kinematic reconstructions and magmatic evolution illuminating crustal and mantle dynamics of the eastern mediterranean region since the late cretaceous the relationship between subduction dynamics and crustal deformation in the mediterranean region has been recently studied using three dimensional 3d numerical models such models require however a detailed information concerning the past geological evolution we use stratigraphic petrologic metamorphic structural paleomagnetic and magmatic data to build new kinematic reconstructions of the eastern mediterranean region since the late cretaceous using the principle of non rigid domains the motions of the 56 deforming domains defined in this work are calculated based on published paleomagnetic rotations the directions and amounts of displacement on crustal scale shear zones and the burial and exhumation histories of the main metamorphic units extracted from these reconstructions paleotectonic maps and lithospheric scale cross sections illustrate that the present day subduction zone has been continuously retreating southward since the late cretaceous and has accreted several small continental domains in the process we find evidence for two back arc related extensional events 1 slow extension along the balkans and the pontides in the late cretaceous while the trench was long and linear and 2 faster extension in the rhodope aegean west anatolian region since the eocene oligocene rapid rotation of the hellenides between 15 and 8 ma probably indicates a slab tearing event below western anatolia that could have further accelerated this extensional kinematics spatial distribution and the geochemical signature of magmatic centers integrated in these reconstructions allow us to trace mantle related processes revealing the deep dynamics that controls both the magma genesis and the crustal deformation

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

kinematics of a former oceanic plate of the neotethys revealed by deformation in the ulukisla basin turkey kinematic reconstruction of modern ocean basins shows that since pangea breakup a vast area in the neotethyan realm was lost to subduction here we develop a first order methodology to reconstruct the kinematic history of the lost plates of the neotethys using records of subducted plates accreted to former overriding plates combined with the kinematic analysis of overriding plate extension and shortening in cretaceous paleogene times most of anatolia formed a separate tectonic plate here termed anadolu plate that floored part of the neotethyan oceanic realm separated from eurasia and africa by subduction zones we study the sedimentary and structural history of the ulukisla basin turkey overlying relics of this plate to reconstruct the tectonic history of the oceanic plate and its surrounding trenches relative to africa and eurasia our results show that upper cretaceous oligocene sediments were deposited on the newly dated suprasubduction zone ophiolites 92 ma which are underlain by melanges metamorphosed and nonmetamorphosed oceanic and continental rocks derived from the african plate the ulukisla basin underwent latest cretaceous paleocene n s and e w extension until 56 ma following a short period of tectonic quiescence eo oligocene n s contraction formed the folded structure of the bolkar mountains as well as subordinate contractional structures within the basin we conceptually explain the transition from extension to quiescence to shortening as slowdown of the anadolu plate relative to the northward advancing africa anadolu trench resulting from collision of continental rocks accreted to anadolu with eurasia until the gradual demise of the anadolu eurasia subduction zone

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

relative paleointensity rpi in the latest pleistocene 10 45 ka and implications for deglacial atmospheric radiocarbon abstract we report magnetic properties and relative paleointensity rpi proxies from a suite of 10 conventional piston cores and kasten cores from the sw iberian margin collected during cruise jc089 of the rss james cook in august 2013 mean sedimentation rates are in the 10 20 cm kyr range age models were acquired by correlation of ca ti and zr sr xrf core scanning data to l reflectance from the cariaco basin that is in turn tied to the greenland ice core chronology the natural remanent magnetization nrm is represented by a single magnetization component carried by a low coercivity mineral magnetite although reflectance and bulk magnetic properties indicate the presence of a high coercivity hematitic magnetic phase possibly from eolian dust the presence of fine grained hematite means that the sediments are not ideal for rpi studies however the detrital hematite does not appear to contribute to the nrm or anhysteretic remanent magnetization arm in order to test the usefulness of the rpi data we construct a stack of 12 rpi records from the sw iberian margin for the 0 45 ka interval and compare it with a stack of 12 globally distributed marine and lake records chosen on the basis of mean sedimentation rates 15 cm kyr and superior age models the two stacks are similar but different from published rpi stacks particularly for the 10 30 ka interval and imply a virtual axial dipole moment vadm high at 15 18 ka followed by a drop in field strength from 15 to 13 ka a revised vadm estimate calculated from greenland 10be ice core flux using a contemporary age model is remarkably consistent with the new overall rpi stack based on iberian margin and global rpi records the elevated atmospheric 14c levels of the last ice age cannot however be fully explained by this rpi stack although relative changes such as the long term drop in atmospheric 14c from 30 to 15 ka are reproduced supporting the hypothesis of a combined influence of production rate and ocean ventilation on 14c during the last ice age

metamorphism during alpine crustal thickening and extension in central anatolia turkey the nigde metamorphic core complex the nig de massif a metamorphic core complex in central anatolia high temperature reactions can obliterate assemblages turkey contains petrologic evidence for the transition from alpine formed during earlier lower temperature phases of meta crustal thickening to extension and exhumation of high grade mid morphism this can hinder use of petrologic information crustal rocks sillimanite potassium feldspar gneiss formed and to interpret tectonic processes if reaction textures are partially melted during barrovian metamorphism and records max preserved however rocks may record a range of pres imum conditions of 5 6 kbar 700 c the two mica uckapili sure temperature conditions from their prograde and granite and a related dike suite intruded the migmatitic metapelitic or retrograde paths and a more complete picture of the rocks forming a contact aureole that contains andalusite and tectonic evolution of a terrane can be reconstructed of cordierite these low pressure minerals indicate that crustal thick particular interest are the mechanisms and timing of ening was followed by exhumation of mid crustal rocks to relatively transition from contraction to extension and the ac shallow depths 10 km at lower temperatures before the em companying exhumation of middle to lower crustal placement of granitic magma formation of andalusite was followed rocks the present study describes a medium pressure by a second prograde episode of sillimanite growth during low high temperature terrane the nig de massif fig 1 in pressure high temperature metamorphism in the central part of the central anatolia turkey that developed as a meta massif where magmatism was most extensive a generalized p t morphic core complex in response to alpine crustal path for the highest grade rocks therefore consists of an initial thickening metamorphic rocks in the central high grade clockwise path with a late thermal spike and characterizes burial part of the massif record in their mineral assemblages and subsequent exhumation accompanied by magmatism reaction textures and structures the processes of burial exhumation and accompanying magmatism

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

calcite twins their geometry appearance and significance as stress strain markers and indicators of tectonic regime a review twin lamellae are a widespread feature in calcites of any type and origin twinning in calcite is an important intracrystalline deformation mechanism with low critical resolved shear stress and virtually no temperature dependence in contrast to most slip systems in rock forming minerals twinning therefore permits intracrystalline deformation at very low temperature and very little confining pressure twinning alone however cannot lead to large strains because only one independent slip system is effectively available twins lead to discontinuous shearing on the grain scale which gives rise to considerable strain incompatibilities at grain boundaries twinning consequently leads to strain hardening detailed observations of the geometry of twin lamellae show that incompatibilities at grain boundaries are eliminated by pressure solution on the grain scale at low temperature and dynamic recovery processes at higher temperatures twins are found in various tectonic environments and record very small strains in rocks deformed under very little cover different twinning strain and twinning stress methods and palaeopiezometers are critically reviewed all methods are limited to strains of less than 15 shortening or extension by twinning twinning nevertheless is an important although not directly measurable contribution to the total strain in highly strained calcite rocks at least up to middle greenschist facies under which conditions it is the most effective contributor to the formation of strong lattice preferred orientations in calcite tectonites the appearance of calcite twin lamellae changes systematically as a function of deformation temperature micro twins and straight narrow 1 5 m but fewer twins are developed above approximately 200 c curved twins twinned twins and completely twinned grains indicate the progressive importance of other slip systems and larger intracrystalline strains are possible at ca 250 c and above ancient straight twin lamellae are modified into irregular geometries by recrystallization and grain boundary migration the appearance of calcite twins is proposed as an approximate but rapid and easy to use geothermometer in low temperature environments

