the stable isotopic composition of modern soil carbonate and its relationship to climate the oxygen isotopic composition of modern soil carbonate is well correlated with the isotopic composition of local meteoric water the carbon isotopic cycle for co 2 in soils can be described in terms of the proportion of biomass using the c 4 photosynthetic pathway and the co 2 respiration rate of the soil at low soil respiration rates significant atmospheric co 2 mixing can occur in general the carbon isotopic composition of soil carbonate is related to the proportion of c 4 biomass present in soil but soils that freeze to the depth of carbonate formation often have a significant atmospheric component this suggests that freezing of the soil solution should be considered as another important mechanism for soil carbonate formation because of these relationships the isotopic composition of soil carbonate may be a paleoclimatic and paleoecologic indicator in cases in which diagenetic alteration has not occurred

foredeep basins the main features and model of formation abstract the comparative study of the foredeep basins of the northern caucasus alpine and apennine foredeeps revealed that there are no significant differences between outer and inner foredeeps situated at the front and the back of the crustal scale thrust so the driving mechanism should be essentially the same for internal and external foredeeps and elastic flexure should not be supposed as the only sometimes as the main mechanism of foredeep formation the common feature of the foredeep evolution is a phase of slow subsidence lasting for 50 million years or more passive margin stage sensu stricto and then relative uplift followed by rapid subsidence this twofold event of relative uplift the duration is several million years giving way to rapid subsidence may be repeated several times the relative uplift or nearly equal to zero subsidence of the foredeep basins appeared to be synchronous with phases of external compression within adjacent mountain belts as well as rapid subsidence took place between phases of external compression thus the first stage of relative uplift could be recognised as the first stage of the foredeeps formation to describe the development of the foredeeps at both sides of the compressional belts a model of evolution of the earth s outer shell has been employed the model predicts that when the earth s outer shell has been once disturbed by external intraplate or mantle induced forces small scale convection within the asthenosphere arises this convection causes deformation in the lithosphere of orogenic belts over a long period of time after the external forces stop this manifests in uplift of belts and subsidence at their periphery the suggested model shows a good agreement with data on the foredeeps structure and evolution in particular application of the model enabled us to explain the thickness of sediments in the foredeep basins and their shape the formation of the foredeeps not only at the front but also at the back of asymmetric compressional thrust belts uplift of foredeeps during compression in the belts and rapid subsidence after this compression stops numerical results for the great caucasus region showed that the first compressional event at the orogenic stage took place there before the formation of the maykopian sediments i e 39 5 ma in the end of the closure of the arabian ocean the three further compressional events can also be recognised one of them being between 16 6 and 15 8 the other between 14 3 and 12 3 ma and the last one between 7 0 and 5 2 ma

global positioning system measurements of present day crustal movements in the arabia africa eurasia plate collision zone we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1994 at 54 sites extending east west from the caucasus mountains of southern russia georgia and armenia to the aegean coast of turkey and north south from the southern edge of the eurasian plate pontus block to the northern edge of the arabian platform viewed from a eurasia fixed reference frame sites on the northern arabian platform move n38 13 w at 20 3 mm yr roughly consistent with the velocity implied by nuvel 1a circuit closure n23 7 w at 24 2 mm yr the motion of arabia appears to be transferred directly to the region of turkey north of the suture however eastern turkey is characterized by distributed deformation while central western turkey is characterized by coherent plate motion involving westward displacement and counterclockwise rotation of the anatolian plate internal deformation within the central part of the anatolian plate is less than 2 mm yr the anatolian plate is decoupled from eurasia along the right lateral strike slip north anatolian fault naf this different response in eastern and western turkey to the collision of arabia may result from the different boundary conditions the hellenic arc forming a free boundary to the west and the asian continent and oceanic lithosphere of the black and caspian seas forming a resistant boundary to the north and east we derive a best fitting euler vector for anatolia eurasia motion of 29 2 0 8 n 32 9 0 4 1 3 0 1 m y the mapped surface trace of the naf corresponds well to a small circle about this pole the new euler vector implies an upper bound for naf slip rate of 30 2 mm yr i e assuming all relative motion is accommodated along the naf using the nuvel 1a euler vector for arabia eurasia and the gps euler vector for anatolia eurasia we determine an arabia anatolia euler vector of 31 2 n 45 2 e 0 9 0 1 m y and an upper bound on the east anatolian fault slip rate of 15 3 mm yr the aegean trough region of western turkey deviates significantly from coherent plate rotation in addition to rotating with anatolia this region shows roughly n s extension at a rate of 14 5 mm yr taken together with satellite laser ranging results along the hellenic arc the contemporary pattern of deformation indicates increasing motions toward the arc suggesting that the westward displacement and counterclockwise rotation of anatolia is driven both by pushing from the arabian plate and by pulling or basal drag associated with the foundering african plate along the hellenic subduction zone

insights into the crustal scale dynamics of a doubly vergent orogen from a quantitative analysis of its forelands a case study of the eastern pyrenees this study was funded by the anr france pyramid research project the french norwegian foundation 13 06 pyr fftp sedimentary basin and north pyrenean foreland fold and thrust belt formation supported study visits to the university of bergen norway collaboration with csic barcelona spain was funded by the project alpimed pie csic 201530e082

inverse chemical modeling and radiocarbon dating of palaeogroundwaters the tertiary ledo paniselian aquifer in flanders belgium groundwater samples from the ledo paniselian aquifer have been interpreted for chemical reaction patterns 14c age and recharge conditions this confined tertiary aquifer dips nne from its outcrop in belgium toward the north sea over a length of 50 km conventional 14c ages of the water samples range from 3 to over 40 ka inverse chemical modeling was done to correct the 14c ages for the chemical reactions in the aquifer while accounting for changes in the recharge water quality during the holocene and late pleistocene the aquifer shows a zonal pattern with going upstream na k nh4 mg and ca hco3 water types the pattern is a result of freshening ca displaces the saline cations na k nh4 and mg from the aquifer s cation exchange complex in a chromatographic sequence the loss of ca2 from solution by cation exchange is by far the most important reaction for dissolution of calcite which increases the apparent 14c age of the water samples the 14c age furthermore depends on open closed conditions of calcite dissolution and co2 gas exchange and co2 pressure in the recharge area it is shown that 13c and co2 pressure in a soil are interrelated and that the changes in co2 pressure can be included in an inverse model which considers variations in infiltration water quality the overall correction for 14c age is obtained by inverse modeling of water quality and 13c with optimization on co2 pressure in recharge water using phreeqc parkhurst 1995 the optimized co2 pressure for the recharge area varies with age and is generally lower in the water samples with an age above 13 ka the lower co2 pressure is corroborated by lower 18o values of the water

