial geoarchaeological data from the site of mosumu in the tropical rain forest of continental equatorial guinea mosumu yielded middle and later stone age assemblages dated to at least the last 30 000 years in a stone line context special attention to the study of vertical and horizontal variations of artifacts sedimentary features and taphonomic indicators allows analysis of the nature meaning and archeological resolution at this site the results are placed in the wider debate over the meaning of stone lines in the african quaternary record

the mid cenozoic succession and evolution of the mut basin southern turkey and its regional significance abstract the hitherto poorly known mut basin occupies a position that is critical to our understanding of the later cenozoic history of south central turkey the biostratigraphic and sedimentological study reported here reveals an extended and complex pattern of basin evolution and enables the history of this basin to be compared in detail with that of adjacent south turkish basins the oldest basin fill deposits are demonstrated to be oligocene to earliest miocene in age and comprise alluvial redbeds thick lacustrine deposits and thin lagoonal sediments mainly supplied from northern tauride sources this mainly terrestrial megasequence resulted from an early oligocene phase of crustal extension leading to rapid trap door subsidence and the formation of narrow e w trending troughs this phase was terminated by a minor marine incursion and through reactivation of basement faults during renewed extension in the earliest miocene the overlying miocene succession thus rests with local angular discordance upon tilted and gently deformed oligocene and older rocks subsequent subaerial erosion created an irregular pre burdigalian palaeotopography that strongly influenced the nature thickness and distribution of the early miocene basin fill in palaeotopographic depressions the miocene sequence commences with alluvial fan braidplain and meander belt redbeds formed in river systems that flowed mainly south and southeast these pass up and laterally into more extensive lagoonal and shallow marine mixed clastic carbonate units yielding late burdigalian to early langhian microfaunas marking the inception of the main miocene marine transgression in this area episodic northwards marine advance led to isolation of the northerly source of siliciclastic detritus and resulted in periodic onlap of mid to inner shelf fine grained carbonates with thin clastic intercalations that include isolated coralgal build ups calcarenite mounds and sand waves at the peak of miocene transgression mid serravallian thick reefal limestones were deposited far to the north and also formed on top of basement highs forming the southern and eastern flanks of the basin significant influxes of coarse and fine siliciclastics from the north attest to periodic progradational events that are more conspicuous and protracted in the late serravallian and tortonian however muddy deeper shelf conditions prevailed throughout the middle miocene in the central part of the basin while stronger currents and unstable slopes characterise the constricted marine strait in the southeast of the basin near silifke in terms of their sequential arrangement palaeoenvironmental and tectonic evolution the oligo miocene sediments of the mut basin closely resemble coeval sequences in the adjacent ecemis aktoprak and karsanti northern adana basins and share a similar history involving complex interplay between regional tectonics and eustasism deeper water oligo miocene sequences in the outboard troughs such as the southern adana basin and the kyrenia misis andirin complex yield more subtle signatures of these tectonic and eustatic events the differences between these basins are attributable to the influence of regional kinematic elements generated during the reorganisation of plate boundaries in the northeast mediterranean that followed final suturing of the arabian and anatolide plates in the mid cenozoic

detecting the limit of slab break off in central turkey new high resolution pn tomography results summary inversion of pn traveltime residuals from a 39 station broad band array provides a highresolution image of the velocity structure in the uppermost mantle beneath central turkey individually picked pn phase arrivals from events recorded by the north anatolian fault passive seismic experiment and the kandilli observatory were combined with additional events associated with the eastern turkey seismic experiment tomography results show no change in pn velocity across the north anatolian fault although longitudinal variations are evident a region of very low pn velocities 8 1 km s 1 w est of the fault the sharp transition along the cafz which follows the palaeotectonic inner tauride suture may represent the location of the edge of the slab window created when the oceanic slab broke off along the bitlis zagros suture around 11 ma as the arabian plate collided with the eurasian plate

reconciling the geological history of western turkey with plate circuits and mantle tomography abstract we place the geological history since cretaceous times in western turkey in a context of convergence subduction collision and slab break off to this end we compare the west anatolian geological history with amounts of africa europe convergence calculated from the atlantic plate circuit and the seismic tomography images of the west anatolian mantle structure western turkish geology reflects the convergence between the sakarya continent here treated as eurasia in the north and africa in the south with the anatolide tauride block atb between two strands of the neotethyan ocean convergence between the sakarya and the atb started at least 95 90 myr ago marked by ages of metamorphic soles of ophiolites that form the highest structural unit below sakarya these are underlain by high pressure low temperature metamorphic rocks of the tavsanli and afyon zones and the oren unit which in turn are underlain by the menderes massif derived from the atb underthrusting of the atb below sakarya was since 50 ma associated with high temperature metamorphism and widespread granitic magmatism thrusting in the menderes massif continued until 35 ma after which there is no record of accretion in western turkey plate circuits show that since 90 ma 1400 km of africa europe convergence occurred of which 700 km since 50 ma and 450 km since 35 ma seismic tomography shows that the african slab under western turkey is decoupled from the african plate this detached slab is a single coherent body representing the lithosphere consumed since 90 ma there was no subduction re initiation after slab break off atb collision with europe therefore did not immediately lead to slab break off but instead to delamination of subducting lithospheric mantle from accreting atb crust while staying attached to the african plate this led to asthenospheric inflow below the atb crust high temperature metamorphism and felsic magmatism slab break off in western turkey probably occurred 15 myr ago after which overriding plate compression and rotation accommodated ongoing africa europe convergence slab break off was accommodated along a vertical ne trending subduction transform edge propagator step fault zone accelerating southwestward slab retreat of the aegean slab the se aegean slab edge may have existed already since early miocene times or before but started to rapidly roll back along the southeastern aegean step in middle miocene times penetrating the aegean region in the pliocene

