the neogene recent hatay graben south central turkey graben formation in a setting of oblique extension transtension related to post collisional tectonic escape structural data and a regional tectonic interpretation are given for the ne sw trending hatay graben southern turkey within the collision zone of the african arabian and eurasian anatolian plates regional gps and seismicity data are used to shed light on the recent tectonic development of the hatay graben faults within upper cretaceous to quaternary sediments are categorized as of first second and third order type depending on their scale location and character normal oblique and strike slip faults predominate throughout the area the flanks of the graben are dominated by normal faults mainly striking parallel to the graben that is 045 225 in contrast the graben axis exhibits strike slip faults trending 100 200 together with normal faults striking 040 060 and 150 190 a subset strikes 110 130 similarly orientated normal faults occur throughout upper cretaceous to pliocene sediments whereas strike slip faults are mostly within pliocene sediments near the graben axis stress inversion of slickenline data from mostly pliocene sediments at ten suitable locations all near the graben axis show that 3 directions minimum stress axis extension direction are uniform in the northeast of the graben but orientated at a high angle to the graben margins more variable 3 directions in the southwest may reflect local block rotations during miocene times the arabian and anatolian plates collided forming a foreland basin associated with flexurally controlled normal faulting during the late miocene there was a transition from extension to transtension oblique extension the neotectonic hatay graben formed during the plio quaternary in a transtensional setting in the light of modern and ancient comparisons it is suggested that contemporaneous strain was compartmentalized into large scale normal faults on the graben margins and mainly small scale strike slip faults near the graben axis overall the graben reflects plio quaternary westward tectonic escape from a collision zone towards the east to a pre or syn collisional zone to the west in the mediterranean sea

sedimentary development of the oligocene karsanti basin southern turkey in its regional tectonic setting abstract following late cretaceous ophiolite and melange emplacement within the tauride belt several neogene sedimentary basins of variable size were formed along the southern flank of the taurus continent in southern turkey these include the pozanti and karsanti basins and the regional scale cukurova basin complex extending southwestwards into the cilicia kyrenia basin the karsanti basin is bounded by the regional scale sinistral ecemis fault zone to the west the east anatolian fault zone to the southeast and the negoene adana basin to the south deformed palaeozoic and mesozoic rock units that display an irregular palaeotopography form the basement of the karsanti basin these units are overlain by an allochthonous kizildag melange and by thrust slices of basic ultrabasic ophiolitic rocks farasa ophiolites that were emplaced in this region during the late maastrichtian the karsanti basin was formed during the oligocene above the thrust sheets the karsanti basin disconformably overlies the ophiolitic nappes and is interpreted as a n s trending half graben which was probably most active following the deposition of lacustrine sediments during the late oligocene the main karsanti basin infill is represented by four lithological units 1 alluvial fan deposits a1 2 shallow marine deposits a2 3 lacustrine deposits a3 and 4 fluvial deposits a4 these sediments were deposited during the oligocene prior to the initiation of the main adana basin which formed in a separate intermontane setting the karsanti basin fill is unconformably overlain by early miocene sediments of the neogene adana basin

petrology of the ispendere malatya ophiolite from the southeast anatolia implications for the late mesozoic evolution of the southern neotethyan ocean

spreading structure of the troodos ophiolite cyprus some paleomagnetic constraints it has been suggested that grabens on the northern flank of the troodos ophiolite formed by listric faulting in an oceanic environment and represent axial valleys fossilized by ridge jumping this paleomagnetic survey of the solea graben was carried out to constrain the structural interpretation an analysis was devised which restores both the dikes sampled to vertical and the primary remanent magnetizations to a previously derived structurally corrected remanent magnetization direction typically two solutions for the original dike orientation and the pole and angle of net rotation are obtained for each dike sampled these solutions can be separated if a locally consistent original dike strike is assumed reasons are discussed for the selection of the solution that gives an original northwesterly dike strike results are consistent with a graben rotations are up to 78 at the sites studied rotation vectors are subhorizontal and subparallel to the original dike strike suggestive of an axial process for the development of the structure however on the basis of field observations an alternative mode of origin is proposed invoking ephemeral extreme upper crustal extension by listric faulting on the west flank of an intermediate to fast spreading axis the grabens being formed by antithetic faulting

spreading structure of the troodos ophiolite cyprus orientations of dikes within the sheeted dike complex of the troodos ophiolite reveal primary spreading structure produced at a complex ridge transform intersection three structural grabens are defined by listric and planar normal faults and rotated dikes that dip symmetrically toward graben axes faults flatten at depth into a detachment within the upper parts of the plutonic complex large exhalative massive sulfide deposits occur within the pillow sections of two of the grabens and appear to be associated with underlying altered and mineralized normal fault zones that channeled hydrothermal fluids we suggest that the grabens are fossil axial valleys produced by successive eastward jumps of an approximately north trending present coordinates slow spreading ridge crest a simple model for ridge migration indicates eastward jumps of 8 13 km changes in ridge orientation are suggested by changes in trends of dikes and graben axes comparison of the pattern of dikes near the arakapas fault zone with the structure of active ridge transform intersections suggests that the fault is a right offset sinistral transform in contrast to earlier models in which a ridge to the west of the exposed troodos complex was proposed

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

role of the palaeogene recent sinistral el kabir lineament and the associated transtensional neogene recent el kabir basin northern syria in distributed deformation between the african and eurasian plates

sedimentology of the nw margin of the arabian plate and the sw ne trending nahr el kabir half graben in northern syria during the latest cretaceous and cenozoic abstract the late cretaceous maastrichtian to recent sedimentary record of nw syria documents the palaeoenvironments and regional tectonic setting during a time when the neotethys ocean to the north was closing culminating in regional collision by mid miocene time this detailed sedimentological study builds on a biostratigraphical framework established by russian workers during the mid maastrichtian the baer bassit ophiolite and related melange were emplaced southwards from neotethys onto the northern margin of the arabian african plate resulting in flexurally controlled deepening to the south after short lived emergence and erosion of emplaced units a renewed marine transgression ushered in shelf depth open marine carbonate deposition during the palaeocene early eocene this deposition was characterized by generally westward channelised mass flow from shallow marine carbonate banks to the east probably influenced by storm conditions flexurally controlled uplift and erosion took place during late eocene oligocene related to final closure of neotethys shelf depth carbonate deposition resumed during the aquitanian early miocene influenced by tectonic subsidence during the burdigalian a sw ne trending narrow up to 15 km wide linear 60 km long basin developed in the vicinity of the present day nahr el kabir river valley this basin is attributed to extension or transtension along the nahr el kabir fault this important lineament runs onshore from the southern limit of the cyprus arc tartous ridge through nw syria it is then offset by the dead sea transform in the ghab valley before merging with the south anatolian transform fault in turkey further northeast the basin in nw syria developed into the asymmetrical nahr el kabir half graben during the mid miocene with uplift of the northern margin and rapid fault controlled subsidence of the basin axis large volumes of terrigenous clastic and shallow marine bioclastic material were redeposited from the flanks into the axis of the basin mainly as gravity flows shelf depth carbonate deposition characterized both basin flanks especially the southern margin regression culminated in gypsum and marl precipitation in tectonically active local depocentres during the messinian salinity crisis pliocene re flooding established argillaceous shelf deposition within and around the pre existing basin coupled with local alkaline basalt volcanism and faulting in the southern coastal area regional regression gave rise to prominently channelised bioclastic sedimentation by the late pliocene the quaternary was marked by regional uplift and terracing influenced by glacio eustatic sea level change climatic change and further movement along the nahr el kabir fault the dominant control on basin development was thus local tectonics related to movements along the el kabir lineament and its interaction with regional scale tectonic events while eustasy played a subsidiary modifying role