postglacial and pre last glacial weathering of till on the high plateaus of central gaspesie quebec canada geochemical data from mineral exploration surveys are used to assess postglacial and pre last glacial weathering on the high plateaus of central gaspesie by comparing the distribution of 30 elements in the b and c horizons of a thin soil developed on glacial deposits under postglacial weathering fe2o3 tio2 p2o5 cr li u and v are immobile relative to al2o3 whereas the other elements are mobile and have been depleted to various degrees from the b horizon loss on ignition value is the only parameter showing a significant enrichment from the c to the b horizons the apparently high degree of geochemical weathering of the glacial deposits in respect to their source bedrock lithologies suggests that the deposits also contain previously weathered material the spatial distribution of the geochemical weathering index values calculated for the c horizon shows no clear relation to the underlying bedrock formations the high values are located on topographic highs with maxima over deeply weathered bedrock

preliminary estimates of plate convergence in the caucasus collision zone from global positioning system measurements global positioning system gps measurements 1991 1994 traversing the greater and lesser caucasus mountains indicate a minimum n s shortening of 10 2 mm yr this represents approximately 30 50 of the nuvel 1a convergence rate between the arabian and eurasian plates the remainder of the convergence appears to be accommodated in the areas south of the lesser caucasus by a combination of right lateral strike slip faulting on planes oriented n120 e and shortening on thrust faults with similar orientations more dense gps observations conducted in the epicentral area of the april 29 1991 m s 7 0 racha georgia earthquake which occurred along the southern boundary fault of the greater caucasus mountains indicate n s shortening following the earthquake which we interpret as due to post seismic slip this mechanism may contribute to the substantially lower shortening rates derived from seismic moment tensors compared with tectonic estimates of shortening rates in the caucasus

burial history and kinetic modeling for hydrocarbon generation part i the galo model this paper discusses the principles and applications of the galo computer program which generates numerical simulations of the evolution of a sedimentary basin the program calculates variations in the sedimentary bed thickness predicts the thermal regime in the sedimentary cover or in the basement and estimates the potential hydrocarbon yield of the source rocks alternative methods for determining the magnitude of tectonic subsidence of the basement surface within the framework of a local isostasy model are applied to provide a detailed model of the sequential tectonic thermal events involved in the development of the basin the program determines reaction parameters controlling the maturation of the organic matter in source rocks these parameters are based largely on the hydrocarbon pyrolysis yield data and the stage of maturation of the organic matter entered into the program neglecting this stage drastically displaces the reaction spectrum toward higher energies leading to considerable underestimation of hydrocarbon output

geochemical and isotopic evolution of groundwater in the wadi watir watershed sinai peninsula egypt the wadi watir delta in the wadi watir watershed is a tourist area in the arid southeastern part of the sinai peninsula egypt where development and growth of the community on the delta are constrained by the amount of groundwater that can be withdrawn sustainably to effectively manage groundwater resources in the wadi watir delta the origin of groundwater recharge groundwater age and changes in groundwater chemistry in the watershed needs to be understood mineral identification rock chemistry water chemistry and the isotopes of hydrogen oxygen and carbon in groundwater were used to identify the sources mixing and ages of groundwater in the watershed and the chemical evolution of groundwater as it flows from the upland areas in the watershed to the developed areas at the wadi watir delta groundwater in the wadi watir watershed is primarily from recent recharge while groundwater salinity is controlled by mixing of chemically different waters and dissolution of minerals and salts in the aquifers the el shiekh attia and wadi el ain areas in the upper wadi watir watershed have different recharge sources either from recharge from other areas or from different storm events the downgradient main channel area receives groundwater flow primarily from the el shiekh attia area groundwater in the main channel area is the primary source of groundwater supplying the aquifers of the wadi watir delta

geochemical mole balance modeling with uncertain data geochemical mole balance models are sets of chemical reactions that quantitatively account for changes in the chemical and isotopic composition of water along a flow path a revised mole balance formulation that includes an uncertainty term for each chemical and isotopic datum is derived the revised formulation is comprised of mole balance equations for each element or element redox state alkalinity electrons solvent water and each isotope a charge balance equation and an equation that relates the uncertainty terms for ph alkalinity and total dissolved inorganic carbon for each aqueous solution inequality constraints on the size of the uncertainty terms and inequality constraints on the sign of the mole transfer of reactants the equations and inequality constraints are solved by a modification of the simplex algorithm combined with an exhaustive search for unique combinations of aqueous solutions and reactants for which the equations and inequality constraints can be solved and the uncertainty terms minimized additional algorithms find only the simplest mole balance models and determine the ranges of mixing fractions for each solution and mole transfers for each reactant that are consistent with specified limits on the uncertainty terms the revised formulation produces simpler and more robust mole balance models and allows the significance of mixing fractions and mole transfers to be evaluated in an example from the central oklahoma aquifer inclusion of up to 5 uncertainty in the chemical data can reduce the number of reactants in mole balance models from seven or more to as few as three these being cation exchange dolomite dissolution and silica precipitation in another example from the madison aquifer inclusion of the charge balance constraint requires significant increases in the mole transfers of calcite dolomite and organic matter which reduce the estimated maximum carbon 14 age of the sample by about 10 000 years from 22 700 years to 12 600 years

horizontal crustal motion in the central and eastern mediterranean inferred from satellite laser ranging measurements four campaigns to acquire satellite laser ranging slr measurements at sites in the mediterranean region have been completed these measurements to the lageos satellite made largely by mobile systems cover a time span beginning in november 1985 and ending in june 1993 the range data from 18 sites in the central and eastern mediterranean have been simultaneously analyzed with data acquired by the remainder of the global laser tracking network estimates of horizontal motion were placed into a regional northern europe fixed kinematic reference frame uncertainties are on the order of 5 mm yr for sites having at least four occupations by mobile systems and approach 1 mm yr for permanently located sites with long histories of tracking the resulting relative motion between sites in the aegean exhibit characteristics of broadly distributed pattern of radial extension but at rates that are about 50 larger than those implied from studies of seismic strain rates based on seismicity of magnitude 6 or greater or across the region the motion estimated for sites in turkey exhibit velocity components associated with the westward motion of the anatolian block relative to eurasia these results provide a present day snapshot of ongoing deformational processes as experienced by the locations occupiedmore by slr systems less

