tectonics fluids and ore deposits mobilization and remobilization abstract the mobilization of metals leading to the formation of many known types of metallic resource involves the focussed flow of very large km 3 fluid volumes different types of fluids such as sea water and metamorphic and meteoric fluids with or without biomolecules may be specific for certain metals or suites of metals where large fluid volumes are part of a geologic process there is potential for local metal enrichment examples of such processes within the context of plate tectonics include convective flow of sea water at ocean ridges in relation to ophiolite cu zn mineralization and black smokers subduction of metal enriched sediments and the tectonic recycling of sn w mineralization metamorphic dewatering of subducted oceanic crust in the context of au deposits metamorphic degassing around high level granitic plutons and metamorphic re equilibration of the underthrust plate in relation to continental thrusting in addition during weathering processes short term leaching produces fertile soils whereas long term leaching can result in lateritic ores the large scale remobilization of ore deposits or of mineralization where metal enrichment is currently sub economic is improbable unless large fluid volumes are involved or the crust undergoes major tectonic re arrangement but it is perhaps possible that these situations are more common than we suppose and that such multistage events are indicated by the long term persistence of metallogenic provinces

the cilicia adana basin complex eastern mediterranean neogene evolution of an active fore arc basin in an obliquely convergent margin abstract detailed interpretation of multi channel seismic reflection profiles showed that the deposition of the miocene successions in the cilicia adana basin complex occurred within a foredeep south of the arcuate tauride fold thrust belt the misis kyrenia fault zone defined the northernmost of a number of smaller thrust culminations developed within this foredeep fluvio deltaic successions suggest that the adana and inner cilicia basins became emergent during the tortonian when the western portion of the piggy back basin retained a marine connection the entire region became emergent during the messinian salinity crisis and up to 1000 m of evaporites were deposited in the cilicia and southern adana basins stratigraphic and structural relationships demonstrated that the late plio quaternary cilicia adana basin complex evolved as an asymmetric piggy back basin on the hanging wall of the large south verging misis kyrenia thrust culmination on the misis kyrenia segment of the culmination thrust activity ceased in early messinian whereas on the kyrenia segment it continued to the present the shift in the kinematics is expressed by the development of the ne sw trending steep faults with extensional separations bounding the plio quaternary depocentre in the adana and inner cilicia basins these basement rooted faults are incompatible with the contractional regime that existed in this part of the basin complex during the miocene in the outer cilicia basin the incompatibility between a domain of continued south directed fold thrust activity and uplift on the kyrenia range and a domain of extension associated with the development of plio quaternary depocentre indicates that strain is strongly partitioned across the e w trending southern basin bounding fault system along the southern margin of the outer cilicia basin progressive westward displacement of the tauride block within the aegean anatolian microplate created a localised transtensional regime within the inner cilicia and adana basins suggesting the presence of hard intra plate fault boundaries centred along the misis kyrenia horst block and the southern basin bounding fault system the northern basin bounding fault system including the kozan fault in the cilicia basin is a set of large antithetic structures linked to the master faults the westward pull out of the tauride block is related to the overall westward escape of the aegean anatolian microplate during the latest miocene to early pliocene whereas the continued contraction south of the basin complex across cyprus is related to the evolving collision and under plating of the continental micro fragment the eratosthenes we propose that the southern master fault of the outer cilicia basin primarily functions as a boundary separating a contractional microplate domain to the south from a transtensional microplate domain to the north

lower crustal earthquakes caused by magma movement beneath askja volcano on the north iceland rift the lower crust of magmatically active rifts is usually too hot and ductile to allow seismicity the icelandic mid atlantic rift is characterized by high heat flow abundant magmatism generating up to 25 30 km thick crust and seismicity within the upper 8 km of the crust in a 20 seismometer survey in july august 2006 within the northern rift zone around the askja volcano we recorded 1700 upper crustal earthquakes cutting off at 7 8 km depth marking the brittle ductile boundary unexpectedly we discovered 100 small magnitude ml 1 5 earthquakes occurring in swarms mostly at 14 26 km depth within the otherwise aseismic lower crust and beneath the completely aseismic middle crust a repeat survey during july august 2007 yielded more than twice as many lower crustal events geodetic and gravimetric data indicate melt drainage from crustal magma chambers beneath askja we interpret the microearthquakes to be caused by melt moving through the crust from the magma source feeding askja they represent bursts of magma motion opening dykes over distances of a few meters facilitated by the extensional setting of the active rift zone

