oxygen and carbon isotope record of east pacific core v19 30 implications for the formation of deep water in the late pleistocene north atlantic abstract a detailed oxygen and carbon isotope record has been obtained from benthic foraminifera in core v19 30 from the carnegie ridge on the south side of the panama basin expressing these records and the oxygen and carbon isotope records previously published for atlantic core m 12392 on a common timescale it is apparent that the oxygen isotope records are very similar but that the carbon isotope records are quite different by obtaining the carbon isotope gradient between the two sites as a function of time we show that the production of north atlantic deep water has varied over a wide range during the late pleistocene and that the pattern of variation is not simply related to the well known oxygen isotope record although the two oxygen isotope records are very similar changes in the interoceanic gradient are detectable and support the hypothesis that in the glacial mode the north atlantic was colder and less oxygenated than it is today shackleton s 1 1977 interpretation whereby the carbon isotope record from the atlantic core reflects changes in the terrestrial biomass is an over simplification however the record from the pacific core v19 30 probably can be explained in these terms since it probably approximates the carbon isotope record of global mean oceanic dissolved co 2

new results and a palaeomagnetic overview of the pontides in northern turkey summary palaeomagnetic results are reported from 16 sites within volcanic and volcano sedimentary rocks of cretaceous and eocene age from the central pontides in northern turkey the sampled area is bounded by the north anatolian fault naf to the south and the black sea to the north the palaeomagnetic data collected demonstrate the presence of both non rotated and anticlockwise rotated regions i declination directions including lower upper cretaceous and eocene sites do not indicate any significant rotations north of where the naf exhibits an arcuate shape ii 20 anticlockwise rotation was observed in the sinop peninsula the northernmost extremity of the central pontides iii in the west of the central pontides two sites with normal and reversed antipodal directions indicate a 20 anticlockwise rotation and iv another region lies to the east of the study area and shows a rotation in an anticlockwise sense of about 5 30 the upper cretaceous and eocene directions reported in this paper and other palaeomagnetic studies show that there is not much difference between the inclination values of the upper cretaceous i 40 1 95 7 2 and the eocene sites i 39 6 95 8 1 furthermore the values of the inclination available from both sedimentary and volcanic upper jurassic lower cretaceous formations are shallower than the upper cretaceous ones this suggests that the entire pontides have undergone a northward drift of over 2000 km since the upper jurassic

examining the ladinian crisis in light of the current knowledge of the triassic biodiversity changes abstract several mass extinctions are known from the history of life but knowledge about minor biotic crises remains incomplete the ladinian is the second stage of the middle triassic epoch available reconstructions of the diversity dynamics of fossil organisms across the entire triassic allow the proposed ladinian biotic crisis to be investigated total biodiversity curves both the conventional curve and that based on sampling standardization fail to identify the crisis but this may be explained by low resolution data or noise in fact the global generic diversity of ammonoids brachiopods and tetrapods declined significantly by 1 1 2 5 times during the ladinian as did the species diversity of conodonts bivalves radiated but their origination rate also decreased during the ladinian land plants were apparently unaffected based on the representative regional record for the northwestern caucasus the number of macroinvertebrate genera dropped by 7 5 times and brachiopods almost totally disappeared foraminifers were also affected significantly thus the proposed biotic crisis appears to have been selective it appears the ladinian biotic crisis was a relatively long term event and its magnitude is comparable to that of other minor mass extinctions e g those of the silurian early jurassic or end cenomanian there are several possible explanations for what caused the ladinian biotic crisis it is possible that global climate cooling was responsible although it is unclear why the palaeobiogeographical differentiation was not favourable for a biotic radiation a eustatic explanation for the drop in diversity is unlikely instead the crisis was mostly likely caused by unstable recovery of the earth s biota after the end permian catastrophe

slip along the sultanhani fault in central anatolia from deformed pleistocene shorelines of palaeo lake konya and implications for seismic hazards in low strain regions

end permian extinction and subsequent recovery of the ophiuroidea echinodermata a worldwide stratigraphical survey of late palaeozoic and early mesozoic ophiuroids echinodermata reveals unique extinction and recovery patterns during and after the end permian mass extinction event the ophiuroidea suffered the loss of all palaeozoic genera however this clade profited greatly from the event by undergoing a significant increase in species number in the postextinction oceans although both sampling and taphonomic biases may have affected ophiuroid diversity changeover patterns across the permian triassic p tr transition to some extent both biases cannot explain adequately the abrupt increase in species numbers and geographically wide distributions of ophiuroids in the early triassic oceans the ophiuroidea recovery follows erwin s model of a logistic increase in diversity beginning immediately after the end of the mass extinction without the survival interval morphological innovation i e emergence of advanced canal systems diversification of life habitats and biogeographical dispersal over the palaeotethyan and gondwanan regions enabled the ophiuroidea to occupy efficiently vacant ecospace created by the end permian extinction enabling the clade to recover and radiate in the early triassic oceans previously reported ophiuroids from the upper permian to lower triassic of china are also taxonomically revised these ophiaulaxoides bijieensis feng huangzhishania gulinensis feng ophiolepis shanxiensis yang and ophioderma schistovertebrata yang were described from the lower triassic while aganaster qingchangensis feng and syntomospina kaiyangensis feng came from the upper permian

palaeomagnetic and geochronological evidence for a major middle miocene unconformity in soke basin western anatolia and its tectonic implications for the aegean region cenozoic convergence between the eurasian and african plates and concurrent slab roll back processes have produced a progressive extension in back arc areas such as the aegean region and western anatolia there is still a long standing controversy as to whether this was a continuous or stepwise process to shed light on this controversy and on the driving mechanism of regional extension we present palaeomagnetic and geochronological results from the soke basin located at the southeastern rim of the izmir balikesir transfer zone our improved geochronology shows that volcanic activity in the region occurred between 11 66 and 12 85 ma middle to late miocene palaeomagnetic data for the soke basin show a c 23 clockwise rotation whereas early miocene data show a c 28 counterclockwise rotation the primary nature of the magnetization is indicated by a positive tilt test the resulting c 51 counterclockwise rotations during the middle miocene signify a major tectonic reorganization during a period when an interruption of exhumation of metamorphic massifs has been reported we suggest that the izmir balikesir transfer zone is the main driver of the reorganization in the region the regional fingerprint of this tectonic reorganization coincides with the acceleration of trench retreat and illustrates the surface impact of tearing of the hellenic slab supplementary material details of 40 ar 39 ar analysis including heating steps and the output pmag file including details of paleomagnetic analysis performed in this study are available at https doi org 10 6084 m9 figshare c 3690871

error analysis for the determination of tectonic rotation from paleomagnetic data appendix b is available with entire article on microfiche order from american geophysical union 2000 florida avenue n w washington d c 20009 document b83 001 2 50 payment must accompany order recent determinations of tectonic rotation and flattening from paleomagnetic data have exaggerated the size of the confidence limits or error bars by about 25 this has been caused by the misuse of conventional error propagation formulas to derive one degree of freedom error bars from a two dimensional cone of confidence 95 an analytical calculation which is valid when error bars are small shows that the correct error bars are 75 to 80 of the values derived in previous studies i have used numerical integration to check on the applicability of the analytical solution and to calculate error bars when the analytical approximation cannot be used the analytical approximation may be used whenever 95 is less than 10 and the mean inclination is not too close to vertical confidence limits given for tectonic rotation and flattening in recent literature are too large and should be reduced by 20 25 narrowing the error bars in this way permits a more accurate interpretation of paleomagnetic data

role of deep sea temperature in the carbon cycle during the last glacial 1 to characterize the response of earth s climate system to increases in atmospheric co2 climate modelers define climate sensitivity as the change in global mean temperature in response to prescribed forcing here we turn this approach around and use estimates of ocean temperature change to investigate the mechanisms driving co2 variations over the last glacial new records provide evidence of a link between deep ocean temperature and atmospheric co2 over the last glacial cycle two mechanisms simultaneously couple pco2 and deep ocean temperature the temperature dependent solubility of co2 in seawater and the atmospheric co2 dependent radiative forcing of temperature each of these forcing mechanisms leaves a unique slope of covariation between co2 and deep ocean temperature which we estimate using numerical models of climate and the carbon cycle the pco2 t slopes derived from paleoclimate data differ between the deglaciation and shorter 5 kyr duration events in marine isotope stage 3 mis 3 revealing different mechanisms driving atmospheric co2 variability the amplitude of changes over the deglaciation coincides with estimates for co2 forcing of temperature however co2 changes during mis 3 can be explained solely by temperature dependent solubility driving variations in atmospheric pco2 the deep water temperature changes during mis 3 may reflect changes in the temperature or relative contribution of antarctic bottom water and play a role in the bipolar seesaw

palaeoenvironments and faunal recovery after the end permian mass extinction abstract strata of the lower triassic werfen formation dolomites northern italy record deposition in a wide range of palaeoenvironments from peritidal to outer ramp settings this enables accurate assessment of faunal recovery following the end permian mass extinction by eliminating facies related effects extinction of the shelly taxa appears to be rapid and occurs in the latest permian tesero oolite horizon disappearance of the various trace fossil taxa appears to be more gradual following the extinction the lower and middle griesbachian are characterised by laminated sediments containing low diversity bedding plane assemblages ichnological geochemical and sedimentological data show evidence of widespread low oxygen conditions normally oxygenated waters return in the late griesbachian and there is a moderate increase in tiering above and below the surface macrofaunal and ichnofossil diversity decrease markedly during the smithian with the appearance of more terrigenous strata possibly reflecting an increased run off and more brackish conditions complete recovery begins in the basal spathian with an increase in tiering above and below the substrate crinoids and ammonoids appear for the first time in the werfen formation and the ichnogenus rhizocorallium re appears global correlation is hindered by poor biostratigraphy in the dolomites region however on a broad scale it appears as though many of the palaeoenvironmental changes are repeated worldwide current available data suggest that the re appearance of some trace fossil taxa e g diplocraterion rhizocorallium may be globally synchronous