tectonic development of the eastern mediterranean region the eastern mediterranean region is a classic area for the study of tectonic processes and settings related to the development of the tethyan orogenic belt the present set of research and synthesis papers by earth scientist from countries in this region and others provides an up to date interdisciplinary overview of the tectonic development of the eastern mediterrenean region from precambrian to recent key topics include continental rifting ophiolite genesis and emplacement continental collision extensional tectonics crustal exhumation and intraplate deformation e g active faulting alternative tectonic reconstructions of the tethyan orogen are presented and discussed with important implications for other regions of the world the book will be an essential source of information and interpretation for academic researchers geologists and geophysicists advanced undergraduates and also for industry professionals including those concerned with hydrocarbons minerals and geological hazards e g earthquakes

active tectonics of the north and central aegean sea summary in this paper we examine the connection between the westward motion of turkey relative to europe and the extension in and around the aegean sea the principal new data available since the last attempt to synthesize the tectonics of this region by mckenzie 1978 are much improved focal mechanisms of earthquakes constrained by p and sh body wave modelling as well as by first motions these mechanisms show that the faulting in the western part of the aegean region is mostly extensional in nature on normal faults with a nw to wnw strike and with slip vectors directed nnw to nne there is evidence from palaeomagnetism that this western region rotates clockwise relative to stable europe in the central and eastern aegean and in nw turkey distributed right lateral strike slip is more prevalent on faults trending ne to ene and with slip vectors directed ne palaeomagnetic data in this eastern region is more ambiguous but consistent with very small or no rotations in the northern part and possibly anticlockwise rotations relative to europe in the south the strike slip faulting that enters the central aegean from the east appears to end abruptly in the sw against the nw trending normal faults of greece the kinematics of the deformation is controlled by three factors the westward motion of turkey relative to europe the continental collision between nw greece albania and the apulia adriatic platform in the west and the presence of the hellenic subduction zone to the south as the right lateral slip on the north anatolian fault enters the aegean region it splays out becoming distributed on several parallel faults the continental shortening in nw greece and albania does not allow the rotation of the western margin of the region to be rapid enough to accommodate this distributed e w right lateral shear and thus leads to e w shortening in the northern aegean which is compensated by n s extension as the southern aegean margin can move easily over the hellenic subduction zone the dynamics of the system once initiated is self sustaining being driven by the high topography in eastern turkey and by the roll back of the subducted slab beneath the southern aegean the geometry of the deformation resembles the behaviour of a system of broken slats attached to margins that rotate in spite of its extreme simplicity a simple model of such broken slats is able to reproduce quantitatively most of the features of the instantaneous velocity field in the aegean region including the slip vectors and nature of the faulting in the eastern and western parts the senses and approximate rates of rotation the overall extensional velocity across the aegean and the distribution of strain rates as seen in the seismicity and topography or bathymetry and using geodetic measurements as part of this study we re examined the relation between the surface faulting and the focal parameters determined seismologically for the three large 1981 gulf of corinth earthquakes and reassessed the evidence for associating particular earthquakes in the sequence with observed surface faulting an important result is that in one of the events there is a resolvable discrepancy between the slip vector measured at the surface and that determined from the seismic body waves

the east anatolian fault an oblique collisional belt abstract the tectonic setting for the area around the arabia africa anatolia triple junction is described from combined landsat spot satellite image analysis and field observations since the late miocene the motion along the east anatolian fault generated major structures corresponding to shortening with a sinistral slip component the 150 km wide area of the triple junction is highly deformed by folding and thrusting distributed mainly on the border of the anatolian block in addition kinematic reconstructions confirm that the arabia anatolia relative motion is both sinistral and convergent the sinistral strike slip faults of the east anatolian fault zone are of second order and local consequences of the n s arabia anatolia collision

decimeter resolution 3d seismic volume in shallow water a case study in small object detection the 3d chirp subbottom profiler provides high resolution imaging of coastal and inshore seabed and subseabed structure by combining the known highly repeatable source waveformofchirpprofilerswiththecoherentprocessingand interpretation afforded by true 3d seismic volumes comprising 60 hydrophone groups arranged around a maltese cross of four chirp transducers 3d chirp permits acquisition of a true 3d volume with a horizontal resolution of 12 5 cm providing an excellent base for shallow water engineering archaeological military and geologic studies here we presentresultsfromsurveyinganatidalbasinonthesouthern coastofenglandtomapbedrockprotrusionsandthesizeand distributionofburiedobjects thestudyareaof150250 m provided a series of unique challenges including a large number of discrete objects ranging from tens of centimeters toseveralmetersinsize buriedinathinveneer0 5to1 5 m of unconsolidated silt overlaying a flat bedrock surface that showed high acoustic contrast and short wavelength roughness by comparing comprehensive postsurvey dredging of the entire site with a prestack time migrated 3d volume it is possibletoconfirma100 detectionrateforalldiscreteburied objects larger than 0 300 30 m in an illuminated area although one acoustic anomaly could not be accounted for in thedredgingresults

provenance and magmatic tectonic setting of campanian aged volcaniclastic sandstones of the kannaviou formation in western cyprus evidence for a south neotethyan continental margin volcanic arc abstract regionally developed late cretaceous subduction related magmatism in the eastern mediterranean records progressive closure of the southern neotethys in western cyprus the late cretaceous c 90 ma troodos ophiolite is depositionally overlain by volcaniclastic sandstones up to 750 m thick that are dominated by redeposited pyroclastic fallout interbedded with both non calcareous and calcareous radiolarian bearing mudstones the sands were mainly deposited by channelised mass flow processes and to a lesser extent by turbidity currents in a deep water forearc basin the succession was folded and locally thrust deformed related to latest cretaceous emplacement of adjacent mesozoic continental margin and oceanic units mamonia complex sims u pb analysis of euhedral to subhedral magmatic zircon crystals yielded a weighted mean 206pb 238u age of 80 1 1 1 ma campanian sandstone petrography including compositional framework q12f21l67 suggests sediment supply from a volcanic arc subordinate continentally derived detritus suggests a continental margin arc setting for the mafic to felsic fallout ash sims analysis of little altered volcanic glass indicates high th nb and th la ratios that suggest the involvement of continental crust and or subducted terrigenous sediments in magma genesis whole rock chondrite normalised ree patterns have comparable trends to modern and ancient forearc basin volcaniclastic sands and sandstones e g northwest pacific region trace element chemistry although scattered towards the continental island arc fields on some geochemical diagrams e g th sc zr mainly suggests an oceanic island arc source for the kannaviou formation sandstones with variable enrichments in v cr ni sc depletion in nb ta and relatively low trace element ratios e g la co th co la sc th sc an explanation for this apparent discrepancy is that the volcaniclastic sandstones were derived from a relatively primitive arc constructed on previously depleted rifted thinned neotethyan continental crust the inferred continental margin arc developed during early stage northward subduction of the southern neotethys beneath a tauride microcontinent to the north large volumes of volcanic ash were derived from continental margin arc volcanism probably in the vicinity of the kyrenia range in northern cyprus

