interpretation of tectonic versus magmatic processes for resetting apatite fission track ages in the nigde massif turkey abstract apatite fission track aft ages may record the timing of exhumation related cooling of formerly deeper rocks or the timing or simple cooling of rocks already at or near the earth s surface the interpretation of aft ages is therefore challenging in regions that experienced coeval or sequential bedrock exhumation and magmatism the nigde massif central turkey is an example of a metamorphic complex for which the tectonic significance of the aft ages has been questioned owing to the location of the massif in a volcanic province the metamorphic rocks of the nigde massif have miocene aft ages of 17 9 ma 30 50 million years younger than the timing of initial unroofing of the rocks to the earth s surface at 60 45 ma according to one model fission tracks in apatite may have been completely reset when the massif was partly to entirely reburied in the tertiary however the massif is located in a region of major neogene volcanism during which ignimbrite was deposited on exhumed metamorphic basement and there is disagreement as to whether the miocene aft ages represent cooling related to final exhumation via denudation or cooling following heating by volcanism or other magmatic activity to evaluate different cooling scenarios we examine aft age and track length characteristics in the context of model temperature time paths integrated thermal modeling modeling of apatite fission track age and track length data and geological observations suggest that the aft ages represent final exhumation and cooling in the miocene and few to no thermal effects from volcanic deposits or other neogene magmatic activity

structural evolution of the tuzgolu basin in central anatolia turkey abstract the central anatolian segment of the alpine himalayan orogen contains interior basins the largest of which is the tuzgolu salt lake basin 20 000 km2 it is bounded on the east by the tuzgolu salt lake fault zone and on the west by the yeniceoba and cihanbeyli fault zones structural stratigraphic and sedimentologic evidence suggests that the tuzgolu basin started as a fault controlled basin during late maastrichtian tectonism when the present day northwest trending faults that bound the basin were initiated these faults may have been formed as normal faults suggesting extension or strike slip faults with a normal component of movement indicating a large transtension at the time of their initiation the late maastrichtian faults were reactivated as strike slip faults in response to late eocene compression in the region that produced the central anatolian thrust belt to the north and the late eocene south dipping thrust faults of the ulukisla basin to the south this reactivation is su

post eocene extensional tectonics in southern new caledonia sw pacific insights from onshore fault analysis and offshore seismic data ductile to brittle extensional deformation following thrusting of the peridotites nappe during the upper eocene has been shown to play a major role in the tertiary tectonic evolution of the northern part of the main island of new caledonia and its eastern and western margins in this study we provide new tectonic data from southern new caledonia that allow to better constrain the tectonic evolution of the southern part of the main island we present a kinematic analysis of faults and striations obtained mainly from exposures of sedimentary rocks in the region of noumea with complements from measurements made farther north at nepoui within post obduction middle miocene deposits we also present additional results of an interpretation of seismic lines from the lagoon south of the noumea peninsula which provide constraints on the current tectonic regime of southern new caledonia extensional faults in the noumea region have been studied within terranes of various ages including pre and syn obduction deposits and ophiolites hence we demonstrate that important extensional events have affected the southern part of the new caledonia block after the obduction of the peridotite nappe the direction of maximum extension is variable at the scale of the region both high angle and low angle normal faults are present and block rotation is observed at some localities this suggests that detachments accommodating significant displacements are cutting through the sedimentary pile the average final strain pattern of the region can be regarded as the results of a multidirectional flattening a hypothesis consistent with vertical uplift associated with regional extension these results are in good agreement with conclusions of earlier workers showing late extensional evolution of the ophiolites along

wavelet based time dependent travel time tomography method and its application in imaging the etna volcano in italy it has been a challenge to image velocity changes in real time by seismic travel time tomography if more seismic events are included in the tomographic system the inverted velocity models do not have necessary time resolution to resolve velocity changes but if fewer events are used for real time tomography the system is less stable and the inverted model may contain some artifacts and thus resolved velocity changes may not be real to mitigate these issues we propose a wavelet based time dependent double difference dd tomography method the new method combines the multiscale property of wavelet representation and the fast converging property of the simultaneous algebraic reconstruction technique to solve the velocity models at multiple scales for sequential time segments we first test the new method using synthetic data constructed using real event and station distribution for mount etna volcano in italy then we show its effectiveness to determine velocity changes for the 2001 and 2002 eruptions of mount etna volcano compared to standard dd tomography that uses seismic events from a longer time period wavelet based time dependent tomography better resolves velocity changes that may be caused by fracture closure and opening as well as fluid migration before and after volcano eruptions

convective instability of thickening mantle lithosphere mantle lithosphere being colder and therefore denser than the underlying mantle is prone to convective instability that can be induced by horizontal shortening numerical experiments on a cold layer with imposed horizontal shortening are carried out to examine the relative importance of mechanical thickening thermal diffusion and gravitational instability in deforming the layer this analysis is then used to develop a method for determining which of these styles dominates for a layer thickening at a given rate if viscosity is non newtonian the imposition of shortening decreases the lithospheric strength which causes perturbations to the lithosphere s temperature structure to grow exponentially with time once these perturbations become sufficiently large they then grow super exponentially with time eventually removing the lithospheric base because lithospheric viscosity is highly temperature dependent at most only the lower 30 per cent of the lithosphere participates in the downwelling associated with this initial super exponential growth event after this event however a downwelling develops that removes material advected into the region of downwelling by horizontal shortening the magnitude of this persistent downwelling depends on the rate and duration of shortening if the total amount of shortening does not exceed 50 per cent doubling of crustal thickness then this downwelling extends to a depth three to four times the thickness of undeformed lithosphere and forms a sheet significantly thinner than the width of the region undergoing shortening once shortening stops this downwelling is no longer replenished by the shortening process and should then detach due to its inherent gravitational instability the hottest 60 per cent of the mantle lithosphere could be removed in such an event which would be followed by an influx of hot buoyant asthenosphere that causes rapid surface uplift because more cold material is removed after the cessation of shortening than by the initial gravitational instability the former has a potentially greater influence on surface uplift the tibetan interior is thought to have been shortened by about 50 per cent in 30myr and afterwards at 8ma experienced a period of rapid uplift that may have resulted from the removal of a large downwelling finger of cold lithosphere generated by shortening