207pb 206pb single zircon evaporation ages of some granitoid rocks reveal continent oceanic island arc collision during the cretaceous geodynamic evolution of the central anatolian crust turkey abstract 207pb 206pb single zircon evaporation age determinations carried out on nine different granitoid units of central anatolia turkey have yielded three distinct granitoid groups with different emplacement ages these are 1 cenomanian turonian granitoids with a weighted mean age wma of 94 9 3 4 ma 2 turonian santonian granitoids with a wma of 85 5 5 5 ma and 3 campanian granitoids with a wma of 74 9 3 8 ma the spatial and temporal relationships between the formation of the metamorphic sole of the supra subduction zone type central anatolian ophiolite ssz type cao crustal metamorphism of the central anatolian crystalline complex cacc and the emplacement of cenomanian turonian to turonian santonian granitoids indicate a geodynamic setting in which all these geological events occurred quasi simultaneously in central anatolia such a geodynamic setting is thought to be related to the cenomanian turonian collision of the tauride anatolide platform tap and an oceanic island arc including the ssz type cao the campanian granitoids appear to be the continuation of this collision related protracted magmatism in central anatolia

dating the exhumation of a metamorphic dome geological evidence for pre eocene unroofing of the nigde massif central anatolia turkey the timing of exhumation of metamorphic rocks and granitoids of the nigde metamorphic dome at the southern tip of the central anatolian crystalline complex is a matter of debate according to some authors the metamorphic rocks are overlain nonconformably by a sedimentary sequence of late maastrichtian to late palaeocene age in contrast other authors recently argued that the nigde dome represents an extensional core complex of oligocene early miocene age finally unroofed during late miocene times on the one hand the results of our study contradict the latter interpretation a sedimentary sequence of earliest eocene to early middle eocene age nonconformably overlies the high grade rocks of the nigde dome on its southeastern flank pebbles from the metamorphic rocks are ubiquitous in the conglomerates of this sequence as a result the nigde metamorphic rocks must have reached the surface before eocene times or at the very beginning of the eocene at the latest the uckapili granite whose crystallization age has been inferred to be early miocene has intruded the metamorphic complex during exhumation the granite is also found as pebbles within the conglomerates of the eocene sedimentary sequence and thus is actually older than the eocene apatite fission track dates of 12 11 ma across the nigde dome do not indicate that the metamorphic rocks were still on their way to the surface at that time instead they must reflect a later event which is most probably heating during late neogene magmatism lastly there is no ductile then brittle extensional detachment in the two areas where it has been invoked that is on the western and southern flanks of the dome an extensional detachment nevertheless exists at the top of the nigde dome best documented in its northern part where the detachment fault superposes a superficial unit made up of massive ophiolitic rocks onto the high grade metamorphic sequence field evidence indicates that this detachment developed before eocene times on the other hand our observations do not confirm the nonconformity of the sedimentary sequence dated as late maastrichtian late palaeocene onto the nigde high grade rocks field relations show either a tectonic contact between the two or the direct nonconformity of the eocene sediments onto the metamorphic rocks the lack of coarse clasts originating from the nigde high grade rocks within the maastrichtian palaeocene sequence further suggests that the metamorphic dome did not reach the surface before late palaeocene times these results compare well with available data from the northwestern part of the central anatolian crystalline complex suggesting that exhumation has been broadly synchronous on the scale of the massif as a result of an episode of high magnitude extension that affected the region in campanian to palaeocene times

the north cycladic detachment system low angle normal faults accommodate a large part of continental post orogenic extension besides the intrinsic rheological characteristics of the continental crust that may lead to the formation of shallow dipping shear zones at the brittle ductile transition the role of pre existing low angle structures such as large thrusts has been proposed by several authors we explore this question with the example of the north cycladic detachment system ncds that is composed of a series of distinct detachments cropping out on the islands of andros tinos and mykonos separating the cycladic blueschists in the footwall from the upper cycladic nappe in the hanging wall we show that these extensional structures are part of a single large scale structure more than 200 km along strike that reactivates the vardar suture zone it extends eastward on ikaria and westward offshore evia and thessalia where it probably connects to recent shallow dipping normal faults evidenced on published seismic reflection profiles the ncds started its activity in the oligocene concommitantly with the aegean extension and was still active in the late miocene it has exhumed a series of metamorphic domes from southern evia to mykonos below low angle detachment systems made of low angle normal faults and low angle ductile shear zones the ductile shear zones and the faults were created with a low dip and they kept the same attitude throughout their exhumation we identify three main detachments that are part of a continuum of extension on the ncds tinos detachment livada detachment and mykonos detachment a fourth detachment vari detachment is the reactivation of an eocene exhumation related structure deformation in the footwall is characterized by intense stretching and flattening using the spatial evolution observed along strike from andros to mykonos we construct a history of formation of the ncds starting with the reactivation of former thrusts leading to the exhumation of high temperature metamorphic domes the aegean example shows that reactivation of earlier shallow dipping discontinuities can play a fundamental role in continental post orogenic extension

integrating timescales with time transfer functions a practical approach for an intimate database the purpose of the intimate project is to integrate palaeo climate information from terrestrial ice and marine records so that the timing of environmental response to climate forcing can be compared in both space and time one of the key difficulties in doing this is the range of different methods of dating that can be used across different disciplines for this reason one of the main outputs of intimate has been to use an event stratigraphic approach which enables researchers to co register synchronous events such as the deposition of tephra from major volcanic eruptions in different archives blockley et al 2012 however this only partly solves the problem because it gives information only at particular short intervals where such information is present between these points the ability to compare different records is necessarily less precise chronologically what is needed therefore is a way to quantify the uncertainties in the correlations between different records even if they are dated by different methods and make maximum use of the information available that links different records this paper outlines the design of a database that is intended to provide integration of timescales and associated environmental proxy information the database allows for the fact that all timescales have their own limitations which should be quantified in terms of the uncertainties quoted it also makes use of the fact that each timescale has strengths in terms of describing the data directly associated with it for this reason the approach taken allows users to look at data on any timescale that can in some way be related to the data of interest rather than specifying a specific timescale or timescales which should always be used the information going into the database is primarily proxy information principally from sediments and ice cores against depth age depth models against reference chronologies typically intcal or ice core and time transfer functions that relate different timescales to each other through the use of event stratigraphies or global phenomena such as cosmogenic isotope production rate variations

atmospheric14c changes resulting from fossil fuel co2 release and cosmic ray flux variability a high precision tree ring record of the atmospheric14c levels between 1820 and 1954 is presented good agreement is obtained between measured and model calculated 19th and 20th century atmospheric 14c levels when both fossil fuel co2 release and predicted natural variations in14c production are taken into account the best fit is obtained by using a diffusion model with an oceanic eddy diffusion coefficient of 3 cm2 s a co2 atmosphere ocean gas exchange rate of 21 moles m 2 yr 1 and biospheric residence time of 60 years for trees in the state of washington the measured 1949 1951 atmospheric 14c level was20 0 1 2 below the 1855 1864 level model calculations indicate that in 1950 industrial co2 emissions are responsible for at least 85 of the 14c decline whereas natural variability accounts for the remaining 15

a shell derived time history of bomb 14c on georges bank and its labrador sea implications bomb produced radiocarbon has been used in the past as an important tracer of ocean circulation and as a valuable tool for calculating co2 air sea exchange however previous studies of the ocean s time varying bomb 14c record have been confined exclusively to analyzing banded corals and thus their application has been limited to the lower latitudes the first time history of bomb 14c from the high latitude north atlantic ocean is obtained from a 54 year old mollusc specimen bivalvia arctica islandica which was collected live from georges bank 41 n in 1990 the annual growth bands of its shell were analyzed for 14c using accelerator mass spectrometry producing a 14c time history from 1939 to 1990 the depleted condition of the georges bank bomb 14c signal relative to two coral derived north atlantic 14c time histories suggests a significant deepwater source for the waters on georges bank supported by previous work linking the origin of waters on georges bank to the labrador sea the 14c budget on georges bank is modeled as labrador sea water which largely becomes confined to the shelf and partially equilibrates with the atmosphere during a 1 year transit time from the labrador sea to georges bank this model is also used to estimate a time history of bomb 14c for the labrador sea prebomb 14c values calculated for the surface labrador sea suggest that a greater inventory of bomb 14c has accumulated here than has previously been reported however the estimated prebomb average 14c 70 6 for this period is nearly identical to the 70 previously calculated for the prebomb source of north atlantic deep water and is in agreement with transient tracers in the ocean subsurface tritium data from the central labrador sea deduced variations in the ventilation and or 14co2 uptake rates in the labrador sea correspond with observed changes in surface salinity of the labrador sea suggesting a reduction in deepwater formation during the late 1960s and 1970s

causes and timing of the 8200 yr bp event inferred from the comparison of the grip be 10 and the tree ring delta c 14 record we analyse the 8200 yr bp cold event by comparing the high resolution be 10 record from the grip ice core from central greenland with the well known tree ring delta 14 c record by transferring the absolute dated tree ring chronology to the ice core time scale we show that the coldest phase in the grip record occurred around 8150 yr bp furthermore this method allows us to disentangle production and climate effects on be 10 and c 14 with important implications for the reconstruction of past solar activity and changes in the carbon cycle and be 10 transport we show that in principle it is possible to infer changes in ocean circulation by comparing be 10 and c 14 records however the duration of the 8200 yr bp event is too short to assign unambiguously a significant change in atmospheric c 14 concentration to changes in the global ocean circulation based on the comparison of be 10 with climate records one could argue that the 8200 yr bp cold event is triggered by a change towards lower solar activity however this link is questioned by the fact that around this period there are other similar and even stronger changes in solar activity that have no apparent connection to climate changes c 2004 elsevier ltd all rights reserved less

rapid changes in ocean circulation and atmospheric radiocarbon a latitude depth coupled global ocean ice atmosphere model is extended to include a simple biosphere component a physically reasonable adjustment of runoff into the north atlantic is invoked to achieve a transient response to glacial meltwater perturbations which closely resembles the younger dryas climate event we then investigate the evolution of the isotopic ratio of atmospheric radiocarbon 14c due to the rapid changes of deep ocean circulation when the north atlantic branch of the conveyor belt circulation is interrupted the oceanic uptake of radiocarbon is reduced resulting in an increase of atmospheric 14c by about 35 the reduction of ventilation in the north atlantic is partly compensated by an increase of the 14c ratios of the biosphere the southern ocean and the upper ocean above 1000 m depth a plateau of the 14c year calendar year relation can be generated at the time of the rapid reinitiation of deep ocean ventilation which begins coincident with the major temperature increase and lasts for about 60 years it is hence significantly shorter than that found by analyzing tree rings during the termination of younger dryas longer than 400 years a sensitivity study reveals that the duration of the plateau depends strongly on the transient evolution of the gas exchange rate and can increase to 150 300 years if changes of pco2 or sea ice coverage are taken into account

