tectonic evolution of a part of the tethyside orogenic collage the kargi massif northern turkey the central part of the rhodope pontide fragment one of the major tectonic units in turkey provides critical data for evaluating the cimmeride and alpide evolution of the mediterranean tethysides tectonic events that affected the central part of the rhodope pontide fragment since the end of the paleozoic generated east west trending belts with the event of every episode redeforming and partly obliterating the structures of previous episodes this evolution may be conveniently described in terms of three major episodes 1 two different realms of pre dogger oceanic rocks are present in the area the northern realm coincided with main branch of paleo tethys that was being actively destroyed by south dipping subduction the southern realm the karakaya ocean a back arc basin related to this subduction began opening by rifting of a retroarc carbonate platform during the permo triassic to the west a continental domain with sparse magmatism seperated the two oceanic areas toward the east the two oceans become united by the wedging out of the continental domain these two pre dogger oceans closed during the lias and their remnants were emplaced between the southern margin of laurasia and the fragments of the cimmerian continent 2 the second episode partly overlapped the first with rifting south of the cimmerian continent fragment during the lias this rifting was followed by a transgression which covered the ruins of the cimmeride orogenic belt by the malm this rifting concurrently led to the development of the northern branch of the neo tethys and a south facing atlantic type continental margin a southerly thickening sedimentary prism developed on this margin during the lias to early cretaceous interval 3 the floor of the northern branch of neo tethys began to be consumed along the north dipping subduction zone beneath the previosly constructed continental margin this convergent margin generated a magmatic arc to the north and to the south a subduction accretion complex present width of which approaches 80 km to the south of the subduction accretion complex yet another convergent margin is indicated by the presence of the remnants of an ensimatic arc the northern branch of the neo tethys was totally consumed in the late cretaceous to eocene interval

global crustal stress pattern based on the world stress map database release 2008 the world stress map wsm project is a global compilation of information on the contemporary crustal stress field from a wide range of stress indicators the wsm database release 2008 contains 21 750 stress data records that are quality ranked using an updated and refined quality ranking scheme almost 17 000 of these data records have a c quality and are considered to record the orientation of maximum horizontal compressional stress sh to within 25 as this is almost a triplication of data records compared with the first wsm database release in 1992 we reinvestigate the spatial wave length of the stress patterns with a statistical analysis on a global 0 5 grid the resulting smoothed global stress map displays both the mean sh orientation that follows from the maximum smoothing radius for which the standard deviation is b25 and a countour map that displays the wave length of the stress pattern this smoothed global map confirms that long wave length stress patterns n2000 km exist for example in north america and ne asia these have been used in earlier analyses to conclude that the global stress pattern is primarily controlled by plate boundary forces that are transmitted into the intraplate region however our analysis reveals that rather short wave length of the stress pattern b200 km are quite frequent too particularly in western europe alaska and the aleutians the southern rocky mountains basin and range province scandinavia caucasus most of the himalayas and indonesia this implies that local stress sources such as density contrasts and active fault systems in some areas have high impact in comparison to plate boundary forces and control the regional stress pattern

variation of lithium isotope composition in the marine environment a preliminary report the li isotopic compositions of ocean waters lake water hydrothermal solutions altered and unaltered basalts have been determined using the technique of thermal ionization mass spectrometry of lithium tetraborate seawater appears to be homogeneous in li isotopic composition the mean delta sup 6 li value is minus 32 3 plus minus 0 5 per thousand relative to an isotopic standard three lakes studied lake tanganyika caspian sea and dead sea yield delta sup 6 li similar to the seawater isotopic composition a fresh basalt glass from 21 degree n east pacific rise displays a delta sup 6 li value of minus 4 7 per thousand a hydrothermal solution from a 21 degree n vent field has delta sup 6 li of minus 10 per thousand indicating incomplete extraction of li from the igneous minerals or partial retention in secondary phases the alteration margin of a basalt from the mid atlantic ridge has delta sup 6 li of minus 8 4 per thousand the isotope data of submarine basalts suggest preferential removal of sup 6 li from seawater into alteration minerals during low temperature weathering the delta sup 6 li values of two hydrothermal solutions from guaymas basin were found to be minus 5 per thousand and minus 10 per thousand the results can be interpreted as the net effect of li addition from basalt and sediments and incorporation in hydrothermal precipitates as the hydrothermalmore fluids interact with basin sediments the observed enrichment of sup 7 li in seawater relative to submarine hydrothermal solutions its principal li input is tentatively attributed to isotopic fractionation associated with low temperature alteration of sea floor basalt and incorporation in authigenic sediments it appears that the li isotope system may have characteristics that can resolve the mass balance of li in the ocean less

smoothing and extrapolation of crustal stress orientation measurements the theory and mechanics of a statistical smoothing algorithm for estimating stress fields based on observed data are described incorporated into the algorithm are tunable parameters which allow the user to adjust the smoothness and fidelity of the fitted stress field in addition the user has the option of using robustness weights or to weight the predicted stress field by assigning quality ranks to each data point fitted stress fields can be displayed as either a gridded map axes of maximum or minimum horizontal stress are shown as short bars located at each point in an evenly spaced grid or as a stress trajectory map examples of predicted stress fields for southern california and western canada based on borehole elongation data are displayed as stress trajectory maps a predicted paleostress field for the spanish peaks intrusion complex in colorado based on vertical dike orientations is displayed as a gridded map the smoothing algorithm is not limited to the analysis of stress orientation data any data consisting of a set of undirected lines measured at discrete locations are appropriate for input possible candidates include strain data mineral or intersection lineations and lineaments

age and geodynamic evolution of the black sea basin tectonic evidences of rifting in crimea the timing and direction of opening of the black sea basin are debated however parts of its margins were inverted during cenozoic and can be studied onshore the crimean mountains are located in the middle of the northern margin of the basin and at the onshore prolongation of the mid black sea high we present the first detailed mapping of large striated normal faults in crimea these faults define graben structures that trend parallel to the continental margin kinematic analysis of the faults combined with new biostratigraphic data show that the syn rift sequence is valanginian to late albian in age it consists of siliciclastic deposits with limestone olistoliths in contrast the post rift late cretaceous carbonaceous sequence of crimea is devoid of normal faults or olistoliths it unconformably overlies the graben structures the onset ages and the trends of extension are quite similar in the northern crimea and the southern turkey inverted margins of the basin the early cretaceous extension directions are normal to the mid black sea high and the black sea margins we conclude that rifting of black sea basin occurred from the valanginian to the late albian 39 ma and drifting during the late cretaceous based on the directions of rifting on the lack of evidence of strike slip motions near the mid black sea high and on published paleomagnetic data we propose that the black sea opened with rotations accommodated by transform faults at its western and eastern margins as a response to asymmetric slab rollbacks of the neo tethys plate the inversion of the crimean margin results from two successive shortening events early eocene ne sw compression eocene to present se nw compression their timing support the idea that compressional stresses generated by continental collisions in turkey were transmitted through the strong black sea lithosphere up to crimea

contemporary stress and strain field in the mediterranean from stress inversion of focal mechanisms and gps data abstract mapping the contemporary stress field of the mediterranean provides fundamental insights on the complexity of plate tectonic forces throughout the region and at different depths despite increased data availability and methodological improvements most recent comprehensive stress field characterization across the entire mediterranean dates back to 1995 to extend the regional stress information we use all earthquake focal mechanisms compiled in the world stress map database release 2016 for a formal stress inversion our main goals are to 1 improve the resolution of the stress field orientation 2 evaluate the performance of the recently refined stress inversion methodology in a tectonically complex region 3 test the hypothesis of a depth dependent stress orientation heterogeneity and 4 compare different types of stress and strain observations from surface using the gps derived information on the strain rate tensor down to the seismogenic crust using summation of normalized seismic potencies the obtained stress orientations generally capture the main seismotectonic features including tectonically complex settings such as the alpine orogeny or the ionian sea the orientation of the maximum horizontal stress shmax tends to be uniform with depth within uncertainties while larger stress heterogeneity quantified by means of the focal mechanism diversity and misfit angles is found between 5 and 14 km both the orientation of the largest horizontal shortening axis of the strain field from potency tensors and horizontal strain rate tensor from gps data are generally sub parallel to shmax orientation indicating a linear stress strain relationship and that the orientations of the co seismic release and interseismic strain accumulation are generally consistent

generation of the early cenozoic adakitic volcanism by partial melting of mafic lower crust eastern turkey implications for crustal thickening to delamination abstract early cenozoic 48 50 ma adakitic volcanic rocks from the eastern pontides ne turkey consist of calc alkaline and high k calc alkaline andesite and dacite with sio2 contents ranging from 56 01 to 65 44 wt this is the first time that early eocene volcanism and adakites have been reported from the region the rocks are composed of plagioclase amphibole quartz and mg rich biotite they have high and low mg values ranging from 55 to 62 and 13 to 42 respectively high mg rocks have higher ni and co contents than low mg samples the rocks exhibit enrichments in large ion lithophile elements including the light rare earth elements depletions in nb ta and ti and have high la yb and sr y ratios their relative high isr 0 70474 0 70640 and low end 50 ma values 2 3 to 0 8 are inconsistent with an origin as partial melts of a subducted oceanic slab combined major and trace element and sr nd isotope data suggest that the adakitic magmas are related to the unique tectonic setting of this region where a transition from a collision to an extension stage has created thickening and delamination of the pontide mafic lower crust at 50 ma the high mg adakitic magmas resulted from partial melting of the delaminated eclogitic mafic lower crust that sank into the relatively hot subcrustal mantle and its subsequent interaction with the mantle peridotite during upward transport leaving garnet as the residual phase elevates the mgo content and mg of the magmas whereas low mg magmas formed by the melting of newly exposed lower crustal rocks caused by asthenospheric upwelling which supplies heat flux to the lower crust the data also suggest that the mafic lower continental crust beneath the region was thickened between the late cretaceous and the late paleocene and delaminated during late paleocene to early eocene time which coincides with the initial stage of crustal thinning caused by crustal extensional events in the eastern pontides and rules out the possibility of an extensional regime before 50 ma in the region during the late mesozoic to early cenozoic