a new groundwater radiocarbon correction approach accounting for palaeoclimate conditions during recharge and hydrochemical evolution the ledo paniselian aquifer belgium abstract the particular objective of the present work is the development of a new radiocarbon correction approach accounting for palaeoclimate conditions at recharge and hydrochemical evolution relevant climate conditions at recharge are atmospheric pco 2 and infiltration temperatures influencing c isotope concentrations in recharge waters the new method is applied to the ledo paniselian aquifer in belgium this is a typical freshening aquifer where recharge takes place through the semi confining cover of the bartonian clay besides cation exchange which is the major influencing process for the evolution of groundwater chemistry particularly in the bartonian clay also mixing with the original porewater solution fossil seawater occurs in the aquifer recharge temperatures were based on noble gas measurements potential infiltration water compositions for a range of possible pco 2 temperature and calcite dissolution system conditions were calculated by means of phreeqc then the sampled groundwaters were modelled starting from these infiltration waters using the computer code netpath and considering a wide range of geochemical processes fitting models were selected on the basis of correspondence of calculated 13 c with measured 13 c the 14 c modelling resulted in residence times ranging from holocene to pleistocene few hundred years to over 40 ka and yielded consistent results within the uncertainty estimation comparison was made with the 13 c and fontes and garnier correction models that do not take climate conditions at recharge into account to date these are considered as the most representative process oriented existing models yet differences in calculated residence times of mostly several thousands of years up to 19 ka are revealed with the newly calculated ages being mostly though not always younger not accounting for climate conditions at recharge pco 2 and temperature is thus producing substantial error on deduced residence times the derived 14 c model ages are correlated with he concentrations measured in the groundwater of the aquifer the obtained residence times show a gap between about 14 and 21 ka indicating possible permafrost conditions which inhibited any groundwater recharge

carbon isotopes to constrain the origin and circulation pattern of groundwater in the north western part of the bohemian cretaceous basin czech republic abstract the bohemian cretaceous basin represents a complex hydrogeological system composed of several aquifers with very favourable hydrogeological properties these aquifers have been exploited for many years the sustainability of such resources might be guaranteed by well organised water management which requires a detailed knowledge about the functioning of the hydrogeological system although many efforts have previously been made to evaluate groundwater residence time the many intricate geochemical processes complicate groundwater dating the current study clarifies the functioning of this complex hydrogeological basin using hydrogeochemical and isotopic investigations chemical data and a combination of 13 c and 14 c isotopes within the cenomanian and the turonian layers indicate groundwater interactions with deep seated co 2 rock matrix surface waters and fossil organic matter very depleted 13 c values average 13 c 13 4 suggest interactions with fossil organic matter whereas enriched values account for the interaction with deep co 2 gas ascending from the upper mantle via the numerous faults and fractures and also to a lesser extent from calcite dissolution geochemical processes that take place in the system cause a clear depletion in 14 c that greatly complicates groundwater residence time evaluation different dilution correction models have been applied considering the different c origins the stable isotope content mainly 18 o values indicates both the contribution of modern precipitation and the partial infiltration of palaeowaters during colder climatic conditions from the end of the pleistocene the apparent 14 c groundwater ages range from modern to 11 1 ka bp which suggests some post glacial infiltration from melting ice sheets finally all the acquired information was used to propose a conceptual model of c origin within the basin

a new correction model for 14c ages in aquifers with complex geochemistry application to the neogene aquifer belgium abstract the objective of this paper is to build a general correction model that takes into account all the different radiocarbon dilution reactions and resolving the processes that are geochemically aging the groundwater in the neogene aquifer for this 13 c and radiocarbon in groundwater are investigated with their relationship to other chemical components in groundwater the 13 c values in the neogene aquifer are influenced by various geochemical reactions like calcite dissolution oxidation of organic matter and methanogenesis calcite dissolution and ch 4 production increase 13 c while the oxidation of organic matter decreases 13 c in the groundwater the reactions that modify 13 c also influence the 14 c activity due to the complex geochemical environment existing correction models are not applicable to this situation a correction model for initial 14 c activity is formulated in which the different c sources that influence 14 c activity are taken into account it is observed that recent dissolved organic matter plays an important role in redox reactions the corrected 14 c ages lie between 0 792 and 6 425 ka representing the maximum age if a part of the organic matter that oxidises is fossil the determined age will represent an overestimated age

using hydrogeochemistry to understand inter aquifer mixing in the on shore part of the gippsland basin southeast australia groundwater in the latrobe valley in the gippsland basin of southeast australia is important for domestic agricultural and industrial uses this sedimentary basin contains a number of aquifers that are used for water supply dewatered for open pit coal mining and which are potentially influenced by off shore oil and gas production major ion chemistry together with stable and sr isotope data imply that the main hydrogeochemical processes are evapotranspiration with minor silicate and carbonate weathering methanogenesis and so4 reduction in reduced groundwater associated with coal deposits have also occurred groundwater has estimated 14c ages of up to 36ka and is largely 3h free carbon 14 ages are irregularly distributed and poorly correlated with depth and distance from the basin margins the observations that the geochemistry of groundwater in aquifers with different mineralogies are similar and the distribution of 14c ages is irregular implies that the aquifers are hydraulically connected and horizontal as well as vertical inter aquifer mixing occurs the connection of shallow and deeper aquifers poses a risk for the groundwater resources in gippsland as contaminants can migrate across aquifers and dewatering of shallow units may impact deeper parts of the groundwater system

diversity dynamics of bajocian middle jurassic ammonites and transgressions regressions in the caucasian sea northern neo tethys ocean a case high resolution test of probable dependence abstract ammonites commonly occur in the bajocian deposits of the greater caucasus basin from where 180 species and 52 genera are reported this back arc basin was located on the northern neo tethyan margin embraced by the caucasian sea an evaluation of diversity patterns for 7 bajocian ammonite zones documents high diversity in the beginning middle and end of the stage with a maximum in the humphriesianum zone and two diversity minima the mid early bajocian impoverishment of ammonite assemblages was caused by both an increase in the rate of disappearance and a decrease in the rate of appearance whereas the only latter was responsible for the mid late bajocian diversity drop an analysis of dominating facies types in the greater caucasus basin documents that the total diversity rose during regressions and fell during transgressions shoreline shifts corresponded better with changes in the number of appearances and worse with those of disappearances a comparison of results from this study with those obtained in the betic cordillera does not clarify the observed dependence changes in the exterior connections of the caucasian sea its depth and oxygen depletion of its waters are unlikely explanations of the regionally documented coincidence of ammonite diversity dynamics and transgressions regressions

tomographic evidence of slab detachment beneath eastern turkey and the caucasus summary teleseismic phase readings from the eastern turkey seismic experiment etse have been inverted using teleseismic tomography in order to create a 3 d image of the underlying mantle beneath eastern turkey the aim was to investigate the existence of an upper mantle negative velocity anomaly that is used to explain the uplift of eastern anatolian plateau and the potential pieces of detached oceanic slabs related to neo tethyan subduction suggested by previous studies using teleseismic waveforms from the 29 stations of the eastern turkey seismic experiment 2926 direct p phases from 146 events were picked by using adaptive stacking techniques in order to increase the station coverage and resolve the surrounding area the phase readings from the international seismological center isc bulletin have also been added the data set consists of 9571 p and pkp phase readings of 79 stations from 503 teleseismic events this study develops the first highresolution 3 d upper mantle p wave tomographic model for this region the tomographic results show the existence of an upper mantle negative velocity anomaly to a depth of 200 km beneath the eastern anatolian accreationary complex eaac as commonly observed in the previous studies that suggest a shallow partially molten asthenosphere the slab like high velocity anomalies beneath the eaac pontides and caucasus are interpreted as the detached southern and northern neo tethys slabs