structural and sedimentary evidence from the northern margin of the tauride platform in south central turkey used to test alternative models of tethys during early mesozoic time abstract critical to reconstruction of the tethys ocean is the nature and significance of a reported latest triassic cimmerian tectonic event in the tauride mountains of south central turkey in one published model a cimmerian continental fragment including the tauride platform rifted from the northern margin of gondwana and collided with a eurasian derived anatolide continental fragment during late triassic time causing orogenic deformation of the tauride continental platform in a second published model southward subduction of a palaeotethyan ocean opened a back arc basin associated with rift related uplift of the tauride platform during early triassic time the tauride platform remained as a north facing passive margin from the mid late triassic to late cretaceous without further deformation in a third published model a continental fragment rifted from a tauride anatolide platform in the south opening a small ocean basin ankara izmir ocean to the north by mid late triassic time late triassic deformation and uplift of the tauride platform possibly resulted from far field stress transmission from the cimmerian orogeny that affected the eurasian margin in an additional model a tauride anatolide continent experienced a rift related evolution culminating in a pulse of extension related uplift during the latest triassic followed by seafloor spreading to the north the models are tested using evidence from relatively autochthonous tauride units geyik dag sultan dag and over riding thrust sheets hadim aladag nappe bolkar nappe geological mapping of critical areas and related structural evidence show that most of the deformation in the area can be related to late cretaceous and early cenozoic alpine emplacement of the tauride nappes although late triassic compressional deformation is likely at one locality sedimentary evidence from the cayir formation a widespread latest triassic earliest jurassic clastic sequence shows that it accumulated in a range of non marine to locally shallow marine fluvial to deltaic settings palaeocurrent data indicate mainly southward sediment transport most of the material was derived from lithologies equivalent to those exposed within the underlying tauride platform and within an upper palaeozoic basement unit konya complex to the north a combination of the available structural sedimentary and stratigraphical information from the tauride region and international comparisons lead us to exclude the presence of a palaeotethyan suture of latest triassic age within the taurides rather we explain the late triassic early jurassic tauride geology mainly in terms of the uplift of a basement unit that was located along northern margin of the tauride carbonate platform associated with opening of the izmir ankara ocean to the north

a key extensional metamorphic complex reviewed and restored the menderes massif of western turkey article i nfo this paper provides a review of the structure and metamorphism of the menderes massif in western turkey and subsequently a map view restoration of its neogene unroofing history exhumation of this massif among the largest continental extensional provinces in the world is generally considered to have occurred along extensional detachments with a ne sw stretching direction restoration of the early miocene history however shows that these extensional detachments can only explain part of the exhumation history of the menderes massif and that ne sw stretching can only be held accountable for half or less of the

a miocene onset of the modern extensional regime in the isparta angle constraints from the yalvac basin southwest turkey the pre neogene tauride fold and thrust belt comprising cretaceous ophiolites and metamorphic rocks and non metamorphic carbonate thrust slices in southern turkey is flanked and overlain by neogene sedimentary basins these include poorly studied intra montane basins including the yalvac basin in this paper we study the stratigraphy sedimentology and structure of the yalvac basin which has a middle miocene and younger stratigraphy our results show that the basin formed as a result of multi directional extension with ne sw to e w extension dominating over subordinate nw se to n s extension we show that faults bounding the modern basin also governed basin formation with proximal facies close to the basin margins grading upwards and basinwards into lacustrine deposits representing the local depocentre the yalvac basin was a local basin but a similar contemporaneous history recently reconstructed from the altinapa basin 100 km to the south shows that multi directional extension dominated by e w extension was a regional phenomenon extension is still active today and we conclude that this tectonic regime in the study area has prevailed since middle miocene times previously documented e w shortening in the isparta angle along the aksu thrust 100 km to the southwest of our study area is synchronous with the extensional history documented here and e w extension to its east shows that anatolian westwards push is likely not the cause synchronous e w shortening in the heart and e w extension in the east of the isparta angle may be explained by an eastwards dipping subduction zone previously documented with seismic tomography and earthquake hypocentres we suggest that this slab surfaces along the aksu thrust and creates e w overriding plate extension in the east of the isparta angle neogene and modern anatolian geodynamics may thus have been driven by an aegean antalya and cyprus slab segment that each had their own specific evolution