crustal stress determination from boreholes and rock cores fundamental principles abstract obtaining quantitative information on the state of stress in the crust can only be accomplished by accessing the zone of interest by drilling the borehole cavity however disrupts the virgin stress state by concentrating stresses in predictable patterns with a number of consequences at sufficiently low stress magnitudes the concentrated stresses amplify the elastic anisotropy azimuthally around the borehole because the elastic properties of most rocks depend nonlinearly on stress at higher levels the stresses damage then fracture the rock near the wellbore wall or within a growing core stub indeed almost all of the borehole techniques indirectly measure stress through these manifestations of the concentrated stresses this contribution reviews at a fundamental level the concentration of stresses by the borehole the effects on the materials in the borehole s vicinity and how these are used to infer stress states stress concentrations applied to rocks which are generally nonlinear elastic materials induce both radial and azimuthal variations in elastic wave speeds near the borehole that can be used to infer stress directions from advanced acoustic logging methods hydraulic fractures initiate propagate and remain propped open by measured pressures that can be interpreted with knowledge of the stress concentrations to obtain quantitative stress magnitudes at higher stress levels the rock fails producing borehole breakouts or drilling induced tensile fractures both of which are indicative of stress directions and can be used to constrain stress magnitudes similarly the various styles of drilling induced core fractures indicate both stress directions and the faulting environment encountered unfortunately no method currently allows for complete determination of the stress tensor using a number of different but complementary techniques is necessary to best constrain in situ stress states

lithostratigraphy facies and deposition environment of the lower jurassic ammonitico rosso type sediments arts in the gumushane area ne turkey implications for the opening of the northern branch of the neo tethys ocean abstract ammonitico rosso type sediments arts form the bottom level of the enkoy formation in the gumushane area the formation accumulated in the rift related basins triggered by extensional tectonic regimes in the early jurassic times six different sections were studied in this area in order to interpret the lithostratigraphy facies and deposition environments of the arts two basic lithofacies were distinguished nodular marly and nodular calcareous these facies provide useful information regarding depositional conditions in the area and environmental energy these factors were mainly related to the relative sea level that in turn was controlled by tectonic and eustasy conditions in addition seven different types of microfacies were recognized and described as a result of the detailed analysis of the sections the results of the analysis show that these sediments in the gumushane area were developed in transgressive phases events these sediments share characteristics with other peri mediterranean regions and sea level curves and show a similarity to the major transgressive pulse during the pliensbachian stage deposition of arts was controlled by syn depositional extensional movements leading to their accumulation on top of tilted blocks slopes and horsts in an open marine environment the arts were developed during the rifting of the continental margins pointing up the phases of the tethys opening neptunian dykes verifying this opening developed at different levels of the arts and were filled with overlying sediments these results support the hypothesis that the arts were formed in tectonically active environments where extensional tectonic movements were continuously improved during the deposition of the arts

boron isotope variations in nature a synthesis the large relative mass difference between the two stable isotopes of boron 10b and 11b and the high geochemical reactivity of boron lead to significant isotope fractionation by natural processes published 11b values relative to the nbs srm 951 standard span a wide range of 90 the lowest 11b values around 30 are reported for non marine evaporite minerals and certain tourmalines the most 11b enriched reservoir known to date are brines from australian salt lakes and the dead sea of israel with 11b values up to 59 dissolved boron in present day seawater has a constant world wide 11b value of 39 5 in this paper available 11b data of a variety of natural fluid and solid samples from different geological environments are compiled and some of the most relevant aspects including possible tracer applications of boron isotope geochemistry are summarized

aluminous granulites from the pulur complex ne turkey a case of partial melting efficient melt extraction and crystallisation abstract in the pulur complex ne turkey a heterogeneous rock sequence ranging from quartz rich mesocratic gneisses to silica and alkali deficient fe mg and al rich melanocratic rocks is characterized by granulite facies assemblages involving garnet cordierite sillimanite ilmenite spinel plagioclase quartz biotite corundum rutile and monazite textural evidence for partial melting in the aluminous granulites particularly leucosomes is largely absent or strongly obliterated by a late stage hydrothermal overprint however inclusion relations high peak p t conditions the refractory modes bulk and biotite compositions of the melanocratic rocks strongly support a model of partial melting the melt was almost completely removed from the melanocratic rocks and crystallised within the adjacent mesocratic gneisses which are silica rich bear evidence of former feldspar and show a large range in major element concentrations as well as a negative correlation of most elements with sio2 peak conditions are estimated to be 800 c and 0 7 0 8 gpa subsequent near isothermal decompression to 0 4 0 5 gpa at 800 730 c is suggested by the formation of cordierite coronas and cordierite spinel symplectites around garnet and in the matrix sm nd rb sr and 40ar 39ar isotope data indicate peak conditions at 330 ma and cooling below 300 c at 310 ma

mapping crustal stress and strain in southwest british columbia 1 this paper investigates the orientation and sources of stress in the forearc of the cascadia subduction zone in southwest british columbia using bayesian inversion results from focal mechanism data and comparing results with gps derived short term strain rates the subduction margin in this region includes a change in orientation from n s in washington state to nw se in british columbia over 1000 focal mechanisms from north american crustal earthquakes have been calculated to identify the dominant style of faulting and 600 were inverted to estimate the principal stress orientations and the stress ratio our results indicate the maximum horizontal compressive stress orientation changes with distance to the trench from approximately margin normal along the coast to approximately margin parallel 100 150 km inland from the coast comparing stress orientations with gps data we relate the margin normal stress direction to subduction related strain rates due to the locked interface between the north american and juan de fuca plates just west of vancouver island further from the margin the plates are coupled less strongly and the margin parallel maximum horizontal compressive stress in the north american plate relates to the northward push of the oregon block which is also observed in the horizontal shortening direction of the residual strain rates after the subduction component is removed

development and structural architecture of the eastern black sea the cenozoic sedimentary fill of the eastern black sea figure 1 is up to 10 km in thickness its bedding is almost horizontal with the the exception of basin flanks the eastern black sea basin is separated from the cenozoic sorokin and tuapse troughs by the buried shatsky and tetyaev ridges which have mesozoic and paleocene eocene sedimentary cover figure 2

the world stress map database release 2016 crustal stress pattern across scales abstract knowledge of the present day crustal in situ stress field is a key for the understanding of geodynamic processes such as global plate tectonics and earthquakes it is also essential for the management of geo reservoirs and underground storage sites for energy and waste since 1986 the world stress map wsm project has systematically compiled the orientation of maximum horizontal stress shmax for the 30th anniversary of the project the wsm database has been updated significantly with 42 870 data records which is double the amount of data in comparison to the database release in 2008 the update focuses on areas with previously sparse data coverage to resolve the stress pattern on different spatial scales in this paper we present details of the new wsm database release 2016 and an analysis of global and regional stress pattern with the higher data density we can now resolve stress pattern heterogeneities from plate wide to local scales in particular we show two examples of 40 60 shmax rotations within 70 km these rotations can be used as proxies to better understand the relative importance of plate boundary forces that control the long wave length pattern in comparison to regional and local controls of the crustal stress state in the new wsm project phase iv that started in 2017 we will continue to further refine the information on the shmax orientation and the stress regime however we will also focus on the compilation of stress magnitude data as this information is essential for the calibration of geomechanical numerical models this enables us to derive a 3 d continuous description of the stress tensor from point wise and incomplete stress tensor information provided with the wsm database such forward models are required for safety aspects of anthropogenic activities in the underground and for a better understanding of tectonic processes such as the earthquake cycle

the black sea basins structure and history new model based on new deep penetration regional seismic data part 2 tectonic history and paleogeography abstract a new lithostratigraphy scheme has been compiled for the western black sea basin and a new geological history scheme from middle jurassic till neogene is suggested for the entire black sea region continental rifting manifested itself from the late barremian to the albian while the time of opening of the basins with oceanic crust was from cenomanian till mid santonian origination of the western and eastern black sea basins took place almost simultaneously during cenozoic time numerous compressional and transpressional structures were formed in different part of the black sea basins it is shown that in pleistocene quaternary time turbidities mass transport deposits and leveed channels were being formed in the distal part of the danube delta

the australian stress map knowledge of the in situ stress field of the australian continent has increased greatly since compilation of the world stress map in 1992 principally by analysis of borehole breakouts and drilling induced tensile fractures in petroleum wells stress orientations are variable across the australian continent as a whole however within 15 of 16 individual stress provinces defined in the australian continent of one to a few hundred kilometres scale mean stress orientations are statistically significant the stress provinces and stress trajectory mapping reveal that there are systematic continental scale rotations of stress orientation within australia unlike many other continental areas stress orientations do not parallel the direction of absolute plate motion nonetheless the regional pattern of stress orientation is consistent with control by plate boundary forces if the complex nature of the convergent northeastern boundary of the indo australian plate and stress focusing by collisional segments of the boundary is recognized

late palaeozoic early cenozoic tectonic development of the eastern pontides artvin area turkey stages of closure of tethys along the southern margin of eurasia

stress orientation on the norwegian continental shelf derived from borehole failures observed in high resolution borehole imaging logs abstract knowledge of stress orientation is crucial for the understanding of many processes in the earth s crust such as tectonic development earthquake occurrence and fluid transport along faults in the case of the norwegian continental shelf which is a prolific area for hydrocarbon production this knowledge also plays an important role for engineering decisions with respect to wellbore stability and reservoir management therefore data on stress orientation have been collected extensively over the past few years in this region however nearly all data published for the norwegian continental shelf for depths less than 6 km are based on the evaluation of four arm caliper data a method with intrinsic limitations for greater depths stress orientation is derived from earthquake focal plane mechanisms this article presents stress orientation data derived from an extensive set of image logs throughout the norwegian continental shelf the analysis is based on the identification of compressive and tensile failures of the borehole wall in electrical and acoustic borehole imaging logs this method for the determination of the stress orientation is found to be highly reliable and capable of delivering detailed and accurate results and thus is far superior to the analysis of breakouts from four arm caliper logs the analysis of image logs shows that the stress orientation is consistent both regionally and with depth strong variations in stress orientation which are often interpreted from earlier analyses of four arm caliper data are not observed this may indicate that some of the earlier four arm caliper analyses may have been biased by the misinterpretation of drilling induced artefacts as stress induced breakouts stress induced failures of the borehole wall are observed in only about 40 of the wells analysed in this paper this does not support the conclusion that the horizontal stresses are isotropic it just indicates that the stress difference in combination with the borehole conditions downhole pressure and temperature was insufficient to induce these failures