northern caucasus basin thermal history and synthesis of subsidence models abstract burial histories of the eastern central and western parts of the northern caucasus basin are reconstructed on the basis of well data and seismic sections subsidence began in the early triassic after the late carboniferous permian orogeny triassic sediments were mainly removed during late triassic early jurassic uplift and erosion platform cover began to form in the middle jurassic and albian sediments covered the whole territory of the basin thermal modelling shows that jurassic eocene subsidence was mainly controlled by late triassic early jurassic intrusive warming this heating event induced thermal uplift of the whole territory followed by exponentially decelerating subsidence due to cooling of the lithosphere in the southern areas adjacent to great caucasus subsidence was also affected by caucasian extensional and compressional events in the oligocene early miocene the eastern and the central basins underwent rapid long wavelength subsidence maikopian subsidence the geodynamic cause of this subsidence is probably associated with the mantle flow appearance after cessation of the tethyan subduction due to reequilibration of subducted slab while in the late miocene quaternary times the eastern and the western basins underwent foreland type asymmetrical subsidence due to loading of the great caucasus orogen the central basin was uplifted according to flexural modelling the main component of orogen loading was the lithospheric root load delamination of the latter under the central caucasus caused rapid uplift of the orogen and adjacent basin

using regional datasets of isotope geochemistry to resolve complex groundwater flow and formation connectivity in northeastern alberta canada abstract in the southern athabasca oil sands saos region located in alberta canada individual in situ oil sands operators have conducted local geochemical and isotope groundwater studies to establish baseline characteristics and to improve understanding of the connectivity of water supply and disposal formations within individual leases canada s oil sands innovation alliance cosia initiated this study to combine the data from these individual studies along with public information into a comprehensive unified dataset to evaluate conceptual models of regional groundwater flow and the degree of interaction and separation between important water supply and disposal aquifers the unified dataset comprised over 293 groundwater samples from the main water source and disposal hydrostratigraphic units and included geochemical and isotopic tracers that can be used to identify sources 18o and 2h and age of water 3h and associated solutes 14cdic 36cl as well as the sources of salinity and diagenetic processes 13cdic 34sso4 87sr 86sr 11b 37cl and 81br and dissolved organics 13cdoc the tds and stable isotope composition 18o and 2h of groundwater from several cretaceous formations were used to identify three main mixing controls i areas where locally recharged groundwater mixes with glaciogenic water were identified by lower 18o and 18o values high tds cl br and 34sso4 87sr 86sr and 37cl values consistent with dissolution of evaporites these areas were situated where vertical pathways through otherwise competent formations are likely to occur ii mixing with paleo waters characterized by high tds and higher 18o and 2h signatures indicating groundwater recharged under warmer climate periods and or evaporative enrichment were identified in the south and southwestern portions of the study area the presence of these paleo waters indicate slow moving groundwater zones with limited lateral and vertical connectivity iii areas with potential connectivity to shallow aquifers were identified by their lower tds values modern meteoric 18o and 2h signatures hco3 type waters and 34s so4 and 87sr 86sr signatures consistent with weathering of shallow aquifer material geochemical and isotopic indicators suggest that in areas where the colorado group aquitard is thin or absent there is greater connectivity between the grand rapids formation and the shallower aquifers interpretation of the new unified dataset has improved understanding of the extent that glacial recharge had on devonian aquifers and overlying cretaceous formations and identified zones with relatively stagnant groundwater flow both of which have implications for regional groundwater resource development monitoring and potential wastewater disposal

geodynamics seismicity and seismic hazards of the caucasus abstract being a part of ongoing continental collision between the arabian and eurasian plates the caucasus region is a remarkable site of moderate to strong seismicity where devastating earthquakes caused significant losses of lives and livelihood in this article we survey geology and geodynamics of the caucasus and its surroundings magmatism and heat flow active tectonics and tectonic stresses caused by the collision and shortening gravity and density models and overview recent geodetic studies related to regional movements the tectonic development of the caucasus region in the mesozoic cenozoic times as well as the underlying dynamics controlling its development are complicated processes it is clear that the collision is responsible for a topographic uplift inversion and for the formation of the fold and thrust belts of the greater and lesser caucasus tectonic deformations in the region is influenced by the wedge shaped rigid arabian block indenting into the relatively mobile region and producing near n s compressional stress and seismicity in the caucasus regional seismicity is analysed with an attention to sub crustal seismicity under the northern foothills of the greater caucasus which origin is unclear whether the seismicity associated with a descending oceanic crust or thinned continental crust recent seismic tomography studies are in favour of the detachment of a lithospheric root beneath the lesser and greater caucasus the knowledge of geodynamics seismicity and stress regime in the caucasus region assists in an assessment of seismic hazard and risk we look finally at existing gaps in the current knowledge and identify the problems which may improve our understanding of the regional evolution active tectonics geodynamics shallow and deeper seismicity and surface manifestations of the lithosphere dynamics among the gaps are those related to uncertainties in regional geodynamic and tectonic evolution e g continental collision and associated shortening and exhumation lithosphere structure deformation and strain stress partitioning and to the lack of comprehensive datasets e g regional seismic catalogues seismic gravity and geodetic surveys

crustal control on the terek caspian trough evolution constraints based on a new paleotectonic analysis method abstract the evolution of the terek caspian trough is investigated using a numerical paleotectonic analysis method based on expanding the tectonic velocity into a series of functions that depend on spatial coordinates and time the method relies on the same kind of data as backstripping analysis including the thicknesses of the sedimentary strata their formation periods and facies composition depth of deposition it allows investigating the rate of motion in greater detail than conventional methods and under certain conditions may be used to estimate the rate of movements not only for periods of sedimentation but for periods of erosion as well and also to determine the position of deep seated faults their periods of activity and amount of slip the analysis has shown that for the terek caspian trough it is possible to represent the rate of motion as a sum of two components the overall motion of the entire profile proportional to the square root of time and the local component as a function of time and distance along the profile with regard to the local component the profile subdivides into two parts northern and southern which have tended to be involved in vertical motion of the respectively opposite senses these parts are separated by a deep seated fault this fault has controlled the trough evolution for at least 180 myr the antiphase movement of its sides may be explained by assuming that the fault plane is inclined a regional compression would then drive one side up and the other down as the compression is removed or changed over by an extension the sense of movement will be the opposite under the assumption that the fault plane plunges beneath the caucasus the phases of compression appear to have occurred 120 140 myr and 50 75 myr ago