tectonic triggers for postsubduction magmatic hydrothermal gold metallogeny in the late cenozoic anatolian metallogenic trend turkey

east anatolian high plateau as a mantle supported north south shortened domal structure an edited version of this paper was published by the american geophysical union agu copyright 2003 agu see also http www agu org pubs crossref 2003 2003gl017858 shtml http atlas geo cornell edu turkey publications sengor et al 2003 htm

effects of antecedent topography on reefal carbonate deposition early middle miocene of the adana basin s turkey abstract early middle miocene reefal limestones and other shallow marine sedimentary sequences were important components of neogene basins especially the adana basin in southern turkey the most important controlling factors of sedimentation were antecedent topography and substratum type clastic input and sea level changes of different scales the effects of these factors can be observed on the southwest extension of the adana basin miocene sediments unconformably overlie the older limestones ophiolite and ophiolitic melange lithological variations and structural properties of pre miocene rocks caused an irregular sea floor topography development that was initially filled by local terrestrial conglomerates during the early miocene transgression these terrestrial clastics transitionally passed into shallow marine clastics and also new pebbly conglomerate sandstone bearing deposits observed in local depressions of pre miocene topography remaining low lying areas were filled by claystones and sandy clayey limestones at the same time reef limestone deposition developed over the higher areas where a hard substratum was available for red algae and other reef builders large shelled organisms in the clastics created a suitable substratum for successive reef level development the carbonate deposition shifted landwards due to continuous transgression intermediate sea level changes causing backstepping reef development small sea level changes in the study area controlled the energy of the environment lithological variations in the clastics and lateral facies changes in each reef body

40ar 39ar dating of neogene pseudotachylytes if fresh abundant and formed over a sufficiently long time interval ar ar dating of pseudotachylytes provides a means of assessing the active histories of exhumed faults due to the combination of generally low k content and young formation age the ar ar dating of neogene pseudotachylyte is analytically difficult moreover interpretation of ages is complicated by different extraneous and radiogenic argon isotope source reservoirs and by the intimate coexistence of unmelted clasts neoformed minerals and frictional glass high spatial resolution uv laser ablation ar ar geochronology of pseudotachylytes together with careful textural and chemical characterization provides a means of precisely dating these fossil paleoseismic events we report results of uv laser ablation ar ar geochronology on neogene pseudotachylyte from tectonically active areas in japan and the swiss alps our data yield age probability plots forming near normal distributions but have discernible tails at older ages due to the contribution of partially outgassed clast material therefore we interpret the peak of the age probability function as a maximum age of pseudotachylyte formation pseudotachylytes at the top of the leventina nappe the deepest part of lepontine dome central alps switzerland contain few large clasts and yield an age of 10 ma consistent with prior estimates of orogen parallel extension in alps in contrast two pseudotachylyte samples from the uchinoura shear zone southern kyushu japan yield an age of 11 ma approximately 2 m a younger than previously determined ages fabbri et al 2004 we attribute this age difference to the fact that our high spatial resolution uv laser analyses were focused on areas with fewer clasts thus minimizing the effects of argon incorporation from partially outgassed clast material

characterization of stress perturbations near major fault zones insights from 2 d distinct element numerical modelling and field studies jura mountains abstract we consider and discuss the presence of discontinuities in the crust as a major source of stress perturbations based on 2 d distinct element modelling we reconstruct the local stress field around a vertical discontinuity in various geological contexts the resulting stress distribution reveals that major directional stress changes occur near the tips of the discontinuity so that stress deviations can reach values as large as 50 we establish simple relationships controlling stress changes around a pre existing fault zone as a function of 1 the remote differential stress magnitude 1 3 2 the friction coefficient on the discontinuity and 3 the strike of the discontinuity relative to the far field stress as a geological example we present the morez fault zone in the internal jura paleostress reconstruction in forty two sites indicates that the trends of the mio pliocene compression are n110 on average near the fault whereas they are n130 in the surrounding areas a comparison between the results of the tectonic study and those of theoretical modelling suggests that the 20 counterclockwise deviation is directly related to the reactivation of this large weak zone we thus evaluate the role of mechanical decoupling along pre existing zones of weakness especially with consideration to the accommodation of the alpine deformation in the jura belt

magnetic properties of fault pseudotachylytes in granites 1 we investigate the petrographic geochemical and magnetic properties of fault pseudotachylytes formed by frictional melting in granitic rocks from southern california the italian alps and kyushyu japan the main magnetic remanence carriers are mixtures of grain sizes of fine grained magnetite these ferrimagnetic grains record a stable multicomponent magnetization that consists of one or more of the following coseismic thermal remanent magnetization coseismic lightning isothermal remanent magnetization and post seismic chemical remanent magnetization fault pseudotachylytes from the three localities display contrasting magnetic properties which suggests that oxygen fugacity and host rock composition ultimately control the magnetic assemblage