palaeomagnetic study of the karaman and karapinar volcanic complexes central turkey neotectonic rotation in the south central sector of the anatolian block abstract in the anatolian sector of the afro eurasian collision zone a palaeotectonic collisional phase paleocene to miocene responsible for emplacement of the pontide and tauride orogens has been replaced by a neotectonic phase of continental deformation late miocene early pliocene to recent the latter phase appears to have been accommodated mainly by crustal thickening during late miocene and pliocene times but was succeeded by complex differential rotations of fault blocks during crustal extrusion in late pliocene and quaternary times in this study we have investigated palaeomagnetism of miocene recent volcanic rocks comprising the western extension of the central anatolian volcanic province located in the south central part of the anatolian block with the aim of resolving deformations near to the border with the tauride orogen rock magnetic investigations identify low ti magnetite assemblages of primary cooling related origin these have predominant multidomain structures but significant fractions of single domains are always present low temperature alteration is largely absent the karaman volcanic complex late pliocene shows a net rotation of 5 7 6 9 not significantly different from the regional field axis during recent times the karapinar volcanic field brunhes epoch identifies a larger net rotation of 23 1 12 0 in a restricted sample the adjoining karacadag volcanic complex late miocene pliocene and middle miocene lavas beneath the hasandag complex define net rotations of 8 1 5 9 and 16 4 8 9 respectively analysis of palaeomagnetic results from late cretaceous recent rock units emplaced in anatolia during the palaeotectonic and neotectonic regimes shows that rates of rotation have accelerated in post pliocene times as crustal thickening has given way to tectonic escape a near uniform anticlockwise rotation of 25 35 has characterised much of this block during the most recent phase of deformation and appears to have occurred in common with the eurasian plate to the north of the north anatolian fault zone whilst this rotation appears to extend south eastwards across the ecemis fault zone towards the east anatolian fault the present study shows that smaller differential anticlockwise rotations have characterised the south central region of the block where it has interacted at its southwestern margin with oroclinal bending focussed on the isparta angle

evidence of late cretaceous oroclinal bending in north central anatolia palaeomagnetic results from mesozoic and cenozoic rocks along the izmir ankara erzincan suture zone

onset of biotic and environmental recovery from the end permian mass extinction within 1 2 million years a case study of the lower triassic of the meishan section south china abstract paleontological sedimentary and geochemical data obtained from the lower triassic strata of the meishan section south china suggest that onset of biotic recovery coincided with amelioration of paleoceanographic conditions and an increase in ocean productivity the griesbachian meishanorhynchia association from meishan indicates biotic recovery between the recovery stages 1 and 2 both the initial biotic recovery and palaeoceanic environmental amelioration occurred within 1 2 myr after the end permian mass extinction in the late griesbachian

the tectonic history of the nigde kirsehir massif and the taurides since the late mesozoic paleomagnetic evidence for two phase orogenic curvature in central anatolia the nigde kirsehir massif known also as the central anatolian block is bordered by the sutures of the neotethys ocean the massif suffered several deformation phases during and after the consumption of the surrounding oceans and the post collisional events of the continental pieces of anatolia in latest cretaceous to miocene previous paleomagnetic studies on the nigde kirsehir massif and its surroundings displayed either insufficient data or have claimed large rotations and or remagnetization in order to understand the tectonic history of the nigde kirsehir massif and its adjacent blocks we have sampled 147 different sites in the age range of upper jurassic to miocene from the nigde kirsehir massif throughout its w sw and e se boundaries and the central southeastern taurides the results display that except the limestones in central taurides all rocks examined carry a primary magnetization among these an important finding is that rotations between the massif and the central eastern taurides indicate an oroclinal bending with counterclockwise rotation of r 41 1 7 6 in the se and clockwise rotation of r 45 9 9 3 in the central taurides from upper cretaceous rocks with respect to the african reference direction paleomagnetic rotations in the se taurides are compatible with the vergent direction of the thrusts generated from consumption of the intra tauride ocean prior to post collisional convergence between taurides and the massif in the central taurides it has been shown that the clockwise rotation of 45 9 9 3 started in middle eocene because of a remagnetization in upper creataceous limestones the deformation was linked to the final closure of the southern neotethys and the collision between the african and eurasian plates in the nigde kirsehir massif counterclockwise rotation up to 25 5 7 3 is recognised during middle eocene and interpreted in terms of block rotation together with the taurides after the miocene a counterclockwise rotation of 16 8 3 9 along the eastern taurides shows that this area was mostly affected by the westward movement of anatolia despite the nigde kirsehir massif and its sw w area the central taurides which is recognised as stable with counterclockwise rotation less than 10

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

influence of late cenozoic mountain building on ocean geochemical cycles in a steady state ocean input fluxes of dissolved salts to the sea must be balanced in mass and isotopic value by output fluxes for the elements strontium calcium and carbon rivers provide the primary input whereas marine biogenic sedimentation dominates removal dissolved fluxes in rivers are related to rates of continental weathering which in turn are strongly dependent on rates of uplift the largest dissolved fluxes today arise in the himalayan and andean mountain ranges and the tibetan plateau during the past 5 m y uplift rates in these areas have increased significantly this suggests that weathering rates and river fluxes may have increased also the oceanic records of carbonate sedimentation level of the calcite compensation depth and delta sup 13 c and delta sup 87 sr in biogenic sediments are consistent with a global increase in river fluxes since the late miocene the cooling of global climate over the past few million years may be linked to a decrease in atmospheric co sub 2 driven by enhanced continental weathering in these tectonically active regions

geophysical data gravity and magnetic from the area between adana kahramanmaras and hatay in the eastern mediterranean region tectonic implications the gravity and magnetic maps of the area between adana kahramanmaras hatay provinces were produced from a compilation of data gathered during the period between 1973 and 1989 reduced to the pole rtp and pseudo gravity transformation pgt methods were applied to the magnetic data while derivative ratio dr processing was applied to both gravity and magnetic data respectively bouguer rtp and pgt maps show the image of a buried structure corresponding to ophiolites under undifferentiated quaternary deposits in the adana depression and iskenderun gulf dr maps show two important faults which reflect the tectonic framework in the study area 1 the karatas osmaniye fault extending from osmaniye to karatas in the south between adana and iskenderun depressions and 2 amanos fault southern part of east anatolian fault in the hatay region running southward from turkoglu to amik basin along amanos mountain forming the actual plate boundary between the anatolian block part of eurasian plate and arabian plate

trace fossil evidence for restoration of marine ecosystems following the end permian mass extinction in the lower yangtze region south china abstract unlike the high abundance low diversity macrofaunas that characterize many early triassic benthic palaeocommunities ichnofossils were relatively common in the aftermath of the end permian mass extinction worldwide ichnofossils therefore are a good proxy for ecosystem recovery after the end permian biotic crisis this paper documents 14 ichnogenera and one problematic form from lower triassic successions exposed in the lower yangtze region south china post extinction ichnodiversity remained rather low throughout the griesbachian early smithian period and abruptly increased in the late smithian however several lines of evidence including extent of bioturbation burrow size trace fossil complexity and tiering levels indicate that diversification of ichnotaxa in the late smithian did not signal full marine ecosystem recovery from the permian triassic p tr mass extinction marine ichnocoenoses did not recover until the late spathian in south china the marginal sea provided hospitable habitats for tracemakers to proliferate in the aftermath of the end permian mass extinction

investigation of the deep structure of the sivas basin innereast anatolia turkey with geophysical methods abstract sivas basin is the easternmost and third largest basin of the central anatolian basins in this study gravity aeromagnetic and seismic data are used to investigate the deep structure of the sivas basin together with the well seismic velocity data geological observations from the surface and the borehole data of the celalli 1 well basement depth is modeled three dimensionally 3d using the gravity anomalies and 2d gravity and magnetic models were constructed along with a n s trending profile densities of the rock samples were obtained from the distinct parts of the basin surface and in situ susceptibilities were also measured and evaluated in comparison with the other geophysical and geological data additionally seismic sections in spite of their low resolution were used to define the velocity variation in the basin in order to compare depth values and geological cross section obtained from the modeling studies deepest parts of the basin 12 13 km determined from the 3d model are located below the settlement of hafik and to the south of zara towns geometry extension and wideness of the basin together with the thickness and lithologies of the sedimentary units are reasonably appropriate for further hydrocarbon exploration in the sivas basin that is still an unexplored area with the limited number of seismic lines and only one borehole

early triassic recovery of the brachiopod faunas from the end permian mass extinction a global review abstract brachiopod faunas in lower triassic deposits from spitzbergen primorye of russia japan mangyslak of kazakhstan alpine europe the caucasus the middle east the himalaya south china new zealand and western usa are taxonomically and stratigraphically reviewed they comprise survivors of the end permian extinction and taxa originating in the early triassic origination of the mesozoic type taxa represents the recovery of early triassic brachiopods the initial recovery of brachiopod faunas began in the late griesbachian and the time interval between the end of extinction and the onset of the recovery of brachiopods is much shorter than previously suspected the early triassic recovery of brachiopod faunas is characterized by widespread brachiopod dispersal multiprovincialism and the presence of rare lazarus genera at that time taxonomic selectivity of the recovery brachiopod faunas favors the rhynchonellids the re population of post extinction brachiopods varies geographically there is a preference for regions either previously barren of latest permian taxa or regions where the pre extinction changhsingian and surviving brachiopods are very rare this unique biogeographic selectivity is probably partly responsible for the impoverished nature of brachiopod faunas in the triassic even mesozoic oceans five intervals of extinction survival survival recovery recovery dispersal and radiation are recognized based on variations in brachiopod faunas from the latest permian to the early triassic a dramatic reduction in brachiopod diversity at the end permian mass extinction is followed by several stepwise declines in diversity in the survival interval the time during which the surviving brachiopods are dominated by geographically widespread generalist faunas that adapted to a wide variety of environments the survival interval was followed by a slow re population of new lineages dominated by progenitor taxa

neotectonic deformation in the western sector of tectonic escape in anatolia palaeomagnetic study of the afyon region central turkey abstract following final closure of the neotethyan ocean during the late miocene deformation in central turkey has led to crustal thickening and uplift to produce the anatolian plateau followed by westward extrusion of terranes by strike slip widespread volcanism has accompanied this latter neotectonic phase and palaeomagnetic study of the volcanism shows a coherent record of differential block rotations indicating that the anatolian region is not a plate or platelet sensu stricto but is undergoing distributed internal deformation to evaluate the scale of neotectonic rotations in the transition zone near the western limit of tectonic escape and the border of the extensional domain in central west turkey we have studied the palaeomagnetism at 82 sites in volcanic suites distributed along a 140 km lineament with north south trend and ranging in age from 18 to 8 ma comparable deflection of magnetic remanence from the present field direction is identified along the full length of the lineament a mean clockwise rotation of 12 3 4 2 is determined for this western sector of the anatolian strike slip province since similar rotations are observed in the youngest and oldest units this cumulative rotation occurred after the late miocene when interpreted together with results elsewhere in anatolia it is inferred that the rotation is later than crustal thickening and uplift of the anatolian plateau and entirely a facet of the tectonic escape inclinations are mostly 10 shallower than the predicted miocene field and are considered to reflect the presence of a persistent inclination anomaly in the mediterranean region larger rotations departing from the regional trend are also observed within the study region but are confined to the vicinity of major faults notably those bounding the afyon aksehir graben the pattern of neotectonic declinations across anatolia identifies strong anticlockwise rotation in the east near the arabian pincer with progressive reduction in the amount of rotation towards the west it becomes zero or slightly clockwise at the western extremity of the accreted terrane collage rotations also appear to become generally younger towards the south crustal deformation has therefore been distributed and the net effect of terrane extrusion to the west and south has been to expand the curvature of the tauride arc the westward radial expansion of the extruded terranes is inferred to combine with backroll on the hellenic arc to produce the contemporary extensional province in western turkey