structure of the kizildag ophiolite a slow spread cretaceous ridge segment north of the arabian promontory the cretaceous kizildag ophiolite in southern turkey is part of the neotethyan ophiolite belt around the arabian promontory and consists of two structurally distinct massifs that are separated by a northwest striking high angle oblique fault this fault is interpreted as an accommodation zone that permitted differential movements between the adjacent crustal blocks during the evolution of the ophiolite the main massif to the west includes an antiformal peridotite core adjoined on the southeast by the normal fault bounded plutonic sequence and sheeted dike complex which collectively form a structural graben reminiscent of slow spreading ridge axes the inferred spreading axis and axis parallel fault contacts are intersected and offset at right angles by tear faults that are geometrically and kinematically analogous to transfer faults in modern oceanic lithosphere at slow spreading ridge environments the secondary massif to the east consists mainly of serpentinized peridotites directly overlain along tectonic and or intrusive contacts by lava flows rotated dike blocks and plutonic rocks and can be interpreted as a segment of oceanic lithosphere evolved at and near the accommodation zone the general structure of the ophiolite suggests its evolution via magmatic accretion and subsequent tectonic extension along a low angle shear zone at a slow spreading ridge environment

structure and paleostresses in the gilboa region western margins of the central dead sea rift abstract the relationships between tectonic paleostresses and major fault systems are analyzed for the gilboa region the gilboa is a folded block on the western margins of the dead sea transform which has been deformed and uplifted at least since the miocene the tectonic paleostresses in the gilboa were determined by inversion of slip striations along small faults measured in the field and from the trends of basaltic dikes one state of stress dominated the gilboa region since the miocene the principal axes of the calculated stress tensor are 1 at 0 122 2 vertical and 3 at 0 032 this stress fits well with the trends of the syrian arc folds in the gilboa and its is compatible with the observed normal slip along the gilboa fault however this stress is incompatible with the either left lateral slip or normal faulting along the dead sea system possible mechanisms to resolve this incompatibility are discussed

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

origin and emplacement of the late cretaceous baer bassit ophiolite and its metamorphic sole in nw syria abstract the baer bassit ophiolite of inferred late cretaceous age was emplaced from the south tethys ocean onto the leading edge of the arabian continental margin in latest cretaceous maastrichtian time dismembered sequences in different thrust sheets can be correlated to produce a complete ophiolite sequence with a metamorphic sole at the base overlain in turn by upper mantle tectonite rare cumulates massive and layered gabbros localized high level plagiogranites sheeted dykes basic extrusives and minor fe mn sediments umbers the restored ophiolite sequence is similar to that of the more intact troodos and hatay ophiolites but dissimilar to oman the baer bassit extrusives are magnesian and strongly depleted comparable to primitive island arc tholeiites and some boninitic lavas which favours a subduction related origin a well developed metamorphic sole is divisible into high grade amphibolite facies assemblages in the north and lower grade greenschist facies assemblages in the centre of the region but no complete inverted metamorphic gradient is preserved in any one local area the protoliths of both the high grade amphibolites and lower grade rocks greenschists are interpreted as alkali basalts and pelagic sediments including chert similar to the volcanic rocks in an underlying unmetamorphosed melange the metamorphic fabrics progressively evolved from ductile to brittle during tectonic transport towards the southeast most of the metamorphic fabrics evolved during intense shearing but some of the alkaline metabasites apparently were metamorphosed under relatively static strain conditions the apparent absence of preserved inverted metamorphic gradients in baer bassit may reflect a complex deformation history during emplacement alternatively differing p t conditions may be recorded at different depths at the base of the over riding mantle wedge during emplacement the front of the ophiolite was tectonically imbricated and overthrust by the main ultramafic slab bassit massif the thickest massif baer is underlain by a high grade metamorphic sole and was internally shortened but without thrust duplication of the entire ophiolite sequence following covering by late maastrichtian palaeogene marine calcareous sediments the area was subjected to mid tertiary regional folding this was followed by neogene dominantly left lateral strike slip deformation along the african eurasian plate boundary extending from south of cyprus to the dead sea transform fault as a result the originally emplaced thrust sheets were dissected into three main composite units baer bassit and the southeastern units separated by strongly faulted and sheared ophiolitic blocks and unmetamorphosed volcanic sedimentary melange

paleomagnetic reconstruction of the cenozoic evolution of the eastern mediterranean abstract a total of 113 paleomagnetic sites were sampled along an anatolian s n transect from the arabian platform the hatay region the eastern taurides the kirsehir block the sivas basin and the eastern pontides reliable characteristic remanent paleomagnetic directions were retrieved from 37 of these sites spanning in time from paleocene to miocene in a general way declinations are westerly deviated and inclinations are shallower than the geocentered dipole value at the present latitudes when combined with previously published results these data indicate that a large scale counterclockwise rotation of anatolia of some 25 has occurred since the miocene assuming that the pole of rotation of anatolia with respect to europe has remained constant in time at the location given by macclusky et al j geophys res 105 2000 5695 on the basis of the geodetic data this rotation implies that a large westward displacement 500 km at the average latitude of 40 has taken place assuming that the rotation was initiated by the arabia europe collision about 12 ma ago this corresponds to an average displacement of about 40 mm year together with previous results from the western part of the aegean arc these results indicate that the main trends of the cenozoic evolution of the eastern mediterranean appear to consist of two post early miocene rotations of opposite senses a clockwise rotation of the western part of the aegean tectonophysics 146 1988 183 around a pole situated in northern albania and a counterclockwise rotation around the pole given by mcclusky et al j geophys res 105 2000 5695 comparison with gps data suggest that both rotations are still active today

analogue modelling of fault reactivation tectonic inversion and oblique remobilisation of grabens abstract analogue models of sand above a silicone layer were examined to determine the effects of normal fault reactivation models were first subjected to extension which lead to the formation of two linear grabens each model was then subjected to a second phase deformation either parallel or oblique to the previous initial extension and either extensional or contractional the influence of sedimentation has been evaluated using experiments with and without sedimentation in cases of oblique secondary deformation all newly formed faults were parallel to the older grabens thus they were oblique to the direction of the principal stress directions during the second deformation phase in experiments without sedimentation all older faults were reactivated whereas in experiments with sedimentation some of the older faults were not reactivated in the case of an oblique compressional secondary deformation phase with post rift sedimentation strain partitioning occurred between reactivated older normal faults and new reverse faults 2 was vertical on reactivated normal fault planes whereas 3 was vertical on reverse fault planes in the case of oblique compressional secondary deformation phase without post rift sedimentation no strain partitioning was observed in this model 3 was vertical on every fault plane it is therefore concluded that sedimentation within grabens induces a variation of stress orientation and strain partitioning

late cenozoic stress evolution along the karasu valley se turkey abstract this study defines the mio pliocene to present day stress regime acting at the northeastern corner of the eastern mediterranean region along the karasu valley i e the amanos range taking in the antakya osmaniye and kahramanmaras provinces the inversion slip vectors measured on fault planes and chronologies between striations indicate that the stress regime varied from transpressional initially to transtensional having consistent nw and ne trending hmax 1 and hmin 3 axes respectively there are significantly different mean stress ratio rm values however the older mean stress state is characterized by n151 11 e trending 1 and n59 12 e trending 3 axes and by a mean arithmetic rm value of 0 76 indicating that the regional stress regime is transpressional the younger stress regime is characterized by n154 8 e trending 1 and n243 8 e trending 3 axes and by a mean arithmetic rm value of 0 17 indicating a transtensional character for this regional stress regime the low r values of the stress deviators related to the recent stress state reflect normal component slips the earthquake focal mechanism inversions confirm that the younger stress regime continues into the recent the inversion identifies a transtensional stress regime representing strike slip and an extensional stress state with a consistent ne trending hmin 3 axis these stress states are characterized by n66 e and n249 e trending 3 axes respectively both significant regional stress regimes induce left lateral displacement along the southern part of the east anatolian fault eaf or amanos fault the temporal change probably in quaternary time within the regional stress regime from transpression to transtension resulted from the coeval influences of subduction processes in the west southwest i e along the cyprus arc continental collision in the east and westward escape of the anatolian block