the beysehir hoyran hadim nappes genesis and emplacement of mesozoic marginal and oceanic units of the northern neotethys in southern turkey the beysehir hoyran hadim nappes crop out over 700 km from nw to se above a regionally autochthonous tauride carbonate platform the beysehir hoyran nappes begin with a thrust sheet c 400 m of mainly redeposited carbonates quartzose sandstones and mudstones of mid late triassic age interpreted as a proximal slope base of slope succession above is a thrust sheet c 1 km of middle upper triassic intermediate acidic extrusive rocks volcaniclastic rocks and minor pelagic carbonates interpreted as a continental rift thin

high pressure metasediments in central turkey constraints on the neotethyan closure history 1 the distribution of oceanic domains and continental blocks in central anatolia remains a challenge in understanding the alpine geodynamic evolution of the tethys realm the consumption of a neotethys oceanic branch at the mesozoic cenozoic boundary welded the central anatolian crystalline complex in central turkey and the anatolide tauride block in western turkey with the northerly eurasian margin whether those two regions constituted a single or two distinct continental masses is still matter of debate high pressure metamorphism has been locally evidenced in the afyon zone which was however defined as a greenschist facies metamorphic zone of the anatolide tauride block since the afyon zone composes a metamorphic equivalent of a continental margin exposed far south of the izmir ankara suture zone this encouraged us to reevaluate its metamorphic evolution in order to better understand the relation between western and central turkey our investigations reveal that the high pressure minerals fe mg carpholite and glaucophane are present in the entire afyon zone which we reconsider as a blueschist facies zone we additionally present a tectonic reconstruction stripping off the postcollisional tectonics it reveals that today s bending of the high pressure belt is consistent with an eocene collision of the anatolide tauride block around the southern edge of the central anatolian crystalline complex we argue that the central anatolian crystalline complex and the anatolide tauride block were two distinct continental masses separated by a neotethyan oceanic stripe the closure of which engendered subduction related metamorphism in the latter and arc volcanism and high grade metamorphism in the former by late cretaceous to early cenozoic

tectono stratigraphic evolution of an early miocene incised valley fill derincay formation in the mut basin southern turkey abstract an early miocene early burdigalian incised valley fill was produced through development of an alluvial system during active extension and block rotation in the mut basin five phases of alluvial activity have been recognized and are linked to specific tectono stratigraphic factors the entrenchment phase phase 1 was a response to a rapid decrease in accommodation caused by a combination of sea level fall and accelerated tectonism that occurred around the basin during active extension a lacustrine depositional system that pre dated entrenchment was abruptly succeeded by an erosional fluvial system the initial erosion the entrenchment phase was followed by the deposition of ephemeral meandering fluvial facies and later by high sinuosity sandy meandering fluvial facies during the aggradational phase phase 2 coarser grained lower sinuosity meandering river facies were vertically stacked in response to successive periods of fault block rotation and basinal subsidence the thickest stratigraphic interval was deposited during this time simultaneously in a basinward position finer grained distal facies were deposited the succeeding backfilling phase phase 3 was marked by further fault block rotation and an increase in the catchment area that resulted in higher flow regime and more sediment input a further increase in accommodation space due to block rotation resulted in the retreat of facies belts and the deposition of a retrogradational stacked gravelly low sinuosity meandering facies during the early transgressive phase phase 4 in the downstream part of the alluvial valley fluvio deltaic and non marine transitional facies were deposited and progressively retreated landwards during marine flooding phase 5 marks the main interval of early miocene marine transgression a combination of global eustasy and regional epeiric subsidence during this time the facies belts within the incised valley fill were dominated by estuarine and lagoonal facies assemblages while the distal parts of the alluvial valley became completely flooded with marine waters at the end of the transgressive phase in the uppermost early burdigalian the estuarine and lagoonal facies migrated further inland while shallow marine sediments reefal limestones were deposited in distal parts of the now drowned valley blanketing the pre existing topography

linking slab break off hellenic trench retreat and uplift of the central and eastern anatolian plateaus abstract the central and eastern anatolian plateaus are integral parts of the world s third largest orogenic plateau in the past decade geophysical surveys have provided insights into the crust lithosphere and mantle beneath eastern anatolia these observations are now accompanied by recent surveys in central anatolia and new data constraining the timing and magnitude of uplift along its northern and southern margins together with predictions from geodynamic models on the effects of various processes on surface deformation and uplift the observations can be integrated to identify probable mechanisms of anatolian plateau growth a changeover from shortening to extension along the southern margin of central anatolia that is coeval with the start of uplift can be most easily associated with oceanic slab break off and tearing this interpretation is supported by tomography deep seismicity or lack thereof and gravity data based on the timing of uplift geophysical and geochemical observations and model predictions slab break off likely occurred first beneath eastern anatolia in middle to late miocene time and propagated westward toward cyprus by the latest miocene alternatively the break off near cyprus could have occurred in late pliocene to early pleistocene time in association with collision of the eratosthenes seamount continental fragment with the subduction zone uplift at the northern margin of central anatolia appears to result from crustal shortening starting in the late miocene or early pliocene which has been linked to the broad restraining bend of the north anatolian fault the uplift history of the interior of central anatolia since the late miocene is unclear although shortening there appears to have ended by the late miocene followed by ne sw extension this change in the deformation style broadly coincides with faster retreat of the hellenic trench as well as uplift of the northern and southern margins of central anatolia these different events throughout the plateau may be linked as faster retreat of the hellenic trench has been predicted to occur after slab break off which could have induced extension of central anatolia and helped to form the north anatolian fault through accelerated westward movement of anatolia relative to eurasia correlative geochronologic evidence that we summarize here supports the hypothesis that the geodynamic activity throughout the aegean anatolian domain starting in latest miocene to early pliocene time defines a series of events that may all be linked to slab break off