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

regional clockwise rotation of the armutlu peninsula western turkey resolved from palaeomagnetic study of eocene volcanics abstract the north anatolian fault naf one of the major tectonic entities of turkey is a dextral fault system lying within an intracontinental transform zone up to 100 km in width this shear zone is composed of continental blocks delimited by strike slip faults with the armutlu peninsula being one of the largest of these blocks and surrounded by two main branches of the naf such fault bounded blocks typically display rotations and a variety of different kinematic models have been proposed to explain these in this study eocene volcanic rocks of the armutlu peninsula have been sampled from 50 palaeomagnetic sites following alternating field and thermal demagnetisation and component analysis a dual polarity axis is resolved which shows that the peninsula has rotated 16 6 8 clockwise relative to the predicted field direction at this location in eocene times this clockwise block rotation is interpreted in terms of dextral motion of a tectonic block bounded by two strands of the naf the palaeomagnetic data also indicate that the eocene rocks of the armutlu peninsula were emplaced at a palaeolatitude statistically identical to the present and we conclude that northward movement of this sector of the anatolides since eocene times has been below the limits of palaeomagnetic detection

the evolution of pleistocene climate a time series approach abstract in the later part of the pleistocene variations in global ice volume have been dominated by an approximate 100 000 year cycle analysis of 2 myr long oxygen isotope record from an equatorial pacific core indicates that this is true only for the last 900 000 years prior to this time the amplitude of the 100 000 year cycle is much reduced as is the variance of all oscillations with periods greater than 60 000 years based on results of time series analysis of this 2 myr long record the pleistocene glacial cycles can be divided into three sections 1 the late pleistocene 0 900 kyr b p where the variations in the isotope record are dominated by the 100 000 year cycle 2 the middle pleistocene 900 1450 kyr b p in which low frequency components are not as important as in the later period of the pleistocene and 3 the early pleistocene late pliocene 1450 2000 kyr b p where general reductions of importance at all frequencies is seen as compared to the later intervals recent modeling efforts which describe variations in global ice volume show that the dominant low frequency component observed in the late pleistocene can result from different time constants for the rate of glacial growth and decay in response to variations in the earth s orbital parameters it is hypothesized that during the early pleistocene the rate of growth and decay of glaciers were more similar and that continental erosion by successive glacial advances lowered the land surface in areas of ice cap formation to below sea level when the ice caps became marine based more rapid decay of the ice became possible

the middle pleistocene transition characteristics mechanisms and implications for long term changes in atmospheric pco2 abstract the emergence of low frequency high amplitude quasi periodic 100 kyr glacial variability during the middle pleistocene in the absence of any significant change in orbital forcing indicates a fundamental change internal to the climate system this middle pleistocene transition mpt began 1250 ka and was complete by 700 ka its onset was accompanied by decreases in sea surface temperatures ssts in the north atlantic and tropical ocean upwelling regions and by an increase in african and asian aridity and monsoonal intensity during the mpt long term average ice volume gradually increased by 50 m sea level equivalent whereas low frequency ice volume variability experienced a 100 kyr lull centered on 1000 ka followed by its reappearance 900 ka although as a broad band of power rather than a narrow persistent 100 kyr cycle additional changes at 900 ka indicate this to be an important time during the mpt beginning with an 80 kyr event of extreme sst cooling followed by the partial recovery and subsequent stabilization of long term north atlantic and tropical ocean ssts increasing southern ocean sst variability primarily associated with warmer interglacials the loss of permanent subpolar sea ice cover and the emergence of low frequency variability in pacific ssts and global deep ocean circulation since 900 ka ice sheets have been the only component of the climate system to exhibit consistent low frequency variability with the exception of a near universal organization of low frequency power associated with marine isotope stages 11 and 12 all other components show an inconsistent distribution of power in frequency time space suggesting a highly nonlinear system response to orbital and ice sheet forcing most hypotheses for the origin of the mpt invoke a response to a long term cooling possibly induced by decreasing atmospheric pco2 none of these hypotheses however accounts for the geological constraint that the earliest northern hemisphere ice sheets covered a similar or larger area than those that followed the mpt given that the mpt was associated with an increase in ice volume this constraint requires that post mpt ice sheets were substantially thicker than pre mpt ice sheets indicating a change in subglacial conditions that influence ice dynamics we review evidence in support of the hypothesis that such an increase in ice thickness occurred as crystalline precambrian shield bedrock became exposed by glacial erosion of a thick mantle of regolith this exposure of a high friction substrate caused thicker ice sheets with an attendant change in their response to the orbital forcing marine carbon isotope data indicate a rapid transfer of organic carbon to inorganic carbon in the ocean system during the mpt if this carbon came from terrigenous sources an increase in atmospheric pco2 would be likely which is inconsistent with evidence for widespread cooling apparently rapid carbon transfer from terrestrial sources is difficult to reconcile with gradual erosion of regolith a more likely source of organic carbon and nutrients which would mitigate pco2 rise is from shelf and upper slope marine sediments which were fully exposed for the first time in millions of years in response to thickening ice sheets and falling sealevels during the mpt modeling indicates that regolith erosion and resulting exposure of crystalline bedrock would cause an increase in long term silicate weathering rates in good agreement with marine sr and os isotopic records we use a carbon cycle model to show that a post mpt increase in silicate weathering rates would lower atmospheric pco2 by 7 12 ppm suggesting that the attendant cooling may have been an important feedback in causing the mpt

dynamics of fossil fuel co2 neutralization by marine caco3 a detailed model of the ocean circulation and carbon cycle was coupled to a mechanistic model of caco3 diagenesis in deep sea sediments to simulate the millennium scale response of the oceans to future fossil fuel co2 emissions to the atmosphere and deep sea simulations of deep sea injection of co2 show that caco3 dissolution is sensitive to passage of high co2 waters through the atlantic ocean but caco3 dissolution has a negligible impact on atmospheric pco2 or the atmospheric stabilization co2 emission in the coming centuries the ultimate fate of the fossil fuel co2 will be to react with caco3 on the seafloor and on land an initial caco3 dissolution spike reverses the net sedimentation rate in the ocean until it is attenuated by an enhanced vertical gradient of alkalinity after about 1000 years the magnitude of the initial spike is sensitive to assumptions about the kinetics for caco3 dissolution but subsequent behavior appears to be less model dependent neutralization by seafloor caco3 occurs on a timescale of 5 6 kyr and is limited to at most 60 70 of the fossil fuel release even if the fossil fuel release is smaller than the seafloor erodible inventory of caco3 additional neutralization by terrestrial caco3 restores a balance between caco3 weathering and seafloor accumulation on a timescale of 8 5 kyr while the deficit of seafloor caco3 the lysocline is replenished with an e folding timescale of approximately 18 kyr the final equilibrium with caco3 leaves 7 8 of the fossil fuel co2 remaining in the atmosphere to be neutralized by the silicate rock cycle on a time frame of hundreds of thousands of years

the permo triassic extinction the end permian mass extinction brought the palaeozoic great experiment in marine life to a close during an interval of intense climatic tectonic and geochemical change improved knowledge of latest permian faunas coupled with recent advances in isotopic studies and biostratigraphy have greatly enhanced our understanding of the events of 250 million years ago and have begun to provide answers to many questions about the causes of extinction

distributed neotectonic deformation in the anatolides of turkey a palaeomagnetic analysis abstract the palaeotectonic phase of deformation in anatolia accompanied closure of the tethyan ocean and was finally completed with sealing of the bitlis suture bordering the arabian shield at 12 ma arabia has since continued to indent the collage of terranes accreted to the eurasian margin by differential northward movement relative to africa along the dead sea fault zone and counterclockwise ccw rotation accompanying the opening of the red sea this neotectonic phase of deformation has accompanied uplift of the anatolian plateau and establishment of intracontinental transforms comprising the north and east anatolian fault zones deformation has included extrusion and rotation of blocks away from the arabian syntaxis by tectonic escape we produce an updated summary of palaeomagnetic results from this region to show that deformation has been distributed so that block rotations vary systematically across anatolia ranging from strongly ccw in the zone of high strain north of the arabian indenter to near zero in central anatolia and then progressively cw in western anatolia new palaeomagnetic results from the ankara igneous district are also reported and help to constrain the east to west change from ccw to cw rotation within central anatolia the transition of tectonic regimes from compression in the east to extension in the west involves the expulsion of blocks and their rotation along arcuate strike slip faults at an acute angle to the maximum compressive stress 1 between arabia and eurasia the comparable distribution of rotations in palaeotectonic and neotectonic units indicates that the bulk of the observed palaeomagnetic rotations have been concentrated within the last plio pleistocene phase of the neotectonic era as is found in the aegean domain to the west and has involved blocks of the order of 100 km in size the weak collage of accretionary terranes sandwiched between the arabian indenter and the eurasian margin now defined by the north anatolian fault zone has evidently taken up the bulk of the strain imparted by the continuing northward motion of arabia to expand the radius of the tauride arc and the perimeter of extruded crust bordering the limit of the extensional province in western turkey the distributed character of neotectonic deformation is illustrated by equivalent polar distributions both palaeotectonic and neotectonic palaeomagnetic poles show arcuate distributions with poles to best fitting small circles focussed close to the study area differences between the distributed neotectonic deformation resolved from palaeomagnetism and the contemporary gps record reflect the contrasting time periods being evaluated the palaeomagnetic record incorporates evolving and changing tectonic regimes whereas the gps signature has no long term validity within the weak anatolian collage hence the full spectrum of techniques for resolving neotectonic deformation is relevant to unravelling deformation in such regions