ventilation of the north atlantic ocean during the last glacial maximum a comparison between simulated and observed radiocarbon ages the distribution of radiocarbon during simulations of the last glacial maximum with a coupled ocean atmosphere sea ice model is compared with sediment core measurements from the equatorial atlantic ceara rise blake ridge caribbean sea and south china sea during these simulations we introduce a perturbation of north atlantic freshwater fluxes leading to varying strengths of the atlantic meridional overturning the best fit with the observations is obtained for an overturning weakened by 40 compared with today further we simulate the phenomenon of an age reversal found in deep sea corals but we suggest that this indicates rather a sudden interruption of deep water formation instead of an increase in ventilation which was suggested earlier

menderes massif western turkey structural metamorphic and magmatic evolution a synthesis the menderes massif covers large areas in western turkey the better understanding of its tectono metamorphic history would provide insight for the alpine evolution of western turkey and the entire eastern mediterranean region this paper summarizes the available literature on the metamorphic rocks of western turkey and that of the menderes massif with special reference and emphasis to the papers presented in the special issue

biogeochemical cycling in the global ocean 1 a new analytical model with continuous vertical resolution and high latitude dynamics a new simple analytical model of ocean chemistry is presented which includes continuous vertical resolution high latitude dynamics air sea exchange and sea ice cover in this high latitude exchange interior diffusion advection hilda model ocean physics are represented by four parameters k and w an eddy diffusion coefficient and a deep upwelling velocity in the stratified interior q a rate of lateral exchange between the interior and a well mixed deep polar ocean and u an exchange velocity between surface and deep layers in the polar ocean first estimates are made of ice free and ice covered areas at high latitudes surface temperatures and air sea exchange velocities from available data then values of the physical parameters are estimated from simultaneous least mean square fits of model solutions for temperature t and abiotic carbon 14 14c to interior profiles of t and 14c and surface layer 14c values all derived from available data best fit values for k w q and u are 3 2 10 5 m2 s 1 2 0 10 8 m s 1 7 5 10 11 s 1 and 1 9 10 6 m s 1 respectively these results are interpreted in terms of modes of ocean circulation and mixing and compared with results from other simplier and more complex models in parts 2 and 3 of this series these values for k w q and u are taken as inputs for studying phosphorus oxygen and carbon cycling in the global ocean with the hilda model

late cretaceous extensional denudation along a marble detachment fault zone in the kirsehir massif near kaman central turkey abstract in the central anatolian crystalline complex cacc 100 km scale metamorphic domains were exhumed in a context of north south plate convergence during late cretaceous to cenozoic times the timing kinematics and mechanisms of exhumation have been the focus of previous studies in the southern nigde massif in this study we investigate the unexplored northern area regarding the tectonic features preserved on the edges of the kirsehir massif based on detailed field mapping in the kaman area where high grade metasediments non metamorphic ophiolites and monzonitic plutons are locally exposed together close to the contact with the ophiolites west dipping foliated marble rich rocks display mylonites and discrete protomylonites with normal shear senses indicating a general top to the w nw direction both of these structures have been brittlely overprinted into cataclastic corridors parallel to the main foliation the mylonite series and superimposed brittle structures together define the kaman fault zone the study of the evolution of calcite deformation fabrics along an ew section supported by electron back scattered diffraction measurements ebsd on representative fabrics indicates that the kaman fault zone represents an extensional detachment in omerhacili in the vicinity of the baranadag quartz monzonite the metamorphic sequence shows static annealing of the calcite mylonitic fabrics this evidence suggests that intrusion took place at shallow depth 10 km into an already exhuming metamorphic sequence as a consequence for the kaman area buried metasediments have been rapidly exhumed between 84 and 74 ma 1 km ma where exhumation along a detachment zone displaying a top to the w nw shear motion took place in the mid to upper crust prior to magmatic intrusion in the late campanian as the intrusion cut through the detachment fault the main shearing deformation ceased brittle tectonics coupled with erosion likely took over during the final unroofing stages at a slower rate

post deformational annealing of calcite rocks abstract the evolution of microstructure and crystallographic preferred orientation cpo during post deformational annealing was studied on three calcite rock types differing in purity and grain size carrara marble 98 calcite mean grain size of 115 m solnhofen limestone 96 5 m and synthetic calcite aggregates 99 7 m samples were first deformed in torsion at 727 c at a shear strain rate of 3 10 4 s 1 to a shear strain of 5 and subsequently heat treated at 727 c for various durations between 0 and 24 h microstructures and cpos were analysed by optical microscopy image analysis and electron backscatter diffraction ebsd all rock types deformed in the dislocation creep field at the same applied conditions but their microstructures and cpos after deformation and after annealing differed depending on starting grain size and material composition in carrara marble and in the synthetic calcite aggregate a strong cpo developed during deformation accompanied by dynamic recrystallisation with significant changes in grain size during annealing widespread grain growth and subtle changes of cpo occurred and equilibrated foam microstructures were approached after long annealing times the cpo is the only feature in annealed samples indicating an earlier deformation phase although it is not always identical to the cpo formed during deformation in the more impure solnhofen limestone secondary phases on grain boundaries suppressed grain boundary mobility and prevented both the formation of a recrystallisation cpo during deformation and grain size modification during deformation and annealing

reply to genc and yurur s comments on late cretaceous extensional denudation along a marble detachment fault zone in the kirsehir massif near kaman central turkey we appreciate the interest of dr yurdal genc and dr tekin yurur in the work we carried out in central turkey in our paper we presented a detailed structural study focused on one single fault zone located in the kaman area in the northwestern metamorphic massif of central anatolia the aim of our work was to provide clear structural evidence to assess the nature and kinematics of this fault zone and to test whether it could be held responsible for part of the exhumation of the high grade metamorphic rocks in the region we demonstrated that the kaman fault is an extensional detachment that was active in the late cretaceous and concluded that it was contemporaneous with late cretaceous extension and exhumation of metamorphic rocks of the central anatolian crystalline complex cacc documented previously this extensional phase has been discussed in numerous works such as the structural and metamorphic analysis from the southern nigde crystalline massif gautier et al 2002 whitney et al 2003 whitney et al 2007 and gautier et al 2008 structural and geochronological data from discrete shear zones across large magmatic intrusions in the north yozgat and the west agacoren of the cacc isik et al 2008 and isik 2009 and the tectonic evolution of the large basins surrounding the cacc e g the tuzgolu and sivas basins cemen et al 1999 and dirik et al 1999 following extension the region underwent compression during the paleogene due to the convergence and consequent collision between the cacc and the central pontides gorur et al 1984 gorur et al 1998 kaymakci et al 2000 kaymakci et al 2009 and meijers et al 2010 in contradiction to the generally accepted tectonic evolution for central anatolia genc and yurur 2010 recently proposed an alternative model based on inferences from digital elevation data and local field observations they interpreted the cenozoic tectonic regime of central anatolia to be dominated by extension associated with coeval compressional zones resulting from gravitational movements taking that into consideration genc and yurur have in their discussion listed several points that they consider to be incoherencies in this reply we answer each point addressed in the comment discussing the validity of our statements and data and taking the opportunity to clarify the ideas that the authors of the comment may have misunderstood

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

intragranular dynamic recrystallization in naturally deformed calcite marble diffusion accommodated grain boundary sliding as a result of subgrain rotation recrystallization abstract intragranular microshear zones within a greenschist facies calcite marble were studied to try to constrain better the processes of dynamic recrystallization as well as the deformation processes that occur within newly recrystallized grains intragranular recrystallized grains within large twinned calcite porphyroclasts can be related to the host from which they have recrystallized and are the focus of an electron backscatter diffraction study lattice distortions low angle boundaries and some high angle boundaries 15 in the microshears within a porphyroclast have the same misorientation axes suggesting that deformation occurred by climb accommodated dislocation creep involving subgrain rotation recrystallization changes in the ratio of host and twin domain as the deformation zone is entered show that twin boundary migration also occurred recrystallized grains have similar sizes 10 60 m to subgrains suggesting that they formed by subgrain rotation however within the intragranular microshear zones the misorientations between recrystallized grains and porphyroclasts are considerably larger than 15 and misorientation axes are randomly oriented moreover recrystallized grain orientations average around the porphyroclast orientation we suggest that the recrystallized grains once formed are able to deform partly by diffusion accommodated grain boundary sliding which is consistent with predictions made from lab flow laws

changes in the carbon cycle during the last deglaciation as indicated by the comparison of 10be and 14c records the variations in atmospheric radiocarbon c 14 concentration during the last 50 000 years can be attributed to changes in the c 14 production rate due to changes in solar activity the geomagnetic field and or interstellar galactic cosmic ray flux and to changes in the global carbon cycle the relative contributions of these processes is the subject of current debate although the discrepancies between the various reconstructions of the past atmospheric radiocarbon concentration increase with age the relatively good agreement over the last 25 000 years allows a quantitative discussion of the causes of the observed c 14 variations for this period using be 10 measurements from greenland summit ice cores we show that in addition to solar and geomagnetically induced production rate changes significant changes in the carbon cycle have to be considered to explain the measured c 14 concentrations there is evidence that these changes are connected to 1 global deglaciation and 2 climate changes in the north atlantic region on centennial to millennial time scales related to changes in the ocean circulation differences between be 10 and geomagnetic field records however suggest that uncertainties of about 20 still exist in determinations of past changes in the c 14 production rate c 2004 elsevier b v all rights reserved less