late cenozoic burial history and dynamics of the northern caucasus molasse basin implications for foreland basin modelling abstract the collisional history of the caucasus segment of the alpine himalayan fold belt started at the end of the eocene the associated development of the northern caucasus foreland basin occurred during two syn collisional stages each displaying different subsidence patterns the 34 16 ma maikopian or pre foreland stage displays a long wavelength subsidence of a broad area whereas the 16 0 ma foreland stage displays asymmetrical foreland subsidence the first is correlated with the termination of subduction in the southern area and can be associated with mantle flow induced by the re equilibration of the subducted slab the along strike configuration of the second molasse basin stage contradicts the hypothesis in which topographical loading is considered to be the main control on foreland subsidence there is a clear anti correlation between basin depths and orogen heights the deepest parts of the basin are at the tips of the orogen where mountain heights are negligible while the area adjacent to the highest mountains central caucasus is uplifted the influence of other types of loading in foreland basin development has therefore been investigated and it has been possible to find a good fit with both gravity and basin architecture by including only two additional model parameters into the model these are crustal and lithospheric thickening thinning the results demonstrate that crustal thickening and removal of lithospheric roots are responsible for supporting the high central caucasus mountains and uplift of adjacent areas the subsidence of the basins at the orogen tips is explained by loading of lithospheric roots both effects are important in the geographically intermediate areas in general it is concluded that topography should not be considered as the main control on foreland subsidence but only as one of several counterbalancing mechanisms the existing flexural model therefore needs improvements such that it can be related directly to subsurface loading by real structures and processes during collision

evolution of the north caucasus foredeep constraints based on the analysis of subsidence curves abstract using a database of more than 130 wells the alpine evolution of the north caucasus foredeep can be described in three main periods 1 the early jurassic to middle late cretaceous including the cenomanian relates to the initial rifting phase and was characterised by succession of comparatively high rates of subsidence and uplift during this stage many events in the eastern and western parts were synchronous whereas some of them appeared to be smoothed in the stavropol high the southern border of the area had a more complex behaviour often moving in the opposite direction relative to the rest of the area the main peculiarities of evolution of the great caucasus region can be explained if we adopt the hypothesis of stamply and pillevuit 1993 and suppose that the early jurassic extension of the trough was accompanied by a strong left lateral transform movement as a result the central part of the great caucasus trough formed as a pull apart basin analysis of the style of movements of the southern border of the scythian plate as well as data on tectonics and volcanism in the great and lesser caucasus showed that other regional compressional and extensional mesozoic events could also have a transform component shear stresses within the lithosphere of the great caucasus can be due to oblique subduction or even transform movements at the plate boundary to the south of the caucasus region dercourt et al 1993 2 the period from the late cretaceous to the middle eocene from the turonian to the bartonian relates to the oceanic suture of the lesser caucasus and was characterised in the great caucasus area by alternating subsidence and uplift events of considerably lower amplitude at least up to the maastrichtian beginning in the late paleocene subsidence curves for almost all the area reflect the same events but in the western part and also in the north of the central part the rate of movements was considerably higher and since the late paleocene short term events in this area took place on the background of rather fast subsidence at nearly constant rate we believe that this subsidence and formation of the east black sea depression have the same origin we consider strong differences in evolution of the eastern western and central parts during the second stage to be due to closure of the lesser caucasus oceanic basin and arrival of the nakhichevan block this led to changes of configuration of the plate boundary and resulted in reorganisation of stress and displacements within the caucasus region this reorganisation was a reason for the opening of the east black sea depression and rapid subsidence of the western and central parts of the area at the end of the second stage 3 the period from the middle eocene to the present relates to the development of a foreland basin coeval with shortening and uplift in the adjacent great caucasus range it was characterised by alternation of relatively short uplift and longer subsidence events an important feature of this stage is that although the amplitude of movements varied from place to place these events were synchronous in all parts of the foredeep at the stavropol region sediments preserved only for the beginning of this stage formation and evolution of the foredeep during the third stage can not be explained exclusively by elastic flexure to do this we used the model of a small scale convection within the asthenosphere mikhailov et al 1996 mikhailov et al 1999 by the comparison of numerical results with the data on the evolution of the north caucasus foredeep we concluded that there were four main stages of compression in the processes of formation of the great caucasus mountain belt the first compression took place before the maykopian between 39 5 and 36 0 ma the other three were in the tarkhanian 16 6 15 8 ma konkian early sarmatian 14 3 12 3 ma and pontian 7 0 5 2 ma the different width of the great caucasus trough by the beginning of the compression as well as variations in thickness of the lithosphere and a different thermal state can cause interruption of the formation of the foredeep at the stavropol high

the caucasus an actual example of the initial stages of continental collision abstract a field study of the neotectonics of the georgian caucasus is combined with geophysical geodetic and geological information in order to obtain a mechanical model of actual deformation the analysis of satellite photos together with topographical and geological maps shows that the great caucasus is bisected by a nne trending sinistral strike slip fault zone the western great caucasus is thrusted to the south over the rioni basin while on the other hand its northern flank is a monocline that descends gently into the russian platform active volcanism is present from elbruz to kazbeg the eastern great caucasus is limited by thrusts to the north and to the south and intermediate structures are disposed in a fan like shape no recent volcanism is observed the eastern limit of the chain is a nnw trending dextral strike slip fault zone seismicity from a local network illustrates the activity of the thrusts and gives evidence for the strike slip faults microtectonic data confirm the recent activity and the sinistral character of the borjomi kazbeg strike slip fault the strike slip faults bordering the eastern caucasus may be seen as the limits of a plastic wedge in front of the arabian plate at an early stage of continental collision