links between the onset of modern walker circulation and the mid pleistocene climate transition sea surface temperatures ssts reconstructed from ocean drilling program sites 806 and 849 in the western and eastern equatorial pacific provide a history of the strength of the walker circulation between 1 5 and 0 5 ma a progressive cooling in the eastern equatorial pacific is paralleled by intensification of the equatorial zonal sst gradient that began 1 17 ma prior to the expansion of global ice volume associated with the mid pleistocene climate transition the ssts in the eastern equatorial pacific and the zonal gradient reached modern values by 0 9 ma we propose that this onset and intensification of the modern walker circulation reduced heat flux but increased moisture transport to high latitudes leading to the development of more extensive ice sheets and the shift toward the 100 ka world

the age of the permian triassic boundary abstract the 5 cm boundary clay bed in the chinese stratotype section through the permian triassic boundary has been recognised as a bentonite shrimp ion microprobe dating of zircons in the bentonite indicates a magmatic age of 251 2 3 4 ma 2 this is the first direct constraint on the numerical age of the permian triassic boundary future refinements of ages at this important but poorly constrained level of the phanerozoic timescale may depend on re analysis of this uniquely placed volcanic horizon and other bentonites in the fossiliferous chinese upper permian and lower triassic the utility of defining the permian triassic boundary in the chinese stratotype section in the vicinity of known dateable horizons should be considered

environmental controls on the post permian recovery of benthic tropical marine ecosystems in western palaeotethys aggtelek karst hungary climate warming during the late permian is associated with the most severe mass extinction event of the phanerozoic and the expansion of hypoxic and anoxic conditions in shallow shelf settings it has been hypothesised that wave aeration provided a habitable zone in the shallowest environments that allowed the survival and rapid recovery of benthic invertebrates during the early triassic we test this hypothesis by studying the rock and fossil records of the aggtelek karst hungary nearshore settings recorded in the bodvaszilas sandstone formation and units a and d of the szin marl formation are characterised by taxonomically homogenous fossil assemblages of low diversity and low evenness ecological and taxonomic recovery in this environmental setting was hampered by persistent environmental stress this stress is attributed to increased runoff related to climate warming during the early triassic that resulted in large salinity fluctuations increased sedimentation rates and eutrophication that led to seasonal hypoxia and an environment only favourable for opportunistic taxa in contrast shoal and mid ramp settings further offshore are characterised by high diversity faunas with a greater functional complexity prior to the late spathian tirolites carniolicus zone the shelly fossils and trace fossils are limited to settings aerated by wave activity which supports the habitable zone hypothesis in the tirolites carniolicus zone however the oxygen minimum zone retreats offshore and the habitable deeper shelf settings are rapidly colonised by shallow water taxa evidenced by the highest levels of diversity and bioturbation recorded in the study locally full recovery of marine ecosystems is not recorded until the illyrian with the establishment of a sponge reef complex

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

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

early onset and tropical forcing of 100 000 year pleistocene glacial cycles between 1 5 and 0 6 myr ago the period of the earth s glacial cycles changed from 41 kyr the period of the earth s obliquity cycles to 100 kyr the period of the earth s orbital eccentricity1 2 which has a much smaller effect on global insolation the timing of this transition and its causes pose one of the most perplexing problems in palaeoclimate research3 here we use complex demodulation to examine the phase evolution of precession and semiprecession cycles the latter of which are phase coupled to both precession and eccentricity in the tropical and extra tropical atlantic ocean we find that about 1 5 myr ago tropical semiprecession cycles with periods of about 11 5 kyr started to propagate to higher latitudes coincident with a growing amplitude envelope of the 100 kyr cycles evidence from numerical models suggests that cycles of about 10 kyr in length may be required to explain the high amplitude of the 100 kyr cycles4 combining our results with consideration of a modern analogue we conclude that increased heat flow across the equator or from the tropics to higher latitudes around 1 5 myr ago strengthened the semiprecession cycle in the northern hemisphere and triggered the transition to sustained 100 kyr glacial cycles

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

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

global analyses of brachiopod faunas through the ordovician and silurian transition reducing the role of the lazarus effect global analyses of 88 families and 284 genera of brachiopods from middle ashgill late ordovician to early middle rhuddanian early silurian indicate that 18 6 and 12 5 of families and 51 0 and 41 3 of genera were eliminated in the first and second phases of the end ordovician mass extinction respectively with the total loss of 28 4 of families and 69 0 of genera in the crisis new investigation demonstrates that brachiopods at both generic and familial levels suffered greater during the first phase than during the second phase four groups victims relicts survivors and new arrivals are distinguished by their stratigraphical ranges generic survivors occurring in the kosov province during the hirnantian can be split into three types with respect to their changing abundance increasing declining and lazarus taxa among the 88 genera that survived numerous declining genera occurred in the hirnantian 16 lazarus families and 18 lazarus genera are provisionally known and may be regarded

palaeomagnetism of the cappadocian volcanic succession central turkey major ignimbrite emplacement during two short miocene episodes and neogene tectonics of the anatolian collage abstract the central anatolian volcanic province in cappadocia includes 13 high volume calc alkaline ignimbrite sheets emplaced by plinian eruptions within a succession the urgup formation after 10 ma recording the last phase of neotethyan subduction and accompanying emplacement of the tauride orogen in southern turkey to evaluate magnetostratigraphy in the context of recent revisions of the chronostratigraphy we have extended palaeomagnetic investigation to 32 new sites yielding significant chrm directions integrated rock magnetic and palaeomagnetic investigations identify magnetic remanence residing predominantly in ti poor titanomagnetites although secondary processes within the ignimbrite sheets notably post emplacement oxidation have locally produced hematisation expressed by composite irm spectra and variable reduction in intensity of magnetisation the ignimbrite sheets possess weak anisotropies of magnetic susceptibility ams mostly 3 of pyroclastic deposits during polarity chron c4r 1n between 9 31 and 9 43 ma subsequent activity from the acigol centre further to the south west cemilkoy gelveri gordeles and kizilkaya produced in excess of 620 km 3 of pyroclastic deposits during polarity chrons between 5 3 and 7 1 ma the younger incesu ignimbrite was sourced in the sultansazligi pull apart basin to the east during the gauss chron 2 58 3 60 ma all pre incesu ignimbrites are rotated uniformly anticlockwise and the overall reversed group mean direction of magnetisation is d i 170 8 52 4 n 9 r 8 91 95 5 4 k 91 the implied tectonic rotation in this sector of central anatolia 16 4 relative to eurasia is young and postdates the 5 3 7 1 ma acigol centre whilst largely predating emplacement of the incesu ignimbrite whilst rotational deformation within anatolia is young it proves to be distributed with a temporal variation from block to block it is embraced by a complex post miocene tectonic regime of strike slip and extension during tectonic escape and suction towards the hellenic arc to the west

neotectonic deformation in the eurasia arabia collision zone the east anatolian plateau e turkey evidence from palaeomagnetic study of neogene quaternary volcanic rocks palaeomagnetic studies of the neogene quaternary rocks of anatolia have been mostly interpreted in the light of its westward escape as a result of the collision between the arabian and eurasian plates along the bitlis zagros suture during the neotectonic period however within the collision zone in east anatolia palaeomagnetic data are not available in order to help understand the deformational history of eastern anatolia during the neotectonic period we have carried out a palaeomagnetic study of miocene quaternary volcanic rocks from 100 sites selected on the basis of their geographical position and known age the results indicate that the study area can be divided into five principal tectonic blocks based on earthquake activity and the rotation that the blocks underwent these blocks are the van block vb the kars block kb the anatolian block ab the pontide block pb and the arabian block arb the largest counterclockwise ccw tectonic rotations were encountered in the ab and pb whereas the largest clockwise cw rotations were recorded in the vb the sinistral east anatolian fault and the erzurum fault zone form the present boundary of these two contrasting cw and ccw rotating domains both the ab and the pb exhibit similar amount of rotation until the quaternary during which the ab rotated 13 ccw while the pb remained stable the quaternary rotation of the ab is attributed to the activity of the north anatolian fault the kb shows the smallest amount of cw rotation during all of the time intervals studied all of the blocks studied indicate an acceleration in the amount of rotations during the quaternary which was preceded by a period of relative tectonic stability during the late pliocene following the collision of the arabian plate with the eurasian plate during the mid miocene the crust was initially thickened by thrusting and folding this was followed by lateral extrusion and differential rotation of the crustal blocks during late miocene pliocene in response to ongoing indentation of the arabian plate our data show that strike slip faults that commonly separate wedge shape crustal blocks are the most significant means of accommodating the tectonic escape and rotation of crustal blocks in east anatolia delamination of the lower crust and the lithospheric mantle may have contributed to the deformation by thermally weakening the crust

paleozoic echinoderm hangovers waking up in the triassic echinoderms are among the marine invertebrates that underwent the most severe losses at the end permian extinction the prevailing paradigm claims an extreme bottleneck with only very few if not single holdovers hangovers herein sparking the post paleozoic radiation here we identify previously overlooked triassic echinoids ophiuroids and asteroids as unambiguous members of paleozoic stem groups these echinoderm hangovers occurred almost worldwide and had spread into a wide range of paleoenvironments by the late triassic our discovery challenges fundamentals of echinoderm evolution with respect to end permian survival and sheds new light on the early evolution of the modern clades in particular on triassic ghost lineages i e inferred but undocumented fossil record of the crown group look alikes of the paleozoic hangovers

a study on the active crustal deformation of the north and east anatolian fault zones abstract active crustal deformation in the north anatolian fault zone nafz and the east anatolian fault zone eafz based on seismicity data is examined the results show that the deformation in the nafz is taken up by extension on an azimuth of 59 at a rate of 27 mm yr and as compression on an azimuth of 149 and a rate of 20 mm yr the average dextral lateral motion on the naf is about 23 mm yr this motion in the western part of the naf is 16 mm yr while it increases in the eastern part of the fault to 27 mm yr in the eafz the deformation is taken up as nearly n s compression n7 e at a rate of 5 mm yr and as nearly e w extension n97 at a rate of about 9 mm yr the average sinistral lateral motion has a rate of about 6 mm yr the expected slip rates from plate motions along the north anatolian fault are of the order of 38 mm yr the predicted slip rates for east anatolian fault are 19 mm yr or 29 mm yr the seismicity of the last 140 years can account for the expected deformation along the nafz for the eafz however it is possible that part of the total deformation has been expressed aseismically