organic geochemistry and depositional environment of the aptian bituminous limestone in the kale gumushane area ne turkey an example of lacustrine deposits on the platform carbonate sequence the jurassic lower cretaceous aged carbonate sequence is widely exposed in the southern zone of eastern pontides aptian black bituminous limestone is found in the upper part of this sequence in the kale area gumushane this limestone contains faunal remains e g gastropod ostracod characean stems and miliolid type benthic foraminifera that indicate a freshwater lacustrine depositional environment the total organic carbon toc values of the bituminous limestone samples range from 0 11 1 30 with an average toc value of 0 54 the hydrogen index hi varies from 119 448 mg hc g toc average hi 298 mg hc g toc indicating that the limestone contains gas prone as well as oil prone organic matter pyrolysis data prove that the organic matter content in the bituminous limestone consists of type ii kerogen the average tmax value for bituminous limestone samples is 438 c 434 448 c bitumen toc ratios for bituminous limestone are 0 05 and 0 04 the tmax values and the ratios indicate that the bituminous limestone samples contain early mature to mature organic matter analysis of solvent extracts from the two richest bituminous limestones show a predominance of high carbon number c26 c30 n alkanes the pr ph ratio and cpi value are 1 34 and 0 96 respectively c29 is the dominant sterane with c29 c27 c28 the bituminous limestone samples have low c22 c21 ratios high c24 c23 tricyclic terpane ratios and very low c31r c30 hopane ratios 0 25 these data are consistent with the bituminous limestones being deposited in a lacustrine environment

criteria for the retention of original seawater 87sr86sr in ancient shelf limestones abstract a suite of 40 pennsylvanian and permian shelf limestones from kansas and oklahoma has been analyzed for major and trace elements and for c o and sr isotopes the chemistry and c and o isotope ratios were compared to the difference between the measured 87 sr 86 sr and original seawater ratio concentrations of mn sr and fe varied most systematically with the change in the seawater sr ratio all samples containing 700 ppm mn yielded altered ratios fe and sr contents were also found to have a less well defined correlation with the retention of the original sr ratio all limestones with 900 ppm sr and 20 of 22 samples with a sr mn 2 0 yielded correct ratios the geochemical guidelines were applied to the chemical and isotopic results from 76 shelf limestones mostly of pennsylvanian age from texas and oklahoma more than 92 of the samples that contain sr mn 2 0 yielded correct seawater ratios every sample with sr mn 2 0 retained the original seawater ratio

plate boundary forces are not enough second and third order stress patterns highlighted in the world stress map database 1 the world stress map project compiles a global database of contemporary tectonic stress information of the earth s crust early releases of the world stress map project demonstrated the existence of first order plate scale stress fields controlled by plate boundary forces and second order regional stress fields controlled by major intraplate stress sources such as mountain belts and zones of widespread glacial rebound the 2005 release of the world stress map project database provides for some areas high data density that enables us to investigate third order local stress field variations and the forces controlling them such as active faults local inclusions detachment horizons and density contrasts these forces act as major controls on the stress field orientations when the magnitudes of the horizontal stresses are close to isotropic we present and discuss examples for venezuela australia romania brunei western europe and southern italy where a substantial increase of data records demonstrates some of the additional factors controlling regional and local stress patterns

heterogeneities and interconnections in groundwaters coupled b li and stable isotope variations in a large aquifer system eocene sand aquifer southwestern france abstract the study of stable isotope of the water molecule and elemental data for groundwater in the large eocene sand aquifer system of sw france showed that the 18 o values of groundwater fall in the range 5 6 to 10 6 vs smow with 2 h values varying between and 34 3 to 72 3 vs smow there is no relationship between 18 o and 2 h values and the salinity but the stable isotopes data plot on or near the global meteoric water line taken as a whole the enriched samples clearly correlate with present day recharge while the most depleted samples reflect an old recharge groundwaters in the present study display large ranges of both boron concentrations 7 to 2550 g l 1 and boron isotopic compositions the lowest 11 b value being close to 18 0 and the highest one near 36 2 the scatter of b concentrations and 11 b values reflects the different rock types contributing to the supply of dissolved boron carbonates evaporites and silicates as well as an input from rainwater and fractionation during water rock interaction with clay minerals lithium concentrations in groundwater also span a wide range 0 6 to 253 g l 1 as do the lithium isotopic signatures that range between 6 5 and 28 6 we can evidence there that the b isotopic compositions are controlled by water rock interactions while li and 7 li variations are also controlled by water rock interaction processes dissolution and formation of alteration minerals that can occur at different temperatures within the groundwater system

developments in the understanding and application of lithium isotopes in the earth and planetary sciences the significant relative mass difference c 16 between the two stable isotopes of li approximately 6li 7 5 7li 92 5 coupled with broad elemental dispersion in earth and planetary materials makes this a system of considerable interest in fingerprinting geochemical processes determining mass balances and in thermometry natural mass fractionation in this system is responsible for c 6 variation among materials examined to date fig 1 although the modern era of li isotope quantification has begun there are still many questions about the li isotopic compositions of fundamental materials and the nature of fractionation by important mechanisms that are unanswered e g hoefs 1997 figure 1 summary of lithium isotopic compositions of earth and planetary materials filled bars are solid samples open bars are liquids see text for references and details the purpose of this chapter is to summarize the current understanding of li isotopes in geo and cosmochemical systems and to indicate 1 where li isotopes have a high probability of adding new understanding of these systems 2 where some of the more significant deficits in knowledge exist the small but burgeoning li isotope community has not yet compiled the volume of peer reviewed literature needed to adequately assess even that which has been studied to date as a result significant portions of this chapter are based on data reported in abstracts and as such are more than normally subject to revisions over time this chapter is anticipated to serve as a starting point for those interested in research incorporating li isotope geochemistry or in understanding the state of extant research experiments in li isotope fractionation knowledge of significant li isotopic fractionation during basic chemical processes is long standing the early experiments by taylor and urey 1938 in which li isotopes were fractionated by incomplete extraction of an aqueous solution from a zeolite exchange

volcanic belts as markers of the mesozoic cenozoic active margin of eurasia abstract from the triassic to the present linear belts of calc alkaline volcanism developed along the southern margin of eurasia in the triassic the calc alkaline belt can be traced in turan fore caucasus crimea and dobrogea its development is related to the closure of the paleo tethys when fragments of gondwana iran afghanistan etc were approaching eurasia since the early jurassic calc alkaline volcanism has been related to subduction of the oceanic crust of the mesozoic tethys five stages of calc alkaline volcanic activity can be distinguished early jurassic middle jurassic early cretaceous late cretaceous paleogene and late miocene quaternary the configuration of the volcanic belts the intensity of the volcanism and the chemistry of the erupted products change considerably from stage to stage mesozoic belts were most pronounced in the pontian transcaucasian segment of the margin starting from the late cretaceous and especially in the cenozoic the volcanic belts can be continuously traced from the balkans to afghanistan most of the belts were actually island arcs formed on the fragments of the hercynian of baikalian basement and in this respect similar to the island arc of japan only the incipient island arcs of senonian age formed close to the passive margin of gondwana are the exceptions they were built on oceanic crust and are geochemically close to the mariana arc at certain times early jurassic eocene parallel chains of island arcs existed in general the situation resembled the present day convergent boundary in the western pacific as closure of the tethys proceeded island arcs gave way to marginal continental volcanic belts with wide spread development of high potassium particularly shoshonitic series peaks of volcanic activity in the bajocian late cretaceous eocene and late miocene present alternated with quiet periods and corresponded to the times when the convergence rate between africa and eurasia increased the opening of the back arc basins is reflected in outbursts of basaltic rift type volcanism these outbursts occurred in the toarcian aalenian bathonian late jurassic aptian turonian and early middle eocene

present day stress orientation in the molasse basin abstract the present day state of stress in western europe is considered to be controlled by forces acting at the plate boundaries it is assumed that the alpine orogen only influence the regional pattern of present day stress in western europe within the alps themselves we examine the present day maximum horizontal stress orientation in the molasse basin in the alpine foreland in order to investigate the possible influence of the alps on the far field stress pattern of western europe four arm caliper and image logs were analysed in 137 wells in which a total of 1348 borehole breakouts and 59 drilling induced fractures were observed in 98 wells in the german molasse basin the borehole breakouts and drilling induced fractures reveal that stress orientations are highly consistent within the molasse basin and that the present day maximum horizontal stress orientation rotates from n s in southeast germany 002 n 19 to approximately nnw sse in southwest germany and the swiss molasse basin 150 n 24 the present day maximum horizontal stress orientation in the molasse basin is broadly perpendicular to the strike of the alpine front indicating that the stress pattern is probably controlled by gravitational potential energy of alpine topography rather than by plate boundary forces the present day maximum horizontal stress orientations determined herein have important implications for the production of hydrocarbons and geothermal energy in the german molasse basin in particular that hydraulically induced fractures are likely to propagate n s and that wells deviated to the north or south may have reduced wellbore instability problems

chemical weathering processes in the great artesian basin evidence from lithium and silicon isotopes variations in lithium and silicon isotope ratios in groundwaters of the great artesian basin in australia and the causes of these variations have been explored the chemistries of li and si in groundwater are influenced by the dissolution of primary phases the formation of secondary minerals and the reaction of solid phases with dissolved constituents while isotopic variations are generated by uptake into clays which preferentially incorporate the light isotopes the lithium isotopic composition expressed as view the mathml source li7 of the groundwaters ranges from 9 to 16 16 and clearly reflects changes in aquifer conditions reaction transport modelling indicates that changes in li concentrations are principally controlled by the ratio of the weathering rate of primary minerals to the precipitation rate of secondary minerals whereas view the mathml source li7 is affected by the extent of isotope fractionation during secondary mineral formation which is dependent on mineralogy the patterns of groundwater si concentrations and view the mathml source si30 values versus flow distance suggest that si is at steady state in the aquifer the view the mathml source si30 value of most of the groundwater samples is close to 1 1 which is significantly lower than the view the mathml source si30 value of the reservoir rocks 0 0 since precipitation of clays preferentially removes the light si isotopes from solution the most plausible explanation for these low groundwater view the mathml source si30 values is addition of si by dissolution of isotopically light secondary minerals these data together with model calculations show that li isotopes are extremely sensitive to changes in the chemical and physical conditions in the aquifer whereas si is not importantly the model suggests that even in large aquifers with long fluid residence times where steady state would be expected to be reached the concentrations and isotopic fractionation of trace elements are not controlled by li adsorption the model developed here provides a basis for using li isotopes measured in groundwaters and surface waters to constrain weathering processes