regularity patterns and zones of seismic potential for future large earthquakes in the mediterranean region large earthquakes m 6 75 in the mediterranean region from iran to the azores were investigated with the aim of establishing possible regularity patterns in their occurrence and identifying regions of seismic potential the earthquakes investigated occurred along the complex boundaries in the zone of convergence between the eurasian and african arabian plates for both historic and modern times the magnitudes of some larger earthquakes were reconsidered the relatively complete record over a long period of time together with space time magnitude diagrams suggest the following patterns 1 1 an alteration of active and quiet seismic periods along the whole region 2 2 a cyclic eastward migration in the hellenic arc 3 3 average recurrence times of 100 150 yr for stress accumulation greece italy and 4 4 the triggering of the largest events at the eastern end of the north anatolian fault by stress transfer resulting from indentation of the arabian plate this has also been used as a hypothesis to explain the main features of space time earthquake evolution before the large 1939 earthquake finally using the observed regularities and some additional criteria e g the time elapsed since the last occurrence dimensions of rupture zones the following zones have been specially investigated with respect to their seismic potential 1 1 the eastern part of the north anatolian fault zone 2 2 northern marmara region 3 3 northeast of crete 4 4 south peloponnesus 5 5 southeastern sicily and central italy 6 6 west of gibraltar

the structural relationship between the east anatolian and dead sea fault zones in southeastern turkey abstract the complex structural relationship between the east anatolian and dead sea fault zones is examined mostly based on field observations in southeastern turkey where the two fault zones are close together several faults previously poorly documented can be traced to connect either to the east anatolian fault zone or to the dead sea fault zone one of these faults connects the dead sea fault zone to the east to the amanos fault to the west the amanos fault a n trending normal fault is a part of the east anatolian fault zone since it is apparently a left step fault between the main and southern strands of the east anatolian fault zone the dead sea fault zone also is connected to the east anatolian fault zone northeast of the town of narli and or northeast of the hazar lake therefore we suggest that the two fault zones can be considered as one broad fault system in southeastern turkey although they are well recognized as two different fault zones this fault system is responsible for several complex neogene structural features of the western part of the southeastern turkey one of these is the hatay graben which can be divided into southern central and northern parts the graben contains down to the west normal faults in its southern part the central part of the graben is a divergent strike slip basin and the northern part is a half graben

quaternary stress regime change in the hatay region se turkey in this study we determine the plio quaternary to present day stress regime acting in the hatay region located at the northeastern corner of the east mediterranean region the modern state of stress is obtained from inversion of focal mechanism solutions of shallow earthquakes this inversion identifies a dominantly extensional stress regime with a ne trending h m i n 3 axis at the present day the stress regime determined from inversion of slip vectors measured on fault planes confirms that this regime is extensional in the studied area both the kinematics and chronologies of fault slip vectors show that the stress state changed from an earlier strike slip regime to a younger extensional stress regime with a consistent ne trending h m i n 3 axis the change from strike slip to extensional stress regimes probably occurred during the quaternary regionally both stress regimes induce sinistral displacement on the east anatolian fault and dead sea fault systems the north anatolian fault naf is a dextral strike slip fault which runs about 1400 km from east to west and has been active since collision between the eurasian and arabian plates together with the sinistral east anatolian fault the naf intracontinental deformation zone contributes to the westward extrusion of anatolia as a consequence of northward drift of arabia consequently the late cenozoic stress regimes acting in the hatay region result from the coeval influence of forces due to 1 the subduction processes in the west and southwest 2 the continental collision in the east and 3 the westward escape of the anatolian block however the timing of the temporal stress transition suggests that the quaternary stress regime change resulted from subduction processes with the extensional stress regime in the hatay region being mainly attributable to roll back of the mediterranean subducted slab along the cyprus arc

neotethyan intraoceanic microplate rotation and variations in spreading axis orientation palaeomagnetic evidence from the hatay ophiolite southern turkey abstract insights into tectonic processes operating in ancient ocean basins are provided by analyses of fragments of oceanic lithosphere preserved as ophiolites during collisional orogenesis here we present a palaeomagnetic analysis of the upper cretaceous hatay kizil dag ophiolite of turkey that provides evidence for intraoceanic microplate rotation and variations in ridge axis orientation in a neotethyan ocean basin magnetizations at 46 sites are shown to be pre deformational in origin and rotated from the relevant reference direction a net tectonic rotation approach to the analysis of the data provides information on permissible net rotation poles and angles and allows uncertainties in input vectors to be considered results demonstrate that all levels of the ophiolite have been rotated anticlockwise by angles in excess of 90 around steeply inclined axes the hatay ophiolite formed in the same supra subduction zone spreading system as the troodos ophiolite cyprus which is known to have rotated 90 anticlockwise in an intraoceanic setting in the late cretaceous to early eocene by considering our results in the context of the known timing of the troodos rotation we infer that 50 60 of rotation of the hatay ophiolite took place as part of an areally extensive troodos microplate this phase of rotation was triggered by initial impingement of the arabian continental margin with the neotethyan subduction trench consistent with models for modern day oceanic microplate rotation in complex convergent plate boundaries the hatay ophiolite then became detached from the actively rotating microplate and was emplaced onto the arabian margin in the maastrichtian undergoing a further 30 40 of anticlockwise rotation during thrusting back stripping of rotations allows correction of the hatay sheeted dykes to their initial orientations the restored dyke trend of 020 differs from that inferred previously for the troodos sheeted dyke complex demonstrating a primary variation in orientation of neotethyan spreading axes such variability is commonly observed in modern spreading systems in marginal basins these may act as analogues for the supra subduction zone spreading inferred for many ophiolites

extreme tectonic rotations within an eastern mediterranean ophiolite baer bassit syria palaeomagnetic results from 27 sites at five localities within the dismembered bae r bassit ophiolite of northern syria are presented the ophiolite forms part of a series of thrust sheets emplaced over mesozoic carbonates of the arabian platform in the middle maastrichtian a positive inclination only area wide tilt test applied to four locality mean remanences and positive fold and reversal tests from palaeohorizontal units pillow lavas lava flows within one of these localities indicate that the ophiolite preserves pre deformation magnetisations variable directions of remanence between localities demonstrate that the ophiolite has experienced extreme relative anticlockwise rotations on a kilometric scale within the most extensively sampled ophiolite massif bassit sheet there is a progressive increase in rotation from north to south the southernmost units at the lowest structural level in the imbricate thrust stack record the highest rotation exceeding 200 although tectonic rotation during imbricate thrusting has been reported in a number of orogenic belts the pattern of rotations in the bassit sheet is difficult to explain by differential thrust sheet rotation instead regional comparisons with the hatay ophiolite of southern turkey and the troodos ophiolite of cyprus suggest that a significant component of rotation may be ascribed to intraoceanic deformation of a coherent region of oceanic crust within the southern neotethyan basin prior to ophiolite emplacement the partially rotated bae r bassit ophiolite was then emplaced and structurally dismembered by thrust faulting during the late tertiary the ophiolitic units were further rotated during the initiation and development of a major sinistral strike slip fault zone linking the cyprus subduction zone to the dead sea transform system the extreme rotations observed in the study are therefore of composite origin and reflect the complex development of structural fabrics within the ophiolite 2002 elsevier science b v all rights reserved