late cenozoic deep weathering patterns on the fennoscandian shield in northern finland a window on ice sheet bed conditions at the onset of northern hemisphere glaciation abstract the nature of the regolith that existed on the shields of the northern hemisphere at the onset of ice sheet glaciation is poorly constrained in this paper we provide the first detailed account of an exceptionally preserved deeply weathered late neogene landscape in the ice sheet divide zone in northern finland we mine data sets of drilling and pitting records gathered by the geological survey of finland to reconstruct regional preglacial deep weathering patterns within a gis framework using a large geochemical data set we give standardised descriptions of saprolite geochemistry using a variant of the weathering index of parker wip as a proxy to assess the intensity of weathering we also focus on mineral prospects and mines with dense pit and borehole data coverage in order to identify links between geology topography and weathering geology is closely linked to topography on the preglacial shield landscape of northern finland and both factors influence weathering patterns upstanding resistant granulite granite gabbro metabasalt and quartzite rocks were associated with fresh rock outcrops including tors or with thin fines values above 3000 and 4000 beneath valley floors developed along mineralised shear and fracture zones weathering penetrated locally to depths of 50 m and included intensely weathered kaolinitic clays with wip fines values below 1000 late neogene weathering profiles were varied in character tripartite clay gruss saprock profiles occur only in limited areas bipartite gruss saprock profiles were widespread with saprock thicknesses of 10 m weathering profiles included two discontinuities in texture materials and resistance to erosion between saprolite and saprock and between saprock and rock limited core recovery when drilling below the soil base in mixed rocks of the tana belt indicates that weathering locally penetrated deep below upper fresh rock layers such deep seated weathered bands in rock represent a third set of discontinuities incipient weathering and supergene mineralisation also extended to depths of 100 m in mineralised fracture zones the thin weathering crusts found extensively beneath till may represent types of early or middle pleistocene palaeosols we confirm that glacial erosion has been very limited

characteristics and significance of two pre late wisconsinan weathering profiles adirondacks usa and miramichi highlands canada abstract the properties of two weathering profiles developed from granitic rocks and covered by deposits of wisconsinan age were studied in order to characterize saprolites and non saprolite residuum of the glaciated area of northeastern north america the warrensburg profile adirondacks new york is more than 9 m thick and formed on a hornblende granitic gneiss total chemical analysis of the sandy saprolite shows slight losses compared to bedrock kaolinite is the main weathering product in the

comment on relict basin closure and crustal shortening budgets during continental collision an example from caucasus sediment provenance by cowgill et al 2016

geochemistry of dissolved inorganic carbon in a coastal plain aquifer 2 modeling carbon sources sinks and δ13c evolution abstract stable isotope data for dissolved inorganic carbon dic carbonate shell material and cements and microbial co2 were combined with organic and inorganic chemical data from aquifer and confining bed pore waters to construct geochemical reaction models along a flowpath in the black creek aquifer of south carolina carbon isotope fractionation between dic and precipitating cements was treated as a rayleigh distillation process organic matter oxidation was coupled to microbial fermentation and sulfate reduction all reaction models reproduced the observed chemical and isotopic compositions of final waters however model 1 in which all sources of carbon and electron acceptors were assumed to be internal to the aquifer was invalidated owing to the large ratio of fermentation co2 to respiration co2 predicted by the model 5 49 compared with measured ratios two or less in model 2 this ratio was reduced by assuming that confining beds adjacent to the aquifer act as sources of dissolved organic carbon and sulfate this assumption was based on measured high concentrations of dissolved organic acids and sulfate in confining bed pore waters 60 100 m and 100 380 m respectively relative to aquifer pore waters from less than 30 m and 2 80 m respectively sodium was chosen as the companion ion to organic acid and sulfate transport from confining beds because it is the predominant cation in confining bed pore waters as a result excessive amounts of na for ca ion exchange and calcite precipitation three to four times more cement than observed in the aquifer were required by model 2 to achieve mass and isotope balance of final water for this reason model 2 was invalidated agreement between model predicted and measured amounts of carbonate cement and ratios of fermentation co2 to respiration co2 were obtained in a reaction model that assumed confining beds act as sources of dic as well as organic acids and sulfate this assumption was supported by measured high concentrations of dic in confining beds 2 6 2 7 mm results from this study show that geochemical models of confined aquifer systems must incorporate the effects of adjacent confining beds to reproduce observed groundwater chemistry accurately

the ribe formation in western denmark holocene and pleistocene groundwaters in a coastal miocene sand aquifer the ribe formation is a regionally extensive miocene sand aquifer that is present in western denmark at depths ranging from 100 to 300 m below ground surface groundwater chemistry and isotope data collected from more than 40 wells show that the ribe formation mainly contains high quality ca bicarbonate type groundwater of holocene age 100 10 000 a bp pleistocene age groundwaters identified on the basis of stable isotopes noble gases and corrected 14c values are present below the island of r0m in discharge areas near the coast and in hydraulically isolated inland areas the groundwater age distribution in the ribe formation was successfully simulated with a numerical groundwater flow model and particle tracking only when the 14c content in groundwater was corrected for both geochemical reactions and diffusion the results indicate that geochemical and physical processes significantly influence the 14c content of groundwater and that the correction factors required for the two processes are of the same magnitude flow modelling results indicate that pleistocene groundwaters were emplaced at depth within the ribe fromation under low base level conditions that prevailed throughout the late pleistocene near the coast these waters are essentially isolated from the present flow system and pleistocene freshwater may be present offshore seismic surveys show that conditions offshore are favourable for the presence of pleistocene freshwater within the ribe formation and other aquifers

periglacial trimlines in the scottish highlands abstract two periglacial weathering limits have been identified on mountains in the highlands of scotland the lower has been interpreted as a periglacial trimline marking the upper limits of loch lomond younger dryas stade glaciers and has been employed to reconstruct the dimensions of parts of the main west highland icefield and certain smaller glaciers and icefields interpretation of the upper weathering limit has been more contentious but recent research has demonstrated 1 significant contrasts in the degree of bedrock weathering above and below this limit 2 that gibbsite a pre devensian weathering product is abundant above the limit but rare in soils farther downslope 3 that the isotopic 26al age of bedrock exposures above the limit greatly exceeds that at lower altitudes and 4 that the altitude of the weathering limit descends regularly along former ice sheet flowlines collectively these attributes suggest that the upper weathering limit is a periglacial trimline defining the maximum altitude of the last ice sheet calculated basal shear stress values are consistent with this interpretation which implies that the mainland ice shed lay at ca 900 m in wester ross and descended gently northwards whilst harris and lewis in the outer hebrides supported an independent ice cap that achieved a maximum altitude of ca 700 m wider implications of this interpretation and the future potential for ice sheet reconstruction are explored