palaeomagnetic study of tertiary volcanic domains in southern turkey and neogene anticlockwise rotation of the arabian plate abstract following collision with eurasia the arabian shield indenter has continued to deform into the weak anatolian collisional collage that resulted from subduction of the neotethyan ocean differential movements have involved rotation and continuing northwards translation and have been accommodated mainly by slip along major transforms including the northward extension of the dead sea fault zone dsfz and the east anatolian fault zone eafz to aid in evaluating post collisional motions the palaeomagnetism of extensive volcanic domains at the northern margin of the stable shield in southern turkey is reported here together with the timing of emplacement as constrained by k ar study the age dating results indicate that volcanic activity occurred mainly during mid late miocene times corresponding to the final stages of suturing volcanic fields in the east of the investigated region are younger and correspond to neotectonic volcanism in brunhes and matuyama chrons thermal and alternating field demagnetization of 399 cores from 83 sites in basaltic lavas identifies 29 units of normal and 43 of reversed polarity with 11 sites having transitional or random directions volcanic fields west of the euphrates kilis gaziantep region with ages in the range 7 0 20 3 ma average 14 9 ma sd 4 3 ma have mean remanence d i 353 52 38 sites 5 3 lava fields east of the euphrates urfa region are dated 10 4 12 1 ma and yield a comparable mean remanence d i 350 50 17 sites 6 0 these collections are shown to have properly recorded palaeosecular variation with only minimal inclination shallowing and inferred anticlockwise rotations with respect to eurasia since mid miocene times are 10 9 4 3 and 14 0 5 0 respectively these contrast with clockwise rotation of 6 3 4 3 derived from late matuyama brunhes epoch volcanic rocks immediately to the north west of the arabian margin where rotational impingement of the shield indenter into fault blocks within the karasu rift at the northern extension of the dsfz interacts with left lateral motion at a rate of 0 5 cm year along this zone to produce small scale vertical axis rotations results from the volcanic suites sited on the stable shield are compared with other results from the arabian plate to conclude that it did not rotate significantly following closure of the bitlis suture until late miocene early pliocene times since when it has rotated anticlockwise at a rate of 1 0 myr this is comparable to the present day rate of rotation deduced from gps and correlates with crustal separation and sea floor spreading in the red sea it also temporally links the rotation of the arabian plate to the initiation of the intracontinental transforms north and east anatolian fault zones within anatolia and to the subsequent extrusion of blocks within this accretionary domain by tectonic escape to the west

a revised magnetostratigraphy for the mid proterozoic gardar lava succession south greenland abstract new palaeomagnetic results from the ca 1300 ma gardar lava succession within the eriksfjord formation of south greenland are presented this study incorporates stepwise thermal demagnetisation of 256 samples from 66 lava flows from all three lava groups in this formation accompanied by principal component analysis the results identify two complete reversals n r n in the upper lava group and two r n and n r in the lower group with a possible palaeoexcursion in the lower group a minimum of two further reversals are predicted in the time interval represented by the sandstone units intercalated with the lava flows both complete reversals in the upper group exhibit inclination asymmetries of 30 this degree of asymmetry is satisfied by a geomagnetic field model equivalent to a dipole axially offset by 570 km however a more complex source is not precluded by the present evidence four new pole positions are calculated for the gardar lavas two for the upper lava group and one each for the middle and lower groups the middle lava group shows an anomalous mean direction and pole position which is unrepresentative of the remainder of the lava succession and is thought to record a virtual geomagnetic pole representative of a transitional field direction the presence of a non axial geocentric dipole field means that the use of the laurentian apparent polar wander path for dating the new poles is not valid

first paleomagnetic evidence for a post eocene clockwise rotation of the western taurides thrust belt east of the isparta reentrant southwestern turkey abstract a paleomagnetic study was carried out on 23 sites sampled in paleocene eocene and lower miocene sedimentary formations of the western taurides belt east of the isparta reentrant the paleomagnetic data based on twelve suitable sites record a coherent post eocene 40 clockwise rotation throughout the area studied we interpret this regional rotation as a semi rigid rotation of the whole western taurides belt above a major deep decollement level together with previously published data these new results suggest that the isparta reentrant would result from diachronous opposite rotations of the two branches first a late eocene oligocene clockwise rotation of the akseki beysehir taurides initiating the tauride arc and then anticlockwise rotation of the lycian taurides probably during middle miocene times

middle triassic carbonate platforms in eastern iberia evolution of their fauna and palaeogeographic significance in the western tethys abstract this article reports the first integrated study of the middle triassic of iberia based on the stratigraphy sedimentology and fossil fauna of muschelkalk facies of the iberian ranges and the catalan coastal ranges in spain on the basis of this study new palaeogeographic reconstructions of the westernmost tethys are proposed and the evolution of the different palaeogeographic domains of iberia e g iberian mediterranean and levantine balearic are described in these domains muschelkalk facies record the development of wide carbonate platforms that were the consequence of the first two broad marine transgressions of the mesozoic in iberia respectively late pelsonian early illyrian and late illyrian longobardian of these marine incursions the oldest only manifested in the mediterranean triassic domain catalan coastal ranges and part of the iberian ranges which acted as a palaeogeographic gulf opening northwards most of the fauna related to this first incursion show strong affinities with the alpine germanic bioprovinces related to the palaeotethys in contrast the second transgressive episode took place in a new regional palaeogeographic setting related to the intra pangea dextral shear and the northward movement of the cimmerian microcontinent a rapid sea level rise induced generalised marine flooding of the iberian mediterranean and levantine balearic triassic domains the resulting carbonate platforms yield fossil assemblages ammonoids bivalves foraminifera and conodonts that show affinities with those of both the alpine and sephardic bioprovinces related to the neotethys these assemblages point to a significant increase in diversity during the late fassanian longobardian possibly related to the prevailing wider connections between the sea corridors an increased continental run off and input of nutrients and or a general cooling of marine waters

palaeoenvironmental reconstruction of the eastern part of the karapinar ayranci coal deposit central turkey abstract regional tectonic movements during the neogene period resulted in the development of several fault controlled basins in central anatolia many of these basins host economic coal deposits the recently discovered karapinar ayranci coal deposit is the most important one due to its large reserves c 1 8 gt and location in the vicinity of important urban areas the paper aims to reconstruct the palaeoenvironmental conditions before during and after coal formation in the eastern part of karapinar ayranci deposit by means of coal petrography and mineralogical data combined with sedimentological and palaeontological data the basinal infilling consists of mainly lacustrine fluvial and alluvial sediments the coal seams comprise several beds intercalating with claystone mudstone and marl the coal being lignite in rank displays high ash yield 36 4 wt on dry basis and high total sulphur content avg 7 7 wt on dry ash free basis facies diagrams and lithological features of the coal seams suggest that peat was accumulating under pure telmatic to limnotelmatic conditions however peat accumulation ceased several times due to a rise in water level therefore clastic e g quartz clay minerals and authigenic e g pyrite mineral contents are variable along the seam profile gastropod and ostracod fauna points to freshwater conditions in the palaeomire high total sulphur and evaporite mineral e g halite contents usually point to brackish saline conditions during peat accumulation however in case of the karapinar ayranci deposit high sulphur contents can be related to sulphate rich karstic aquifer which contributed to the palaeomire water supply

revised and synthetic apparent polar wander paths of the african eurasian north american and indian plates and true polar wander since 200 ma we have reviewed paleomagnetic data available for the eurasian african north american and indian plates over the last 200 ma selection criteria are those generally accepted with an emphasis on evidence for lack of remagnetization accurate dating and proper structural analysis this results in 23 35 51 and 2 poles for eurasia africa north america and india respectively we believe that this limited set of higher quality data is more likely to reveal key features of apparent polar wander apw paths than averaging of larger data sets involving less stringent selection criteria we propose and describe revised apw paths but more importantly we next use relative motion models to transfer all data in a common reference frame we find good agreement between transferred data when they are averaged separately for each plate in independent 20 ma windows this is a check on consistency of paleomagnetic data kinematic models and of the geocentric dipole hypothesis transferred data from all plates are averaged in 20 ma windows to generate synthetic apw paths for all plates studied these synthetic paths are in agreement with the original revised apw paths that use only data from a single plate moreover both geographic and time resolution are improved spatial confidence intervals are of the order of 5 the synthetic paths display interesting features such as a previously ill recognized apw loop for eurasia paleomagnetic and hotspot apw are next compared and a determination of true polar wander tpw is derived we find significant tpw amounting to over 20 in the last 200 ma tpw appears to be episodic with a standstill between 180 and 110 ma there is general agreement with a previous study of livermore et al 1984 the tpw standstill appears to correlate with a time of decreasing reversal frequency ending with the cretaceous long normal superchron other periods of fast tpw would seem to correspond to increasing reversal frequency however it is suggested that the major tpw hairpin at 50 ma might correspond to the collision of india with eurasia tentative correlations with core or mantle indicators can be understood as a result of couplings between the core mantle and lithosphere we believe primarily related to episodic evolution of the d layer

origin of the middle pleistocene transition by ice sheet erosion of regolith the transition in the middle pleistocene 0 9 ma seen in 18o deep sea core records from relatively low amplitude high frequency 41 kyr to high amplitude low frequency 100 kyr ice volume variations under essentially the same orbital forcing can be attributed to a change from an all soft bedded to a mixed hard soft bedded laurentide ice sheet through glacial erosion of a thick regolith and resulting exposure of unweathered crystalline bedrock a one dimensional ice sheet and bedrock model which includes transport of sediment and ice by subglacial sediment deformation demonstrates that a widespread deforming sediment layer maintains thin ice sheets before the transition which respond linearly to the dominant 23 and 41 kyr orbital forcing progressive removal of the sediment layer eventually causes a transition to thicker ice sheets whose dominant timescale of change 100 kyr reflects nonlinear deglaciation processes in model simulations over the last 3 ma initialized with no ice and a uniform 50 m sediment layer the time series of ice volume and extent agree in several important aspects with the observed records