petrogenesis of collision related plutonics in central anatolia turkey central anatolia exhibits good examples of calc alkaline and alkaline magmatism of similar age in a collision related tectonic setting continent island arc collision in the central anatolia region late cretaceous post collisional plutonic rocks intrude palaeozoic mesozoic metamorphic rocks overthrust by upper cretaceous ophiolitic units to make up the central anatolian crystalline complex in the complex three different intrusive rock types may be recognised based on their geochemical characteristics i calc alkaline behrekdag cefalikdag and celebi ii subalkaline transitional baranadag and ii alkaline hamit the calc alkaline and subalkaline plutonic rocks are metaluminous i type plutons ranging from monzodiorite to granite the alkaline plutonic rocks are metaluminous to peralkaline plutons predominantly a type ranging from nepheline monzosyenite to quartz syenite all intrusive rocks show enrichment in lile and lree relative to hfse and have high 87sr 86sr and low 143nd 144nd ratios these characteristics indicate an enriched mantle source region s carrying a subduction component inherited from pre collision subduction events the tectonic discrimination diagram of rb vs y nb suggests that the calc alkaline subalkaline and alkaline plutonic rocks have been affected by crustal assimilation combined with fractional crystallisation processes the coexistence of calc alkaline and alkaline magmatism in the central anatolian crystalline complex may be attributed to mantle source heterogeneity before collision the former carries a smaller intraplate component and pre subduction enrichment compared to the latter either thermal perturbation of the metasomatised lithosphere by delamination of the thermal boundary layer tbl or removal of a subducted plate slab breakoff is the likely mechanism for the initiation of the post collisional magmatism in the complex

re os molybdenite ages of granitoid hosted mo cu occurrences from central anatolia turkey abstract the central anatolian crystalline complex cacc where many granitoids are emplaced and related ore occurrences deposits occur is tectonically located in the alpine himalayan belt the cacc hosts numerous ore occurrences deposits cu mo fe pb and zn that are spatially associated with granitoids the calc alkaline karacaali baliseyh and basnayayla granitoids that form the northern granitoid belt of the cacc host important mo cu occurrences in this paper we document re os isotopic age data in molybdenites to determine the timing of the granitoid hosted mineralizations in the cacc the re content of molybdenite in the basnayayla is significantly higher 108 9 148 5 ppm than molybdenites from the karacaali 16 3 74 8 ppm and baliseyh 4 2 ppm two molybdenite samples from karacaali and two samples from basnayayla occurrences give re os ages ranging from 73 8 0 4 to 76 2 0 4 ma and 77 1 0 4 to 78 0 0 4 ma respectively furthermore one molybdenite sample from baliseyh gives a 73 6 0 4 ma re os age these ages are consistent with those of post collisional granitoids and indicate close relationship between mineralization events and granitic magma differentiation crystallization processes the new re os age data obtained from this study show that mineralization events developed earlier 78 77 ma in the east basnayayla as compared with the west 76 73 ma karacaali and basliseyh of central anatolia moreover one molybdenite sample from karacaali gives 76 2 ma which is very close to the basnayala ages 78 and 77 1 ma according to these data one possible explanation is that older molybdenite ages in karacaali and basnayayla probably represent the mineralization period related to crystallization differentiation processes on the other hand the younger molybdenite age 73 8 ma in the karacaali may represent prolongation of the life of magmatic hydrothermal processes cycles and or the remobilization of molybdenum within the solidified granitic system by the intrusion of the basic magma

hidden calderas evidenced by multisource geophysical data example of cappadocian calderas central anatolia abstract the cappadocian volcanic field in central anatolia turkey is characterised by a sequence of 10 neogene ignimbrites the associated calderas have been partly dismantled and buried by subsequent tectonic and sedimentary processes and therefore cannot be readily recognized in the field recent progress in the understanding of the stratigraphic correlations and flow patterns has identified two main probable source areas for the ignimbrites detailed study of these areas based on gravity surveys remote sensing data spot and ers1 images and digital elevation models dem has provided evidence for two major caldera complexes and their relationship to old stratovolcanoes and neogene tectonics the older nevsehir acigol caldera complex located between the towns of acigol nevsehir and cardak is inferred to be the source of the kavak and zelve ignimbrites the nevsehir acigol caldera complex is defined mainly by a 35 mgal circular gravimetry anomaly about 15 km in diameter the boundaries of this now buried caldera complex are shown by high gradients on the bouguer gravity anomaly map the younger derinkuyu caldera complex located between the erdas stratovolcano and the ciftlik basin is inferred to be the source of the sarimaden cemilkoy gordeles and kizilkaya ignimbrites it is well defined by a rectangular 35 23 km gravity low 30 mgal with a positive high 20 mgal in the center gravity remote sensing data and the dem provide evidence that the erdas stratovolcano on the northern margin of the derinkuyu caldera complex represents the remnants of a large stratovolcano partly cut by one or more caldera collapses the positive anomaly within the derinkuyu caldera complex is centered on the 15 km wide sahin kalesi volcanic massif field evidence and structural features inferred from the dem and remote sensing data strongly suggest that this massif is a resurgent doming associated with the gordeles ignimbrite eruption high resolution ers1 spot and dem images reveal that the transtensive regime active at least since the miocene influenced the location of eruptive centers and caldera complexes in cappadocia the two caldera complexes are located in transtensive grabens the subsidence of these grabens continuing after the caldera collapse events most likely resulted in the burying of the calderas and could explain the difficulties in identifying them in the field