paleostress analyses in nw syria constraints on the cenozoic evolution of the northwestern margin of the arabian plate abstract fault analysis between the dead sea transform and the euphrates region in northern syria shows two main directions of compression connected to the recent evolution of the northwestern wedge of the arabian plate e w open folds due to n s compression gently deform the cretaceous to tortonian successions of the aleppo plateau and the eastern termination of the palmyrides west of the euphrates conjugate sets of strike slip and normal faults pre as well as post dating folding occur in the plateau and are still consistent with the same stress field n s normal faults cross recent deposits and control quaternary volcanoes along the euphrates suggesting the persistence of this stress regime a nw se compression related to the syrian segment of the dead sea transform dst was detected in the western part of the study area the activation of large n s left lateral strike slip and wnw ese right lateral faults follows in time the growth of in line folds and thrusts permutation of the 1 and 2 stress axes is related to activation of nw se normal faults which generally accompany strike slip faults and post date e w folds within the plateau recent e w extension in the euphrates region is consistent with a horizontal n s maximum direction of compression and seems to be partially coeval with the stress regime induced by the dst this stress pattern can be explained by the superposition of the northward push of the arabian plate to the n s left lateral shearing along the dst

intermediate chromitite in kizildag ophiolite se turkey formed during subduction initiation in neo tethys abstract chromitites in the kizildag ophiolite mostly occur in the mantle harzburgites and some of them in crustal cumulate dunites olivine in both the dunites and chromitites is highly magnesian fo 90 5 92 8 and 90 2 96 1 respectively while the coexisting chromite varies widely in composition cr 52 9 68 6 and 57 1 76 2 respectively placing it between high al and high cr varieties concentrations of ni v and ga in the chromite ni 741 1310 ppm v 521 1227 ppm ga 20 51 ppm are also highly variable straddling the range of high al and high cr chromite olivine in the dunites and chromitites has a large range of li concentrations 0 27 2 47 ppm and 7li values 7 20 29 90 based on the calculated al2o3 12 1 17 2 wt contents feo mgo values 0 92 1 57 and trace element concentrations of the parental magmas of the dunites and chromitites it is suggested that they are transitional between morb and boninitic melts and should have been derived by mixing of geochemically and spatially distinct magmas generated by partial melting of different sources the li isotopic compositions of olivine from the dunites and chromitites except kz14 38 and kz15 38 are neither controlled by diffusion nor fractional crystallization and thus may be intrinsic features of their parental melts the range of 7li values of olivine in the dunites and chromitites is analogous to that of arc lavas and marine sediments indicating that the chromitites record various degrees of melt penetration the wide range of li isotopic variations in olivine and chemistry in chromite from the kizildag chromitites suggest that the parental melts were originated in a proto forearc mantle during subduction initiation

short term variations of deep water masses in drake passage revealed by a multiparametric analysis of the ant xxiii 3 bottle data short term variations of deep water masses in drake passage revealed by a multiparametric analysis of the ant xxiii 3 bottle data j sudre v garcon c provost n sennechael o huhn and m lacombe doi 10 1016 j dsr2 2011 01 005 a multiparametric analysis is applied on the ant xxiii 3 bottle data to determine the spreading and mixing of water masses across drake passage during january february 2006 focusing our interest on the flow of the deep water masses mixing proportions are quantified along both the southward and northward journeys between the tip of south america and the antarctic peninsula the method is sensitive enough to detect a marked variability in the flow pathways of the circumpolar deep water the southeast pacific deep water spdw and the weddell sea deep water at the intersection of the shackleton fracture zone sfz and the west scotia ridge wsr between the southward and northward journeys indeed the presence of a sharp meander of the southern branch of the polar front pfs together with the displacement of the northern branch of the southern antarctic circumpolar current front saccfn above the complex bathymetric structure of the wsr induced a strong perturbation in the deep flow field during the southward journey the height of the sfz crests clearly sets the lower limit of the spdw in the ona basin an enhanced 3 he signature is confined to the north of the polar front between 55 5 s and 56 5 s in the 1500 2200 m depth range it clearly indicates the signature of the core of the southeast pacific deep slope water the entry pathway in the acc of the spdsw during ant xxiii 3 was farther to the south off the continental slope of south america than it was during the woce a21 expedition in 1990 probably due to the sharp changes in the slope orientation at the extreme tip of the south america

spreading induced faulting and fracturing of oceanic crust examples from the sheeted dyke complex of the troodos ophiolite cyprus

neotectonic deformation linking the east anatolian and karatas osmaniye intracontinental transform fault zones in the gulf of iskenderun southern turkey deduced from paleomagnetic study of the ceyhan osmaniye volcanics 1 left lateral strike slip along the dead sea fault zone dsfz between the african and arabian plates is partitioned into a complex set of motions at its northern extension where arabia impinges into the anatolian collage as a result the nature of the contemporary link between the east anatolian and dead sea transforms is unclear to quantify strike slip motion expressed as tectonic rotations along the inferred southwest continuation of the east anatolian fault zone eafz we have investigated the paleomagnetism of young 1 ma volcanics in the adana basin gulf of iskenderun region comprising the ceyhan osmaniye volcanic suite this volcanism is sited close to the intersection between the sinistral karatas osmaniye fault zone kofz and the neotethyian suture nine sites from a basaltic lava field in the vicinity of osmaniye are entirely of normal polarity and in the context of their very young morphologies are assigned to the brunhes chron declinations are mostly clockwise from the present field this age assignment identifies rapid recent 780 ka uplift at the head of the gulf of iskenderun and is linked to a diversion of the ceyhan river drainage and ongoing regional tilting eight sites yield a mean declination of 11 3 10 implying clockwise block rotation on riedel type fractures on the northwest side of the kofz seven lavas sites from a volcanic succession near botas at the southwestern extension of the volcanic lineament are of reversed polarity and rotated counterclockwise by 43 7 with respect to the present field polarity k ar and morphological evidence indicate an assignment toward the latter part of the matuyama chron and identify rapid neogene block rotation of a flake within the kofz an inferred maximum slip rate of 0 6 cm year on this fault zone is comparable with lower estimates of slip on the eafz and suggests that most strike slip on the dsfz is now being partitioned to the west of the gulf of iskenderun on a developing strike slip zone linking with the cyprus arc