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

earthquakes and strength in the laminated lower crust can they be explained by the corset model abstract we present a model that may explain deep crustal earthquakes observed in particular in several areas of highly reflective laminated lower continental crust we combine observations from earthquake seismology crustal reflection seismics and tectonic rheological concepts the study concentrates on parts of the northern alpine foreland where many earthquakes occur inside the laminated lower crust which is generally considered to be warm and weak thin mafic ultramafic sill like intrusions and invisible dykes are assumed to form a corset like network with high strength this model can explain the observed strong and multiple reflections and the occurrence of rupture inside a stable structure within a weak lower crust tectonic stress transfer from the alpine collision zone or and the upper rhine graben and its release may follow classical friction concepts in addition the heterogeneity of the laminated lower crust may also favour various viscous instabilities

structural and rheological implications of lower crustal earthquakes below northern switzerland abstract a detailed study of the recent seismicity in the northern alpine foreland of switzerland reveals that earthquakes with magnitudes between 0 9 and 4 2 occur not only in the upper part of the crust but contrary to observations in most other intracontinental settings seismicity extends down to depths of about 30 km in the lower crust observed p wave velocities in the focal region of even the deepest earthquakes are less than 6 3 km s 1 the average value of poisson s ratio for the entire focal depth range 6 30 km lies between 0 23 and 0 24 focal mechanisms are mostly a combination of strike slip and normal faults with consistent orientations of p and t axes but without any systematic dependence on focal depth from geological observations regional strain rates are of the order of 10 13 s 1 two dimensional temperature modelling indicates that temperatures in the lower crustal seismogenic zone are well above 450 c under the assumption of a dry environment the observed p wave velocities and poisson s ratios imply either a granitic or quartz rich gneissic composition or possibly a gabbroic quartz free granulite the deformation would be governed either by the rheology of quartz or of plagioclase the onset of ductility observed in laboratory studies lies around 300 c for quartz and around 450 c for plagioclase thus conditions in the lower crust beneath northern switzerland appear to be incompatible with the occurrence of either brittle failure or plastic instabilities as is implied by the existence of earthquakes alternatively lower crustal earthquakes could be a manifestation of the presence of fluids in the lower crust fluids under near lithostatic pressure either evolved in situ from metamorphic reactions or from infiltration from the mantle would tend to decrease the effective stress on pre existing faults and thus allow brittle friction failure to occur at depths where under dry conditions or low fluid pressures only ductile deformation would be expected

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

layer parallel shortening and related structures in zones undergoing active regional horizontal extension folds and thrust faults formed by layer parallel shortening coaxial with extensional structures such as normal dip slip faults and ductile necking structures with orthorhombic fabric symmetry are usual but little recognised structures formed within normal dip slip shear zones bounding rifts they are generated because of the shear distribution in a zone of progressive deformation and may be later extended and disrupted depending on which part of the strain ellipsoid they may be located we here describe folds and thrust faults from the southern margin of the alasehir rift in western turkey as an opportunity to discuss the properties of pureextension related structures formed by layer parallel shortening such structures are more commonly generated during the early stages of rifting when deformation rates are slow and the shear zones broader than those forming later in the life of a rift when strain rates are usually higher such structures have commonly been mistaken for witnesses documenting regional episodes of shortening rather than as integral parts of the extensional structures forming rifts not all layer parallel shortening related structures therefore indicate regional shortening we plead that hasty statements concerning the meaning of geological structures at all scales be avoided before a thorough understanding of bulk strains that have affected a region are properly understood