a high resolution palaeoclimatic record for the last 27 500 years in tropical west africa from the carbon and nitrogen isotopic composition of lacustrine organic matter variations in the carbon and nitrogen isotopic composition of bulk organic matter in the sediments of lake bosumtwi ghana reflect climatically induced changes to the lake and the catchment flora cores spanning the last 27 5 kyr of sedimentation in the lake show large oscillations in 13corg pdb and 15norg air the late pleistocene record is particularly detailed showing changes of ca 20 in carbon and ca 10 in nitrogen isotopic compositions these variations are of complex origin although different in magnitude major isotopic excursions in the two records are generally in phase and reveal the occurrence of two major dry intervals at and immediately following the last glacial maximum the allerod younger dryas period also seems to have been marked by generally dry conditions in this part of tropical west africa nitrogen isotopic evidence suggests that during the period 9 2 3 2 kyr the lake had an extremely stable water column probably due to the absence of a windy or cool dry season or both regular circulation of the water column recommenced during the late holocene and has persisted until the present day

rapid late miocene surface uplift of the central anatolian plateau margin abstract the central anatolian plateau cap turkey is bordered to its south by a steep mountain belt that emerged 8 7 ma ago from the mediterranean sea knowledge of the onset duration and rate of surface uplift and orographic barrier formation along the plateau margin is crucial for understanding the geodynamic drivers of plateau uplift we present a new comprehensive data set that includes 12 40ar 39ar ages and lacustrine carbonate 18 o data n 637 from 13 sections in upper oligocene to pliocene continental basins of the cap interior we aim at documenting the development of a rain shadow and therefore the surface uplift history of the cap and its southern margin tauride mts in the rain shadow of the tauride mts we observe a gradual 3 9 decrease of 18 o values of lacustrine carbonate between 11 and 5 ma that we interpret to originate from a similar change in 18 o values of precipitation owing to the late miocene development of an orographic barrier our stable isotope paleoaltimetry data show that by 5 ma the southern cap margin had reached similar to present elevations of 2 km surface uplift was coeval with ignimbritic magmatism forearc shortening and distributed compression we suggest that the removal of lithospheric mantle below anatolia led to surface uplift of the cap interior which was followed by surface uplift of the southern cap margin due to crustal thickening as a result of northward subduction of the african plate below central anatolia

paleostress stratigraphy a new technique for analyzing tectonic control on sedimentary basin subsidence the authors propose a new technique paleostress stratigraphic analysis based on the orientation of minor structures particularly striated fault surfaces in the strata of sedimentary basins these structures are interpreted to be the response to local or regional stress field controlling subsidence of tectonically active basins a method is used that allows multiple stress tensors to be extracted from a fault population by extracting the stress tensor from the youngest part of a stratigraphic sequence and by imposing that same tensor on the underlying rocks one can in principle isolate the faults associated with the youngest tectonic event by reiterating this procedure on progressively older units until the fault data are exhausted a chronologic succession of paleostress tensors during basin subsidence emerges the authors paleostress stratigraphy to the relatively undeformed paleogene central basin of spitsbergen and its underlying cretaceous strata and define five major paleostress tensors coeval with the earliest stages of the opening of the norwegian greenland sea a late cretaceous dextral transpressive regime was probably responsible for the major pre tertiary unconformity and possibly initiated development of the central basin during subsequent sedimentation movement reversed yielding well constrained sinistral shearing during early danian time a composite compressional event followed that themore authors interpret as being coeval with the culmination of folding and thrusting west of the central basin the youngest strata studied record a final extensional event that they correlate with rifting of spitsbergen from greenland less

first balanced cross section across the taurides fold thrust belt geological constraints on the subduction history of the antalya slab in southern anatolia eastern mediterranean subduction accommodated africa eurasia convergence since mesozoic time and produced multiple subducted slab fragments in the mantle below anatolia these included the north dipping cyprus and ene dipping antalya slabs which are currently separated by an upper mantle slab gap segmentation of these slabs and associated mantle flow may have contributed to 400 km of post to middle eocene plate convergence was accommodated between the taurides and its beydaglari platform foreland and instead must have been accommodated south of beydaglari the associated southward plate boundary jump separated the antalya slab from the african plate and the cyprus slab the isolated antalya slab was left in an intraplate setting and is probably still attached to beydaglari today we suggest the continental composition of the antalya slab may have prevented its detachment finally the gap between the antalya and cyprus slabs existed since at least eocene time their decoupling likely did not contribute to late neogene central anatolian plateau uplift