active normal faulting and crustal extension a world wide review of fault plane solutions and focal depths for large normal faulting earthquakes on the continents shows that the overwhelming majority of such earthquakes nucleate in the depth range 6 15 km on faults dipping between 30 and 60 in the few cases where levelling or seismic data are good enough these normal faults are shown to be approximately planar from the surface to their nucleation depth at the base of the brittle crust there is evidence that in some cases as a result of the enormous transitory increase in strain rate during large earthquakes rupture continues into the normally ductile lower crust on surfaces with substantially gentler dips these low angle surfaces may be analogous to some of the detachments seen in metamorphic core complexes of the western usa but the nature of the motion on them depends on strain rate as well as on rheological contrasts between the detachments and the blocks on either side such contrasts however are unlikely to introduce substantial curvature to an originally planar shear zone if the observed spread in active normal fault dips is caused by rotation of the faults and the blocks they bound during extension then a maximum value of 1 7 can be accommodated by seismic activity on a single generation of normal faults with continued extension either a new generation of steeper faults cutting the rotated first faults is likely to form or the deformation will continue aseismically on faults dipping at less than 30 large earthquakes have not been observed to nucleate on very low angle 20 normal faults within the continental crust anywhere in the world such faults can of course move aseismically but are unlikely to do so on a large scale within the upper crust in areas where steep normal faults are seismically active thus extensional models that require concentrated simple shear on large sub horizontal faults within the brittle upper crust will also require a spatial separation between aseismic very low angle faulting and seismic highangle faulting since seismogenic high angle faults dominate the topography of extending regions upper crustal very low angle faulting if it occurs on a large scale presumably does so in areas that are relatively fiat

late pleistocene intraplate extension of the central anatolian plateau turkey inferences from cosmogenic exposure dating of alluvial fan landslide and moraine surfaces along the ecemis fault zone here we documented the vertical displacement slip rate extension rate and geochronology of normal faults within a narrow strip along the main strand of the ecemis fault zone the kartal cevizlik and lorut faults are normal faults that have evident surface expression within the strip terrestrial cosmogenic nuclide geochronology revealed that the kartal fault deformed the 104 2 16 5 ka aged alluvial fan surface and the cevizlik fault deformed the 21 9 1 8 ka old moraine and talus fan surfaces our topographic surveys indicated 120 10 m and 13 1 1 4 m surface breaking vertical displacements along the kartal and cevizlik faults respectively accordingly we suggest a 1 15 0 21 mm a 1 slip rate and 0 66 0 12 mm a 1 extension rate for the last 104 2 16 5 ka on the kartal fault and a 0 60 0 08 mm a 1 slip rate and 0 35 0 05 mm a 1 extension rate for the last 21 9 1 8 ka on the cevizlik fault we believe that these structures are an integral part of intraplate crustal deformation in the central anatolia they imply that intraplate structures such as the ecemis fault zone may change their mode through time presently the ecemis fault zone has been deformed predominantly by normal faults the presence of steep preserved fault scarps along the kartal cevizlik and lorut faults point to surface breaking normal faulting away from the main strand and particularly signify that these structures need to be taken into account for regional seismic hazard assessments

emplacement of volcanic vents and geodynamics of central anatolia turkey abstract observations on synthetic aperture radar sar scenes of the european remote sensing ers satellite and digital elevation models dems complemented by field structural analysis permit a new understanding of relationships between tectonics and volcanism since the late miocene 10 ma in central anatolia volcanic edifices form elongate stratovolcanoes linear clusters and volcanic ridges they indicate emplacement on tension fractures and tail crack or horsetail features for instance the kara dag volcano is rooted on a tail crack which accommodates a horizontal left lateral throw component at a fault termination caldera complexes of cappadocia are associated with horsetail fault patterns the emplacement of volcanoes also benefits from larger scale tectonic structures the erciyes dag volcano is localized by the sultan saz releasing bend which opens along the sinistral strike slip ecemis fault deformation has been analysed from tension fractures which are perpendicular to the direction of extension and from field structural analysis on a regional scale the tectonic regime responsible for the distribution of volcanic vents in this area of convergence and lateral extrusion is not compression but extension the central taurus range is the thermally uplifted shoulder of the adana cilicia basin which is related to lithosphere thinning westward movements in the northwestern part of the studied area are influenced by the active back arc aegean extension situated to the west farther to the south the direction of motion turns southwest and south under the influence of the opening of the adana cilicia basin we interpreted that extension in the central anatolian plateau is related to crustal blocks moving above sub horizontal detachment surfaces located in the lower crust this is based on several facts the tuz golu fault zone is a within crust detachment the tuz golu basin does not affect the whole lithosphere because otherwise it would have been bordered by thermally uplifted shoulders movements change trend within a small 50 km region

tomographic pn velocity and anisotropy structure beneath the anatolian plateau eastern turkey and the surrounding regions an edited version of this paper was published by the american geophysical union agu copyright 2003 agu see also http www agu org pubs crossref 2003 2003gl017391 shtml http atlas geo cornell edu turkey publications al lazki et al 2003 htm