geophysical investigations on the gravity and aeromagnetic anomalies of the region between sapanca and duzce along the north anatolian fault turkey abstract in this paper it is aimed to model subsurface structures to the east of the gulf of izmit through duzce by using the gravity and aeromagnetic anomaly data 1 500 000 scaled gravity anomaly map of the area was taken from the general directorate of mineral research and exploration mta and it was digitized the aeromagnetic anomaly data were obtained in the digital form 3d and 2d models were constructed to reveal the subsurface structure in two different inset regions in the study area including most important negative and positive gravity anomalies seismic velocities obtained from the deep seismic recordings were converted to densities in addition density information from a previous research was also taken these densities were used for construction of 3d and 2d gravity models where it was shown that there are narrow and long sedimentary basins and depressions with 0 5 3 km depths these sedimentary basins with the shape of negative flower structures indicating pull apart basins are controlled by the active fault segments of the north anatolian fault naf earthquake epicenter data were also correlated with the constructed models from the gravity anomalies positive gravity anomalies are also caused by very shallow about 2 km masses that are accepted as the crustal origin intrusions into the fractures of the naf and ophiolites and gabbro outcropping on the surface of the studied regions these intrusives and remnants of the tethys ocean are located between the fault segments where the fault bifurcates and they also constitute barriers for straight extension of the naf analytic signal method was applied to the aeromagnetic anomaly data to determine the locations and boundaries of the causative bodies those bodies are observed around duzce and to the e se of it to the nw of golyaka and a large mass between adapazari and sapanca shallow settlement of these magmatics was confirmed by the second vertical derivative of the aeromagnetic data an anti clockwise block rotation is evident in the northeast of the study area from the polarity changes of the magnetic anomalies

palaeomagnetic study of the karacadag volcanic complex se turkey monitoring neogene anticlockwise rotation of the arabian plate abstract the karacadag volcanic centre in south east turkey is a major basaltic complex sited at the northern margin of the arabian plate and emplaced in several pulses between 11 ma and late quaternary times we have sampled 71 sites in lavas of this complex to constrain the palaeomagnetic record and hence the chronology of magmatic activity and regional rotation palaeomagnetic study at sixty two sites yields significant component definition with mixed normal and reversed polarities from age dating and morphologic criteria we identify three major episodes of lava emplacement and site mean directions of magnetisation for these divisions resolve migration of the palaeofield direction for the northern sector of the arabian plate since mid miocene times successive reversed polarity group mean directions are d i 175 50 5 n 37 r 33 13 95 4 1 for the oldest siverek division mean age estimate 11 1 6 7 ma d i 173 4 46 0 n 16 r 15 67 95 5 5 for the middle karacadag division mean age 3 3 ma and d i 167 7 47 6 n 6 r 5 93 95 7 9 for the youngest ovabag division 1 9 ma present the first two results merit a tectonic interpretation and consistent anticlockwise rotation of 9 is recognised in the karacadag volcanic centre between 11 and 3 3 ma the mean directions conform to palaeomagnetic results from other undeformed neogene igneous complexes of comparable age range further to the west along the northern perimeter of the arabian plate the amount of tectonic rotation observed in late pliocene and older volcanic units from this plate is found to be statistically constant tectonism responsible for rotation therefore appears to have been temporally confined to the last 2 myr which is long after collision with the anatolides and closure of the bitlis suture this conclusion conforms to the young distributed block rotations recognised in the anatolides and aegean and correlates with the regime of tectonic escape of terranes to the west

investigations into the tectonic lineaments and thermal structure of kutahya denizli region western anatolia from using aeromagnetic gravity and seismological data abstract residual aeromagnetic map of western anatolia displays intense anomalies especially in the nw of the region curie point depth cpd map obtained from the residual aeromagnetic anomalies is indicative of larger area of shallow curie levels than previously defined two important shallow depth regions located at between kutahya and denizli are determined from cpd and thermal gradient tg map the intense aeromagnetic anomalies are located in the west of kutahya along the e w direction these anomalies are resulted from the metamorphic units of menderes massif the analytic signal as map produced from residual aeromagnetic data shows the e w trending geological bodies causing magnetic anomalies which become intense in the west and south of kutahya it is also observed from the as map that thermal structures or bodies are buried under the non magnetic surface geology the maxspot map derived from the location of the horizontal gradient of aeromagnetic anomalies can be well correlated with not only tectonic lineaments but also the distribution of earthquake data bouguer anomalies of the region can also be well correlated with the graben system and thus provide supportive information about the geothermal energy potential of the study area

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

palaeomagnetic study of block rotations in the niksar overlap region of the north anatolian fault zone central turkey abstract this palaeomagnetic study investigates crustal deformation within and adjacent to the niksar overlap area of the north anatolian fault zone nafz in central east turkey the studied rock formations comprise 1 red limestones of late cretaceous age 3 sites 2 mafic lavas of eocene age on the north side 13 sites and south side 9 sites of the nafz and 3 volcanic rocks of pliocene quaternary age from the niksar pull apart basin within the nafz 8 sites comparisons with reference palaeofield directions computed from apparent polar wander paths of the eurasian and afro arabian plates identify two scales of regional and local tectonic rotation 1 1 a pre tilting remanence in the eocene volcanic rocks south of the nafz d i 144 1 47 5 95 7 6 is interpreted to reflect counterclockwise rotation by 30 40 from the reference palaeofields contemporaneous volcanic rocks from the north side of the nafz have the same reverse polarity recorded in pre tilting magnetisations the remanence is also rotated counterclockwise d i 152 4 42 5 95 11 3 but by about 8 less than the volcanics on the south side of the nafz hence similar amounts of rotation are observed on both sides of the nafz and are interpreted to reflect motions during the pre middle miocene collisional history in this sector of the pontides no distributed clockwise rotations anticipated from subsequent dextral motion along the nafz intracontinental transform are observed the slightly larger anticlockwise rotation found on the south side of the nafz probably records relative rotation of en echelon wedges by continental escape during post middle miocene strike slip along the transform 2 2 within the narrow zone of intense deformation along the nafz cretaceous limestones appear to be rotated clockwise by dextral strike slip motion whilst plio quaternary lavas within a fault bounded block in the overlap region associated with the niksar pull apart basin have magnetisations consistently directed 240 270 e magnetic inclinations are not diagnostic of polarity but both polarity solutions identify rapid clockwise rotation at rates in excess of 50 m y a normal polarity solution is favoured and implies that a block ca 5 km across has undergone a strike slip displacement of around 12 km within the nafz during the last polarity chron cretaceous eocene palaeolatitudes are closer to those predicted from eurasia than afro arabia but a study of older rocks is required to resolve affinities of this sector of the anatolian block theoretical models of crustal deformation across intracontinental transforms obeying power law behaviour and treating the lithosphere as a viscous medium predict that distributed clockwise rotations should be observed about as broad across the nafz these rotations are not observed instead intense clockwise rotation is confined to a narrow zone close to the major fault break the concentration of historic seismic activity here also implies that the bulk of the dextral motion between the eurasian plate and the anatolian block is accommodated by slip along faults close and parallel to the main trace of the nafz

a palaeomagnetic study of the sivas basin central turkey crustal deformation during lateral extrusion of the anatolian block abstract the sivas basin is a complex collage of eocene and younger rocks located within the wedge shaped eastern margin of the anatolian block between the dextral north anatolian fault zone and the sinistral eastern anatolian fault zone it has been subject to ongoing deformation by movement of the arabian block into eurasia and concomittant sideways expulsion of the anatolian block post collisional deformation since mid miocene times has been dominated by n s to nw se compression expressed by thrusting and strike slip faulting cretaceous and eocene rocks were magnetically overprinted to variable degrees during the collisional phase although these overprints have since been rotated mostly anticlockwise rocks emplaced during the neotectonic history are high fidelity palaeomagnetic recorders of subsequent block movements regional anticlockwise rotation is recognised across the basin with differential rotation of fault and thrust bounded blocks an absence of perceptible differences between group mean rotations identified from miocene pliocene and quaternary units shows that most regional rotation has been concentrated within the latest phase of the neotectonic history during quaternary times at an average rate of 10 ma commencement of this rotation postdates initiation of the north anatolian fault zone implying that compression following collision was accomodated initially by crustal thickening during late miocene and pliocene times subsequent anticlockwise rotations have resulted from sideways expulsion of blocks to the south of the central anatolian thrust along major ne sw sinistral faults to achieve the crustal shortening resulting from n s compression these fault orientations and their sense of motion are explained by a prandtl model involving deformation of a triangular plastic terrane the anatolian block between two rigid plates eurasia and afro arabia the variations in regional rotation identified by palaeomagnetism show that average contemporary anticlockwise rotation of anatolia revealed by gps data 1 2 ma is achieved by variable and locally large block rotations between major thrusts and strike slip faults

differential neotectonic rotations in anatolia and the tauride arc palaeomagnetic investigation of the erenlerdaǧ volcanic complex and isparta volcanic district south central turkey abstract in the anatolian sector of the alpine himalayan collisional belt a palaeotectonic phase of terrane accretion has been succeeded by a neotectonic phase of intracontinental deformation as the afro arabian plate has continued to impinge differentially into the accreted collage the resulting tectonic escape has during the last few million years extruded and rotated blocks in a southwesterly direction this paper reports a palaeomagnetic investigation of the erenlerda volcanic complex and isparta alkaline volcanic district undertaken to extend analysis of crustal rotation into the southwestern part of the anatolian region and investigate the interaction with the isparta angle and the extensional province of western turkey the erenlerda volcanism comprises three phases of volcanism the oldest sille volcanics 11 7 11 4 ma yield a mean d 150 i 52 rotated anticlockwise during early stages of crustal thickening and deformation before a later miocene episode c 10 9 8 9 ma d 183 i 47 and a mio pliocene episode d 179 i 51 the latter two episodes indicate that no significant rotation has resulted during the neotectonic crustal extrusion in this southwestern sector of anatolia further to the west within the isparta angle a 4 7 4 0 ma alkaline episode yields a mean of d 186 i 53 rotated slightly clockwise the pattern of palaeomagnetic declinations across anatolia shows rotations that are strongly anticlockwise in the east near the arabian pincer and diminish towards the west to become zero or slightly clockwise at the western extremity of the collage the timing of rotation also appears to become younger towards the south crustal deformation has therefore been distributed and the net effect of terrane extrusion to the west and south has been to expand the curvature of the tauride arc and by inference the cyprian arc where good age control exists in cappadocia and the sivas basin rotations are found to be concentrated within the last few million years and are up to an order higher than rates deduced from global positioning system the palaeomagnetic data imply that the neotectonic deformation following collision initially produced crustal thickening resulting in uplift of the anatolian plateau and was only subsequently accommodated by major differential block rotation during tectonic escape

palaeomagnetic study of the erciyes sector of the ecemis fault zone neotectonic deformation in the southeastern part of the anatolian block