present day seismicity and seismotectonics of the cilician basin eastern mediterranean region of turkey the nature of the interaction between the anatolian arabian and af rican plates is an important problem of northeastern mediterranean tectonics the dead sea fault and east anatolian fault zone are the most prominent structural elements in this region the cilician basin which is located at the junction of these faults is known to have a very active seismic history however instrumental obser vations have been insufficient because of the lack of an adequate local seismic net work to monitor ongoing seismic activity and to analyze the seismotectonics of the cilician region 36 to 38 n 34 to 38 e a digital seismic network of 18 stations with velocity transducers has been operated by the earth and marine sciences re search institute emsri of the scientific and technical research council of turkey tubitak since 1993 no previous studies have been carried out in this region for crustal structure an optimum 1d velocity model was obtained by using the velest algorithm for reliable determination of earthquake hypocenter locations approxi mately 2500 earthquakes detected between 1993 and 2002 with local magnitude greater than 1 5 have been located by using this optimum velocity model the most notable feature of the epicentral distribution is the presence of dense clusters of activity along local fault trends the majority of hypocentral depths of the events range between 5 and 35 km single fault plane solutions of reliable events were calculated in order to analyze the seismotectonic characteristics of the region results show that the cilicia region constitutes a wide left lateral shearing zone that indicates a diffuse plate boundary between the african arabian and anatolian plates

widespread extension in the core of the western alps revealed by earthquake analysis the western alps are an active collision belt whose current stress field is inhomogeneous muller et al 1992 we report new seismological data which significantly improve our knowledge of this stress field about 1600 earthquakes which occurred in the western alps during the last 10 years were precisely located and 79 new focal solutions were computed the analysis of this database shows that widespread extension affects all the internal zones of the belt to better constrain the associated stress regime six stress tensors were computed using the gephart and forsyth 1984 method they show that the current tectonics of the western alps are contrasted with close variation in the stress regime transpression to the front of the belt contrasting with extension in the core of the belt the extensional direction is radial to the arcuate geometry of the belt and bounded outboard by the former thrust of the internal zones onto the external zone suggesting extensional reactivation of this inherited crustal discontinuity such widespread extension within the inner part of an actually ongoing collision belt cannot be explained by simple collision related tectonics we propose that intrabelt buoyancy forces such as those produced by a slab retreat or slab break off interfere with the boundary forces driven by the ongoing europe africa convergence

lower crustal seismic activity in the adana basin eastern mediterranean possible connection to gravitational flexure abstract high quality broadband data together with the application of the double difference relocation technique has been used to study the characteristics of the lower crustal seismicity in the adana basin in southwestern turkey deep events are clearly seen to be restricted only to the adana basin and never extend outside its boundaries furthermore the seismogenic zone is observed to align roughly with the main axis of the basin and plunges steadily in the ssw direction following the basement trend of the adana basin similarities between geometries of the basin evolution and the deep seismic production suggest that both processes are closely related a flexure process is proposed related to the subsidence of the adana basin the seismogenic zone originally at a shallow depth is assumed to have been displaced vertically into the lower crust by flexure the temperature evolution of the crust during the flexure has been studied in detail using finite difference modeling with amplitude and duration parameters taken from earlier studies it has been concluded that the physical conditions for brittle fracturing remained unchanged for an extended period of time after the flexure the brittle layers originally at shallow depths preserved their original thermal properties after the subsidence and will continue to produce earthquakes at considerable depths numerical tests using inferred parameters imply a total vertical shift of 7 8 km for the seismogenic zone discussions for additional processes which may further contribute to the cooling of the crust are also included