subduction evolution and mantle dynamics at a continental margin central north island new zealand 1 central north island new zealand provides an unusually complete geological and geophysical record of the onset and evolution of subduction at a continental margin whereas most subduction zones are innately two dimensional north island of new zealand displays a distinct three dimensional character in the back arc regions specifically we observe mariana type subduction in the back arc areas of central north island in the sense of back arc extension high heat flow prolific volcanism geothermal activity and active doming and exhumation of the solid surface evidence for emplacement of a significant percent of new lithosphere beneath the central north island comes from heat flux of 25 mw km of strike of volcanic zone and thinned crust underlain by rocks with a seismic wave speed consistent with underplated new crust seismic attenuation qp 1 is high 240 and rhyolitic and andesitic volcanism are widespread almost complete removal of mantle lithosphere is inferred here in pliocene times on the basis of the rock uplift history and upper mantle seismic velocities as low as 7 4 0 1 km s in contrast southwestern north island exhibits chilean type back arc activity in the sense of compressive tectonics reverse faulting low heat flow thickened lithosphere and strong coupling between the subducted and overriding plates this rapid switch from mariana type to chilean type subduction occurs despite the age of the subducted plate being constant under north island moreover stratigraphic evidence shows that processes that define the extensional back arc area the central volcanic region are advancing southward into the compressional system wanganui basin at about 10 mm yr we link the progression from one system to another to a gradual and viscous removal of thickened mantle lithosphere in the back arc regions thickening occurred during the miocene within the taranaki fault zone the process of thickening and convective removal is time and temperature dependent and has left an imprint in both the geological record and geophysical properties of central north island which we document and describe

curie point depth investigation of central anatolia turkey the residual aeromagnetic total field intensity anomalies in central anatolia were calculated from the regional aeromagnetic anomalies surveyed by the mineral research and exploration mta of turkey the residual aeromagnetic data were analyzed to produce curie point estimates by the method of okubo et al 1985 the curie point depth of central anatolia varies from 7 9 km and 22 6 km the shallowest curie point depths were observed around the cappadocia and erciyes volcanic complexes in central anatolia a good correlation was deduced between the curie point depths and the heat flow data measured previously which is most certainly important for the geothermal resources of the region the shallow curie point depths also correlate well with the hot spring locations in central anatolia

on the geodynamics of the aegean rift abstract the aegean rift is considered to be either a classic backarc basin or the result of the westward escape of anatolia or the effect of a gravitational collapse of an over thickened lithosphere here these models are questioned we alternatively present a number of geodynamic and magmatic constraints suggesting a simple model for the genesis of the extension as being related to the differential advancement of the upper lithosphere over a heterogeneous lower african plate the greek microplate overrides the ionian oceanic segment of the african plate faster than the anatolian microplate over the thicker levantine more continental segment this setting is evidenced by gps velocity gradient in the hangingwall of the hellenic cyprus subduction system and requires a zone of rifting splitting the hangingwall into two microplates this mechanism is unrelated to the replacement of retreated slab by the asthenosphere as typically occurs in the backarc of west directed subduction zones the supposed greater dehydration of the ionian segment of the slab is providing a larger amount of fluids into the low velocity channel at the top of the asthenosphere allowing a faster decoupling between the greek microplate and the underlying mantle with respect to the anatolian microplate slab ruptures associated with the differential retreat controlled by the inherited lithospheric heterogeneities in the lower plate and the proposed upwelling of the mantle suggested by global circulation models would explain the occurrence and coexistence of slab related and slab unrelated magmatism

curie point depths of the island of kyushu and surrounding areas japan as part of a comprehensive nationwide evaluation of geothermal resources for japan the first of the curie point depth maps covering the island of kyushu has been prepared the map was created by inverting gridded regional aeromagnetic data two satisfactory algorithms were developed to invert the gridded data based upon a distribution of point dipoles the first algorithm estimates x0 y0 and z0 the coordinates of the centroid of the distribution by computing a least squares fit to the radial frequency of the fourier transform the second algorithm estimates centroid depth only by computing a least squares fit to the squared amplitude of the frequency estimates the average depth to the top zt of the collection of point dipoles was estimated by a variation of the second algorithm the depth to the bottom of the dipoles inferred curie point depth is zb 2z0 zt the depth estimates are hand contoured to produce the final map the curie point depth map is then compared to regional geology and heat

a new intracontinental transcurrent structure the central anatolian fault zone turkey abstract recent neotectonic studies including remote sensing aerial photographs geological field mapping on various scales and measured stratigraphic section substantiate the existence of a large sinistral intracontinental transcurrent structure which we call the central anatolian fault zone cafz this is an approximately 730 km long 2 km to 80 km wide ne trending active sinistral strike slip fault zone that cuts across the anatolian plateau between duzyayla in the northeast and anamur county in the southwest it continues onward beneath the eastern mediterranean sea and determines the boundary of the antalya and adana basins as far as to the west of cyprus the cafz is a very young neotectonic structure it resulted from the reactivation and propagation of an older paleotectonic structure the so called ecemi s corridor in both nne and sw directions across the inner tauride suture in the plio quaternary times based on geometric discontinuities the cafz is divided into 24 segments each of them is characterized by a number of strike slip morphotectonic features reflecting recent motions the easternmost part of the anatolian platelet is being deformed internally by several dextral to sinistral intraplate strike slip faults these are the lake salt fault zone lsfz the salanda fault sf the cafz the goksu yazyurdu fault zone gyfz and the malatya ovacik fault zone mofz they take up lesser motion and are younger than boundary faults of the anatolian platelet the gyfz and mofz splay from the natf cut across the anatolian platelet and then meet to the eatf whereas other faults are confined into the anatolian platelet and seem to be independent structures however present day structural pattern of all these intraplate faults and boundary faults of the anatolian platelet indicates a regional strain pattern of nnw sse directed shortening and ene wsw directed extension and they seem to have developed to accommodate northward motion of the arabian plate since late early pliocene times