on estimating the strength of calcite rocks under natural conditions abstract field studies of calcite mylonites often document microstructures produced by dislocation creep in contrast flow laws derived from experiments predict that calcite rocks should deform mostly by diffusion creep during tectonic processes to investigate this apparent discrepancy we compare stresses estimated by microstructural piezometers to those obtained by extrapolation of experimentally derived flow laws considering shear zones from different geological settings a clear trend is observed of increasing recrystallized grain size with increasing temperature however there is a large spread in grain size and associated stress because separate flow laws have been defined for various different marbles and limestones the strengths predicted for a given set of conditions differ significantly the stress estimates based on the piezometers and strength extrapolated from the various experimentally derived dislocation creep flow laws agree qualitatively but no single flow law predicts all the palaeostress estimates even if experimental data are disregarded the field observations are not consistent with a hypothetical law for coble creep they are consistent with a power law for dislocation creep but only if the material constants are different from those currently determined in laboratory experiments

multiple exhumation phases in the central pontides n turkey new temporal constraints on major geodynamic changes associated with the closure of the neo tethys ocean

influence of crystallised igneous intrusions on fault nucleation and reactivation during continental extension abstract continental rifting is commonly accommodated by the nucleation of normal faults slip on pre existing fault surfaces and or magmatic intrusion because crystallised igneous intrusions are pervasive in many rift basins and are commonly more competent i e higher shear strengths and young s moduli than the host rock it is theoretically plausible that they locally intersect and modify the mechanical properties of pre existing normal faults we illustrate the influence that crystallised igneous intrusions may have on fault reactivation using a conceptual model and observations from field and subsurface datasets our results show that igneous rocks may initially resist failure and promote the preferential reactivation of favourably oriented pre existing faults that are not spatially associated with solidified intrusions fault segments situated along strike from laterally restricted fault intrusion intersections may similarly be reactivated this spatial and temporal control on strain distribution may generate 1 supra intrusion folds in the hanging wall 2 new dip slip faults adjacent to the igneous body or 3 sub vertical oblique slip faults oriented parallel to the extension direction importantly stress accumulation within igneous intrusions may eventually initiate failure and further localise strain the results of our study have important implications for the structural of sedimentary basins and the subsurface migration of hydrocarbons and mineral bearing fluids

the hellenic subduction system high pressure metamorphism exhumation normal faulting and large scale extension the cenozoic history of the retreating hellenic subduction system in the eastern mediterranean involves subduction accretion arc magmatism exhumation normal faulting and large scale continental extension from 60 mya until the recent ages for high pressure metamorphism in the central aegean sea region range from 53 ma in the north the cyclades islands to 25 20 ma in the south crete younging of high pressure metamorphism reflects the southward retreat of the hellenic subduction zone the shape of pressure temperature time paths of high pressure rocks is remarkably similar across all tectonic units suggesting a steady state thermal profile of the subduction system and persistence of deformation and exhumation styles the high pressure metamorphic events were caused by the underthrusting of fragments of continental crust that were superimposed on slab retreat most of the exhumation of high pressure units occurred in extrusion wedges during ongoing lithospheric convergence at 23 19 mya large s

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

alpine high p low t metamorphism of the afyon zone and implications for the metamorphic evolution of western anatolia turkey abstract carpholite chloritoid pyrophyllite association occurs widely in the triassic metaclastic rocks of the afyon zone in west central turkey fe mg carpholite is associated with rare aragonite pseudomorphs and glaucophane in marbles and metabasites respectively the afyon zone consists stratigraphically of a pan african basement and an overlying mesozoic cover sequence the pan african basement which shows barrovian type amphibolite facies metamorphism comprises garnet mica schists intruded by sodic amphibole bearing metagabbros and leucocratic metagranites it is unconformably overlain by a continuous metasedimentary sequence extending from triassic to early palaeocene this cover sequence begins with metaconglomerates which pass upwards into phyllites fe mg carpholite occurs within this metaclastic sequence as rosette like crystals in metapelites and fibres in quartz segregations the metaclastic rocks are succeeded by metamorphosed platform carbonates grading into latest mesozoic metamorphosed pelagic limestones which in turn progress up to a late mesozoic early tertiary olistostrome this sequence is tectonically overlain by the blueschists of the tavsanli zone fe mg carpholite bearing assemblages imply temperatures of about 350 c and minimum pressures of 6 9 kbar corresponding to burial depths of about 30 km for the mesozoic passive continental margin sediments and the underlying pan african supracrustal metasediments and metaintrusives the metamorphic rocks of the afyon zone are unconformably overlain by upper palaeocene lower eocene sedimentary rocks indicating a paleocene age for the regional hp lt metamorphism this implies continuous younging of hp lt metamorphism in the anatolides related to northward subduction of the anatolide tauride platform beneath the sakarya zone from north to south this involved the tavsanli zone campanian 80 5 ma the afyon zone palaeocene the menderes massif middle eocene and the lycian nappes late cretaceous eocene all of which were probably derived from the frontal part of the anatolide tauride platform

solar activity during the last 1000 yr inferred from radionuclide records identification of the causes of past climate change requires detailed knowledge of one of the most important natural factors solar forcing prior to the period of direct solar observations radionuclide abundances in natural archives provide the best known proxies for changes in solar activity here we present two independent reconstructions of changes in solar activity during the last 1000 yr which are inferred from be 10 and c 14 records we analyse the tree ring c 14 data shcal intca104 from 1000 to 1510 ad and annual data from 1511 to 1950 ad and four be 10 records from greenland ice cores camp century grip milcent and dye3 together with two be 10 records from antarctic ice cores dome concordia and south pole in general the be 10 and c 14 records exhibit good agreement that allows us to obtain reliable estimates of past solar magnetic modulation of the radionuclide production rates differences between be 10 records from antarctica and greenland indicate that climatic changes have influenced the deposition of be 10 during some periods of the last 1000 yr the radionuclide based reconstructions of past changes in solar activity do not always agree with the sunspot record which indicates that the coupling between those proxies is not as close as has been sometimes assumed the tree ring c 14 record and be 10 from antarctica indicate that recent solar activity is high but not exceptional with respect to the last 1000 yr c 2006 elsevier ltd all rights reserved less

effect of pre existing crystallographic preferred orientation on the rheology of carrara marble abstract localized deformation during high temperature plastic flow is frequently attributed to mechanical weakening caused by grain size reduction and in some cases by the development of a crystallographic preferred orientation cpo this study aims to investigate experimentally the contribution of cpo development to the strain weakening seen in carrara marble samples during large strain torsion experiments at temperatures in the range 600 800 c at constant strain rate and confining pressure the starting material shows little or no cpo samples were treated in three steps first they were deformed to achieve a well developed cpo and recrystallized to a finer grain size second the samples were annealed at 727 c for 5 h to grow the grains to approximately their original size and shape while maintaining a reasonably strong cpo finally the samples were deformed again under the same conditions as the first step re deformed samples showed a strain weakening lower than during the first step we infer that this strength difference is caused primarily by the cpo developed during the first deformation event this implies that cpo development is an important process that contributes to strain weakening during flow of carrara marble and likely of other rock types as well

pluton pinning of an active miocene detachment fault system eastern mojave desert california the miocene kingston range halloran hills detachment fault system of the eastern mojave desert california delineates part of the eastern breakaway zone for a profoundly extended area between the sierra nevada and the spring mountains structural blocks the shallow dipping west rooting detachment fault cuts discordantly across paleozoic and precambrian units in the mesozoic foreland fold and thrust belt exhibits west to southwest trending corrugations with structural relief of up to 1 5 km and underlies the terrestrial shadow valley basin middle miocene fault displacement and syntectonic sedimentation in the northern basin were terminated at 12 4 ma by intrusion of the large 130 km 2 shallow level 4 km depth kingston peak pluton across the detachment fault soon after faulting began basin sedimentation and fault displacement southeast of the pluton were not however disrupted by its emplacement and continued to evolve northern pluton pinned and southern pluton free domains were separated by the blacksmith hills fault a northeast striking right slip lateral ramp that accommodated more than 3 km of postpluton differential extension between pinned and nonpinned domains in more western regions late phases of detachment fault related extension beneath formerly pinned areas including western and central parts of the pluton itself are believed to have led to the development of two generations of east striking left slip faults collectively these dextral and sinistral transfer faults illustrate the complex patterns of differential extension and accommodation that can characterize detachment fault systems as adjacent areal domains of extension are generated and die

information on past solar activity and geomagnetism from 10 be in the camp century ice core a nearly continuous record of the concentration of 10be from ice core data is compared with the tree ring derived record for 14c over the same period and it is found that short term trends in these data sets provide a record of solar activity no definitive relationship between the long term trends and the geomagnetic dipole moment is found