thermal constraints on earthquake depths in california the high quality databases for california seismicity from the southern and northern california earthquake centers and an extensive compilation of thermal measurements in california are used to quantify the concept of temperature as a fundamental parameter for determining the thickness of the seismogenic zone the base of this zone below which only a small percentage of crustal earthquakes occur is termed the cutout depth and it is at or near the brittle ductile transition in the crust based on laboratory deformation studies this transition should be temperature strain rate lithology and stress state dependent in this study qualitative comparisons between the heat flow in california and earthquake hypocentral distributions show first that as expected earthquake cutout depths are inversely related to heat flow second the epicentral distributions tend to parallel thermal transitions this correlation is probably related to stress concentrations in these locations an ancillary observation is that the cooler western mojave block in southern california appears to be behaving similarly to the tibetan indenter block in asia as faults tend to go around it into areas of higher heat flow where the seismogenic zone is thinner and the crust may be weaker and it is pushed toward and under the southern cold sierra nevada block third to quantitatively compare the data sets temperatures for the seismicity cutout depth in california were calculated using the steady state 1d heat conduction equation with the variables based on published values for heat flow heat generation and thermal conductivity the analysis was restricted to profiles along which the heat flow and earthquake databases were constrained which allowed the error in the temperature calculation to be determined using monte carlo simulations the results show that two distinct ranges of temperatures dependent upon location describe the cutout depth d 99 of seismicity for california 450 50 c and 260 40 c the 450 50 c cutout depth temperature is most widespread geographically occurs within many provinces and is higher than the frequently referenced temperature of 300 50 c for the brittle ductile transition the lower temperature 260 c seems to be restricted to provinces where the heat flow is near or below 50 mw m 2 such as the mojave block and sierra nevada the differences in these cutout temperatures suggest that additional factors such as strain rate stress regime and or lithology may contribute to the seismicity cutout depth fourth along a profile with significant seismic activity and a 450 c cutout temperature the envelope for the maximum energy released by earthquakes falls at or below the 300 c isotherm detailed characterization of the heat flow and earthquake synergy in this manner furthers the understanding of the earthquake process and can aid in the estimation of the maximum depth of rupture for great earthquakes particularly in areas of low seismicity thus reducing uncertainties in hazard calculations manuscript received 26 february 2003

seismotectonics of the southern boundary of anatolia eastern mediterranean region subduction collision and arc jumping the pattern of seismicity and fault plane solutions of earthquakes are used to outline the tectonic features of the southern boundary of anatolia in the eastern mediterranean and southeastern turkey the results of this study show that this boundary is composed of two distinct parts one in southeastern turkey and syria is a wide and complex zone of continental collision the other in the levantine basin of the eastern mediterranean is a zone of oceanic subduction in the region of continental collision three zones of seismicity are observed most of the seismic activity in this region follows the bitlis zone and is associated with a zone of thrusting and mountain building this appears to be the zone of most active deformation and plate consumption in the plate boundary region between arabia and turkey a less active zone of seismicity to the north of the bitlis zone is interpreted to have been more active in the past whereas another active zone of seismicity to the south is interpreted to be a zone which may be more active in the future as the main zone of plate consumption jumps to the south in the subduction zone of the eastern mediterranean the depth of the subducted slab and the rate of seismicity generally increase from east to west the zone of present day convergence between africa and turkey in the levantine basin can be best outlined by the northern edge of the mediterranean ridge the subduction zone in this area sequentially jumps to the south as small continental fragments collide with existing zones of subduction deep seismic activity near the gulf of antalya is associated with a detached subducted slab north of the anaximander mountains that is distinctly different from the seismic trend which is associated with present day active subduction the plate boundary between africa and turkey at the center of the levantine basin appears to have shifted to the south of the anaximander mountains and florence rise most of the focal mechanisms of the earthquakes along the entire southern boundary of anatolia indicate that n to nnw thrusting is the dominant mode of seismic deformation the present set of data is inconsistent with a major transform fault in the cyprean arc east of cyprus and in southeastern turkey

folding in regions of extension summary many extension zones have been subjected to folding and shortening in a direction perpendicular to the stretching such deformation can be accounted for by the extension of a thin superficial elastic layer overlying a substrate that has small elastic moduli or that deforms in a viscous regime laboratory experiments are used to document the wavelength and amplitude of the folds for a range of geometrical configurations folding is observed even for very small amounts of extension less than 1 per cent with characteristics that are consistent with finite amplitude scaling laws because of the intrinsically 3 d nature of the deformation field the size of the region affected by folding and the direction of the fold axes depend on the orientation of the extension with respect to the rigid blocks that bound the deforming region for regions of extension where the elastic thickness is about 10 km as in the basin and range province for example it is predicted that folding occurs with wavelengths in a 20 40 km range such that it induces little deformation in the lower crust and maintains a flat moho discontinuity these predictions are consistent with the observations the characteristics of faulting that is associated with such deformation are discussed