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

tectonic controls on metamorphism partial melting and intrusion timing and duration of regional metamorphism and magmatism in the nigde massif turkey protracted heating and melting of orogenic middle crust followed by emplacement of a syn extensional pluton during decompression and cooling are demonstrated for a metamorphic core complex in central turkey new geochronologic data for the nigde massif of the central anatolian crystalline complex document an interval of melting crystallization and pb loss at elevated ambient temperature 85 92 ma determined by u pb shrimp within a single sample of peraluminous granite crustal melting was syn to post peak metamorphism 725 c dated at 91 0 2 0 ma by shrimp analysis of zircon rims in sillimanite schist that is part of the country rock to the pluton metamorphic monazite in sillimanite schist yields a younger age of 84 7 0 7 ma for matrix grains and inclusions in garnet hornblende 40ar 39ar ages from amphibolites interlayered with the sillimanite schists coincide with the timing of emplacement of magma into metamorphic country rock that had experienced cooling and decompression to 12 km and 550 c the similarity of 40ar 39ar ages for biotite in the pluton 79 ma and hornblende 79 81 ma biotite 74 76 ma and muscovite 78 83 ma in the metamorphic country rock document rapid cooling 100 c my following intrusion the coincidence of the youngest u pb magmatic zircon ages and the oldest 40ar 39ar ages combined with structural evidence for normal sense shearing and tectonic unroofing in the late cretaceous suggests that intrusion was driven by extension we propose that crustal melting occurred in the middle crust during prograde metamorphism and or initial decompression and that ascent and emplacement of magma as a pluton were only triggered once extension occurred and removed upper crustal rocks

effects of margin parallel shortening and density contrasts on back arc extension during subduction experimental insights and possible application to anatolia so as to investigate the parameters influencing subduction and back arc extension we have done three series of laboratory experiments 32 in all on physical models each model consisted of adjacent oceanic and continental plates floating on an asthenosphere in experiments of series a a wide rigid piston moving horizontally controlled the rate of convergence of the oceanic and continental plates whereas in series b or c a wide or narrow piston produced lateral compression parallel to the continent ocean boundary cob and perpendicular to the subduction direction the parameters that we tested were 1 the velocity of plate convergence series a 2 the width of the compressing piston series b and c and 3 the density ratio between oceanic and continental plates series b and c this density ratio was a key factor for a ratio of 1 4 the amount of extension in the continental plate increased regularly throughout time for a ratio of 1 3 the extension remained small until the piston stopped moving laterally and for a ratio of 1 1 there was little or no extension the width of the compressing piston had a smaller effect although a narrow piston provided more space into which the continental plate could extend one possible application of our models is to anatolia despite similar geological settings the areas north of the hellenic and cyprus subduction zones differ in that extension is large in the former and much smaller in the latter we suggest that one of the main driving forces for aegean extension may have been a high density ratio between subducting oceanic lithosphere and a hellenic balkanic upper plate

core complex development in central anatolia turkey tectonic models for the central anatolian segment of the alpine himalayan orogen have not considered this region as part of the aegean extensional province we have found evidence however for oligocene miocene extension and exhumation of midcrustal rocks in a metamorphic dome nigde massif that is structurally and petrologically similar to miocene core complexes 500 km to the west strong correspondence in the timing and kinematic development of the menderes western turkey and nigde core complexes suggests that extensional tectonics and exhumation of mid to lower crustal rocks affected much of the eastern mediterranean region in the nigde massif supracrustal rocks were buried to depths of 16 20 km at high temperatures 700 c during contraction associated with closure of neo tethyan seaways in late mesozoic early cenozoic time following cooling and decompression to 600 c and 10 km metasedimentary rocks underwent a second heating event at low pressures during miocene magmatism that postdated much of the unroofing of the massif development of the nigde core complex was related to exhumation of thickened and thermally weakened continental crust in the upper plate of a north dipping subduction zone the partial subduction of the tauride carbonate platform in the eocene resulted in choking of the subduction zone followed by isostatic rebound and exhumation of the buoyant platform this in turn caused a rapid emergence of the upper plate resulting in erosion of upper crustal rocks and exhumation of midcrustal rocks along the northern edge of the inner tauride suture zone although northern regions of central anatolia contain the same protoliths as the nigde massif and underwent extensive tertiary magmatism they did not undergo similar extension suggesting that core complex development in south central turkey was controlled by the location of thickened and thermally weakened crust adjacent to a suture zone

tectonomagmatic evolution of cenozoic extension in the north american cordillera the spatial and temporal distributions of cenozoic extension and magmatism in the cordillera suggest that the onset of major crustal extension at a particular latitude was confined to a relatively narrow belt 100 km pre extension and followed the onset of intermediate and silicic magmatism by no more than a few million years extension began in early eocene time in southern british columbia northern washington idaho and montana farther s extension began at about the eocene oligocene boundary in the great basin and slightly later in the mojave sonora desert region the intervening area at the latitude of las vegas remained quiescent until mid miocene time compositional and isotopic characteristics of most pre miocene magmas are consistent with their containing major components of melted continental crust in mid miocene time two major changes occurred widening of the area of extension and the widespread appearance of basaltic magmas the area affected by extension from southwestern montana to the lake mead region widened to several hundred kilometres by this time extension in southern british columbia northern washington and northern montana had ceased probably before the end of the eocene and extension s of lake mead except in the gulf of california had waned regions affected by the broader belt of extension during late miocene pliocene and quaternary time experienced basaltic magmatism which began along a central rift zone in the northern part of the region and which had within a few million years spread to include most of the region later basaltic activity has tended to concentrate in restricted zones especially near the margins of the extended area we recognize a correlation between the amount of earlier crustal thickening and cenozoic extension and between the length of time after shortening but before extension and the degree to which a given region was intruded by late cretaceous plutons the localization of extension in areas of previous crustal thickening and the dependence of the timing of extension on the thermal state of the overthickened crust is consistent with a simple thermal mechanical model developed in a companion paper sonder et al this raises the possibility that stresses inherent in the north american plate dominated over plate interaction forces as controls of the cenozoic tectonomagmatic evolution of the north american cordillera especially in its earlier stages

sn attenuation in the anatolian and iranian plateau and surrounding regions an edited version of this paper was published in geophysical research letters by the american geophysical union agu copyright 2003 agu see also http www agu org pubs crossref 2003 2003gl018020 shtml http atlas geo cornell edu turkey publications gok et al 2003 htm