plate tectonic evolution of the southern margin of eurasia in the mesozoic and cenozoic abstract thirteen time interval maps were constructed which depict the triassic to neogene plate tectonic configuration paleogeography and general lithofacies of the southern margin of eurasia the aim of this paper is to provide an outline of the geodynamic evolution and position of the major tectonic elements of the area within a global framework the hercynian orogeny was completed by the collision of gondwana and laurussia whereas the tethys ocean formed the embayment between the eurasian and gondwanian branches of pangea during late triassic early jurassic times several microplates were sutured to the eurasian margin closing the paleotethys ocean a jurassic cretaceous north dipping subduction boundary was developed along this new continental margin south of the pontides transcaucasus and iranian plates the subduction zone trench pulling effect caused rifting creating the back arc basin of the greater caucasus proto south caspian sea which achieved its maximum width during the late cretaceous in the western tethys separation of eurasia from gondwana resulted in the formation of the ligurian penninic pieniny magura ocean alpine tethys as an extension of middle atlantic system and a part of the pangean breakup tectonic system during late jurassic early cretaceous times the outer carpathian rift developed the opening of the western black sea occurred by rifting and drifting of the western central pontides away from the moesian and scythian platforms of eurasia during the early cretaceous cenomanian the latest cretaceous paleogene was the time of the closure of the ligurian pieniny ocean adria alcapa terranes continued their northward movement during eocene early miocene times their oblique collision with the north european plate led to the development of the accretionary wedge of the outer carpathians and its foreland basin the formation of the west carpathian thrusts was completed by the miocene the thrust front was still propagating eastwards in the eastern carpathians during the late cretaceous the lesser caucasus sanandaj sirjan and makran plates were sutured to the iranian afghanistan plates in the caucasus caspian sea area a north dipping subduction zone jumped during paleogene to the scythian turan platform the shatski terrane moved northward closing the greater caucasus basin and opening the eastern black sea the south caspian underwent reorganization during oligocene neogene times the southwestern part of the south caspian basin was reopened while the northwestern part was gradually reduced in size the collision of india and the lut plate with eurasia caused the deformation of central asia and created a system of nw se wrench faults the remnants of jurassic cretaceous back arc systems oceanic and attenuated crust as well as tertiary oceanic and attenuated crust were locked between adjacent continental plates and orogenic systems

slab breakoff a model of lithosphere detachment and its test in the magmatism and deformation of collisional orogens we present a model proposing that oceanic lithosphere detaches from continental lithosphere during continental collision slab breakoff allowing an explanation of syn to post collisional magmatism and metamorphism continental collisions are preceded by subduction of dense oceanic lithosphere and followed by attempted subduction of buoyant continental lithosphere this situation of opposing buoyancy forces leads to extensional deformation in the subducted slab a narrow rifting mode of deformation will result if there is strain localization slab breakoff results we have assessed the plausiblity of this process by quantitatively evaluating an upper bound for the strength of the lithosphere and have compared it with the change in buoyancy force during continental sbduction whether breakoff will occur and the depth at which it will occur is a strong function of temperature and hence the subduction velocity for a subduction velocity of 1 cm yr breakoff could occur at depths of between 50 and 120 km while at higher velocities it is still likely to occur but at deeper depths as a result of the rifting during breakoff the asthenosphere upwells into the narrow rift and following breakoff it impinges on the mechanical lithosphere of the overriding plate the resulting conducted thermal perturbation leads to melting of the metasomatised overriding mantle lithosphere producing basaltic magmatism that leads to granitic magmatism in the crust dry asthenospheric mantle will melt only if breakoff occurs at a depth shallower than ca 50 km breakoff removes the force at the downdip side of the continental crust while the enhanced heating leads to a reduction of the strength of the underlying crust both effects facilitate the freeing of buoyant crustal sheets which can then rise towards the surface leading to the rapid exhumation of eclogite facies continental crust the cessation of subduction and replacement of the cold oceanic lithosphere by asthenosphere leads to rapid uplift of the orogen we have tested the variety of predicted expressions of slab breakoff in the geological record of the alps the aegean islands and the dabie shan a comparison of the various belts highlights 1 that the magmatism and metamorphism are found near the suture and the centre of the orogen demonstrating the general steepening of suture during collision 2 that a vague inverse correlation exists between maximum depth of metamorphism and volume of syn orogenic magmatism and 3 that the melts can be emplaced in both compressive and extensional environments we suggest that slab breakoff is an important step in the evolution of many orogenic belts and it allows an explanation for the combined presence in collisional orogens of magmatism with a mantle parentage and ultra high pressure metamorphics

the formation and inversion of the western greater caucasus basin and the uplift of the western greater caucasus implications for the wider black sea region the western greater caucasus formed by the tectonic inversion of the western strand of the greater caucasus basin a mesozoic rift that opened at the southern margin of laurasia subsidence analysis indicates that the main phase of rifting occurred during the aalenian to bajocian synchronous with that in the eastern alborz and possibly the south caspian basin secondary episodes of subsidence during the late tithonian to berriasian and hauterivian to early aptian are tentatively linked to initial rifting within the western and possibly eastern black sea and during the late campanian to danian to the opening of the eastern black sea initial uplift subaerial exposure and sediment derivation from the western greater caucasus occurred at the eocene oligocene transition oligocene and younger sediments on the southern margin of the former basin were derived from the inverting basin and uplifted parts of its northern margin indicating that the western greater caucasus basin had closed by this time a predominance of pollen representing a montane forest environment dominated by pinacean pollen within these sediments suggests that the uplifting caucasian hinterland had a paleoaltitude of around 2 km from early oligocene time the closure of the western greater caucasus basin and significant uplift of the range at approximately 34 ma is earlier than stated in many studies and needs to be incorporated into geodynamic models for the arabia eurasia region

ridge forces absolute plate motions and the intraplate stress field torque poles are calculated for a variety of possible forces acting on the plates including ridge push slab pull and collisional resistance these torque poles are then compared to the directions of absolute plate motions there is a strong correlation between ridge torque poles and the azimuth of absolute plate motions for the north american south american pacific cocos and eurasian plates simple slab pull torques correlate well with absolute motion azimuths for the pacific nazca and cocos plates and moderately well with the absolute motion azimuth of the indoaustralian plate collisional resistance torque poles correlate with the absolute motion azimuth of the eurasian plate only the correlations are presented as further evidence that the absolute reference frame for plate motion is determined by the surface plates themselves torque poles for various forces are also compared with several long wavelength features of the global intraplate stress field that also tend to be aligned with absolute motion directions in general ridge torque directions agree well with the orientations of maximum horizontal stresses for stable north america western europe and south america and provide an alternative explanation for the alignment in terms of ridge push forces rather than basal drag collisional resistance forces can also explain the alignment of stresses in western europe for the indoaustralian plate the torque pole for collisional resistance forces is consistent with the general pattern of stresses in at least the western half of the plate but is not a good predictor of the entire data set for the plate other processes in addition to collisional resistance must be important for the indo australian plate ridge push forces may account for a significant portion of the long wavelength features of the intraplate stress field especially away from continental collisions such a conclusion is consistent with negative buoyancy of the slab being an important component of the driving mechanism as previously suggested slab forces may be largely balanced within the subducted slab itself and thus have limited effect on deformation of the surface plates

paleoreef maps evaluation of a comprehensive database on phanerozoic reefs to get a better understanding of controls on reef development through time we created a comprehensive database on phanerozoic reefs the database currently comprises 2470 reefs and contains information about geographic position paleoposition age reef type dimensions environmental setting paleontological and petrographical features and reservoir quality of each buildup reef data were analyzed in two qualitatively different ways the first type of analysis was by visualization of paleogeographic reef distribution maps five examples late devonian early permian late triassic late jurassic middle miocene are presented to show the potential of paleoreef maps for paleogeographic and paleoclimatological reconstructions the second type of analysis was a numerical processing of coded reef characteristics to realize major trends in reef evolution and properties of reef carbonates the analysis of paleolatitudinal reef distributions through time shows pronounced asymmetries in some time slices probably related to climatic asymmetries rather than controlled by plate tectonic evolution alone the dominance of particular reef builders through time suggests that there are seven cycles of phanerozoic reef development first curves for the phanerozoic distribution of bioerosion in reefs bathymetric setting and debris potential of reefs are presented the observed pattern in the temporal and spatial distribution of reefs with reservoir quality may assist in hydrocarbon exploration statistical tests on the dependencies of reefal reservoir quality suggest that large size high debris potential low paleolatitude high amount of marine aragonite cement and a platform shelf edge setting favor reservoir quality reefal reservoirs are significantly enhanced in times of high evaporite sedimentation elevated burial of organic carbon low oceanic crust production low atmospheric co2 content and cool paleoclimate as well as when they are present in aragonite oceans

boron and lithium isotopes as groundwater tracers a study at the fresh kills landfill staten island new york usa abstract a study was conducted at the fresh kills landfill staten island new york to investigate the use of b and li isotopes as tracers of mixing and flow in the groundwater environment four end member waters are present at the fresh kills freshwater seawater a geochemically distinct transitional groundwater that occurs in the zone of mixing between seawater and freshwater and landfill leachate the 11b and 6li values of end member waters are distinct and have isotopic compositions that reflect the solute sources freshwater 11b 30 6li 22 transition zone groundwaters 11b 20 6li 27 seawater 11b 40 to 75 6li 37 to 44 leachate 11b 10 6li not determined those wells influenced by seawater exhibited a clear chemical mixing trend with seawater contributions ranging from 3 to 85 well waters with a high percentage of seawater 30 had 11b values that were within 1 of the seawater value 40 whereas a trend of increasing 11b values 55 to 75 was observed for wells with a lower percentage of seawater