geochemical modeling of the madison aquifer in parts of montana wyoming and south dakota stable isotope data for dissolved carbonate sulfate and sulfide are combined with water compo sition data to construct geochemical reaction models along eight flow paths in the madison aquifer in parts of wyoming montana and south dakota the sulfur isotope data are treated as an isotope dilution problem whereas the carbon isotope data are treated as rayleigh distillations all reaction models reproduce the observed chemical and carbon and sulfur isotopic composition of the final waters and are partially validated by predicting the observed carbon and sulfur isotopic compositions of dolomite and anhydrite from the madison limestone the geochemical reaction models indicate that the dominant groundwater reaction in the madison aquifer is dedolomitization calcite precipita tion and dolomite dissolution driven by anhydrite dissolution sulfate reduction ca mg2 ina cation exchange and halite dissolution are locally important particularly in central montana the groundwater system is treated as closed to c02 gas from external sources such as the soil zone or cross formational leakage but open to c02 from oxidation of organic matter coupled with sulfate reduction and other redox processes occurring within the aquifer the computed mineral mass transfers and modeled sulfur isotopic composition of madison anhydrites are mapped throughout the study area carbon 14 groundwater ages adjusted for the modeled carbon mass transfer range from modem to about 23 000 years b p and indicate flow velocities of 7 7 ftlyr 2 1 26 5 rnlyr most horizontal hydraulic conductivities calculated from darcy s law using the average 14 c flow velocities are within a factor of 5 of those based on digital simulation the calculated mineral mass transfer and adjusted 14 c groundwater ages permit determination of apparent rates of reaction in the aquifer the apparent rate of organic matter oxidation is typically 0 12 jlidol uyr sulfate and to a lesser extent ferric iron are the predominant electron acceptors the kinetic biochemical fractionation of 34 s between sulfate and hydrogen sulfide is approximately 44 o at 25 c with a temperature variation of

dating of glacial palaeogroundwater in the ordovician cambrian aquifer system northern baltic artesian basin abstract the ordovician cambrian aquifer system in the northern baltic artesian basin contains glacial palaeogroundwater that originates from the scandinavian ice sheet that covered the study area in the pleistocene previously no absolute dating of this palaeogroundwater has been attempted in this multi tracer study we use 3h 14c 4he and stable isotopes of water to constrain the age distribution of groundwater we apply the geochemical modelling approach developed by van der kemp et al 2000 and blaser et al 2010 to calculate the theoretical composition of recharge waters in three hypothetical conditions modern glacial and interstadial for 14c model age calculations in the second phase of the geochemical modelling the calculated recharge water compositions are used to calculate the 14c model ages using a series of inverse models developed with netpath the calculated 14c model ages show that the groundwater in the aquifer system originates from three different climatic periods 1 the post glacial period 2 the late glacial maximum lgm and 3 the pre lgm period a larger pre lgm component seems to be present in the southern and north eastern parts of the aquifer system where the radiogenic 4he concentrations are higher from 3 0 10 5 to 5 5 10 4 cc g 1 and the stable isotopic composition of water is heavier 18o from 13 5 to 17 3 glacial palaeogroundwater from the north western part of the aquifer system is younger and has 14c model ages that coincide with the end of the lgm period it is also characterized by lower radiogenic 4he concentrations 2 0 10 5 cc g 1 and lighter stable isotopic composition 18o from 17 7 to 22 4 relations between radiogenic 4he and 14c model ages and between radiogenic 4he and cl concentration show that groundwater in the aquifer system does not have a single well defined age rather the groundwater age distribution has been influenced by mixing between waters originating from end members with strongly differing ages overall the results suggest that in the shallower northern part of the aquifer system significant changes in groundwater composition can be brought about by glacial meltwater intrusion during a single glaciation however multiple cycles of glacial advance and retreat are needed to transport glacial meltwater to the deeper parts of the aquifer system

geodynamic evolution of the caucasus and adjacent areas in alpine time abstract the alpine geodynamics of the caucasus and adjacent areas is discussed palinspastic reconstructions are given on the basis of new geologic paleomagnetic and paleobiogeographic data the dynamic unity of extension and compression processes is shown to take place within the central segment of the mediterranean belt the closure of the paleotethys oceanic basin coincides approximately with the opening of the mesotethys owing to this the opening between afro arabia and eurasia persists as is confirmed by paleomagnetic and other data the closure of the mesozoic tethys is on the whole synchronous with the opening of the central and south atlantic the formation of the present structure of the caucasus and adjacent areas is connected with the unidirectional compression of this area and the rotation of the compressional axis from a northeastern to a sub meridional direction in the course of the cimmerian alpine cycle

paleomagnetic implications on the evolution of the tethys belt from the atlantic ocean to the pamirs since the triassic abstract we first re examined the apparent polar wander curves for stable eurasia and africa since the triassic these curves were then combined together with curves of north and south america according to the kinematics of the atlantic ocean and a synthetic polar wander curve was given then most of the paleomagnetic results from the tethys mobile belt from the atlantic to the pamirs were analysed several groups of plates microplates and blocks can be seen first relatively stable regions like maghreb and sicily which have not moved much then we have a group formed by iberia sardinia italy and to a lesser extent corsica and the western and central alps for these blocks movements are anticlockwise rotations chiefly driven by the anticlockwise rotation of africa but they are sometimes stronger to the east a major change takes place the north of the aegean sea and the ionian zone are clockwise rotated and these rotations are recent oligocene miocene for the first part pliocene to the present for the second part a major problem arises in turkey caucasus and iran paleomagnetic results indicate a position far to the south of eurasia and at the same time geological evidence is in favour of a position close to eurasia we discuss these discrepancies

quantifying arabia eurasia convergence accommodated in the greater caucasus by paleomagnetic reconstruction since the late eocene convergence and subsequent collision between arabia and eurasia was accommodated both in the overriding eurasian plate forming the greater caucasus orogen and the iranian plateau and by subduction and accretion of the neotethys and arabian margin forming the east anatolian plateau and the zagros to quantify how much arabia eurasia convergence was accommodated in the greater caucasus region we here provide new paleomagnetic results from 97 volcanic sites 500 samples in the talysh mountains of nw iran that show 15 net clockwise rotation relative to eurasia since the eocene we apply a first order kinematic restoration of the northward convex orocline that formed to the south of the greater caucasus integrating our new data with previously published constraints on rotations of the eastern pontides and lesser caucasus this suggests that north of the talysh 120 km of convergence must have been accommodated north of the eastern pontides and lesser caucasus this is significantly more 200 280 km our reconstruction independently confirms previous caucasus convergence estimates moreover we show for the first time a sharp contrast of convergence between the lesser caucasus and the talysh this implies that the ancient paleozoic mesozoic transform plate boundary preserved between the iranian and east anatolian plateaus was likely reactivated as a right lateral transform fault since late eocene time

kinematic evolution of the tethys belt from the atlantic ocean to the pamirs since the triassic abstract we present an updated series of kinematic reconstructions of the major plates around the tethys from the atlantic ocean to the pamirs between the early jurassic and the present this set is used elsewhere as a basis for paleogeographic maps of the entire region the problems related to the positions of the continents in the lower triassic are also discussed no direct analyses of magnetic anomalies and fracture zones in the atlantic have been made rather all available poles and rotations have been tested in order to eliminate or minimize possible kinematic errors the reconstructions are shown for nine key geological periods which correspond to well recognized magnetic anomalies except for the jurassic cretaceous boundary and the cretaceous tertiary boundary which correspond to interpolated positions paleolatitudes have been drawn using the study of westphal et al 1986 an attempt has been made to take into account the displacements caused by formation of the continental margins and basins by stretching the resulting relative vector of motions along the northern boundary of the tethys shows a significant change 80 m y ago left lateral motion with compression dominates before whereas right lateral motion with compression dominates after to the east rates of motion vary by a factor of three with time and four maxima can be clearly related to tectonic events in the late jurassic late cretaceous eocene and post middle miocene to the west north of apulia on the contrary the motion rate has not changed significantly since the early cretaceous and is close to 1 cm yr as an average these rather complex adjustments in rates and directions of relative motion are produced in great part through a complex migration of the africa eurasia pole of rotation and seem to be mostly governed by the tectonics of the tethys plate boundary