active tectonics of the alpine himalayan belt between western turkey and pakistan summary over 80 new fault plane solutions combined with satellite imagery as well as both modern and historical observations of earthquake faulting are used to investigate the active tectonics of the middle east between western turkey and pakistan the deformation of the western part of this region is dominated by the movement of continental material laterally away from the lake van region in eastern turkey this movement helps to avoid crustal thickening in the van region and allows some of the shortening between arabia and eurasia to be taken up by the thrusting of continental material over oceanic type basement in the southern caspian mediterranean makran and black sea thus central turkey bounded by the north and east anatolian strike slip faults is moving west from the van region and overrides the eastern mediterranean at two intermediate depth seismic zones one extending between antalya bay and southern cyprus and the other further west in the hellenic trench the motion of northern iran eastwards from the van region is achieved mainly by a conjugate system of strike slip faults and leads to the low angle thrusting of iran over the southern caspian sea the seismicity of the caucasus shows predominantly shortening perpendicular to the regional strike but there is also some minor elongation along the strike of the belt as the causcasus overrides the caspian and black seas the deformation of the eastern part of this region is dominated by the shortening of iran against the stable borders of turkmenistan and afghanistan the north east direction of compression seen in zagros is also seen in north east iran and the kopet dag where the shortening is taken up by a combination of strike slip and thrust faulting large structural as well as palaeomagnetic rotations are likely to have occurred in ne iran as a result of this style of deformation north south strike slip faults in southern iran allow some movement of material away from the collision zone in ne iran towards the makran subduction zone where genuinely intermediate depth seismicity is seen within this broad deforming belt large areas such as central turkey nw iran azerbaijan central iran and the southern caspian appear to be almost aseismic and therefore to behave as relatively rigid blocks surrounded by active belts 200 300 km wide the motion of these blocks can usefully be described by poles of rotation the poles presented in this paper predict motions consistent with those observed and also predict the opening of the gulf of iskenderun ne of cyprus the change within the zagros mountains from strike slip faulting in the nw to intense thrusting in the se and the relatively feeble seismicity in se iran baluchistan this description also explains why the north south structures along the iran afghanistan border do not cut the east west ranges of the makran within the active belts surrounding the relatively aseismic blocks a continuum approach is needed for a description of the deformation even though motions at the surface may be concentrated on faults the evolution of fault systems within the active zones is controlled by geometric constraints such as the requirement that simultaneously active faults do not in general intersect many of the active processes discussed in this paper particularly large scale rotations and lateral movement along the regional strike are likely to have caused substantial complexities in older mountain belts and should be accounted for in any reconstructions of them

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

proterozoic paleomagnetism in the nipigon embayment of northern ontario pillar lake lava waweig troctolite and gunflint formation tuffs abstract by using unusual combinations of demagnetization techniques proterozoic paleomagnetic vectors and paleopoles are provided for two recently discovered post tectonic proterozoic units near armstrong northern ontario and also for well dated gunflint formation which by previous techniques yielded problematical paleomagnetic data the first paleomagnetic data are provided also for the seagull pluton and inspiration sills characteristic remanent magnetizations chrm for the pillar lake lavas indicate a keweenawan age more specifically 1000 1040 ma by comparison with the well established apwp for the late proterozoic superior craton four combinations of demagnetization techniques yield declinations in the range 108 133 and inclinations in the range 65 to 70 n 100 which define paleopoles near 200 w 48 n corresponding to a location on the keweenawan apwp near 1040 ma in the underlying basement a recently discovered proterozoic igneous complex the waweig troctolitic complex yields new paleomagnetic data with declination and inclination 42 54 n 14 defining a paleopole at 238 w 09 n its ages may be 1400 1600 or 2000 ma by comparison with the presently available ambiguous and sparsely populated apwp the first paleomagnetic results for the seagull pluton u pb age 1113 ma yield a mean declination of 87 4 75 7 n 32 corresponding to a keweenawan paleopole near 233 42 n consistent with other paleopoles near 1200 ma tuffs of the oft studied but problematical gunflint formation u pb age1878 ma yielded stable and presumably primary vectors using several different demagnetization techniques on the same specimens their mean primary declination and inclination 303 48 8 n 17 yields a paleopole now located near 178 w 42 n comparable with the published locations of paleopoles of 2000 ma of broader interest we recognized that low temperature demagnetization preceding conventional demagnetization techniques enhanced the isolation of characteristic vectors combining the conventional techniques thermal and af demagnetization also improved the resolution of characteristic vectors not achieved by other means low grade metamorphism affected the non tectonized proterozoic cover to the canadian shield due to burial or hydrothermal effects obfuscating or erasing primary vectors in some lithologies and especially at certain sites

low angle normal faults and seismicity a review although large low angle normal faults in the continental crust are widely recognized doubts persist that they either initiate or slip at shallow dips 30 because 1 global compilations of normal fault focal mechanisms show only a small fraction of events with either nodal plane dipping less than 30 and 2 andersonian fault mechanics predict that normal faults dipping less than 30 cannot slip geological reconstructions thermochronology paleomagnetic studies and seismic reflection profiles mainly published in the last 5 years reinforce the view that active low angle normal faulting in the brittle crust is widespread underscoring the paradox of the seismicity data for dip slip faults large enough to break the entire brittle layer during earthquakes m w 6 5 consideration of their surface area and efficiency in accommodating extension as a function of dip suggests average recurrence intervals of earthquakes r tan assuming stress drop rigidity modulus and thickness of the seismogenic layer do not vary systematically with dip if the global distribution of fault dip normalized to total fault length is uniform the global recurrence of earthquakes as a function of dip is shown to be r tan sin this relationship predicts that the frequency of earthquakes with nodal planes dipping between 30 and 60 will exceed those with planes shallower than 30 by a factor of 10 in good agreement with continental seismicity assuming major normal faults dipping more than 60 are relatively uncommon revision of andersonian fault mechanics to include rotation of the stress axes with depth perhaps as a result of deep crustal shear against the brittle layer would explain both the common occurrence of low angle faults and the lack of large faults dipping more than 60 if correct this resolution of the paradox may indicate significant seismic hazard from large low angle normal faults