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

constraints on arabian plate motion and extensional history of the red sea analysis of the geologic and geophysical data from the western and northern margin of the arabian plate combined with data from the red sea gulf of aden leads to an interpretation of arabian plate motion that supports an episodic extensional history in the red sea and gulf of aden phase 1 extension began in medial to late eocene and was caused by the nw propagation of the reoriented central indian ridge spreading center it stretched and thinned continental crust along numerous wrench and normal faults that reactivated preexisting structures first phase extension stopped when the arabian plate terminally sutured to eurasia in the medial miocene and halted northward movement of arabia relative to africa the combined african arabian plates moved north more slowly constricting and thickening continental crust in the bitlis zagros sutures while the red sea remained technically quiescent and accumulated salt by the early pliocene continued northward movement was accommodated by lateral extrusion of large continental wedges north of the bitlis zagros sutures this allowed arabia to move northward faster than africa and reopen the red sea where phase 2 extension was expressed by seafloor spreading extension within the red sea gulf of aden rift system has been controlled by the interactions and effects of two factors 1 convergent processes between the north margin of the arabian plate and the eurasian plate to the north and 2 northwest propagation of extension associated with the medial eocene reorganization of the central indian spreading center

tectonic evolution of the troodos ophiolite within the tethyan framework a new tectonic model reconciles conflicting structural and geochemical evidence for the origin of the troodos ophiolite a well preserved remnant of neotethyan oceanic crust grabens and normal faults within the sheeted dike complex and the extrusive sequence of the troodos ophiolite resemble those of oceanic spreading centers diverse intrusive and tectonic contact relationships between the sheeted dike complex and the underlying plutonic sequence indicate multiple and episodic intrusion of magma and along and across strike variation in volcanic and tectonic activity during development of oceanic crust coupled with the existence of the arakapas transform fault to the south these structural and intrusive relationships suggest origin at an intersection between a spreading center and a transform fault the arclike chemistry of sheeted dikes and related extrusive rocks and the inferred highly depleted and hydrous nature of the mantle source of the late stage intrusive and extrusive rocks argue however for generation of part of the ophiolite within a subduction zone environment regional reconstructions suggest that the mesozoic neotethys may have evolved as a marginal basin both to the afro arabian continent and the paleotethyan ocean over an active or recently active south dipping subduction zone the troodos ophiolite and other eastern mediterranean ophiolites whose magma compositions were affected by the subducted paleotethyan slab may have formed along east west trending spreading centers separated by north south trending transform faults within this marginal basin a rapid change in relative plate motion in late cretaceous time between eurasia and afro arabia created a regional compressive regime that may have resulted in plate boundary reorganizations within the neotethyan realm and in initiation of north dipping subduction zone s beneath the troodos and other ophiolites in the region the apparent forearc setting of the troodos ophiolite is a consequence of this intraoceanic displacement after its formation and thus is unrelated to its generation

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

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

structure and tectonics of the eastern cyprean arc abstract the geometry and nature of the eastern segment of the cyprean arc are little understood several hypotheses have been put forward to explain the tectonic situation there recent marine geophysical data for this region mapped several deep and shallow structural elements the most prominent element is a ridge the latakia ridge which extends from the syrian coast near latakia south westward to meet with an east west trending bathymetric escarpment east of the hecateus ridge the new seismic profiles suggest that these two elements mark the present plate boundary along the eastern cyprean arc the latakia ridge is a young and still active feature it was formed by southward migration of the plate boundary the ridge probably originated as a large thrust sheet which later when the convergence direction was changed became a zone of wrench faulting the ridge is still forming today and serves as a dam to the sediments north of it the wrench faulting activity is more pronounced in the eastern segment of the ridge

successive structural events in the hatay ophiolite of southeast turkey distinguishing oceanic emplacement and post emplacement phases of faulting abstract new structural data are presented and interpreted for the cretaceous hatay ophiolite which was emplaced onto the arabian continental margin during latest cretaceous maastrichtian time although lacking a preserved metamorphic sole a thick serpentinitic basal shear zone provides evidence of emplacement kinematics whilst structures developed in an extensive cenozoic sedimentary cover help to constrain the nature of post emplacement deformation combining field structural measurements with palaeostress analyses enables several discrete structural events to be recognised of which three appear to pre date the cenozoic sedimentary cover the earliest event involved extension parallel to the ophiolitic sheeted dyke complex and relates to oceanic spreading whereas the second and the third events relate to compression and strike slip during intra oceanic displacement or emplacement of the ophiolite onto the arabian continental margin some structures at the base of or within the ophiolite that were previously attributed to sea floor spreading processes e g oceanic detachment faults are more likely to have formed during subsequent ophiolite displacement emplacement and post emplacement formation of the regional hatay graben

u pb and sm nd geochronology of the kizildag hatay turkey ophiolite implications for the timing and duration of suprasubduction zone type oceanic crust formation in the southern neotethys the kizildag hatay ophiolite in turkey represents remnants of the southern neotethyan ocean and is characterized by a complete ocean lithospheric section it formed in a fore arc setting above a n dipping intraoceanic subduction zone and represents the undeformed more northerly part of the same thrust sheet that also forms the baer bassit ophiolite to the south the ophiolite was emplaced southwards from the southerly neotethyan ocean in maastrichtian time u pb and sm nd dates are used to constrain the crystallization age and duration of magmatic activity of the kizildag ophiolite u pb dating yielded ages of 91 7 1 9 ma for a plagiogranite and 91 6 3 8 ma for a cumulate gabbro the cumulate gabbro also yielded a sm nd isochron age of 95 3 6 9 ma the measured ages suggest that the oceanic crust of the kizildag ophiolite formed in a maximum time period of 6 ma and that the plagiogranite may have formed later than the gabbroic section the u pb zircon ages from the kizildag ophiolite and the cooling age of a metamorphic sole beneath the baer bassit ophiolite are indistinguishable within the analytical uncertainties this indicates the presence of young and hot oceanic lithosphere at the time of intraoceanic subduction thrusting in the southern neotethys the u pb zircon ages from the kizildag the troodos and the semail ophiolites overlap within analytical uncertainties suggesting that these ophiolites are contemporaneous and genetically and tectonically related within the same late cretaceous southern neotethyan ocean

uniform sense normal simple shear of the continental lithosphere geophysical studies suggest that the thin crust characteristic of the basin and range province extends eastward beneath the west margin of the colorado plateau and rocky mountain regions in arizona and utah zones perhaps over 100 km wide may be defined bounded on the west by the east limit of upper crustal normal faults that account for more that 10 extension and on the east by the east limit of thinning beneath the colorado plateau a discrepancy exists within these zones between the negligible extension measurable in the upper crust and the substantial extension apparent from crustal thinning assuming the discrepant zone crust was as thick as or thicker than the colorado plateau rocky mountain crust prior to extensional tectonism if various theories appealing to crustal erosion are dismissed mass balance problems evident in the discrepant zones are most easily resolved by down to the east normal simple shear of the crust moving lower and middle crustal rocks that initially were within the zones up and to the west to where they now are locally exposed in the basin and range province west of the discrepant zones in both arizona and utah east directed extensional allochthons with large displacement are exposed these geophysical and geological observations complement one another if it is accepted that the entire crust in both arizona and utah failed during extension on gently east dipping east directed low angle normal faults and shear zones over a region several hundred kilometres wide large scale uniform sense normal simple shear of the crust suggests the entire lithosphere may do the same such a hypothesis predicts major lithospheric thinning without crustal thinning will occur in plateau areas in the direction of crustal shear in the case of the arizona utah and red sea extensional systems and possibly the death valley extensional terrain a broad topographic arch typically 1500 2000 m higher than the extended terrain is present suggesting lithospheric thinning in areas predicted by the hypothesis