extreme lithium isotopic fractionation during continental weathering revealed in saprolites from south carolina the lithium concentration and isotopic composition of two saprolites developed on a granite and diabase dike from south carolina have been measured in order to document the behavior of lithium isotopes during continental weathering both saprolites show a general trend of decreasing d 7 li with increasing weathering intensity as measured by both bulk density and the chemical index of alteration cia the saprolite developed on the granite is isotopically lighter than the fresh igneous rock d 7 li 6 8x to 1 4x vs 2 3x respectively and is generally depleted in lithium these observations are consistent with leaching of lithium via rayleigh distillation during progressive weathering most saprolites fall on a rayleigh distillation curve corresponding to an apparent fractionation factor a of 0 997 however two samples have higher lithium contents than the fresh granite and thus point to additional processes affecting lithium in the saprolite e g sorption of lithium on to clay minerals the saprolite profile developed on the diabase dike shows highly variable d 7 li values ranging down to extremely light compositions 20x previous work has identified a chemical and mineralogical discontinuity at a depth of 2 m but our lithium data show a marked discontinuity at 6 m depth saprolite samples at or above 6 m depth are highly weathered cia 88 95 depleted in lithium having b50 of the original diabase lithium and isotopically light 10x to 20x vs 4 3x for the unweathered diabase most of the data are consistent with leaching of lithium via rayleigh distillation during intense weathering with apparent a values of 0 995 to 0 980 samples experiencing lower apparent a values tend to have higher kaolinite smectite ratios suggesting a mineralogical control on isotopic fractionation however the lightest sample at 20x is only slightly depleted in lithium and would require extremely low a values to explain via rayleigh distilliation this extreme composition remains enigmatic saprolite samples below 6 m have highly variable d 7 li 5x to 14x and importantly lithium concentrations that are higher than that of the unweathered diabase up to 2 4 times the concentration of the fresh diabase these deeper saprolites thus cannot be explained by rayleigh distillation a positive correlation between d 7 li and li

short scale variations of tectonic regimes in the western european stress province north of the alps and pyrenees the data of the european part of the world stress map wsm are used to study the western european stress province north of the alps and pyrenees the study area is characterised by an almost homogeneous n 145 degrees e orientation of the maximum horizont

the use of strontium and lead isotopes to identify sources of water beneath the fresh kills landfill staten island new york usa abstract a study was undertaken to explore whether the isotopic compositions of pb and sr are useful to distinguish mixtures of uncontaminated groundwater seawater and landfill leachate at the fresh kills landfill staten island new york ratios of 87sr 86sr ranged from 0 7088 to 0 7137 and could be used to distinguish sr that was derived from seawater from that in uncontaminated groundwater lead isotopic abundances did not vary systematically among the different water sources plots of 87sr 86sr versus dissolved organic c b and nh4 defined perpendicular trends documenting where leachate or sea water mixed with uncontaminated groundwater and demonstrating that leachate has not contaminated groundwater in aquifers beneath the landfill

active crustal deformation in southeastern tibetan plateau the kinematics and dynamics abstract crustal deformation in southeastern tibetan plateau has been attributed to tectonic extrusion and gravitational spreading here we analyzed the present day strain partitioning in this region using gps data the results show highly localized shear strain along the xianshuihe anninghe xiaojiang strike slip faults as expected by the model of tectonic extrusion however the localized shear strain along strike slip faults ends in southern yunnan and transfers to crustal extension in yunnan and contraction in myanmar we developed three dimensional visco elastoplastic finite element models to investigate the causes of the observed crustal deformation our results indicate that the present day crustal deformation in southeastern tibetan plateau can be largely explained by gravitational spreading

tourmaline in a mesoarchean pelagic hydrothermal system implications for the habitat of early life abstract the rna world hypothesis requires the synthesis of rna to allow the emergence of life on earth hydrothermal systems have been proposed as potential candidates for constructing complex biomolecules however in order to successfully form rna it is necessary to stabilize ribose a rna carbohydrate component borate has been found to stabilize ribose therefore boron rich hydrothermal systems are important environments concerning the origin of life on earth the 3 2 ga dixon island formation of the west pilbara superterrane western australia is a volcano sedimentary sequence the formation represents a mesoarchean pelagic hydrothermal system which formed adjacent to an immature island arc fine grained tourmaline in addition to biogenic carbonaceous matter and spherulitic and tubular bacteriomorphs are found in black chert a boron rich environment was responsible for the formation of these deposits to explore the implications of such a boron enriched environment on microbial activity modes of occurrence and chemical compositions of the tourmaline were examined the tourmaline is schorl or dravite of the alkali tourmaline group and the boron isotope compositions range in 11b from 7 3 to 2 6 the tourmaline occurs in microcrystalline quartz matrix of black chert veins that cross cut a volcanic unit and also in a bedded black chert which overlays the volcanic unit the volcanic unit contains highly altered zones with hydrothermal veins the associated lithologic and stratigraphic features suggest that the black chert veins were the conduits for upward moving hydrothermal fluids which reached the sea floor subsequently the volcanic unit was covered by organic matter rich cherty sediments that in part were fed and or altered by the hydrothermal fluids these results suggest that the origin of boron enrichment to form dixon island tourmaline is not the associated sedimentary mineral assemblage which includes diagenetic clay low grade metamorphic mica and organic matter instead the tourmaline was directly precipitated from hydrothermal fluid enriched in boron furthermore the hydrothermal fluids had already concentrated the boron in the mesoarchean pelagic system prior to the apex of organic matter production and microbial activity our findings support a hypothesis that the boron enriched hydrothermal environment aided the survival and evolution of early life

lithium isotope fractionation in the ganges brahmaputra floodplain and implications for groundwater impact on seawater isotopic composition abstract lithium isotopes are a promising proxy for reconstructing past weathering processes but unraveling the seawater record requires a comprehensive understanding of the magnitude and isotopic composition of li fluxes to the oceans and of how these change over time little information is available on the role of floodplain sediments and groundwater systems in setting the li isotope signature of the dissolved flux delivered from the continents to the oceans here we investigate the li dissolved fluxes of river waters and groundwaters in the ganges brahmaputra floodplain the data suggest that a maximum of 3 1 10 8 and 1 5 10 8 moles li yr are carried to the bay of bengal by ganges brahmaputra rivers and groundwaters respectively the riverine flux has a significantly heavier li isotope composition average 7li 26 than the groundwater flux average 7li 16 and increases downstream across the floodplain 7li in both river waters and shallow groundwater can be explained by li scavenging by quaternary floodplain sediments following a rayleigh fractionation process with preferential removal of 6li on the other hand deep groundwaters 40 m contributing to submarine groundwater discharge to the bay of bengal are enriched in 6li at depth likely due to the dissolution of floodplain sediments releasing li with a light isotope composition similarly low 7li has been reported in other large sedimentary aquifers the deep groundwater values are close to the average isotope composition of the global li inputs to the ocean 15 so groundwater submarine discharge has only a minor influence on the assessment of the modern li isotope budget of the ocean our analysis further suggests that groundwater discharge of li has probably played at most a small and secondary role in past changes in the isotope composition of the total continental flux of li to the ocean

the effect of hydrothermal spring weathering processes and primary productivity on lithium isotopes lake myvatn iceland lithium isotopes are rapidly becoming one of the most useful tracers of silicate weathering processes but little is known on their behaviour in groundwaters and hydrothermal springs and how these sources might influence the weathering signal in surface waters this study presents lithium isotope compositions 7li for cold groundwaters 3 7 c and hydrothermal springs that were at geothermal temperatures 200 300 c but have cooled during transport 17 44 c both represent an important source of water and nutrients for lake myvatn iceland we also present a time series from the laxa river which is the single outflow from the lake the 7li values in the input springs to lake myvatn are highly variable 5 27 and correlate inversely with temperature and total dissolved solids these co variations imply that even in such waters the processes controlling 7li variations during weathering still operate that is the ratio of primary rock dissolution to secondary mineral formation where the latter preferentially incorporates 6li with a temperature dependent fractionation factor in high temperature geothermal waters 300 c secondary mineral formation is inhibited and has a low fractionation factor leading to little 7li fractionation even in waters that have cooled considerably over several months from their geothermal temperatures fractionation is still low and 7li values are similar to those reported from waters measured at 350 c in contrast cooler groundwaters promote relatively high proportions of clay formation which scavenge dissolved solids including 6li the time series on the laxa river the single outflow from lake myvatn shows little 7li variation with time over the 12 month sampling period 17 21 demonstrating that in contrast to tracers such as si isotopes li isotopes are unaffected by the significant seasonal phytoplankton blooms that occur in the lake thus these results clearly illustrate that li isotopes are ideally suited to constrain silicate weathering processes because fractionation by secondary mineral formation operates even when groundwater and hydrothermal inputs are significant and because li isotopes are demonstrably unaffected by phytoplankton or plant growth

late jurassic magmatism and stratigraphy in the eastern sakarya zone turkey evidence for the slab breakoff of paleotethyan oceanic lithosphere abstractmiddle late jurassic cimmerian events in turkey have been actively discussed in the past three decades but proposed tectonic models associated with magmatism metamorphism and stratigraphic features remain controversial to address this issue upper jurassic mafic lavas are investigated at three locations alucra gumushane and olur in the eastern sakarya zone northeastern turkey these lavas are submarine and form planar flows parallel with the bedding plane in the upper jurassic carbonate sequence near the base or just below in the clastic sedimentary rocks the basaltic lavas show calc alkaline features and possess nb ta values and nb u nb la and ce pb ratios that are greater than those of island arc basalts multielement patterns are almost hump shaped similar to ocean island basalts which experience pb depletion and weak negative nb ta zr hf and ti anomalies the low initial 87sr 86sr ratios 0 70372 0 70554 positive initial end values 2 7 to 4 4 and initial pb isotope rat

crustal stress pattern in china and its adjacent areas abstract during the update of the world stress map wsm database we integrated the china stress database by strictly using the internationally developed quality ranking scheme for each individual stress data record this effort resulted in a comprehensive and reliable dataset for the crustal stress of china and its adjacent areas with almost double the amount of data records from the wsm database release 2008 i e a total of 8228 data records with reliable a c qualities in the region of 45 155 east and 0 60 north we use this dataset for an analysis of the stress pattern for the orientation of maximum compressive horizontal stress s hmax in contrast to earlier findings that suggested that the mean s hmax orientation would be aligned with the direction of plate motion we clearly see from our results that the plate boundary forces as well as topography and faulting are important control factors for the overall stress pattern furthermore the smoothing results indicate that the s hmax orientation in china rotates clockwise from the west to the east which results in a fan shaped crustal stress pattern for the continental scale the plate boundary forces around china which are the indian eurasian plate collision in the west and the pacific plate subduction and the push from the philippine plate in the east can still be seen as the key driving processes and the first order controls for the crustal stress pattern the south north seismic zone can be seen as the separation zone for the western and eastern plate boundary forces topographic variation and faulting activity however provide second order changes and lead to local variations and different inhomogeneity scales for the stress pattern due to differences in these factors northeast china and the central part of the tibetan plateau have notably homogeneous stress patterns while the south north seismic zone the hindu kush pamir region and the taiwan region have extremely inhomogeneous stress patterns furthermore the different behaviors of stress orientations around continental and oceanic plate boundaries could imply that complicated mechanisms exist and warrant further and more specific studies