rock fragment distributions and regolith evolution in the ouachita mountains arkansas usa rock fragments in the regolith are a persistent property that reflects the combined influences of geologic controls erosion deposition bioturbation and weathering the distribution of rock fragments in regoliths of the ouachita mountains arkansas shows that sandstone fragments are common in all layers even if sandstone is absent in parent material shale and sandstone fragments are produced at the bedrock weathering front but the shale weathers rapidly and intact fragments are rare in the solum sandstone is weathered from ridgetop outcrops and transported downslope some of these fragments are moved downward by faunalturbation and by transport into pits associated with rotting tree stumps upward movement by treethrow is common resulting in a net concentration of rocks near the surface however the highest fragment concentrations are in the lower regolith indicating active production at the weathering front the regolith is a dynamic feature reflecting the influences of vertical and horizontal processes of active weathering at the bedrock interface and of surficial sediment movements the role of trees in redistributing rock fragments suggests that significant regolith mixing occurs over time scales associated with forest vegetation communities and that forest soils have likely been extensively mixed within holocene and historic time copyright 2005 john wiley sons ltd

behavioural and taphonomic patterning at katanda 9 a middle stone age site kivu province zaire katanda 9 an open air middle stone age site contains a dense vertically compressed accumulation of lithic and faunal remains the physical state of these materials indicates prolonged surface exposure before burial and the site shares essential characteristics therefore with many lower and middle stone age and lower and middle palaeolithic occurrences in africa and eurasia an important goal of archaeological research is to determine what if any anthropogenic signature can be extracted from distributional data and this article utilizes katanda 9 to suggest an approach to such spatial analysis it employs a bottom up top down strategy which works in sequential fashion first to determine and control for taphonomic bias and secondly to fit the resultant pattern to models of hominid behaviour it proposes that questions be posed in nested hierarchical fashion and that probabilities of correctness be assessed it concludes that the distribution of materials observed at katanda is most consistent with a nuclear family pattern

pervasive palaeogene remagnetization of the central taurides fold and thrust belt southern turkey and implications for rotations in the isparta angle the turkish anatolide tauride block rifted away from the northern margin of gondwana in the triassic which gave way to the opening of the southern neo tethys by the late palaeocene to eocene it collided with the southern eurasian margin leading to the closure of the northern neo tethys ocean to determine the position of the anatolide tauride block with respect to the african and eurasian margin we carried out a palaeomagnetic study in the central taurides belt which constitutes the eastern limb of the isparta angle the sampled sections comprise carboniferous to palaeocene rocks mainly limestones our data suggest that all sampled rocks are remagnetized during the late palaeocene to eocene phase of folding and thrusting event related to the collision of the anatolide tauride block with eurasia to further test the possibility of remagnetization we use a novel end member modelling approach on 174 acquired isothermal remanent magnetization irm curves we argue that the preferred three end member model confirms the proposed remagnetization of the rocks comparing our data to the post eocene declination pattern in the central tauride belt we conclude that our clockwise rotations are in agreement with data from other studies after combining our results with previously published data from the isparta angle that includes our study area we have reasons to cast doubt on the spatial and temporal extent of an earlier reported early to middle miocene remagnetization event we argue that the earlier reported remagnetized directions from triassic rocks in tilt corrected coordinates from the southwestern antalya nappes western taurides are in good agreement with other studies from the area that show a primary origin of their characteristic remanent magnetization this implies that we document a clockwise rotation for the southwestern antalya nappes since the triassic that is remarkably similar to the post eocene 40 rotation of the central taurides for the previously published results that are clearly remagnetized we argue that their remagnetization has occurred in the palaeocene to eocene

a single cause for uplift of the central and eastern anatolian plateau regional observations suggest that the central anatolian plateau central turkey has risen by 1 km since the tortonian 8 ma while significant crustal shortening did not occur this uplift was preceded by the onset of widespread volcanism 14 9 ma the lithospheric context of these events is however unknown for the eastern anatolian plateau similar events have been attributed to the late stage evolution of the northern neotethys slab resulting in delamination and slab breakoff recent tomographic results indicate that this slab extended beneath both below the eastern and central anatolian plateau just prior to delamination we propose a new lithospheric scenario for the regional evolution in the aegean anatolian near east region that combines a recent compilation of surface geology data with the structure of the upper mantle following the cretaceous eocene closure of the northern neotethys africa eurasia convergence was accommodated by horizontal subduction at a trench that was located south of anatolia like before the closure the northern neotethys slab continued to sink into the deeper mantle beneath the izmir ankara erzincan suture in the early miocene 20 15 ma the northern neotethys slab started to retreat southward to the trench resulting in delamination of the lithospheric mantle the last part of this scenario is testable whether delamination can explain the uplift of both the central and eastern anatolian plateau in the east uplift due to collision of arabia is included we use a coupled thermal flexural model of the lithosphere the model results show that delamination can explain the average present day long wavelength topography of the central anatolian plateau for the eastern anatolian plateau delamination explains half the present day elevation we find that a single delamination event also accounts for the present day surface heat flow and curie point depth in both plateaus we therefore propose to refer to central and east anatolia since the middle miocene as the anatolian plateau