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

evolutionary models in the early triassic marine realm abstract the relative influences of extrinsic compared to intrinsic drivers of evolutionary change have long been theorized and debated in the fossil record ecological recoveries from mass extinction events present records in which to examine these contrasts competition in a low diversity world reproductive strategy reconstruction of trophic systems and ecological specialization represent possible intrinsic controls on diversification feedback between diversity and abundance shifts of marine organisms with biogeochemical cycling and environmental conditions act as extrinsic controls on recovery process and rate disentangling these evolutionary pressures is a major challenge for understanding evolutionary recovery from mass extinction the end permian mass extinction 251 88 ma represents the largest mass extinction in earth history and led to an extended recovery interval which lasted the duration of the early triassic 4 8 myr and beyond recent analyses suggest that the survivors of the mass extinction were biased toward organisms with higher metabolic rates that were more resilient against the volatile environmental changes that pervaded the early triassic including extreme temperature events low ph and low oxygen conditions we use the early triassic recovery of gastropods echinoids and ammonoids to examine the processes of taxonomic and ecological evolution in response to or in spite of extrinsic environmental perturbations the case studies of benthic gastropods and echinoids when compared to pelagic ammonoids reflect similarities and differences in recovery following the end permian mass extinction gastropods and echinoids exhibit evidence of strong extrinsic environmental limitations which implicate the availability of refugia as a control on recovery low initial taxonomic diversity of survivors may have also limited the evolutionary recovery of both clades abundant and diverse microgastropod assemblages are interpreted as an adaptation to extreme environmental conditions the morphological diversity of disarticulated echinoid spines and plates described in the southwestern united states and examination of phylogenetic ghost lineages hints at a significant hidden diversity of early triassic echinoids ammonoids experienced taxonomic resets but are shown to be resilient to repeated environmental perturbations in the boreal ocean over the duration of the early triassic ammonoids may have adapted to persistent latitudinal temperature gradients and oxygen minimum zones that developed in the early triassic ocean basins

environmental controls on marine ecosystem recovery following mass extinctions with an example from the early triassic abstract the recovery of marine ecosystems following a mass extinction event involves an extended interval of increasing biotic diversity and ecosystem complexity the pace of recovery may be controlled by intrinsic ecosystem or extrinsic environmental factors here we present an analysis of changes in marine conditions following the end permian mass extinction with the objective of evaluating the role of environmental factors in the protracted 5 myr long recovery of marine ecosystems during the early triassic specifically our study examines changes in weathering productivity and redox proxies in three sections in south china chaohu daxiakou and zuodeng and one in northern india mud our results reveal 1 recurrent environmental perturbations during the early triassic 2 a general pattern of high terrestrial weathering rates and more intensely reducing marine redox conditions during the early griesbachian late griesbachian mid smithian and more weakly the mid spathian 3 increases in marine productivity during the aforementioned intervals except for the early griesbachian and 4 stronger and more temporally discrete intervals of environmental change in deepwater sections chaohu and daxiakou relative to shallow and intermediate sections zuodeng and mud our analysis reveals a close relationship between episodes of marine environmental deterioration and a slowing or reversal of ecosystem recovery based on metrics of biodiversity within community alpha diversity infaunal burrowing and ecosystem tiering we infer that the pattern and pace of marine ecosystem recovery was strongly modulated by recurrent environmental perturbations during the early triassic these perturbations were associated with elevated weathering and productivity fluxes implying that nutrient and energy flows were key influences on recovery more regular secular variation in deepwater relative to shallow water environmental conditions implies that perturbations originated at depth i e within the oceanic thermocline and influenced the ocean surface layer irregularly finally we compared patterns of environmental disturbance and ecosystem recovery following the other four big five phanerozoic mass extinctions to evaluate whether commonalities exist in general the pace of ecosystem recovery depends on the degree of stability of the post crisis marine environment

a triassic sponge from vancouver island possible holdover from the cambrian tiny cap shaped fossils recovered from silicified residues in upper triassic rocks of vancouver island wrangellia are identified as a calcareous sponge nucha vancouverensis n sp nov the genus nucha pickett and jell was first reported from middle cambrian rocks of australia the triassic example constitutes the first occurrence outside the cambrian system and the continent of australia the absence of representatives in rocks between triassic and cambrian age suggests that it is a long range refugium taxon the occurrence of such a wide ranging holdover organism reinforces the role of refugia in preferential survivorship over long periods of geologic time other holdover taxa are known from volcanic displaced terranes of western american cordillera and their study may help clarify neglected aspects of survival and evolution

the influence of air and sea exchange on the carbon isotope distribution in the sea we explore here the influence of the temperature dependence of isotope fractionation between atmospheric co2and ocean co2 on the distribution of carbon isotopes in the ocean this is accomplished by an analysis of departures from the expected redfield tie between po4 and 13c we find that for the surface ocean the temperature influence largely compensates for the biologic influence in the deep ocean the temperature influence imprinted at the sites of deepwater formation reduces somewhat the biologically induced difference between the carbon isotope ratios for deep waters produced in the northern atlantic and in the antarctic these same features are reproduced in the hamburg ocean model in order to assess the impact of changes in the ratio of ocean mixing rate to wind speed we have made a model run in which co2 exchange rates between air and sea were everywhere doubled as expected the influence of the thermodynamic effect on the oceanic carbon isotope distribution is magnified

interpretation of suluklu cihanbeyli goloren magnetic anomaly central anatolia turkey an integration of geophysical data abstract the most obvious aeromagnetic anomaly in turkey is the suluklu cihanbeyli goloren anomaly which is extending in nw se direction along the western margins of the haymana tersakan and tuzgolu basins in the central anatolia the surface conditions either topography or surface geology are not related to this anomaly and do not reflect any characteristic features of the causative body buried in the subsurface this evident anomaly was modelled two dimensionally 2d from the aeromagnetic and gravity data along the two different profiles taken in two different locations around the lake tuzgolu the modelling results were compared and verified by the seismic and well data according to the results obtained from this study the suluklu cihanbeyli goloren anomaly is produced by a magmatic mass located at the boundary of the kirsehir block and menderes taurus platform the models suggest that shape of the causative body is an inclined 2 km thick magmatic dike and its posture changes becoming to a sill like body at the depth around 2500 m its southernmost extremity is ended and exposed at the goloren mountain that is a small scale volcanic high the causative magmatic body is thought to be revealed from a basin related normal fault that was activated at the end of cretaceous through the paleocene eocene time the fault activation and magmatic intrusion ceased in the eocene and the intrusive body was completely covered by the mio pliocene sediments seismological records show that the buried fault zone can be considered inactive in the recent times

north atlantic thermohaline circulation during the past 20 000 years linked to high latitude surface temperature during a surface cooling event 10 000 to 12 000 years ago higher cd ca and lower 13c 12c ratios are observed in benthic foraminifera shells from rapidly accumulating western north atlantic sediments data from sediment cores show that marked nutrient depletion of intermediate waters occurs in association with reduced glacial north atlantic deep water flux it is proposed that cold high latitude sea surface temperatures enhance intermediate water formation at the expense of deep water formation

why are there no clockwise rotations along the north anatolian fault zone mechanical analysis of lithospheric deformation associated with an intracontinental transform fault suggests that it should be associated with a pattern of vertical axis rotations governed by the length of the fault its displacement and the mechanical properties of the lithosphere paleomagnetic results from two transects across the north anatolian fault zone indicate that there have been no measurable clockwise rotations on a regional scale associated with neogene dextral strike slip motion along the fault the data come from two groups of volcanic rocks that have been dated by k ar whole rock geochronology and have yielded ages ranging from 45 3 3 1 m y to 41 8 1 3 m y eocene and 21 7 1 5 m y to 7 5 0 2 m y miocene the absence of clockwise rotations suggests one of the following explanations 1 in contrast to the assumptions underlying current mechanical analyses deformation in the upper crust may not directly reflect the flow in the lithosphere and is localized along a single fault trace 2 deformation is distributed but rotations have been prevented by the presence of elongate fault blocks subparallel to the trace of the main fault 3 displacement along the north anatolian fault may be too small or the rheologic properties of the lithosphere such that rotations about vertical axes cannot be resolved instead of the predicted clockwise rotations measured declinations show that there has been approximately 30 of anticlockwise rotation of both the eocene and miocene volcanic rocks this suggests that no significant rotation occurred between eocene and miocene times and that the anticlockwise rotation occurred either immediately before or concurrent with the plio pleistocene slip on the north anatolian fault

the north anatolian fault zone distributed neogene deformation in its northward convex part abstract the north anatolian fault zone is composed of two almost rectilinear branches which join in a northward convex bend in this bent zone the pontide anatolide collisional system has been cut across by two transpressional belts of fold and thrust and wrench faults of lower neogene age these structures were reactived during the neotectonic period the time of deposition of the pontus group for both of these deformational events and up to the present the tectonic regime remained generally transpressional with a nw se direction of compression and a ne sw direction of extension it is only recently during the upper pleistocene that the dextral wrench faults became more localized and more straight than previously the complexity of the eastern part of the north anatolian fault zone is better understood if one takes into account the role of inherited miocene pliocene transpressional structures

lake baikal record of continental climate response to orbital insolation during the past 5 million years the sedimentary record of biogenic silica from lake baikal in south central siberia suggests that this region of central asia was impacted by two major cooling episodes at 2 8 to 2 6 and 1 8 to 1 6 million years ago the spectral evolution of this continental interior site parallels the evolutionary frequency spectra for various marine oxygen isotope records in the baikal record the 41 000 year obliquity cycle is particularly strong from 1 8 to 0 8 million years ago variance in the 100 000 year eccentricity band increases during the past 0 8 million years the expected precession frequency of 23 000 years is highest during the past 400 000 years the modulation of the predicted 23 000 and 41 000 year insolation forcing by the 100 000 and 400 000 year eccentricity bands indicates that the transfer of variance from the precession and obliquity frequencies to the eccentricity part of the spectrum occurred in the eurasian continental interior as well as in tropical and high latitude ocean sites

upwelling intensification as part of the pliocene pleistocene climate transition a deep sea sediment core underlying the benguela upwelling system off southwest africa provides a continuous time series of sea surface temperature sst for the past 4 5 million years our results indicate that temperatures in the region have declined by about 10 c since 3 2 million years ago records of paleoproductivity suggest that this cooling was associated with an increase in wind driven upwelling tied to a shift from relatively stable global warmth during the mid pliocene to the high amplitude glacial interglacial cycles of the late quaternary these observations imply that atlantic ocean surface water circulation was radically different during the mid pliocene