new sedimentological and structural data from the ecemis fault zone southern turkey implications for its timing and offset and the cenozoic tectonic escape of anatolia fig 1 map of the cukurba abg demirkazik area adapted from cetin 2000 fig 6 tcu is the

geochemistry and geochronology of meta igneous rocks from the tokat massif north central turkey implications for tethyan reconstructions located in the eastern pontides of the sakarya zone in north central turkey the tokat massif records the closure of both the paleo tethyan karakaya complex and neo tethyan ocean basins meta igneous samples collected from the region were studied to determine their sources and ages we find significant geochemical differences between metagabbros of the karakaya and neo tethyan units in terms of their trace elements neo tethyan rocks are consistent with generation in an island arc setting whereas karakaya assemblages were likely generated in an oceanic spreading center environment karakaya metagabbros also contain glaucophane consistent with subduction subsequent to formation small 2 50 m zircon and baddeleyite grains from four karakaya metagabbros were dated in thin section using an ion microprobe the results demonstrate the reliability of the method to directly constrain the tectonomagmatic history of these types of assemblages the rocks yield late permian early triassic 238u 206pb crystallization ages of 258 14 ma 1 zircon and 254 8 ma 1 baddeleyite and an early cretaceous minimum metamorphic age of 137 8 ma 1 zircon some zircon grains and baddeleyite grains with zircon overgrowths yield early to middle jurassic ages here we present a model in which metamorphism and deformation in this region occurred during northward subduction and closure of a paleo tethyan ocean basin and accretion of the karakaya units to the laurasian continental margin this was followed by the onset of closure of the neo tethys during the campanian paleocene and accretion of island arc units to the tokat region

convergence and extension driven by lithospheric gravitational instability evolution of the alpine carpathian pannonian system summary lithospheric gravitational instability may play a significant role in the neogene alpine carpathian pannonian system where the extensional pannonian basin formed over a 10 myr period simultaneously with contraction in the surrounding alpine and carpathian orogens we investigate the idea that gravitational collapse of low density crust previously thickened in the collision of the european plate with adria has caused the simultaneous development of depth variable lithospheric thinning beneath the pannonian basin and contractional deformation in the carpathian arc implicit in this model is asthenospheric upwelling beneath the basin and lithospheric downwelling beneath the surrounding mountains we investigate the interplay between convergence and extension in this type of continental orogen using 2 d axisymmetric finite element models we show how key model parameters such as crust to lithosphere thickness and viscosity ratios affect the evolution of the system an initially thicker lithosphere enhances mantle instability and leads to a greater degree of thinning of the crust and lithospheric mantle and stronger downwelling in the mantle increasing the viscosity of the crust relative to the mantle slows the growth of the instability and reduces crustal deformation relatively low crustal viscosity however implies too rapid a collapse of initial topography and rapid re equilibration after deformation induced by mantle flow non newtonian viscosity localizes the deformation in a narrower spatial region and a shorter time interval following a relatively slower phase of initial growth in the alpine carpathian pannonian system development of the instability requires lithospheric thickness prior to extension on the order of 150 km and lithospheric mantle viscosity on the order of 2 10 20 pa s with crustal strength similar to that of the mantle

comment on late cretaceous extensional denudation along a marble detachment fault zone in the kirsehir massif near kaman central turkey by c lefebvre et al 2011 doi 10 1016 j jsg 2011 06 002

one dimensional models of shear wave velocity for the eastern mediterranean obtained from the inversion of rayleigh wave phase velocities and tectonic implications summary on a sw ne profile from the libyan coast towards central turkey phase velocity curves of the fundamental rayleigh mode were measured using a two station method the inversion of phase velocity curves yields 1 d models of shear wave velocity down to approximately 200 km depths that may be interpreted as estimates of average models between neighbouring stations on the profile strong lateral variations in the shear wave velocity structure are imaged along the profile the subducted oceanic african mantle lithosphere is indicated in 1 d models for the region around crete by significantly enlarged shear wave velocities it is also imaged by an average model of the structure between stations on crete and santorini on a path crossing the libyan sea south of crete the resulting model is slower than a model expected for 110 myr old oceanic lithosphere the passive african margin is thus assumed to extend northwards beneath the libyan sea anomalous low shear wave velocities are found for the uppermost mantle beneath central turkey down to a depth of approximately 130 km using two stations on crete the average depth of the oceanic moho within the subducting slab is estimated to be at approximately 50 km beneath crete for this arc parallel path an enlarged standard deviation of the measured phase velocities of approximately 0 2 km s 1 between 10 and 30 mhz is observed that is probably caused by strong lateral heterogeneity related to the subducting slab in addition in this frequency range an anomalous propagation of the fundamental rayleigh mode is detected that is indicated by measured phase velocities that are approximately one standard deviation faster than phase velocities expected from a great circle approximation an average shear wave velocity of approximately 3 5 km s 1 is observed above the oceanic moho in order to explain the recent lithospheric structure of the hellenic subduction zone a tectonic model is assumed for the ne sw striking profile considered it is based on the calculated 1 d models tectonic reconstructions and on a model derived from the metamorphic history of rocks exposed on crete the suggested model summarizes the tectonic development at a lithospheric scale starting in the late cretaceous accretion of crustal material of two microcontinents to eurasia is assumed while continuous subduction of the oceanic lithosphere of different ocean basins and possibly of the mantle lithosphere of the microcontinents resulted in a single slab the length of the oceanic lithosphere that was subducted south of crete is estimated to be not greater than approximately 550 km