late neogene oroclinal bending in the central taurides a record of terminal eastward subduction in southern turkey abstract the tauride fold thrusts belt formed during s n convergence between africa and eurasia since cretaceous time the western end of the central taurides strike nw se highly obliquely to the overall convergence direction and connect to the ne sw beydaglari lycian nappe flank of the western taurides forming the so called isparta angle in neogene time the western and central taurides and the inner part of the isparta angle became overlain by neogene sedimentary basins including manavgat koprucay and aksu characterized by marine clastics and carbonates the eastern limb of the isparta angle experienced multidirectional miocene to present extension whereas e w shortening affected the marine sedimentary basins in the heart of the isparta angle to quantitatively reconstruct the neogene kinematic evolution of the taurides towards restoring the subduction system accommodating africa eurasia convergence we paleomagnetically assess if and when vertical axis rotations affected the manavgat koprucay and aksu basins in early miocene to pliocene times we show that the northern koprucay basin rotated 20 30 clockwise the manavgat basin underwent 25 35 counterclockwise rotation and the aksu basin underwent no rotation since the early middle miocene it was previously shown that the beydaglari region underwent a post middle miocene 20 counterclockwise rotation these results show that the prominent oroclinal salient geometry of the western taurides thus acquired at least in part since miocene times that the koprucay basin rotated relative to the aksu basin along the aksu thrust and that the beydaglari platform rotated relative to the aksu basin along the bucak thrust which must have both been active until late neogene time this synchronous e w shortening in the heart of the isparta angle and multidirectional extension in its eastern limb may be explained by relative westward retreat of an eastward dipping subducting antalya slab that has previously been imaged by seismic tomography and a benioff zone the neogene bucak thrust west of the aksu basin may represent the most recent surface expression of the antalya subduction zone

pollen evidence of late quaternary vegetation and inferred climate changes in congo a detailed palynological analysis of two cores recovered from a swamp in the southern bateke plateaux congo provides information on the botanical history of this region during the last 24 000 yr b p rich and well diversified pollen counts exhibit changes in the vegetational communities related to hydrological and climatic fluctuations around 24 000 yr b p the occurrence of hydromorphous forest elements gives evidence of a humid phase between 24 000 and around 13 000 yr b p swampy herbaceous communities expanded indicating slightly drier climatic conditions from approximately 13 000 yr b p onward the beginning of a humid episode is reflected by the development of mesophilous forests the decrease of these forests is documented since 3000 yr b p grasslands are found to extend locally whereas elaies guineensis oil palm spreads out indicating both climatic change but also anthropogenic activities

nature of the levantine eastern mediterranean crust from multiple source werner deconvolution of bouguer gravity anomalies the nature of the levantine eastern mediterranean crust has been the subject of controversy for many years revolving around two hypotheses the continental crust hypothesis and the oceanic crust hypothesis the proponents of the first hypothesis suggest that the levantine eastern mediterranean basin is characterized by a thick sedimentary succession overlying thinned crust of continental origin through which a number of aborted mesozoic rifts were etched however multiple source werner deconvolution mswd estimates and other geophysical data integrated with earlier geological and geophysical results provide further support to the second hypothesis oceanic crust and lead to the following conclusions 1 the depth to moho ranges from about 20 km to about 28 km below sea level with an average crustal thickness of about 22 km 2 the large thickness about 10 km of phanerozoic section leaves only about 12 km of thickness for the igneous metamorphic basement complex 3 the northern boundary of the levantine easternmost mediterranean lithosphere is delineated by an arcuate belt of seismic activities along the southern margin of cyprus 4 the formation of the phoenician and latakia basins and the iskenderun bay is probably controlled by the counterclockwise rotation of the lithospheric slices southeast of cyprus 5 the apparent absence of magnetic anomaly lineations reversals is due probably to the thick phanerozoic cover and or the formation of the oceanic crust during a long magnetic chron

tectonic evolution and paleogeography of the kirsehir block and the central anatolian ophiolites turkey in central and western anatolia two continent derived massifs simultaneously underthrusted an oceanic lithosphere in the cretaceous and ended up with very contrasting metamorphic grades high pressure low temperature in the tavsanli zone and the low pressure high temperature in the kirsehir block to assess why we reconstruct the cretaceous paleogeography and plate configuration of central anatolia using structural metamorphic and geochronological constraints and africa europe plate reconstructions we review and provide new 40ar 39ar and u pb ages from central anatolian metamorphic and magmatic rocks and ophiolites and show new paleomagnetic data on the paleo ridge orientation in a central anatolian ophiolite intraoceanic subduction that formed within the neotethys around 100 90 ma along connected n s and e w striking segments was followed by overriding oceanic plate extension already during suprasubduction zone ocean spreading continental subduction started we show that the complex geology of central and southern turkey can at first order be explained by a foreland propagating thrusting of upper crustal nappes derived from a downgoing dominantly continental lithosphere the kirsehir block and tavsanli zone accreted around 85 ma the afyon zone around 65 ma and taurides accretion continued until after the middle eocene we find no argument for late cretaceous subduction initiation within a conceptual inner tauride ocean between the kirsehir block and the afyon zone as widely inferred we propose that the major contrast in metamorphic grade between the kirsehir block and the tavsanli zone primarily results from a major contrast in subduction obliquity and the associated burial rates higher temperature being reached upon higher subduction obliquity