geomagnetic field intensity during the last 60 000 years based on 10be and 36cl from the summit ice cores and 14c abstract based on 10 be 36 cl and 14 c records we reconstruct past changes in the geomagnetic field intensity under the assumption that radionuclide records are mainly influenced by changes in their production rates subsequent comparison of these records with independent geomagnetic field reconstructions allows us to assess the reliability of our approach and to identify periods where our method or the geomagnetic field reconstructions might be problematic the geomagnetic field derived from the 10 be flux to summit in central greenland agrees well with independent geomagnetic field intensity reconstructions however compared to independent palaeomagnetic data the radionuclide record suggests increased geomagnetic field intensities especially for the period from 20 000 to 30 000 years bp 36 cl from the grip ice core agrees well with the 10 be record for the last ice age and hence also the reconstructed geomagnetic field based on the tree ring radiocarbon record it is possible to reconstruct geomagnetic field intensity changes during the holocene a comparison of radiocarbon based and independent geomagnetic field reconstructions indicates that changes in the carbon cycle significantly influenced the atmospheric radiocarbon concentration before 10 000 years bp

global temperature response to century scale degassing from the siberian traps large igneous province abstract the siberian traps large igneous province was a key player in the end permian extinction and climatic change due to degassing from lavas and heated sedimentary rocks although the specific degassing scenarios from the province are debated this implies that gas release on a timescale tuned to the cooling of lava flows and subvolcanic intrusions i e decades to centuries must have been sufficient to affect the atmospheric chemistry here we test this assumption by using simple box model calculations to constrain century scale degassing of co2 and ch4 from high end volumes of individual lava flows and sills from the siberian traps the model includes gas fluxes of ch4 and co2 their atmospheric lifetimes and radiative forcing as well as the climate sensitivity in a global average climate system calibrated to end permian time the fluxes are estimated based on lava degassing and contact aureole volumes and devolatilization during the first 100 years following emplacement we test the sensitivity to extreme emissions of up to 25 gtc yr ch4 fractions from 0 to 100 wide ranges of climate sensitivities 1 5 6 0 c for co2 doubling pre event concentrations and atmospheric lifetimes we find that the global annual mean temperature perturbation is 7 0 c in our baseline case using a 10 gtc yr emission and a 60 ch4 fraction assuming 4 5 c as the climate sensitivity even for low emission scenarios 0 7 1 2 gtc yr the temperature response is 1 5 c we conclude that sporadic individual large scale volcanic events in large igneous provinces have the potential to cause a strong global warming on very short timescales in addition to the emission strength the ch4 fraction and the climate sensitivity have the strongest impact on the century scale temperature perturbation

neotethys closure history of anatolia insights from 40ar 39ar geochronology and p t estimation in high pressure metasedimentary rocks the multiple high pressure hp low temperature lt metamorphic units of western and central anatolia offer a great opportunity to investigate the subduction and continental accretion related evolution of the eastern limb of the long lived aegean subduction system recent reports of the hp lt index mineral fe mg carpholite in three metasedimentary units of the gondwana derived anatolide tauride continental block namely the afyon zone the oren unit and the southern menderes massif suggest a more complicated scenario than the single continental accretion model generally put forward in previous studies this study presents the first isotopic dates white mica 40ar 39ar geochronology and where possible are combined with p t estimates chlorite thermometry phengite barometry multi equilibrium thermobarometry on carpholite bearing rocks from these three hp lt metasedimentary units it is shown that in the afyon zone carpholite bearing assemblages were retrogressed through greenschist facies conditions at c 67 62 ma early retrograde stages in the oren unit are dated to 63 59 ma in the kurudere nebiler unit hp mesozoic cover of the southern menderes massif hp retrograde stages are dated to c 45 ma and post collisional cooling to c 26 ma these new results support that the oren unit represents the westernmost continuation of the afyon zone whereas the kurudere nebiler unit correlates with the cycladic blueschist unit of the aegean domain in western anatolia three successive hp lt metamorphic belts thus formed the northernmost tavsanli zone c 88 82 ma the oren afyon zone between 70 and 65 ma and the kurudere nebiler unit c 52 45 ma the southward younging trend of the hp lt metamorphism from the upper and internal to the deeper and more external structural units as in the aegean domain points to the persistence of subduction in western anatolia between 93 90 and c 35 ma after the accretion of the menderes tauride terrane in eocene times subduction stopped leading to continental collision and associated barrovian type metamorphism because by contrast the aegean subduction did remain active due to slab roll back and trench migration the eastern limb below southwestern anatolia of the hellenic slab was dramatically curved and consequently teared it therefore is suggested that the possibility for subduction to continue after the accretion of buoyant e g continental terranes probably depends much on palaeogeography

high resolution analyses of an early holocene climate event may imply decreased solar forcing as an important climate trigger early holocene lacustrine tree ring ice core and marine records reveal that the northern hemisphere underwent a short cooling event at 10 300 calendar yr b p 9100 14 c yr b p the records were compared on a common high resolution time scale and show that the event lasted less than 200 yr with a cooling peak of 50 yr and the event coincides with a distinct holocene thermohaline disturbance recognized in the north atlantic ocean in spite of wellknown freshwater forcings at the time of the event the negligible difference between the modeled d 14 c record based on the gisp2 greenland ice sheet project 2 10 be data and the measured values does not allow for detectable d 14 c changes related to global ocean ventilation we can however show that the onset of the cooling coincides with the onset of one of the largest holocene 10 be flux peaks this finding may imply that the climate system is more

metamorphism of the central anatolian crystalline complex turkey influence of orogen normal collision vs wrench dominated tectonics on p t t paths the central anatolian crystalline complex cacc is a microcontinent in the alpine himalayan belt it has previously been considered as a coherent structural entity but although the entire cacc is comprised of similar rocks primarily metasedimentary rocks and granitoids it consists of at least four tectonic blocks characterized by different p t t paths these blocks are the kirsehir north west akdag north east nigde south and aksaray west massifs the northern massifs experienced thrusting and folding during collision and were slowly exhumed by erosion metamorphic rocks are characterized by clockwise p t paths at moderate p t and local low p high t lp ht overprinting in the highest grade rocks apatite fission track ages are eocene to oligocene 47 32 ma the aksaray block represents the hot shallow mid crust of a late cretaceous early tertiary arc it is dominated by intrusions rare metapelitic rocks record low p 4 kbar regional metamorphism overprinted by lp ht contact metamorphism apatite fission track ages are 50 45 ma the nigde massif is different from the other cacc blocks because it evolved as a core complex in a wrench dominated setting it is characterized by clockwise p t paths at moderate p t followed by widespread lp ht metamorphism apatite fission track ages are miocene 12 9 ma significantly younger than those in the northern massifs nigde rocks resided in the mid crust at a time when the rest of the cacc was at or near the earth s surface variations in p t t and tectonic histories especially timing of exhumation between the northern and southern cacc reflect the difference between head on collision vs mid crustal wrenching

late cenozoic tectono sedimentary evolution of the ulukisla basin progressive basin development in south central turkey the ulukisla basin is one of the most important late cretaceous cenozoic basins in central anatolia the basin is surrounded by the bolkar mountains of tauride platform in the south the nigde massif of central anatolian crystalline complex to the north and the ecemis fault zone and aladag mountains in the east the fact that time interval proposed for the formation of ulukisla basin is quite wide and more than one tectonic regime prevailed in the region have led to various suggestions concerning the evolution of the basin while the suggestions majorly examine the character of the basin during the late cretaceous early cenozoic the number of detailed studies on the status of the basin in the late cenozoic is limited in this study we focused on the less studied late cenozoic evolution to differentiate the tectonic phases that controlled the development of ulukisla basin through structural data and elaborate the responses of sedimentation and paleogeography during this period through detailed facies analyses our findings indicate that the ulukisla basin which started to develop as a supradetachment basin in the late cretaceous has continued its extensional development progressively during its cenozoic history while the relatively well studied early cenozoic sequences represent a marine environment that was rapidly changed shallow to deep sea environment and then gained a shallow character by the middle eocene sedimentary features and fossil contents of the late cenozoic units characterize deposition started in a paralic environment changing into a terrestrial environment rapidly as a result of isolation by the uplifting of surrounding topographies while the basin continues its development under an extensional tectonic regime however the extensional basin history surceased in post middle eocene and post middle miocene probably caused by the closing processes of the different branches of neotethys ocean

apatite fission track data from central anatolian granitoids turkey constraints on neo tethyan closure 1 apatite fission track age versus elevation profiles and temperature time path modeling indicate an early to middle paleocene 57 62 ma rapid exhumation of the middle to late cretaceous granitoids in central anatolia and an oligocene 28 30 ma rapid exhumation of the eocene kosedag batholith in the ne sivas region part of eastern central pontides the early to middle paleocene rapid exhumation is thought to result from a regional compressional regime following the collision of the eurasian plate and the tauride anatolide platform at the closure of the izmir ankara erzincan branch of the northern neo tethys the oligocene accelerated exhumation of the kosedag batholith is contemporaneous with the oligo miocene closure of the southern neo tethys which juxtaposed the amalgamated eurasian and tauride anatolide platform and the african arabian plate along the bitlis zagros suture in southeast anatolia the compressional regime due to this collision affected a large area between the greater caucasus in the north and northern african arabian plate in the south