timing of the last glacial maximum from observed sea level minima during the last glacial maximum ice sheets covered large areas in northern latitudes and global temperatures were significantly lower than today but few direct estimates exist of the volume of the ice sheets or the timing and rates of change during their advance and retreat here we analyze four distinct sediment facies in the shallow tectonically stable bonaparte gulf australia each of which is characteristic of a distinct range in sea level to estimate the maximum volume of land based ice during the last glaciation and the timing of the initial melting phase we use faunal assemblages and preservation status of the sediments to distinguish open marine shallow marine marginal marine and brackish conditions and estimate the timing and the mass of the ice sheets using radiocarbon dating and glacio hydroisostatic modelling our results indicate that from at least 22 000 to 19 000 calendar years before present land based ice volume was at its maximum exceeding today s grounded ice sheets by 52 5 x 10 exp 6 cu km a rapid decrease in ice volume by about 10 percent within a few hundred years terminated the last glacial maximum at 19 000 250 years

palaeomagnetically defined rotations of fault bounded continental blocks in the north anatolian shear zone north central anatolia abstract the 1200 km long north anatolian transform fault connects the east anatolian post collisional compressional regime in the east with the aegean back arc extensional regime to the west this active dextral fault system lies within a shear zone reaching up to 100 km in width and consists of southward splining branches these branches which have less frequent and smaller magnitude earthquake activity compare to the major transform cut and divide the shear zone into fault delimited blocks comparison of palaeomagnetic data from 46 sites in the eocene volcanics from different blocks indicate that each fault bounded block has been affected by vertical block rotations although clockwise rotations are dominant as expected from dextral fault bounded blocks anticlockwise rotations have also been documented these anticlockwise rotations are interpreted as due to anticlockwise rotation of the anatolian block as indicated by gps measurements and the effects of unmapped faults or pre north anatolian fault tectonic events

early triassic gulliver gastropods spatio temporal distribution and significance for biotic recovery after the end permian mass extinction a reduction in body size lilliput effect has been repeatedly proposed for many marine organisms in the aftermath of the permian triassic pt mass extinction specifically reduced maximum sizes of benthic marine invertebrates have been proposed for the entire early triassic this concept was originally based on observations on early triassic gastropods from the western usa basin and the dolomites n italy and it stimulated subsequent studies on other taxonomic groups however only a few studies have tested the validity of the lilliput effect in gastropods to determine whether the paucity of large sized gastropods is a genuine signal or the result of a poor fossil record and insufficient sampling in combination with a review of the literature we document numerous new abundant large sized gastropods from the griesbachian outcrops of greenland and from the smithian early spathian interval in the southwestern usa we show that large sized gulliver gastropods i were present soon after the pt mass extinction ii occurred in various basins sedimentary facies and environmental contexts from shallow to deeper settings and iii belong to diverse higher rank taxa focusing on the western usa basin we investigate areas from which microgastropod shell beds were previously presented as being typical however we show that gulliver gastropods do occur in the very same areas insufficient sampling effort is probably the main reason for the rarity of reports of large early triassic gastropods which is supported by preliminary rarefaction based simulations finally it appears that the recently documented middle to late smithian climate shifts and the severe end smithian extinction of nekto pelagic faunas did not reduce maximum shell sizes of gastropods

palaeomagnetism and magnetic properties of the cappadocian ignimbrite succession central turkey and neogene tectonics of the anatolian collage abstract the cappadocian ignimbrite succession of central southern anatolia comprises at least nine major and two minor calc alkaline rhyolitic sheets emplaced at 1 2 ma intervals between 11 2 and 1 1 ma it records the last phase of neotethyan subduction during final emplacement of the tauride orogen in southern turkey this study reports magnetostratigraphy and describes associated rock magnetic properties remanence resides in ti poor titanomagnetites haematisation is locally produced by post emplacement oxidation but does not contribute significantly to the palaeomagnetic signature although secondary processes within the ignimbrite sheets have produced composite isothermal remanent magnetisation spectra and variable intensities of magnetisation weak anisotropy of magnetic susceptibility describes tensors with maximum axes close to bedding and minimum axes perpendicular to this plane directions of kmax with weak imbrication mostly suggest flow away from centres of eruption located by gravity and remote sensing older ignimbrites upper and lower goreme akdag zelve from the cardak centre are all of normal polarity later ignimbrites partly erupted from the derinkuyu centre comprise the sarimaden r cemilkoy r tahar r kizilkaya r incesu n and valibaba sofular r ignimbrites the overall reversed group mean is d i 174 51 n 10 units r 9 84 95 6 6 k 55 and all magnetisation directions from the upper goreme 9 0 ma onwards are rotated anticlockwise with respect to eurasian and african palaeofields this sense of rotation characterises most of central anatolia and averages 9 5 in this sector the rotation rate from 8 to 1 ma bp was 1 25 ma but it appears to have accelerated during the latter part of the quaternary to about an order higher than rates determined from gps rotation has resulted from extrusion of fault blocks during tectonic escape of the anatolian collage to the southwest and followed crustal thickening as the afro arabia plate has continued to impinge differentially into eurasia cenozoic magnetic inclinations are systematically shallower across anatolia than inclinations expected from the geocentric dipole model and the apparent polar wander of bordering major plates only part of this difference 400 km can be accommodated by northward movement and crustal thickening in central anatolia since mid miocene times shallow inclinations observed in the aegean region extend into turkey they are observed in young volcanics and appear to reflect a regional geomagnetic anomaly the pattern of neotectonic declinations across anatolia shows rotations that are strongly anticlockwise rotated in the east near the arabian pincer but diminish towards the west to become zero or slightly clockwise at the western extremity of the collage rotations also seem to become generally younger towards the south crustal deformation has therefore been distributed and the net effect of terrane extrusion to the west and south has been to expand the curvature of the tauride arc and by inference the cyprus arc

survival strategies of brachiopod faunas from the end permian mass extinction abstract global reviews reveal that 102 brachiopod species including 40 indeterminate species belonging to 43 genera within 27 families survived the end permian mass extinction in south china the himalayan regions southern tibet nepal salt range and kashmir southern alps italy arctic canada western usa and western australia of these the surviving brachiopods are most abundant and widespread in south china where they occur in 32 of the 42 permian triassic p t boundary sections around the world brachiopod faunas are the most abundant and diverse post extinction survivors and their appearance above the end permian mass extinction horizon somewhat masks recognition of the end permian extinction these surviving brachiopods occur in three stratal intervals corresponding to the mixed fauna beds mfb hereafter 1 3 of the p t boundary beds a sharp drop in diversity of the brachiopod faunas coincides with the widely accepted end permian mass extinction horizon the post extinction brachiopods were also affected by a subsequent crisis corresponding to the boundary between mfb 2 and mfb 3 so that most survivors were extinct approximately 0 7 ma after the end permian mass extinction the surviving brachiopods were mainly productida followed by spiriferida in particular small chonetids chonetid like productellids and smooth thin shelled ambocollid spiriferids are most abundant lingula is extraordinarily abundant and widespread approximately 0 7 ma after the greatest extinction when many regions became devoid of articulate brachiopods widespread broadly adapted and small sized taxa preferentially survived frequent intrageneric speciation of widespread widely adapted generalist genera enabled survival brachiopods to occupy rapidly and efficiently vacant ecospace in the aftermath of the end permian extinction the ecological habitats of the post extinction brachiopods are subdivided into nearshore epeiric sea restricted carbonate platform open carbonate platform ramp and outer shelf environments of these the survival brachiopods are most diverse in the open platform environments the nearshore zone provided ideal habitats for the nonarticulated brachiopods to occupy whereas the survivors in the outer shelf are predominantly chonetids and chonetid like productellids the most successful survivors the productid brachiopods are widely distributed in six types of ecological habitats and thus have no apparent preference for specific environments the end permian extinction resulted in the movement of biogeographical provinces towards the palaeo equator the brachiopods survived mostly in the palaeo equatorial provinces and along the southern margins of the palaeo tethys ocean

on the origin of the 100 kyr cycles in the astronomical forcing 1 investigations during the last 25 years have demonstrated that the astronomically related 19 23 and 41 kyr quasiperiodicities actually occur in long records of the quaternary climate however the same investigations also identified the largest climatic cycle as being about 100 kyr long as the 100 kyr variations in standing insolation due to eccentricity change are too small they cannot be the direct cause of the ice ages this is the reason why most of the modeling studies attempting to explain the relation between the astronomical forcing and climatic change have focused on this 100 kyr cycle in this paper we will show the astronomical origin of the periods at about 100 kyr that characterize the long term variations of eccentricity of its first derivative of the frequency modulation of obliquity and of the inclination of the earth s orbit on the invariable plane of reference five independent values are found between 95 and 107 kyr and a wavelet signature is suggested to test the possible relationships between the astronomical and climatic variables proxy records from deep sea cores and european programme for ice coring in antarctica ice core and modeling results from the louvain la neuve two dimensional model are used for illustration

continental arc volcanism and tectonic setting in central anatolia turkey abstract the neogene and quaternary volcanism of central anatolia represents the central sector of the anatolian volcanic arc related to continental collision between the afro arabian and eurasian plates it is closely associated with a complex system of tectonic depressions related to brittle deformations of transtentional type and which commenced in the late miocene the volcanism here considered can be divided into three main periods of activity separated by important deformative and erosive events the first period is represented by a mostly andesitic effusive activity the second period is characterized by the emplacement of a thick ignimbritic sequence and shows an areal distribution up to 11 000 km 2 seven ignimbrite units have been recognized the three main units were found at a distance of more than 100 km from the presumed source area geological and sedimentological data lead us to recognize the melendiz dag volcanic complex and the ciftlik caldera as the probable ignimbrites source vent during the third period great andesitic basaltic stratovolcanoes and a number of prevalently acid monogenic centres developed the relationship between the volcanic activity is clearly conditioned by the main transcurrent fault systems present in central anatolia the neogene quaternary volcanic activity prevalently developed along the ene wsw karaman sivas lineament most of the great central volcanoes developed at the intersection between the ene wsw trends and the ecemis and tuz golu transcurrent faults the structural interpretation of the quaternary monogenic centres is more difficult probably they are related to the very recent n s fault swarms which cross the anatolides and the taurus range