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

orthogonal folding of extensional detachments structure and origin of the sierra nevada elongated dome betics se spain 1 a close relationship of the kinematics and timing between low angle extensional faulting and upright folding is established for the miocene detachment systems in the hinterland of the betics in southeastern spain folding accompanied tectonic denudation developing elongated domes with fold axes both parallel and perpendicular to the direction of extension the geometry kinematics and tectonic evolution of two major sequentially developed extensional fault systems have been characterized in several e w elongated mountain ranges of the central betics on the basis of new cartographic and structural data and a comprehensive revision of other available geological and geophysical observations the extensional systems have an average wsw direction of extension and led to exhumation of the two lower metamorphic complexes of the betics the nevado filabride and the alpujarride during the middle and upper miocene serravallian to tortonian the extended domain contains a core complex with distal and proximal antiformal hinges separated by around 60 km and with a fold amplitude of 6 km measured parallel to the direction of extension the total amount of extension across the core complex is about 109 116 km corresponding to a stretching factor of 3 5 3 9 estimated using the distance between fold axial surfaces and a geometrical model accomplishing footwall deformation during tectonic denudation via subvertical simple shear the elongated domal and basinal geometry of the detachments and their respective footwalls is due to the interference between two sets of orthogonal large scale open folds trending n s and e w longitudinal n s trending folds are interpreted as isostatic folds i e folds that developed in response to differential unloading of the extensional detachment footwalls inducing ductile flow in the middle crust these folds formed in a rolling hinge anticline in which rotation migrates westward through the footwall as it is progressively unroofed in contrast e w trending folds being subparallel to the direction of extension have a contractional origin and progressively affect to the west the isostatically readjusted segments of the detachments once they are inactive orthogonal folding occurred since the serravallian to lower pliocene extension is still active from the rolling hinge anticline in sierra nevada to the west the middle miocene to pliocene tectonic evolution of the sierra nevada elongated dome at the core of the betic hinterland is another example of the coexistence of extension and contraction during continued overall convergence and mountain building

tectonic controls on stratigraphic evolution of the adana basin turkey the neogene adana basin of se turkey was initiated after thrust emplacement of the tauride belt to the north of the basin seismic reflection profiles across the southern part of the adana basin provide information on structural and stratigraphic evolution of the basin based on seismic character and the identification of unconformities three megasequences and two mega sequence boundaries are identified the first megasequence is partly coincident with an early miocene rifting event and it comprises reefs that have grown on fault footwall crests with fore and back reef sediments in intervening lows subsequent rapid flexurally induced subsidence generated an underfilled basin which was then passively filled by turbiditic sediments megasequence 2 showing aggradational character on seismic profiles further extensional faulting and coupled sinistral wrench faulting took place after the deposition of megasequence 2 erosional truncation of its upper part is followed by the deposition of continental and shallow marine sediments of megasequence 3 which shows localized progradational sequences characteristic of shallow water deposition further minor extensional faulting took place after the deposition of megasequence 3

discussion on the extensional folding in the alașehir gediz graben western turkey erdin bozkurt writes seyitoglu et al 2000 described their interpretation of the broad folds exposed in the miocene sediments exhumed on the southern margin of the gediz graben western turkey as products of extensional tectonics they also concluded that present day north south extensional tectonics and consequent east west graben formation in western turkey commenced by early miocene and continued since then previously kocyigit et al 1999a provided the first ever field evidence for the presence of east west folds in the gediz graben and interpreted these structures as suggesting a shortlived north south compressional deformation during the late serravalian late early pliocene times as much of the evidence presented by seyitoglu et al 2000 contradicts the available literature on the origin of extensional folding in particular rollover anticlines and as other detailed publications on the age and origin of extensional tectonics in western turkey and that of the east west folds in the gediz graben present evidence for a contradictory model s i would like this opportunity to describe diffculties that arise over the published evidence and interpretation of seyitoglu et al 2000 tectonic significance of sart formation the map pattern of various lithologies and the relationships between the structures in figures 2 and 3 of seyitoglu et al 2000 are useful to drive a relative chronology of faulting the pliocene sart formation lies unconformably above the miocene kursunlu formation in the hanging wall of the fault ii indicating synchronous faulting and sedimentation i e the movement along fii commenced by the pliocene as the sart formation is exhumed in the footwall of fault iii and fii antithetic is cut by fiii fiii faulting must postdate pliocene since the folds in extensional terrains form at the same time or just prior to the faulting the folds in the miocene kursunlu formation cannot be attributed to