mineralogical geochemical constraints on intrusives in central anatolia turkey tectono magmatic evolution and characteristics of mantle source collision related rocks intrude metamorphic rocks overthrust by ophiolitic units to make up the central anatolian crystalline complex a wide variety of rock types were produced by the latest cretaceous magmatism in the complex these rocks can be divided into three distinct units 1 calc alkaline agacoren behrekdag cefalikdag celebi ekecikdag halacli karamadazi kosefakili terlemez uckapili yozgat 2 sub alkaline baranadag and 3 alkaline atdere davulalan egrialan hamit idisdagi karacayir the calc alkaline rocks are metaluminous peraluminous i to s type plutons ranging from monzodiorite to granite the sub alkaline rocks are metaluminous i type plutons ranging from monzonite to granite the alkaline rocks are metaluminous to peralkaline plutons predominantly a type ranging from foid bearing monzosyenite to granite these plutons crystallized under varying pressures 5 3 2 6 kbar and a wide range of temperatures 858 698 c from highly oxidized magmas log f o 2 17 to 12 all intrusive rocks display enrichment in lile and lree compare to hfse and have high 87 sr 86 sr and low 143 nd 144 nd ratios these characteristics indicate that these rocks are derived from a mantle source containing large subduction components and have experienced assimilation coupled with fractional crystallization afc during uprise through crust the coexistence of calc alkaline and alkaline magmatism in the complex may be ascribed to mantle source heterogeneity before collision either thermal perturbation of the metasomatized lithosphere by delamination of the thermal boundary layer or removal of a subducted plate slab breakoff are the likely mechanisms for the initiation of the collision related magmatism in the complex

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

tectonic denudation of a late cretaceous tertiary collisional belt regionally symmetric cooling patterns and their relation to extensional faults in the anatolide belt of western turkey t hermochronological data reveal that the late cretaceous tertiary nappe pile of the anatolide belt of western turkey displays a two stage cooling history three crustal segments differing in structure and cooling history have been identified the central menderes metamorphic core complex represents an inner axial segment of the anatolide belt and exposes the lowest structural levels of the nappe pile whereas the two outer submassifs the g ordes submassif to the north and the ci ne submassif to the south represent higher levels of the nappe pile a regionally significant phase of cooling in the late oligocene and early miocene affected the outer two submassifs and the upper structural levels of the central menderes metamorphic core complex in the northern part of the g ordes submassif cooling was related to top to the nne movement on the simav detachment as the apatite fission track ages show a northward younging trend in the direction of movement on this detachment in the ci ne submassif relatively rapid cooling in late oligocene and early miocene times may have been related to top to the s extensional reactivation of the basal thrust of the overlying lycian nappes the second phase of cooling in the anatolide belt is related to pliocene to recent extension resulting in the formation of the central menderes metamorphic core complex in the inner part of the anatolide belt core complex development caused the formation of supra detachment graben which document the ongoing separation of the central menderes metamorphic core complex from the outer submassifs

evolution of a calcite marble shear zone complex on thassos island greece microstructural and textural fabrics and their kinematic significance abstract the deformation history of a monophase calcite marble shear zone complex on thassos island northern greece is reconstructed by detailed geometric studies of the textural and microstructural patterns relative to a fixed reference system shear zone boundary szb strain localization within the massive marble complex is linked to decreasing p t conditions during the exhumation process of the metamorphic core complex solvus thermometry indicates that temperatures of 300 350 c prevailed during part of the shear zone deformation history the coarse grained marble protolith outside the shear zone is characterized by symmetrically oriented twin sets due to early coaxial deformation a component of heterogeneous non coaxial deformation is first recorded within the adjacent protomylonite enhanced strain weakening by dynamic recrystallization promoted strong localization of plastic deformation in the ultramylonite of the calcite shear zone where high strain was accommodated by non coaxial flow this study demonstrates that both a pure shear and a simple shear strain path can result in similar crystallographic preferred orientations single c axis maximum perpendicular to the szb by different dominant deformation mechanisms separated a axis pole figures a and a axis show different density distributions with orthorhombic texture symmetry in the protolith marble and monoclinic symmetry in the ultramylonite marble consistently with the observed grain fabric symmetry

effects of plate convergence obliquity on timing and mechanisms of exhumation of a mid crustal terrain the central anatolian crystalline complex abstract apatite fission track ft ages from the central anatolian crystalline complex cacc a microcontinent within the turkish segment of the alpine himalayan orogen vary dramatically from north to south this variation correlates with differences in the obliquity of convergence of the continental fragment relative to the pontide belt for the northern cacc and the tauride belt for the southern cacc the northern cacc was deformed and metamorphosed during late cretaceous orogen normal collision and was exhumed from the mid crust to shallow crustal levels 50 ma to the present in contrast the southern cacc nigde massif was initially deformed and metamorphosed during late cretaceous contraction but subsequently developed as a metamorphic core complex in a wrench dominated regime and was exhumed to

uptake of excess co2 by an outcrop diffusion model of the ocean a carbon cycle model is presented in which direct ventilation of intermediate and deep ocean waters in high latitudes is taken into account the 1 dimensional ocean model is an extension of a box diffusion model including a deep sea outcrop at the surface if both are calibrated in a consistent way the outcrop diffusion ocean takes up more excess co2 than the box diffusion ocean because the outcropping deep water is essentially virgin as to fossil co2 two calibration methods are compared using the distribution either of natural or of bomb produced 14c the latter leads to a higher oceanic uptake of excess co2 than the former and to a better agreement with the observed atmospheric increase long term model responses are also discussed

understanding the causes and consequences of past marine carbon cycling variability through models abstract on geological time scales the production and degree of recycling of biogenic carbon in the marine realm and ultimately its removal to sediments exerts a dominant control on atmospheric co 2 and hence variability in climate this is a highly complex system involving a myriad of inter connected biological chemical and physical processes for this reason alone linking observations often highly abstracted in the form of proxies to the primary processes involved and ultimately to explanatory hypotheses for specific geological events and transitions is challenging the past few decades have seen a progressive improvement in theoretical and process based understanding of the various components that make up the marine carbon cycle and hand in hand with this the development of numerical model representations of the complete system models have also been designed and or adapted with paleoclimate questions in mind and applied to quantitatively explore the role of the marine carbon cycle in both perturbations and long term geologic evolutionary trends in global climate and possible feedbacks between them however we must ask whether paleoclimate models incorporate sufficiently appropriate representations of the dynamics and sensitivities of the marine carbon cycle and indeed whether in the geological context we really know what these dynamics are here we provide a comprehensive overview of how marine carbon cycling and the biological carbon pump is treated in available paleoclimate models with the aim of critically evaluating their ability to help interpret past marine carbon cycle and climate dynamics to this end we first provide an overview of commonly used paleoclimate models and some of their associated paleo applications drawing from a wide range of global carbon cycle box models and earth system models of intermediate complexity emics secondly we review and evaluate the three dominant processes involved in the cycling of organic and inorganic carbon in the marine system and how they are represented in models namely biological productivity at the ocean surface remineralisation dissolution of particulate carbon within the water column and the benthic pelagic coupling at the seafloor we generate and employ illustrative examples using the model genie to show how different parameterisations of water column and sediment processes can lead to significantly different model projections our compilation reveals the prevalence of static parameterisations of marine carbon cycling among existing paleoclimate models which are commonly empirically derived from present day observations although such approaches tend to represent carbon transfer in the modern ocean well they are potentially compromised in their ability to reflect the true degree of freedom and strength of feedbacks with respect to past climate events particularly those characterised by environmental boundary conditions that differ fundamentally from today finally we discuss the importance of using models of different complexities and how questions of model uncertainty may start to be addressed

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

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

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

a long lived late cretaceous early eocene extensional province in anatolia structural evidence from the ivriz detachment southern central turkey abstract central anatolia exposes previously buried and metamorphosed continent derived rocks the kirsehir and afyon zones now covering an area of 300 400 km so far the exhumation history of these rocks has been poorly constrained we show for the first time that the major 120 km long top ne ivriz detachment controlled the exhumation of the hp lt metamorphic afyon zone in southern central anatolia we date its activity at between the latest cretaceous and early eocene times combined with previously documented isolated extensional detachments found in the kirsehir block our results suggest that a major province governed by extensional exhumation was active throughout central anatolia between 80 and 48 ma although similar in dimension to the aegean extensional province to the east the central anatolian extensional province is considerably older and was controlled by a different extension direction from this we infer that the african slab s that subducted below anatolia must have rolled back relative to the aegean slab since at least the latest cretaceous suggesting that these regions were underlain by a segmented slab whether or not these early segments already corresponded to the modern aegean antalya and cyprus slab segments remains open for debate but slab segmentation must have occurred much earlier than previously thought

assessing the differences between the intcal and greenland ice core time scales for the last 14 000 years via the common cosmogenic radionuclide variations variations in galactic cosmic rays reaching the earth s atmosphere produce globally synchronous variations in the production rates of cosmogenic radionuclides in consequence they leave their imprint in tree ring 14c and ice core 10be records by identifying this signal and correcting for the known geochemical influences on the radionuclides it is possible to compare and synchronize the tree ring chronology and the greenland ice core time scale here we compare the intcal13 and the gicc05 time scales for the last 14 000 years via identification and synchronization of the common short term variations in the ice core 10be and tree ring 14c records most likely induced by variations in the solar modulation of galactic cosmic rays we conclude that systematic time scale differences have to be accounted for if ice core and 14c dated records are compared on decadal time scales these are mostly within the uncertainties of the time scales and the method proposed here however for large parts of the mid to late holocene i e after 7000 yrs bp the best agreement between ice core 10be and tree ring 14c records is obtained for time shifts outside the stated errors of the respective time scales a transfer function is proposed that can be applied to synchronize the gicc05 ice core time scale to the radiocarbon time scale