stratigraphical evidence for the depression of the northern margin of the menderes tauride block turkey during the late cretaceous abstract upper cretaceous units on the menderes tauride block show a transition from a passive continental margin to a pelagic basin this transition is related to the emplacement of ophiolitic nappes the pelagic sediments were studied in the aydincik and arslankoy mersin areas in the central tauride region and in the munzur mountains in eastern tauride region in the aydincik area upper cretaceous units consist of upper campanian carbonate breccias with rudist fragments upper campanian lower maastrichtian slope to basinal sediments overlie these carbonate breccias disconformably in the arslankoy area the upper campanian maastrichtian yavca formation consists of globotruncana bearing biomicrites siliciclastic turbidites calciturbidites and debris flows and overlies jurassic cretaceous platform carbonates disconformably the uppermost levels of the liassic cenomanian platform carbonates in the munzur mountains are composed of cenomanian hippurites orbitolina bearing reefal limestones and then turonian campanian globotruncanidae bearing biomicrites the stratigraphic sequence in the menderes tauride block shows that rifting to form a northern neotethyan basin took place in the triassic and gave rise to the inner tauride ocean from jurassic to cenomanian times the northern part of the menderes tauride platform formed a passive continental margin in the late cretaceous the inner tauride ocean is believed to have commenced intra oceanic northward subduction inner tauride oceanic crust derived nappes were emplaced southward onto the menderes tauride block flexural foreland basins in which pelagic sediments were deposited were formed in the taurus mountains related to southward thrusting and the emplacement of the ophiolite nappes

an integrated magnetic and geological study of cataclasite dominated pseudotachylytes in the chiapas massif mexico a snapshot of stress orientation following slip summary the permian age chiapas massif in southeast mexico is locally host to well exposed pseudotachylyte vein networks the veins are black to dark grey and aphanitic in appearance and consist mostly of microbreccia of angular fragments of plagioclase k feldspar biotite and quartz in a cryptocrystalline microscopically irresolvable matrix evidence of melting is present in the form of glass seams dikelets glass clasts included in cataclasite and a distinct chemistry in the pseudotachylite veins pristine glass represents a relatively small volume of the pseudotachylite veins at an exposure along the tablon river valley where the host rock is a medium to coarse grained equigranular quartz diorite individual veins are consistently oriented about 280 are up to 16 mm wide tens of cm apart display a consistent left lateral offset and can be traced for several metres individual pseudotachylyte veins rarely cross each other and they cannot be directly linked to a regional scale fault pseudotachylytes are apparently formed by a combination of crushing comminution and frictional melting but they are cataclasite dominated textures indicate that cataclasis continued after frictional melting had ceased a 40ar 39ar age determination from whole rock chips of one vein shows a climbing ar release spectrum with a date of 114 ma as the most reliable age estimate for ar retention this result is interpreted in the context of pseudotachylyte formation recrystallization and resetting of k bearing minerals for the k ar system in the late early cretaceous ten veins were sampled for palaeomagnetic and magnetic fabric studies with samples collected from both the veins and their host rock remanence data give moderate natural remanent magnetization nrm intensities for both the veins e g nrm mean 6 6 10 3 a m 1 5 5 and host rock mean 7 7 10 3 a m 1 10 8 many samples of host rock yield an ill defined east west directed and shallow magnetization which we interpret as a late permian magnetization based on previous studies of the chiapas massif this magnetization resides in haematite veins as well as immediately adjacent host rock typically have well defined single polarity magnetizations of north northwest declination and moderate positive inclination and these resemble the cretaceous expected field direction the overall mean of the veins is of dec 348 7 and inc 33 6 k 30 5 and 95 12 3 n 6 site means rock magnetic parameters suggest that the remanence in the veins principally resides in low ti pseudo single domain magnetite and maghemite grains but haematite coarse grained magnetite rutile fe cr ni oxides and ilmenite are also present in the veins bulk magnetic susceptibility values range between 0 3 and 1 1 10 3 si volume units and host rock values do not differ significantly from vein values the orientations of the principal susceptibility axes in the host rock and the veins are indistinguishable in both magnetic foliations are near vertical and are essentially parallel to the nearly east west orientation of the veins nonetheless host rock fabrics are predominantly prolate whereas vein fabrics are oblate the mean susceptibility tensors of host rocks and pseudotachylyte are characterized by p t values of 1 041 0 327 and 1 033 0 302 respectively this result suggests that the fabric reflected by magnetic susceptibility anisotropy in the veins was formed under pure shear stress during cooling of the veins the lack of evidence of fabric rotation supports models that associate partial melt with viscous break during fault slip