variscan amphibolite facies rocks from the kurtoglu metamorphic complex gumushane area eastern pontides turkey the kurtoglu metamorphic complex that forms part of the pre liassic basement of the sakarya zone in northern turkey consists of at least two tectonic units blueschist facies rocks of unknown metamorphic age in the southern part of the complex are tectonically overlain by variscan low pressure high temperature metamorphic rocks the latter comprise mica schists and fine grained gneisses cut by metaleucogranitic dikes as well as migmatitic biotite gneisses and subordinate amphibolite intercalations structural data indicate that metamorphism and penetrative deformation occurred after dyke intrusion peak metamorphic conditions of the mica schists fine grained gneisses and metaleucogranites are estimated to 650 c and 0 4 gpa based on phase relationships in the system nckfmash fe mg partitioning between garnet and biotite as well as garnet aluminosilicate quartz plagioclase gasp and garnet plagioclase biotite quartz gbpq barometry peak temperatures of the migmatitic biotite gneisses and amphibolite intercalations are not well constrained but might have been significantly higher 690 740 c as suggested from hornblende plagioclase thermometry 40ar 39ar incremental dating on muscovite and biotite fractions from the mica schists and fine grained gneisses yielded plateau ages of 323 ma significantly older model ages of 329 and 337 ma were obtained on muscovite fractions from two metaleucogranite samples these fractions contain both relict igneous and newly formed metamorphic muscovite

the utilization of boron and strontium isotopes for the assessment of boron contamination of the cecina river alluvial aquifer central western tuscany italy abstract the groundwater b concentration in the alluvial aquifer of the upper cecina river basin in tuscany italy often exceeds the limit of 1 mg l 1 set by the european union for drinking water on the basis of hydrogeological and geochemical observations the main source of the b contamination of groundwater has been attributed to past releases into streams of exhausted b rich geothermal waters and or mud derived from boric acid manufacturing in larderello the releases were discontinued 25 30 years ago this study confirms that the b dissolved in groundwater is anthropogenic in fact the 11b values of groundwater b match the range 12 2 to 13 3 of the turkish b mineral colemanite processed in boric acid manufacturing in the course of which no significant isotopic effects have been observed this isotopic tracing of the cecina alluvial aquifer occurs just below the confluence of the possera creek which carries the b releases from larderello strontium isotope ratios support this conclusion at about 18 km from the possera creek confluence the groundwater 11b drops to much more negative values 22 to 27 which are believed to be produced by adsorption desorption interactions between dissolved b and the aquifer matrix the 11b of b fixed in well bottom sediments shows a similar variation at present desorption is prevailing over adsorption because the releases of b rich water have ceased a theoretical model is suggested to explain the isotopic trends observed thus b isotopes appear to be a powerful tool for identifying the origin of b contamination in natural waters although isotopic effects associated with adsorption desorption processes may complicate the picture to some extent

jurassic accretionary complex and ophiolite from northeast turkey no evidence for the cimmerian continental ribbon permian triassic and late cretaceous accretionary complexes ascribed to the consumption of two distinct oceans the paleo and neo tethys are exposed over extensive areas in the eastern mediterranean region however a separating continental ribbon the so called cimmeride continent between the paleo and neo tethys during early mesozoic time cannot be defined here we report a previously unknown early jurassic metamorphic oceanic accretionary complex and ophiolite from northeast turkey bounded by oceanic accretionary complexes of permian triassic and late cretaceous age to the north and the south respectively without a continental domain in between this special tectonic position and widespread coexistence of permian triassic and late cretaceous accretionary complexes alongside the izmir ankara erzincan suture imply that 1 the southern margin of laurasia in the eastern mediterranean region grew by episodic accretionary processes from late paleozoic to end mesozoic time without involvement of a cimmerian continental ribbon and 2 the paleo tethys and northern branch of the neo tethys were not distinct oceans in the eastern mediterranean region

lithium and its isotopes in major world rivers implications for weathering and the oceanic budget abstract the outstanding problem in the lithium geochemical cycle is the lack of an isotopic mass balance in the ocean the 6li compositions of fresh basalts 4 the hydrothermal fluids derived from them average 9 and seawater significantly heavier at 32 are well understood but only very sparse river input data are available for li mass balance calculations in an attempt to rectify the situation we have measured the lithium concentrations and isotopic compositions of major world rivers draining representative geological terrains this helps both to constrain the river endmember and to understand the behavior of lithium isotopes in the continental weathering environment fluvial isotopic compositions display a very large range 6 0 to 32 2 there is no definitive relationship between 6li and lithology but in general rivers draining marine evaporites are 20 to 22 carbonates 26 to 32 black shales 26 shields 6 6 to 19 and mixed siliceous terrains 6 to 28 the flow weighted mean concentration of the measured rivers is 215 nm at 23 this updated riverine 6li value responsible for 30 of the global riverine discharge does not solve the isotopic imbalance if the measured li concentrations and isotopic compositions are representative of all rivers the presence of a yet unidentified sink with a higher fractionation factor 1 023 than determined for low temperature basalt alteration 1 019 is required for an isotopic steady state of li in the ocean authigenic clays are a possible candidate as clays are known to be enriched in both lithium and in the light isotope preferentially alternatively the hydrothermal flux must be much less than half of that estimated by the 3he inventory and the oceanic budgets for 87sr 86sr and mg the relationship of 6li to the major ions and 87sr 86sr suggests that the important processes affecting river dissolved lithium isotopic compositions are fractionation between solution and secondary minerals and thus the intensity of weathering

the sedimentary cycle of the boron isotopes abstract marine sediments contain two isotopically distinct components a non desorbable fraction with 11b between 4 3 and 2 8 per mil n 10 and a desorbable component with 11b between 13 9 and 15 8 per mil n 6 the adsorption coefficient k for the uptake of b from seawater by fluvial suspended material mississippi has an experimentally determined value of 1 54 0 05 the associated isotope fractionation factor is 0 974 0 003 empirical values for k determined from the analysis of marine sediments n 6 were between 3 and 4 the amount of b adsorbed onto fluvial suspended material during estuarine mixing is about 9 109 moles yr based on pore water data adsorption experiments and comparative size fraction analyses suspended sediments from the mississippi river vs bottom deposits from the delta there is no evidence for the incorporation of b into detrital sediments at low temperature however the high b content of bauer deep metalliferous sediments must be due to incorporation of seawater b during formation of authigenic silicates the 11b of these minerals is 2 3 per mil hydrothermally altered sediments from dsdp hole 477 guaymas basin gulf of california have variable b contents from 33 ppm similar to the unaltered detritus to 1 2 ppm in the recrystallized material the latter has 11b as low as 9 0 per mil substantially lower than the unaltered material hydrothermal solutions collected from vents adjacent to the hole have boron contents elevated by about a factor of 4 relative to seawater and 11b between 16 5 and 23 2 per mil the b mobilized from the sediments is isotopically fractionated with the fluids being preferentially enriched in the heavy isotope analysis of an oxisol profile developed over granite in the guyana shield showed that boron is partially mobilized during weathering with an isotopic offset of 2 5 per mil between bedrock and soil the observed enrichment of b in shales relative to igneous rocks does not occur during weathering or during exposure to seawater at low temperature incorporation occurs only during burial diagenesis at temperatures greater than about 60 c however the enrichments cannot be attained during a single cycle of primary weathering and burial but must be cumulative over many cycles

modern tectonic stress field in the mediterranean region evidence for variation in stress directions at different scales summary a compilation of more than one thousand stress indicators which include in situ stress measurements focal mechanisms microtectonic and other geological data allowed us to reconstruct the modern stress field in the mediterranean region and the surrounding area average stress directions at different scales have been reconstructed by means of a linear interpolation method this method takes into account the distribution scale and quality of stress data the results of the interpolation at plate scale allow us to recognize slightly deformed regions such as the northwestern european platform where average maximum horizontal stress direction is oriented roughly nnw sse subparallel to absolute and relative plate velocity directions other regions such as the caucasus alps and pyrenees where recent tectonic deformation and seismicity are present display important variations of stress directions the reconstruction of the average stress directions at different scales within the french alps pointed out that the average stress field pattern may vary from one scale to another nevertheless variations of stress directions at a given scale are consistent with the kinematics of faults of the same scale

boron isotope geochemistry of salt sediments from the dongtai salt lake in qaidam basin boron budget and sources abstract dongtai salt lake in qaidam basin contains abundant boron and lithium resources and has the highest reserve of lithium found in the world but the origin of these resources is highly controversial in this study we carried out a detailed study on chemical compositions and boron isotope characteristics of salt sediments collected from a drill core in the dongtai salt lake the evaporite carbonate and silicate phases of the sediments show 11 b values of 6 4 to 2 2 17 3 to 0 5 and 14 6 to 2 8 respectively which suggest a non marine origin for the salt lake the variation of 11 b vs k identified the evolution process of the salt lake the geochemical hydrochemical signatures and the reserve estimation of boron resources approved the dominant sources of saline resources containing abundant b k and li from the inflowing nalenggele river the boron isotopic fractionation factors between evaporite and brine i e evaporite brine vary from 0 9869 to 0 9955 and the linear variation of evaporite brine vs li mg molar ratios reflects the boron isotopic fractionation during crystallization of the salts the positive correlation between 11 b and b in the carbonate phase reflects the ph control on the incorporation of boron into the carbonates and the equilibrium isotope fractionation follows the rayleigh isotope fractionation rule in a closed system the variation of 11 b values in the silicate phase behaved as an oscillating pattern and the more negative shift of 11 b values corresponds to the mudstone strata deposited under warm humid climate conditions indicating the influence of intensive weathering