palaeomagnetic insights into the evolution of neotethyan oceanic crust in the eastern mediterranean abstract a synopsis of palaeomagnetic data from three late cretaceous eastern mediter ranean tethyan ophiolites troodos hatay and baer bassit and their sedimentary coversequences is presented these data provide valuable insights into the role of regional andlocal scale tectonic rotations in the geodynamic evolution of neotethyan oceanic crust thegeologically earliest phases of tectonic rotation are documented in the troodos ophiolite where rotations around both subvertical and subhorizontal axes are readily related to thedevelopment of the spreading fabrics and structures during crustal genesis subsequent c 74 anticlockwise intra oceanic rotation of a troodos microplate has been quantified throughanalysis of the in situ sedimentary cover of the troodos ophiolite results indicate that bulkanticlockwise rotation began soon after the cessation of spreading and ended by the end ofthe eocene with c 50 60 of microplate rotation being over by the maastrichtian the timeat which ophiolite thrust sheets were emplaced onto the arabian continental margin to theeast of troodos recent results from the emplaced structurally dismembered baer bassitophiolite indicate extreme anticlockwise rotations of ophiolitic thrust sheets varying on akilometre scale new data from the post emplacement sedimentary cover confirm that onlya small component of these rotations is due to post emplacement tectonism baer bassitrepresents the leading edge of the emplaced ophiolitic sheet new data from the morecoherent section preserved in the hatay ophiolite to the north demonstrate significantanticlockwise rotation this is equivalent to the rotation of the most northerly part of thebaer bassit units to the south and is of the same sense and magnitude as the pre maastrichtian phase of microplate rotation documented in the troodos this suggests acommon intra oceanic origin for the majority of the troodos and hatay rotations and asignificant component of the more variable rotations observed in baer bassit overall therefore the data support a model involving 1 intra oceanic rotation of a coherent regionof crust within the southern neotethyan basin this rotated unit is more areally extensivethan has previously been inferred from consideration of data from the troodos ophiolitealone 2 emplacement of part of the rotated unit onto the arabian platform 3 subsequentlocalized post emplacement modification related to the development of the current plateconfiguration

structures and kinematics in the northeastern mediterranean a study of an irregular plate boundary abstract extensional structures are prominent in the northeastern mediterranean a unique sector of the africa eurasia plate convergence zone to explain this paradoxical situation we analyse here the young tectonics of this region by examining its structural elements and plate kinematics offshore multichannel seismic reflection profiles and onland geology show that the stuctural settings are different on the two sides of the northeastern mediterranean triple junction afr arb ana on the east stuctures controlled by strike slip and by compression coexist whereas on the west compression is not very conspicuous here deep basins separated by a partly submerged ridge are prominent we interpret the ridge which comprises the kyrenia misis andirin unit at its core as a large flower structure which extends from southeastern turkey to cyprus the adana cilicia and the iskenderun latakia mesaoria basins on its flanks are interpreted as due to extension this interpretation agrees with the relative motions between the africa arabia eurasia and anatolia plates in this region analysis of the local plate kinematics reveals that strike slip predominates along the southern boundary of the anatolia plate in this region as a result of anatolia s westward escape east of the triple junction this motion is associated with comparable shortening transverse to the plate boundary whereas west of the triple junction the motion transverse to the plate boundary varies between slight compression to extension depending mainly on the local strike of the plate boundaries these variations calculated from regional data correlate well with the observed structural changes along the northeastern mediterranean sector of the plate convergence zone the structural kinematic analysis explains both the lateral changes in the deformation style and the existence of local extension in the northeastern mediterranean

kinematics of late cretaceous subduction initiation in the neo tethys ocean reconstructed from ophiolites of turkey cyprus and syria formation of new subduction zones represents one of the cornerstones of plate tectonics yet both the kinematics and geodynamics governing this process remain enigmatic a major subduction initiation event occurred in the late cretaceous within the neo tethys ocean between gondwana and eurasia suprasubduction zone ophiolites i e emerged fragments of ancient oceanic lithosphere formed at suprasubduction spreading centers were generated during this subduction event and are today distributed in the eastern mediterranean region along three e w trending ophiolitic belts several models have been proposed to explain the formation of these ophiolites and the evolution of the associated intra neo tethyan subduction zone here we present new paleospreading directions from six upper cretaceous ophiolites of turkey cyprus and syria calculated by using new and published paleomagnetic data from sheeted dyke complexes our results show that nne ssw subduction zones were formed within the neo tethys during the late cretaceous which we propose were part of a major step shaped subduction system composed of nne ssw and wnw ese segments we infer that this subduction system developed within old triassic lithosphere along fracture zones and perpendicular weakness zones since the neo tethyan spreading ridge formed during gondwana fragmentation would have already been subducted at the pontides subduction zone by the late cretaceous our new results provide an alternative kinematic model of cretaceous neo tethyan subduction initiation and call for future research on the mechanisms of subduction inception within old and cold lithosphere and the formation of metamorphic soles below suprasubduction zone ophiolites in the absence of nearby spreading ridges

tectonic history of the hatay ophiolites south turkey and their relation with the dead sea rift abstract the kizildag ophiolite massif lies in the hatay region of s turkey some structural relationships in the area are examined and two geological sections through the ophiolite are presented a sequence of structural events dealing with the emplacement and post emplacement history is established the significance of the events is discussed and it is suggested that the post emplacement structural history was dominated by movements along the dead sea rift

a braided strike slip model for the northern continuation of the dead sea fault and its implications for levantine tectonics abstract the assumption that the 100 110 km sinistral displacement on the dead sea fault is transmitted northwards along a single structure the yammouneh fault which runs ne sw across lebanon is here reviewed a number of valid objections to this concept exist a more attractive model supported by the limited data available from the area is that the motion is transmitted along a number of faults on this basis the temporary rightward flexure of the levant fracture through lebanon has given rise to a braided strike slip fault complex the yammouneh serrhaya fault system this model overcomes the objections against the older concept and allows the explanation of the mt lebanon bekaa valley anti lebanon complex in terms of transpressive and transtensive blocks a tentative outline of the cenozoic structural evolution of the area in terms of two or more phases of motion along the levant fracture is presented

the miocene of the hatay area s turkey transition from the arabian passive margin to an underfilled foreland basin related to closure of the southern neotethys ocean abstract miocene sediments of the hatay area document the distal southerly part of an underfilled peripheral foreland basin related to the closure of the southern neotethys the basin is underlain by latest cretaceous and eocene shallow marine carbonates interpreted as the youngest part of the arabian passive margin succession unconformably overlying lower miocene conglomerates sandstones and palaeosols up to 250 m thick represent braided river deposits derived from an uplifted area to the south during the middle miocene carbonate sediments accumulated in a variety of shallow marine environments dominated by a northward sloping ramp with non marine peritidal lagoonal and coral reef deposition in local areas the upper miocene succession is mainly deeper water hemipelagic marl with clastic interbeds messinian evaporites were deposited near the depocentre the early miocene coarse fluvial sediments above the regional unconformity reflect the development of a flexural bulge or re activated basement structure the middle miocene carbonates and upper miocene marls are interpreted as the lower and middle units of an underfilled trinity considered typical of peripheral foreland basins similar lower miocene coarse clastic sediments and mid miocene shallow water carbonates unconformably overlie the arabian platform succession c 75 km to the north where the succession continues upwards into thick shallow marine to non marine terrigenous sediments upper unit of the trinity sourced from the overthrust load comparable coarse clastic sediments are absent from the distal foreland basin in the hatay area probably reflecting its more southerly position structural barriers in the foreland and the westward bypassing of sediment towards the mediterranean sea regional convergence halted by the end of the miocene and was followed by strike slip and westward tectonic escape as a result the miocene foreland basin was dismembered to form the plio quaternary transtensional hatay graben this like many other foreland basins shows some features which are not accommodated by ideal models of foreland basin evolution