curie point depth map of turkey summary a curie point isotherm map of the whole of turkey has been prepared from aeromagnetic data by means of a spectral analysis technique the most characteristic signature of this map is that the shallow depths generally correlated with the young volcanic rocks and the thinned crustal thicknesses in the west reveal geothermal fields and several hot springs the orogenic pontide belt of the black sea region in the north the western taurus belt in the south and some high plateaus in eastern turkey show that the deepest curie isotherm depths range between 20 and 29 km depth contour lines elongating in an almost e w direction are due to the overlapping percentage of adjacent data blocks of 50 per cent in the e w direction and to magnetic anomalies trending in the e w direction curie isotherm depths are in the range 6 to 10 km in the aegean region and are characterized by e w and ne sw trending graben structures as expected since the region has crustal thinning and many hot springs and geothermal fields these imply the existence of shallow heat sources that could be utilized for electricity heating of towns and cities greenhouse and health purposes

coeval extension and compression in late mesozoic recent thin skinned extensional tectonics in central anatolia turkey abstract the central anatolian crust is composed of high grade metamorphic rocks covered by tertiary shallow marine to continental sedimentary rocks with a middle miocene recent volcanic activity in cappadocia after the late cretaceous closure of the tethyan ocean and following plate collision core complexes formed in nigde and kirsehir regions of central anatolia recent geophysical studies indicate the presence of low seismic velocity zones beneath central anatolia interpreted as regionally thinned and or hot mantle lithosphere or asthenospheric upwelling we present new structural data covering a 300 km wsw nne trending transect between konya and yozgat cities to suggest that central anatolian cenozoic tectonic regime is extensional and the narrow fold thrust zones once taken as evidence of crustal convergence resulted from gravitational movements curie point depths map of central anatolia shows a large scale diameter 140 km upwarping c 15 km of the regional crust we interpret as due to asthenospheric upwelling these considerations suggest that 1 the central anatolian crust deforms by extension transcurrent faults like the central anatolian fault zone accommodate the crustal stretching by transfer faulting 2 post late cretaceous crustal extension favored the placement of hot and low density asthenospheric material in cappadocia by processes that may be explained by rayleigh taylor instability phenomenon 3 in central anatolia large post eocene horizontal crustal displacements we estimate a minimum of 50 km are not achieved by crustal contraction as previously proposed but thin skin extensional tectonics and 4 tethyan suture lines need to be reviewed since their traces may be modified by later extensional displacements

reconstructing the geometry of central anatolia during the late cretaceous large scale cenozoic rotations and deformation between the pontides and taurides the central anatolian crystalline complex cacc exposes metamorphic ophiolitic and igneous rocks that were formed and deformed during closure of the neotethyan ocean the cacc is located in central turkey between the pontides in the north and the taurides in the south separated by major fault zones composite plutons intruded the meta sedimentary and ophiolitic units between 95 and 75 ma and form linear magmatic belts 100 km long along the western and northern margins of the cacc exhumation of the metamorphic and igneous complex was finalized by the paleocene time in this study we paleomagnetically study fifteen plutons spanning the entire non deformed upper cretaceous granitoid belt to test whether the initial configuration of the cacc was modified by vertical axis rotations after its exhumation our results show three internally coherent domains with significantly different vertical axis rotations 1 in the north east the akda block ayb records 151

coeval extensional shearing and lateral underflow during late cretaceous core complex development in the nigde massif central anatolia turkey 1 the nigde massif at the southern tip of the central anatolian crystalline complex consists of two structural units foliations in the lower unit define a dome cored by migmatites the contact between the two units bears all the elements of a ductile to brittle extensional detachment hence the nigde massif represents an extensional metamorphic core complex top to ne ene shearing at higher levels of the lower unit relates to displacement along the detachment deeper levels of the lower unit display high temperature top to ssw ductile shearing the two shearing deformations show a difference in the mean trend of stretching lineations of up to 58 new 40ar 39ar ages combined with previously published data enable us to infer that the two shears were contemporaneous in our favored interpretation oblique shearing in the core of the dome reflects lateral underflow i e horizontal flowing of the lower crust in a direction highly oblique to the direction of extension as a result of the interaction between lateral underflow and downdip shearing along the overlying detachment distinct structural domains are expected to exist within the migmatitic part of the core complex with observed counterparts in the nigde dome lateral underflow may reflect inward flow on the scale of the core complex regional scale channel flow is an alternative that would better account for the record of non coaxial deformation in the core of the dome more generally we suspect that the development of lateral underflow in a metamorphic core complex more likely reflects regional channel flow rather than local inward flow

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

thermal constraints on the tectonic evolution of a metamorphic core complex santa catalina mountains arizona abstract we present an analysis of the thermal evolution of the metamorphic core complex of the santa catalina rincon and tortolita mountains in south arizona the structural and kinematic data are briefly reviewed granite mylonites result from three successive shearing events respectively compressional top west during paleocene and top ne during mid eocene and extensional top sw after eocene in a preliminary part of the paper available radiometric data are reviewed in detail for both deformed and undeformed granites with closing temperatures from 565 to 105 c these data are then used to constrain the temperature history for three intrusions which were emplaced respectively during paleocene eocene and miocene times the general temperature time curve shows 1 rapid cooling for the three intrusions just after emplacement and 2 a large and rapid cooling of the entire complex between 35 and 22 ma from 530 to 100 c in the final part this thermal history is used to constrain the tectonic history of the metamorphic core complex the thermal effects of erosion tectonic denudation homogeneous and heterogeneous thinning are computed using a finite difference scheme in one dimension an analysis of the parameters involved in the models shows that the crust of the santa catalina metamorphic core complex has undergone mainly a thinning of its upper part of at least 15 km and more reasonably 20 25 km in less than 10 ma this estimation is discussed considering thermal effects of magmatism