changing controls on oceanic radiocarbon new insights on shallow to deep ocean exchange and anthropogenic co2 uptake 1 the injection of radiocarbon 14c into the atmosphere by nuclear weapons testing in the 1950s and 1960s has provided a powerful tracer to investigate ocean physical and chemical processes while the oceanic uptake of bomb derived 14c was primarily controlled by air sea exchange in the early decades after the bomb spike we demonstrate that changes in oceanic 14c are now primarily controlled by shallow to deep ocean exchange i e the same mechanism that governs anthropogenic co2 uptake this is a result of accumulated bomb 14c uptake that has rapidly decreased the air sea gradient of 14c c 14c and shifted the main reservoir of bomb 14c from the atmosphere to the upper ocean the air sea 14c gradient reduced further by fossil fuel dilution is now weaker than before weapons testing in most regions oceanic 14c and particularly its temporal change can now be used to study the oceanic uptake of anthropogenic co2 we examine observed changes in oceanic 14c between the woce save 1988 1995 and the clivar 2001 2007 eras and simulations with two ocean general circulation models the community climate system model ccsm and the estimating the circulation and climate of the ocean model ecco observed oceanic 14c and its changes between the 1980s 90s and 2000s indicate that shallow to deep exchange is too efficient in ecco and too sluggish in ccsm these findings suggest that mean global oceanic uptake of anthropogenic co2 between 1990 and 2007 is bounded by the ecco based estimate of 2 3 pg c yr 1 and the ccsm based estimate of 1 7 pg c yr 1

geochemical cycles in an ocean general circulation model preindustrial tracer distributions a state of the art report is given of the hamburg model of the oceanic carbon cycle the model advects geochemical tracers important to the carbon cycle by the currents of a general circulation model the geochemical cycling is driven by a michaelis menten type production kinetics the model is an extension of the bacastow and maier reimer 1990 model it is based on a more realistic current field and includes a mechanism of lysocline sediment interaction principal variables are co2 alkalinity phosphate oxygen and silicate the carbon variables are defined for 12c 13c and 14c separately in addition to these carbon isotopes 39a and 18o of dissolved oxygen are predicted the model predicts realistic global patterns of tracer distribution in the equatorial eastern pacific however the structures are exaggerated due to a strong upwelling which is a common feature of coarse resolution models of the general circulation of the ocean

metamorphic core complexes of cordilleran type in the cyclades aegean sea greece the islands of ios and naxos in the cycladic archipelago greece contain elongate domes over which a pervasive north to north northeast stretching lineation is warped these islands may be metamorphic core complexes of cordilleran type involving middle crustal rocks drawn upward and outward from underneath the sedimentary basins now 100 km to the south from ca 25 ma onward during uplift the crystalline rocks now exposed on the islands were deformed noncoaxially in the deeper levels of a major shallow dipping ductile shear zone this shear zone may have connected with low angle normal faults in its upper levels because it is probable that its later history involved the metamorphic complexes being dragged out from under a stretching and fracturing upper plate composed mainly of unmetamorphosed sedimentary and ophiolite suite rocks this model can be extended to explain the exhumation of the high pressure low temperature metamorphic rocks on crete which with the cyclades forms a distended paired metamorphic belt separated by an active sedimentary basin

exhumation of blueschists along a tethyan suture in northwest turkey a blueschist belt formed during the mid cretaceous 88 ma high pressure metamorphism of a passive continental margin sequence of shale siltstone quartzite and limestone occurs immediately south of the tethyan suture in northwest turkey a transect across the tethyan suture was mapped to constrain the exhumation of blueschist facies assemblages the presence of jadeite glaucophane and lawsonite in the blueschists indicates p t conditions of 20 kbar and 430 c the blueschists are tectonically overlain by a cretaceous oceanic accretionary complex showing an incipient blueschist metamorphism a peridotite slab with subvertical layering lies along a low angle fault contact over the blueschists and the accretionary complex isolated slices of early cretaceous 101 4 ma garnet amphibolites occur at the base of the peridotite the garnet amphibolites which show an incipient blueschist facies overprint have probably formed during the oceanic subduction in the foot wall of the subduction zone and later underplated the hanging wall blueschists and peridotites are abruptly truncated in the north by the steeply dipping suture fault that juxtaposes unmetamorphosed and slightly deformed triassic to jurassic sediments of the northern continent against the peridotite and the accretionary complex tectonic juxtaposition of the lower pressure accretionary complex and peridotites over the higher pressure blueschists implies the removal of a 45 km thick oceanic mantle sequence above the blueschists regional geological and geometric constraints suggest that the exhumation of the blueschists was achieved by a combination of two simultaneously acting mechanisms the first was the detachment of the upper crustal blueschist sequence from its basement in the subduction zone and its incorporation to the hanging wall followed by buoyant ascent the second mechanism is the progressive shallowing of the subducted continental lithosphere resulting in the thinning of the mantle wedge above the subducted slab the blueschists were partly exposed prior to the paleocene continent continent collision post collisional eocene 52 48 ma calc alkaline plutons that were emplaced in the blueschists and the overlying peridotite at 10 km depth are interpreted to have formed by crustal anatexis from advective heating by mantle melts these have probably been generated during the upwelling of the asthenosphere under the shallowing continental lithosphere

the ductile shear zone in granitoid of the central anatolian crystalline complex turkey implications for the origins of the tuzgolu basin during the late cretaceous extensional deformation abstract the emizozu shear zone is the west northwest trending ductile shear zone within the agacoren granitoid in central turkey deformation that affected the granitoid along the emizozu shear zone resulted in mylonites with mylonitic foliation and stretching lineation the textural features of the deformed minerals suggest that mylonitization occurred under conditions of upper greenschist facies the shear indicators including asymmetric porphyroclasts oblique foliation and shear bands suggest a down dip top to the southwest displacement the orientation of stretching lineation as well as kinematic indicators indicates the extensional character of the emizozu shear zone although it is not precisely dated the available age constraints suggest that the zone formed at 78 71 ma according to field and micro structural data the agacoren granitoid was most likely emplaced during a regional deformation in central turkey and synchronously or shortly after was overprinted by the extensional emizozu shear zone the zone can also be correlated with the earlier stage development of the tuzgolu basin in central turkey

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

tree rings and ice cores reveal c 14 calibration uncertainties during the younger dryas the younger dryas interval during the last glacial termination was an abrupt return to glacial like conditions punctuating the transition to a warmer interglacial climate despite recent advances in the layer counting of ice core records of the termination the timing and length of the younger dryas remain controversial also a steep rise in the concentration of atmospheric radiocarbon at the onset of the interval recorded primarily in the cariaco basin has been difficult to reconcile with simulations of the younger dryas carbon cycle here we discuss a radiocarbon chronology from a tree ring record covering the late glacial period that has not been absolutely dated we correlate the chronology to ice core timescales using the common cosmic production signal in tree ring 14c and ice core 10be concentrations the results of this correlation suggest that the cariaco record may be biased by changes in the concentration of radiocarbon in the upper ocean during the early phase of the younger dryas climate reversal in the cariaco basin this bias in the marine record may also affect the accuracy of a widely used radiocarbon calibration curve over this interval our tree ring based radiocarbon record is easily reconciled with simulated production rates and carbon cycle changes associated with reduced ocean ventilation during the younger dryas attaching a floating tree ring chronology to ice core records that cover the abrupt younger dryas cold interval during the last glacial termination provides a better estimate of the onset and duration of the radiocarbon anomaly the chronology suggests that marine records may be biased by changes in the concentration of radiocarbon in the ocean which may affect the accuracy of a popular radiocarbon calibration program during this interval

the pre obduction to post obduction evolution of the sivas ophiolite turkey and implications for the precollisional history of eastern anatolia

timing of post obduction granitoids from intrusion through cooling to exhumation in central anatolia turkey abstract the middle to late cretaceous central anatolian granitoids intrude the supra subduction zone type central anatolian ophiolite and medium to high grade metasediments of central anatolian crystalline complex and are overlain by late palaeocene to early middle eocene sediments their single zircon 207 pb 206 pb evaporation ages define three clusters 1 cenomanian turonian weighted mean age 94 9 3 4 ma 2 turonian santonian 85 5 5 5 ma and 3 campanian 74 9 3 8 ma their hornblende and biotite 40 ar 39 ar and k ar cooling ages cluster around 80 65 ma the close hornblende and biotite ages reflect rapid exhumation of a mid crustal section during the campanian maastrichtian early to middle palaeocene 57 62 ma apatite fission track age clusters date the tail end of this exhumation episode it is proposed that the central anatolian granitoid melts were generated in a post collisional extensional setting following the docking of an oceanic island arc onto the tauride anatolide platform campanian maastrichtian to early middle palaeocene rapid exhumation event is considered to result from continent continent collisions between eurasian plate and the tauride anatolide platform along the izmir ankara erzincan suture zone