topography boundary forces and the indo australian intraplate stress field the relative contribution of topographic e g ridge push continental margins and elevated continental crust and plate boundary e g subduction and collisional forces to the intraplate stress field in the indo australian plate iap is evaluated through a finite element analysis two important aspects of the iap intraplate stress field are highlighted in the present study 1 if substantial focusing of the ridge push torque occurs along the collisional boundaries i e himalaya new guinea and new zealand many of the first order features of the observed stress field can be explained without appealing to either subduction or basal drag forces and 2 it is possible to fit the observed shmax maximum horizontal stress orientation and stress regime information with a set of boundary conditions that results in low tectonic stress magnitudes e g tens of megapascals averaged over the thickness of the lithosphere throughout the plate this study therefore presents a plausible alternative to previous studies of the iap intraplate stress field which predicted very large tectonic stress magnitudes hundreds of megapascals in some parts of the plate in addition topographic forces due to continental margins and elevated continental material were found to play an important role in the predicted stress fields of continental india and australia and the inclusion of these forces in the modeling produced a significant improvement in the fit of the predicted intraplate stresses to the available observed stress information in these continental regions a central focus of this study is the relative importance of the boundary conditions used to represent forces acting along the northern plate margin we note that a wide range of boundary conditions can be configured to match the large portion of the observed intraplate stress field and this nonuniqueness continues to make modeling the iap stress field problematic while our study is an important step forward in understanding the sources of the iap intraplate stress field a more complete understanding awaits a better understanding of the relative magnitude of the boundary forces acting along the northern plate margin

a revised crustal stress orientation database for canada abstract the canadian database on contemporary crustal stress has not been revised systematically in the past two decades here we present the results of our new compilation that contains 514 new data records for the orientation data of maximum compressive horizontal stress and 188 data records that were re assessed in total the canadian stress database has now 1667 data records which is an increase of about 45 from these data a new canadian stress map as well as one for the province of alberta is presented to analyse the stress pattern we use the quasi median on the circle as a smoothing algorithm that generates a smoothed stress map of the maximum compressive horizontal stress orientation on a regular grid the newly introduced quasi interquartile range on the circle estimates the spreading of the data and is used as a measure for the wave length of the stress pattern the result of the hybrid wavelength analysis confirms that long spatial wavelength stress patterns 1000 km exist in large areas in canada the observed stress pattern is transmitted through the intra plate regions the results reveal that shorter spatial wave length variation of the maximum compressive horizontal stress orientation of less than 200 km prevails particularly in south eastern and western canada regional stress sources such as density contrasts active fault systems crustal structures etc might have a significant impact in these regions in contrast to these variations the observed stress pattern in the alberta basin is very homogeneous and mainly controlled by plate boundary forces and body forces the influence of curvature of the rocky mountains salient in southern alberta is minimal the present day horizontal stress orientations determined herein have important implications for the production of hydrocarbons and geothermal energy in the alberta basin

the black sea basins structure and history new model based on new deep penetration regional seismic data part 1 basins structure and fill abstract this work is based upon results of interpretation of about 8872 km long regional seismic lines acquired in 2011 within the international project geology without limits in the black sea the seismic lines cover nearly the entire black sea basins including russia turkey ukraine romania and bulgaria sectors a new map of acoustic basement relief and a new tectonic structure scheme are constructed for the black sea basins the basement of the black sea includes areas with oceanic crust and areas with highly rifted continental crust a chain of buried seamounts which were interpreted as submarine volcanoes of late cretaceous santonian to campanian age has been identified to the north of the turkish coast on the shatsky ridge probable volcanoes of albian age have also been recognized synorogenic turbidite sequences of paleocene eocene and oligocene ages have been mapped in the cenozoic numerous compressional and transpressional structures were formed in different parts of the black sea basin during the pleistocene quaternary turbidites mass transport deposits and leveed channels were formed in the distal part of the danube delta

the lithium boron and strontium isotopic systematics of groundwaters from an arid aquifer system implications for recharge and weathering processes abstract saline groundwaters are common to inland australia but their hydrochemical evolution and origin remain largely unknown the saline groundwaters in the alluvial aquifers of the darling river have previously been found to exhibit broad similarity in traditional hydrochemical and isotopic tracers by contrast in this study the trace element isotopes 7li 11b and 87sr 86sr have illuminated more complex hydrogeochemical processes in the same aquifer system this paper reports the first ever set of 7li values in any groundwater system in australia they varied from 5 8 to 16 2 with an average value of 9 7 n 19 in the alluvial aquifers of the darling river catchment the 11b values were all higher than seawater and close to some of the highest 11b values ever reported in the literature for a groundwater system 44 4 to 53 9 average 48 8 n 17 the 87sr 86sr ratios ranged from 0 708 to 0 713 with an average value of 0 709 n 19 the differing signatures in these trace element isotope values highlighted by discovery of the deeper older groundwater system with heavier li isotope values and higher 87sr 86sr is an important finding of this research simple mixing models between river water and saline groundwater cannot explain the observed variation in trace element isotopes hydrochemical evolution was found to be dependent on proximity to the darling river and depth varying degrees of li and b isotopic fractionation during water sediment interaction were interpreted to account for the evolution of the saline groundwaters the measurement of these trace element isotopes has permitted delineation of groundwater end members that would have otherwise not been identified in their absence an inaccurate interpretation of the hydrochemical evolution of these saline groundwaters would have been made this study highlights the importance of a multi tracer approach which includes trace element isotopes in resolving complex geochemical processes in groundwater in semi arid to arid zone environments

kilop cretaceous hardground kale gumushane ne turkey description and origin abstract a hardground surface is well exposed in the kilop area of kale gumushane ne turkey which forms part of the eastern pontides here the hardground is underlain by shallow water lower cretaceous limestones and overlain by upper cretaceous red limestones marls which contains a planktonic microfauna including globotruncanidae in the field the recognition of the hardground is based on the presence of extensive burrows especially vertical burrows the encrusting rudistid bivalve requienia neptunian dykes with infills of pelagic sediments and synsedimentary faults skolithos and thalassinoides type burrows are present some burrow walls show iron hydroxide staining the extensive burrowing occurred prior to lithification on the other hand the neptunian dykes and synsedimentary faults which cut the hard ground occurred after the lithification these features indicate the progressive hardening of the substrate the burrowed limestone consists of an intrabioclastic peloidal grainstone which was deposited in an intertidal to shallow subtidal moderate to relatively high energy environment the peloidal limestone shows little or no evidence of submarine cementation characterized by only scarce relics of isopachous cement rims of bladed calcite spar the grainstone cement is composed predominantly of blocky calcite and overgrowth calcite cements on the echinoid fragments the origin of this cement is controversial biostratigraphic analysis of the limestones demonstrates that there is a marked stratigraphic gap hiatus spanning the aptian to the santonian in the cretaceous of the kilop area the formation of the kilop hardground is related to the break up and subsidence of the eastern pontides carbonate platform during the formation of the black sea backarc basin hardground development was initiated in a shallow marine environment of slow sedimentation and with moderate to high energy indicating slow subsidence later the hardground subsided abruptly as shown by the deposition of pelagic sediments on the hardground surface during drowning the kilop area was converted to a bypass margin where currents were effective the formation of the hardground may also have been associated with an eustatic rise in sea level

stratigraphic and structural development of the eastern pontides turkey this paper describes the stratigraphic and structural development of the eastern pontides north turkey based on section logging at eight localities construction of three structural profiles across the mountains and published literature the eastern pontides comprise a late carboniferous to miocene sequence resting on a basement of hercynian metamorphics late carboniferous to scythian sediments are continental clastics interpreted as having been deposited in an extensional half graben the middle triassic is limestone reflecting the development of a south facing passive margin in the late triassic the ocean palaeotethys began to close flysch was deposited in most places with minor shallow water limestones in the sinemurian above an inverted half graben all pre aalenian strata were deformed during the cimmerian orogeny after a phase of subduction related volcanism in the mid jurassic limestones were deposited during the late jurassic and early cretaceous mainly in shallow water the aptian and albian are absent due to doming in the western pontides prior to the opening of the western black sea but there is a thick sequence of upper cretaceous arc volcanic rocks and intervening turbidites the upper palaeocene is absent possibly due to rifting in the eastern black sea major compression affected the pontides from the eocene to the pliocene associated with the closure of the tethyan ocean oligocene and younger rocks are accordingly non marine

geochemical and boron oxygen and hydrogen isotopic constraints on the origin of salinity in groundwaters from the crystalline basement of the alpine foreland abstract the b isotopic composition in combination with o and h isotopes and hydrochemical tracers is utilized to constrain the evolution of basement hosted groundwaters via water rock interactions and fluid infiltration from external sedimentary reservoirs two distinct groundwater types have been identified in the central european crystalline basement n switzerland sw germany 1 fresh groundwaters characterized by low values of 11b 3 5 to 0 6 18o 12 0 to 10 0 and d 86 8 to 71 9 and 2 brackish groundwaters with distinctly heavier b o and h isotopic compositions 11b 6 4 to 17 6 18o 9 4 to 5 6 d 67 6 to 60 8 fresh groundwaters show a systematic decrease in 11b related to an increase in b concentrations and degree of total mineralization along the pathway of groundwater migration which can only be interpreted in terms of leaching of crystalline host rocks a 11b value of 3 3 is inferred for the crustal b source mainly hercynian granites involved in the leaching process in agreement with the known 11b range of granitic rocks the evolution of brackish groundwaters derived from crystalline basement reservoirs with little water circulation is more complex as indicated by b o h stable isotope and hydrochemical e g b cl na cl and br cl constraints brackish groundwaters from the study area are influenced by admixture of sediment derived fluids which infiltrated from late paleozoic permo carboniferous and early mesozoic lower triassic sedimentary strata the data presented show that b isotopes are sensitive to mixing processes of fluids derived from different crustal reservoirs and hence may be utilized as a tracer for constraining the internal autochthonous vs external allochthonous origin of salinity in basement hosted groundwaters