alpine lithosphere slab rollback causing lower crustal seismicity in northern foreland abstract beneath the northern foreland of the central alps deep crustal earthquakes up to magnitude 4 regularly occur in the continental lithosphere at 20 km to 30 km depths where most of these earthquakes are located temperatures above 450 c are expected this leads to a more ductile rheology of the lower continental crust to better understand occurrence and underlying processes of these unusual earthquakes we homogenize and improve hypocenter locations of events in the period 1984 to 2012 using a high precision multi phase earthquake location method in combination with a reliable three dimensional p wave velocity model of the crust and uppermost mantle with the new approach the average uncertainty in focal depth of well locatable earthquakes is less than 1 km the homogeneously relocated hypocenters suggest a relatively uniform depth distribution throughout the lower crust in agreement with previous studies seismicity is entirely restricted to the crust and no evidence for seismicity in the mantle lithosphere beneath the northern central alpine foreland was found the geographical distribution of lower crustal earthquakes in the foreland correlates remarkably well with the lateral extent of the european slab beneath the central alps where it is still attached to the european lithosphere in addition the directions of extensional axes derived from focal mechanisms of the deep crustal earthquakes are predominantly parallel to the alpine front this consistency of extensional axes can be interpreted as the result of the transferred buoyancy force of the lower crust in the subduction transformed to a compressional force in the foreland perpendicular to the alpine front existing 2 d thermo mechanical models predict such viscous bending and stress transfer to the foreland in our proposed model the anomalously deep crustal seismicity is driven by stresses transferred into the foreland interrelated with the exhumation of the crust form the orogenic root caused by the rollback of the european lithosphere

miocene to recent tectonic evolution of the eastern mediterranean new pieces of the old mediterranean puzzle the mediterranean sea and its surrounding land mass fig 1 have long been recognized as an excellent bnatural laboratoryq for the study of fundamental plate tectonic processes including rifting passive margin development contraction and associated subduction ophiolite emplacement and orogenesis and as such it is one of the most extensively studied regions of the world e g hsu et al 1975 dixon and robertson 1984 kastens et al 1990 emeis et al 1996 comas et al 1996 robertson 1998 mcclusky et al 2000 the late cretaceous to holocene tectonic evolution of the eastern mediterranean region is extremely complex and controversial and several commonly conflicting hypotheses have been proposed the scope of this special issue does not permit a full discussion of these hypotheses we refer the reader to robertson 1998 for a review however there is general agreement that the eastern mediterranean evolved as a small ocean basin during the late triassic robertson and dixon 1984 robertson et al 1991 this embryonic ocean achieved its maximum

a lower crustal event in the northeastern mediterranean the 1998 adana earthquake mw 6 2 and its aftershocks we analyse the main and aftershocks of the june 27 1998 adana earthquake using data from the short period cilician seismograph network in order to investigate the seismotectonics of the northeastern mediterranean region the mainshock is found to have a pure left lateral strike slip mechanism strike 50 dip 85 rake 10 mo 3 63 1018 nm the inferred strike direction of 50 n closely aligns with the surface trend of the goksun fault zone gfz the depth and size of the mainshock and the distribution of the aftershocks indicate that the rupture nucleated within the lower crust and did not extend to shallower zones this seismicity pattern indicates that these events are associated with actively interacting african and anatolian lithospheres in a strike slip manner at depth thus we propose that the southern segment of the gfz belongs to the diffuse africa anatolia plate boundary and plays a major role in the plate kinematics of the northeastern mediterranean