the stratification and water masses at drake passage the waters at drake passage are known to be separated horizontally into four distinct zones of relatively small geostrophic shear by three fronts in which the shear and eastward flow are large the two northern fronts subantarctic front and polar front that bound the polar frontal zone comprise most of the transport of the antarctic circumpolar current vertical sections of closely spaced 50 km oceanographic stations made across drake passage in the summers of 1975 and 1976 produced quality measurements of temperature salinity oxygen silicate nitrate and phosphate based on these data a traditional description of characteristic distributions is presented good sampling resolution in the vertical allows maxima in hydrostatic stability to be traced laterally approximately along isopycnals between individual stations eleven strata of maximum stability are identified most vertically separate distinct water masses the most pronounced stability stratum is associated with the seasonal pycnocline north of the polar front it separates the subantarctic surface waters from subantarctic mode water to the south of the polar front the seasonal pycnocline is found slightly above the temperature minimum characteristic of the antarctic surface waters in austral summer this stability stratum extends northward near the base of the subantarctic mode water another stability stratum extending across the entire passage forms the upper boundary for the circumpolar deep water south of the polar front this stratum is at the base of the antarctic surface water to the north it is the lower boundary of the antarctic intermediate water although subantarctic mode water and antarctic intermediate water are separated by a stability stratum north of the polar front there is no such separation between antarctic intermediate water and the temperature minimum of the antarctic surface water south of the front this suggests that subantarctic mode water and antarctic intermediate water are distinct and that the latter derives from the surface waters south of the polar front at greater depths a horizontally discontinuous stratum is found between the upper and lower circumpolar deep water two horizontally continuous stability strata are found near the base of the circumpolar deep water marking the transition to a high silicate variety of denser deep water from the southeast pacific basin the densest water mass found is weddell sea deep water which flows through a gap in the south scotia ridge and along the southern scotia sea to fill the trough in the southern drake passage it is overlain by a laterally continuous stratum of relative maximum stability

timing and climatic consequences of the opening of drake passage age estimates for the opening of drake passage range from 49 to 17 million years ago ma complicating interpretations of the relationship between ocean circulation and global cooling secular variations of neodymium isotope ratios at agulhas ridge southern ocean atlantic sector suggest an influx of shallow pacific seawater approximately 41 ma the timing of this connection and the subsequent deepening of the passage coincide with increased biological productivity and abrupt climate reversals circulation productivity linkages are proposed as a mechanism for declining atmospheric carbon dioxide these results also indicate that drake passage opened before the tasmanian gateway implying the late eocene establishment of a complete circum antarctic pathway

the deep waters from the southern ocean at the entry to the argentine basin hydrographic data from the world ocean circulation experiment woce and south atlantic ventilation experiment save in the region of transition between the scotia sea and the argentine basin are examined to determine the composition of the deep water from the southern ocean that enters the atlantic and to describe the pathways of its constituents the deep current that flows westward against the falkland escarpment is formed of several superposed velocity cores that convey waters of different origins lower circumpolar deep water lcdw southeast pacific deep water spdw and weddell sea deep water wsdw different routes followed by the wsdw upstream of and through the georgia basin lead to distinctions between the lower wsdw 4 46 09 and the upper wsdw 46 04 4 46 09 the lower wsdw flows along the south sandwich trench then cyclonically in the main trough of the georgia basin although a fraction escapes northward to the argentine basin a comparison of the woce data with those from previous programmes shows that this component had disappeared from the southwestern argentine basin in 1993 1994 this corroborates previous results using save and pre save data a part of the upper wsdw recognizable from different s characteristics flows through the scotia sea then in the georgia basin along the southern front of the antarctic circumpolar current northward leakage at this front is expected to feed the argentine basin through the northern georgia basin the spdw is originally found to the south of the polar front pf in drake passage the northward veering of this front allows this water to cross the north scotia ridge at shag rocks passage it proceeds northward to the argentine basin around the maurice ewing bank the lcdw at the falkland escarpment is itself subdivided in two cores of which only the denser one eventually underrides the north atlantic deep water nadw in the atlantic ocean this fraction is from the poleward side of the pf in drake passage it also crosses the north scotia ridge at shag rocks passage then flows over the falkland plateau into the atlantic the lighter variety from the northern side of the pf is thought to cross the north scotia ridge at a passage around 55 w it enters the argentine basin in the density range of the nadw

geometry and kinematics of vertical axis rotations in fold and thrust belts abstract vertical axis rotations indicated by palaeomagnetic study are a common and important component of deformation in fold and thrust belts the kinematics of rotating thrust sheets may be best described as a combination of a far field rotation or translation in a planar geometry and a near field or local rotation so that the instantaneous rotation axis lies outside the body of the sheet this simplifies the thrust sheet kinematics significantly as it means that all the points on the sheet have a component of forward motion and the bounding fault is a thrust over all its area the consequences of a simple thrust sheet rotation for the interpretation of fault lineation data are investigated the lineations recorded in the footwall and the hangingwall are likely to be different the hangingwall lineations being skewed towards the direction of rotation the principal mechanism for local thrust sheet rotation is differential shortening either on folds or thrusts or by a combination of these structures the forward propagation of thrusting towards the foreland can accumulate large 120 rotations on the uppermost sheets these rotational thrust sheets cannot extend indefinitely along strike instead they terminate against lateral ramps or transfer faults sidewall duplexes may form as a consequence of rotation over a lateral ramp examples of rotational geometries from the subbetic zone of southern spain are described on a larger scale obliquely convergent orogenic wedges can evolve by rotation of faults with an initial thrust geometry into progressively greater components of strike slip motion reliable palaeomagnetic data are not always available for fold and thrust belts so independent evidence for rotational deformation is of great importance fold and thrust geometries particularly along strike variability in fold geometries highly variable axial traces of folds evidence for near synchronous refolding and the deviation of regional trends may all be a consequence of thrust sheet rotation detailed mapping and particularly the identification of the position of footwall and hangingwall cut offs can also provide strong evidence for rotation

improving estimates of the antarctic circumpolar current streamlines in drake passage abstract accurately resolving the mean antarctic circumpolar current acc is essential for determining southern ocean eddy fluxes that are important to the global meridional overturning circulation previous estimates of the mean acc have been limited by the paucity of southern ocean observations a new estimate of the mean surface acc in drake passage is presented that combines sea surface height anomalies measured by satellite altimetry with a recent dataset of repeat high resolution acoustic doppler current profiler observations a mean streamfunction surface height field objectively mapped from the mean currents is used to validate two recent dynamic height climatologies the new streamfunction has narrower and stronger acc fronts separated by quiescent zones of much weaker flow thereby improving on the resolution of acc fronts observed in the other climatologies distinct streamlines can be associated with particular acc fronts and tracked in time dependent maps of dynamic height this analysis

active tectonics of the aegean region the aegean sea and its surrounding regions comprise one of the most rapidly deforming parts of the alpine himalayan mountain belt though the deformation of the belt as a whole is related to thc northward move ment of africa arabia and india relative to eurasia the tectonics of the aegean region itself is dominated by strike slip and extensional motions the actively deforming part of the aegean region is not large about 700 x 700 km2 compared with that in asia yet it has had an influence on our views of continental tectonics disproportionate to its size and comparable perhaps only to tibet fundamental contributions from the aegean have been made to many topics including