age constraints on intra formational unconformities in upper jurassic lower cretaceous carbonates in northeast turkey geodynamic and hydrocarbon implications abstract upper jurassic lowermost cretaceous carbonate build ups are imaged on seismic data in the black sea they form important untested hydrocarbon reservoirs that are the focus of active exploration outcrop analogues to these build ups around the black sea contain a series of subaerial exposure surfaces the hiatuses associated with a number of these subaerial exposure surfaces have been dated in a well exposed callovian or upper oxfordian to barremian shallow water inner platform carbonate succession the berdiga formation in the eastern pontides using strontium isotope stratigraphy and foraminiferal biostratigraphy they span the latest kimmeridgian to tithonian or berriasian and the hauterivian to barremian less well constrained but broadly contemporaneous stratigraphic gaps in multiple successions around the black sea provide additional insights and point to a regional driving mechanism the timing of hiatus formation does not correspond to periods of eustatic lowstand it does coincide however with late tithonian to berriasian and hauterivian to early aptian episodes of rifting in the greater caucasus basin located farther to the north thus it is possible that subaerial exposure was caused by rift flank uplift during periods of regional extension uplift due to slab break off is discounted as a control because it post dates rather than pre dates locally developed kimmeridgian magmatism rift flank uplift is likely to have also affected carbonate build ups on the intervening rift shoulders of the eastern black sea the shatskiy ridge and the mid black sea high at outcrop subaerial exposure is often associated with karstification and secondary porosity development similar processes may have occurred in the offshore helping to enhance the reservoir quality of these exploration targets

calculating horizontal stress orientations with full or partial knowledge of the tectonic stress tensor calculating horizontal stress orientations with full or partial knowledge of the tectonic stress tensor

lithium isotopic composition of submarine basalts implications for the lithium cycle in the oceans abstract we have measured the li isotope composition of young pristine basalts from active ocean ridge crests of progressively older basalts along a dredging transect and a limited number of hydrothermally altered basalts the data significantly extend our limited knowledge of the isotopic abundance ratio of li in geological material fresh mid ocean ridge basalts have 6li values of between 3 4 and 4 7 relative to isotope standard l svec during low temperature weathering on the seafloor the isotopic composition of the rock becomes increasingly heavier due to addition of seawater li 6li 32 3 the oldest 46 m y and most altered rock studied has an isotopic composition of 14 a linear relationship exists between 6li and the inverse of li concentration suggesting that li in weathered basalts can be regarded as a two component mixture of basaltic li and seawater derived li that has been incorporated in alteration minerals most likely secondary clays such as smectite and phillipsite the inferred li isotopic composition of the alteration endmember indicates an apparent isotopic fractionation factor of 1 019 relative to the seawater source thus li uptake by secondary minerals from the low temperature weathering process and by analogy incorporation in similar authigenic minerals in marine sediments provides a mechanism for preferential removal of the lighter li isotope from ocean water however isotopic fractionation due to authigenic clay formation alone cannot account for the isotopic difference between seawater and its principal sources unless the hydrothermal flux is comparable to the river flux alternatively more important sinks of6li must exist if the steady state isotopic composition of li in ocean water is to be maintained

lithium isotopes as tracers of groundwater circulation in a peat land abstract water circulation in the peat bog of a maar depression in the massif central france was traced with lithium isotopes on water samples collected in the area from springs surface and groundwaters as well as on solid samples taken from peat bogs lithium contents fluctuate significantly in the groundwaters ranging from 0 01 mol l 1 in springs feeding the peat bog up to 28 mol l 1 in the groundwater collected in the peat bog lithium isotope compositions 7li are extremely variable within the site ranging from 12 in the stream draining the area up to a 7li rich value of 1226 in groundwater from the peat bog the 7li values in the streams agree with those reported in the literature for surface waters while those of groundwater are far beyond the range of values measured in nature in the present study we explain the extremely enriched 7li signature of the groundwaters by an external input due to ca amendment used in local agriculture the relationships between li content and ca mg and hco3 as well as the lack of a relationship between li and na plead in favour of 7li enriched carbonate amendments this hypothesis was tested by li isotope analyses on the peat and on several amendment samples carbonates and npk fertilizers confirming the potential role of amendments in the control of li isotopes in peat land groundwater and showing high 7li values in fertilizers application of 7li ratios to peat land waters provides a unique perspective on the hydrogeochemical dynamics at the scale of this site as the 7li values for the surface water were quasi constant throughout the survey period and the peat land groundwater does not supply the surface water runoff and may evolve as a stagnant system to conclude the water within the peat land exhibits very high 7li values consistent with artificially enriched 7li associated with ca amendments this study opens a new field for li isotope investigations in hydro systems and highlights the possibility of using li isotopes as environmental tracers

reply to the discussion by granier of vincent et al 2018 marine and petroleum geology 91 639 657 abstract granier 2019 questioned the identification of a number of foraminifer species within the study of vincent et al 2018 we dispute his findings and provide supporting evidence for our original identifications our biostratigraphic work was carried out to support the strontium isotope stratigraphy study of an upper jurassic lower cretaceous carbonate succession in the eastern pontides northeast turkey this was undertaken to constrain the age and duration of a number of hiatal surfaces within the succession that we proposed have geodynamic significance for the black sea region even if granier s identifications are correct they do not impact upon the conclusions of our study thus rather than being a disappointing application of a geochemical tool our study illustrates the utility of the powerful strontium isotope stratigraphy approach

variscan orogeny in the black sea region two gondwana derived paleozoic belts rim the archean paleoproterozoic nucleus of the east european platform in the black sea region in the north is a belt of paleozoic passive margin type sedimentary rocks which extends from moesia to the istanbul zone and to parts of the scythian platform the mois block this belt constituted the south facing continental margin of the laurussia during the late paleozoic this margin was deformed during the carboniferous by folding and thrusting and forms the variscan foreland in the south is a belt of metamorphic and granitic rocks which extends from the balkanides through strandja sakarya to the caucasus bassac block the protoliths of the metamorphic rocks are predominantly late neoproterozoic granites and paleozoic sedimentary and igneous rocks which were deformed and metamorphosed during the early carboniferous there are also minor eclogites and serpentinites mostly confined to the northern margin of the bassac block typical metamorphism is of low pressure high temperature type and occurred during the early carboniferous visean 340 330 ma coevally with that observed in the central europe volumetrically more than half of the crystalline belt is made up of carboniferous earliest permian 335 294 ma granites the type of metamorphism its concurrent nature over 1800 km length of the bassac block and voluminous acidic magmatism suggest that the thermal event probably occurred in the deep levels of a continental magmatic arc the bassac arc collided with laurussia in the mid carboniferous leading to the foreland deformation the ensuing uplift in the permian resulted in the deposition of continental red beds which are associated with acidic magmatic rocks observed over the foreland as well as over the bassac block in the black sea region there was no terminal collision of laurussia with gondwana during the late paleozoic and the laurussia margin continued to face the paleo tethyan ocean in the south

regional patterns of tectonic stress in europe nearly 1500 stress orientation determinations are now available for europe the data come from earthquake focal mechanisms overcoring measurements well bore breakouts hydraulic fracturing measurements and young fault slip studies and sample the stress field from the surface to seismogenic depths three distinct regional patterns of maximum compressive horizontal stress shmax orientation can be defined from these data a consistent nw to nnw shmax stress orientation in western europe a wnw ese shmax orientation in scandinavia similar to western europe but with a larger variability of shmax orientations and a consistent e w shmax orientation and n s extension in the aegean sea and western anatolia the different stress fields can be attributed to plate driving forces acting on the boundaries of the eurasian plate locally modified by lithospheric properties in different regions on average the orientation of maximum stress in western europe is subparallel to the direction of relative plate motion between africa and europe and is rotated 17 clockwise from the direction of absolute plate motion the uniformly oriented stress field in western europe coincides with thin to medium lithospheric thickness approximately 50 90 km and high heat flow values 80 m w m2 in western europe a predominance of strike slip focal mechanisms implies that the intermediate principal stress is vertical the more irregular horizontal stress orientations in scandinavia coincide with thick continental lithosphere 110 170 km and low heat flow 50 m w m2 the cold thick lithosphere in this region may result in lower mean stresses associated with far field tectonic forces and allow the stress field to be more easily perturbed by local effects such as deglaciation flexure and topography the stress field of the aegean sea and western anatolia is consistent with n s extension in a back arc setting behind the hellenic trench subduction zone the stress field is influenced in places by regional geologic structures e g in the western alps where shmax directions show a slight tendency toward a radial stress pattern not all major geologic structures however appear to affect the shmax orientation e g in the vicinity of the rhine rift system horizontal stress orientations are continuous

testing models of late palaeozoic early mesozoic orogeny in western turkey support for an evolving open tethys model field evidence from north south transects tests three tectonic models for tethys in western turkey for when a late palaeozoic ocean was closing and an early mesozoic ocean opening in model 1 a palaeozoic ocean subducted southwards rifting continental fragments from gondwana and opening a triassic neo tethys to the south closure and collision occurred by latest triassic time in model 2 a wide palaeozoic tethys subducted northwards with an active eurasian margin and a passive gondwana margin the northern gondwana margin rifted in the triassic fragments either remained nearby taurides or drifted northwards e g karakaya attached to a north subducting plate new oceanic crust replaced palaeo tethys with neotethys and back arc marginal basins opened along the south eurasian margin e g kure in model 3 a palaeozoic ocean also subducted northwards opening wide marginal basins a wide southern neotethys opened along the gondwana margin rifted eurasian anatolides and gondwana taurides fragments collided in mid tethys by latest triassic time field evidence from the pontides supports north dipping subduction models model 2 or 3 above key features are a south vergent hp lt accretionary prism magmatic arc and back arc basin system bordering the eurasian margin also evidence from the tauride mountains favours model 2 over model 3 critically the anatolides and taurides appear to have a common history and were unlikely to have been located on opposite sides of tethys as in model 3

discussion of the paper by vincent et al 2018 entitled age constraints on intra formational unconformities in upper jurassic lower cretaceous carbonates in northeast turkey geodynamic and hydrocarbon implications marine and petroleum geology 91 639 657 abstract a recent publication on the jurassic cretaceous transition in carbonate platforms of ne turkey reported some major discontinuities based on biostratigraphy and sr derived ages one associated hiatus was estimated spanning the tithonian whereas the remaining three minor hiatuses are supposed to have occurred during the hauterivian barremian interval the revision of the material foraminifers and calcareous algae from the 2 localities studied led to identify kimmeridgian strata below the discontinuity and valanginian to lower hauterivian strata above the discontinuity but no upper hauterivian or barremian strata at the top of the section the major stratigraphic gap possibly corresponds to the berriasian and most if not all of the tithonian at this location