diachronous demise of the neotethys ocean as a driver for non cylindrical orogenesis in anatolia continent continent collision drives crustal deformation topographic rise and geodynamic change africa eurasia convergence accommodated in the eastern mediterranean involved subduction of the neotethyan oceanic lithosphere in anatolia subduction was followed by collision of continental crust of greater adria with eurasia to form the izmir ankara erzincan suture zone discerning the effects of this collision from pre collisional ophiolite obduction related orogeny of greater adria is notoriously difficult estimates on the timing of collision in central anatolia are based on a forearc to foreland basin transition along the eurasian margin and suggest a 60 ma age of initial collision here we assess whether this age is also representative for collision in eastern anatolia and across the cenozoic sivas basin that straddles the greater adria europe suture to this end we retro deform regional block rotations in the pontides the kirsehir block and the taurides building a first order regional block circuit around the sivas basin we show that up to 700 km of convergence must have been accommodated across the sivas basin after central anatolian kirsehir pontide collision at 60 ma an order of magnitude more than estimated crustal shortening and that wholesale lithospheric subduction must have occurred throughout much of the cenozoic paleocene collision would require that this subduction consumed continental lithosphere which is unlikely we consequently infer that oceanic subduction continued much longer in eastern anatolia perhaps well into the miocene we postulate that prolonged oceanic subduction and slab pull drew the eastern taurides north relative to the central taurides leading to shortening and oroclinal bending in central anatolia the diachronous demise of the neotethys ocean in anatolia as a function of its paleogeography is thus a likely driver for the strong non cylindricity of the cenozoic anatolian collisional orogen

persistent link between solar activity and greenland climate during the last glacial maximum changes in solar activity have previously been proposed to cause decadal to millennial scale fluctuations in both the modern and holocene climates1 direct observational records of solar activity such as sunspot numbers exist for only the past few hundred years so solar variability for earlier periods is typically reconstructed from measurements of cosmogenic radionuclides such as 10be and 14c from ice cores and tree rings2 3 here we present a high resolution 10be record from the ice core collected from central greenland by the greenland ice core project grip the record spans from 22 500 to 10 000 years ago and is based on new and compiled data4 5 6 using 14c records7 8 to control for climate related influences on 10be deposition we reconstruct centennial changes in solar activity we find that during the last glacial maximum solar minima correlate with more negative 18o values of ice and are accompanied by increased snow accumulation and sea salt input over central greenland we suggest that solar minima could have induced changes in the stratosphere that favour the development of high pressure blocking systems located to the south of greenland as has been found in observations and model simulations for recent climate9 10 we conclude that the mechanism behind solar forcing of regional climate change may have been similar under both modern and last glacial maximum climate conditions

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

modeling the signal transfer of sea water δ18o to the δ18o of atmospheric oxygen using a diagnostic box model for the terrestrial and marine biosphere we make use of a simple diagnostic box model to determine the sensitivities of the influencing parameters for the isotopic signal transfer of seawater oxygen to atmospheric oxygen we calculate the 18o of atmospheric oxygen from prescribed oxygen fluxes of the living and dead biomes on land and in the ocean respectively the model is driven by an assumed experiment 1 or measured experiments 2 and 3 temporal seawater 18o signal and a land biomass estimation in experiment 1 we calculated the required changes of several model parameters in order to study fast variations of 18o of atmospheric oxygen as seen in the greenland ice core project grip ice at depths assigned to the eemian time period our calculations support evidence of stratigraphic problems at these depths in the grip ice core in experiment 2 we adjusted the model output which was driven by the benthic seawater 18o record from v19 30 to the measured greenland ice sheet project 2 18o record of atmospheric oxygen for the last 110 000 years by varying the model parameter single and multi parameter matchings were performed the results for single parameter runs exceed the uncertainty ranges for most of the parameters while multiparameter variations are well within these ranges the model calculations are most sensitive to the land respiration factor our results support the findings of van de water et al 1994 that the fractionations associated with biomes activities were most probably lower during cold periods which could point to a combination of fractionations with different temperature dependencies the model results indicate periods of higher marine biological activity during the ice age than today temporal variations of the model parameters show a double peak around 10000 and 8000 years ago which could be associated with meltwater pulses as shown in experiment 3 however they are hardly the well known fairbanks fairbanks et al 1992 pulses since these occur 3000 to 4000 years earlier

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

39ar 40ar ages from the yozgat batholith preliminary data on the timing of late cretaceous extension in the central anatolian crystalline complex turkey abstract isotopic dating of sheared and unsheared rocks can be important in understanding deformational processes in orogenic belts this study examines 40ar 39ar dating of granitoids and mylonitic rocks to constrain intrusive and deformational events within the northern part of the central anatolian crystalline complex cacc the kerkenez granitoid within this complex comprising primarily quartz monzonite and hornblende granite contains discrete ductile shear zones these zones are characterized by protomylonite and mylonite formations with metamorphism conditions that reach lower amphibolite facies mylonitic foliations and lineations and asymmetric kinematic indicators e g asymmetric porphyroclasts composite shear bands with top to the northwest shear senses considering the high closure temperatures 500 c for hornblende and 350 c for k feldspar both hornblende quartz monzonite and hornblende granite in the kerkenez granitoid may have cooled rapidly suggesting that hornblende quartz monz

geochemical character and tectonic environment of neotethyan ophiolitic fragments and metabasites in the central anatolian crystalline complex turkey

three dimensional structure of the upper mantle beneath the atlantic ocean inferred from long period rayleigh waves 2 inversion the three dimensional shear wave velocity structure of the upper mantle beneath the atlantic ocean is investigated by inversion of fundamental mode of rayleigh wave group and phase velocities the results are reliable down to 300 km depth and improve upon the image of upper mantle structure given by global tomographic models the inversion of two dimensional lateral distributions of group and phase velocities regionalized without a priori constraints shows that shear wave velocities are correlated with lithospheric age beneath the north atlantic our data set fails to quantify the correlation between shear velocities and lithospheric age because of the small lateral extent of young regions 22 ma and of strong transverse gradients in contrast with similar studies in the indian and pacific oceans slow velocities associated with the location of the mid atlantic ridge are restricted to the lithosphere therefore the atlantic mid oceanic ridge behaves as a shallow structure which is weakly related to deep upwelling asthenospheric flows at depths greater than 200 km the central part of the atlantic is characterized by the highest velocity anomaly this anomaly can be interpreted in different ways part of this anomaly might correspond to a negative vsh vsv vsv ratio implicitely included in the isotropic inversion we also tentatively interpret this anomaly as an important contributor to a shallow degree two pattern of shear wave velocity distribution for the atlantic area

kinematic evolution of the eastern chalk draw fault during basin and range extension evaluating the role played by preexisting structural fabrics in along strike displacement patterns abstractbasin and range extensional structures in trans pecos texas have been interpreted to be strongly influenced by preexisting structures including igneous centers in the big bend region these igneous centers are interpreted to have deflected propagating faults as they are rheologically strong relative to the surrounding rocks we conducted detailed field mapping and analysis of fracture and fault data along the eastern segment of the chalk draw fault in big bend national park to evaluate its kinematic evolution and interaction with paleogene plutons our primary results document the following key relationships 1 the rosillos laccolith and other paleogene plutons in the study area are pervasively fractured dominantly by northwest striking mode i fractures which generally do not extend into adjacent sedimentary rock sequences 2 throw on the eastern chalk draw fault is strongly asymmetric decreasing rapidly as it enters the rosillos laccolith and 3 analysis of fault slip data in the regio

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

tectonostratigraphic evolution of the upper cretaceous cenozoic central anatolian basins an integrated study of diachronous ocean basin closure and continental collision

southern ocean wind response to north atlantic cooling and the rise in atmospheric co2 modeling perspective and paleoceanographic implications 1 a recent study found enhanced upwelling rates in the southern ocean during the last glacial termination that coincided with the deglacial warming in antarctica and the rise in atmospheric co2 they hypothesized that the intensification of southern hemisphere midlatitude westerlies the presumed cause of the increased wind driven upwelling was triggered by an initial cooling within the glacial north atlantic whose influence was then communicated to the southern midlatitudes through an atmospheric teleconnection in this study we explore the viability of the above hypothesis using a modeling strategy focusing on the atmospheric teleconnection in simulations where north atlantic cooling was applied the model intertropical convergence zone shifted southward and westerlies and wind stress over southern ocean increased by as much as 25 while the perennial westerly anomalies occur over the entire southern ocean they are strongest over the south pacific during the austral winter when the wind stress anomalies were applied to an earth system model incorporating interactive marine biogeochemistry atmospheric co2 rises between 20 and 60 ppm depending on the biological response we thus confirm the viability of the proposed atmospheric teleconnection hypothesis the teleconnection appears to involves two distinct steps first the north atlantic cooling shifts the intertropical convergence zone southward weakening the southern branch of the hadley circulation and second how the altered hadley circulation in turn modifies the structure of midlatitude westerlies in the south pacific via the former s influence on the southern hemisphere subtropical jet this study underscores the control of the northern hemisphere has on southern midlatitude westerlies mediating by tropical circulation in contrast to past paleoclimate hypotheses that the magnitude and position of the southern midlatitude westerlies was controlled by global mean temperature our results do not preclude other potential mechanisms for affecting southern ocean ventilation in particular through oceanic pathways