estimating 14c groundwater ages in a methanogenic aquifer this paper addresses the problem of 14c age dating of groundwaters in a confined regional aquifer affected by methanogenesis increasing ch4 concentrations along the groundwater flow system and 13c and 14c isotopic data for dissolved inorganic carbon dissolved organic carbon and ch4 clearly show the effect of methanogenesis on groundwater chemistry inverse reaction path modeling using netpath indicates the predominant geochemical reactions controlling the chemical evolution of groundwater in the aquifer are incongruent dissolution of dolomite ion exchange methanogenesis and oxidation of sedimentary organic matter modeling of groundwater 14c ages using netpath indicates that a significant part of groundwater in the alliston aquifer is less than 13 000 years old however older groundwater in the range of 15 000 23 000 years is also present in the aquifer this paper demonstrates that 14c ages calculated using netpath incorporating the effects of methanogenesis on the carbon pools provide reasonable groundwater ages that were not possible by other isotopic methods

global positioning system constraints on plate kinematics and dynamics in the eastern mediterranean and caucasus we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1997 at 189 sites extending east west from the caucasus mountains to the adriatic sea and north south from the southern edge of the eurasian plate to the northern edge of the african plate sites on the northern arabian platform move 18 2 mm yr at n25 5 w relative to eurasia less than the nuvel 1a circuit closure rate 25 1 mm yr at n21 7 w preliminary motion estimates 1994 1997 for stations located in egypt on the northeastern part of africa show northward motion at 5 6 2 mm yr also slower than nuvel ia estimates 10 1 mm yr at n2 4 e eastern turkey is characterized by distributed deformation while central turkey is characterized by coherent plate motion internal deformation of 2 mm yr involving westward displacement and counterclockwise rotation of the anatolian plate the anatolian plate is de coupled from eurasia along the right lateral strike slip north anatolian fault naf we derive a best fitting euler vector for anatolia eurasia motion of 30 7 0 8 n 32 6 0 4 e 1 2 0 1 myr the euler vector gives an upper bound for naf slip rate of 24 1 mm yr we determine a preliminary gps arabia anatolia euler vector of 32 9 1 2 n 40 3 1 1 e 0 8 0 2 myr and an upper bound on left lateral slip on the east anatolian fault eaf of 9 1 mm yr the central and southern aegean is characterized by coherent motion internal deformation of 2 mm yr toward the sw at 30 1 mm yr relative to eurasia stations in the se aegean deviate significantly from the overall motion of the southern aegean showing increasing velocities toward the trench and reaching 10 1 mm yr relative to the southern aegean as a whole

oligocene uplift of the western greater caucasus an effect of initial arabia eurasia collision the greater caucasus is europe s largest mountain belt significant uncertainties remain over the evolution of the range largely due to a lack of primary field data this work demonstrates that depositional systems within the oligocene early miocene maykop series on either side of the western greater caucasus wgc display a similar provenance and divergent palaeocurrents away from the range constraining a minimum age for the subaerial uplift of the range as early early oligocene an eocene oligocene hiatus basal oligocene olistostromes and a marked increase in nannofossil reworking also point to initial deformation in the earliest oligocene the initial uplift of the wgc occurred during the final assembly of the tethysides to its south uplift commenced after the late eocene final suturing of northern neotethys and during the initial collision of arabia with the southern accreted margin of eurasia this suggests that compressional deformation was rapidly transferred across the collision zone from the indenting arabian plate to its northern margin

jurassic transgressions and regressions in the caucasus northern neotethys ocean and their influences on the marine biodiversity abstract in the jurassic the caucasus presently located in the southwest of russia georgia armenia and azerbaijan was located on the northern active margin of the neotethys ocean facies interpretation in all 62 areas distinguished by differences in facies allows to semi quantitatively evaluate jurassic regional transgressions and regressions for this region major transgressive regressive cycles took place in the hettangian aalenian bajocian bathonian and callovian tithonian each transgression was more extensive than the previous the same cycles are established in the greater caucasus basin deep marine environments were common in the pliensbachian late aalenian and late bathonian whereas they were very restricted in the late jurassic the jurassic transgressions and regressions in the caucasus coincided with the proposed global eustatic changes however some differences were caused by the regional tectonic activity although transgressions and regressions cause some changes in marine biodiversity it seems that only ammonites might have been directly influenced by them diversity of bivalves brachiopods and belemnites was driven by other factors however global changes in marine biodiversity were more closely related to the eustatic fluctuations than it was documented on a regional scale

chemical weathering studies in relation to geomorphological research in southeastern canada abstract although chemical weathering provides fundamental information relevant to geomorphology the subject has been overlooked during the 20th century in canada this paper provides an overview of the current state of canadian research on chemical weathering in southeastern canada and takes into account three spatial and temporal contexts 1 the formation of bedrock morphology by chemical weathering 2 occurrences characteristics and age of saprolites and 3 contemporary chemical denudation rates long term geomorphological evolution of southeastern canadian landscapes shows that chemical weathering has played an important role an example is taken from the laurentide region of the canadian shield north of montreal quebec the present topography resulted from the stripping of the former weathering mantle and from the probable subsequent modification of the weathering front first by the action of hillslope processes and rivers and then by glaciers before and during plio pleistocene times the present landscape reflects the timing of the formation of erosion surfaces and of the stripping of the paleozoic cover rocks and exposure of the shield since the late seventies several isolated occurrences of saprolite soil profiles have been discovered in eastern canada and prompted a renewal of the study of these materials about the cenozoic evolution of these regions one of the problems in this field of research is the dating of saprolites and their inclusion in a chronostratigraphic framework along with the other cenozoic surficial deposits and landforms because of the multiple factors involved in the development of secondary minerals in saprolites during the course of weathering it is preferable to distinguish the dating of saprolites from the study of their mineralogical and geochemical evolution fortunately several new techniques are becoming available for the absolute dating of surficial deposits and saprolites including the use of cosmogenic radionuclides saprolites provide a strong potential field of research for our understanding of the geological evolution of eastern canada during the cenozoic contemporary weathering and erosion rates are fields of research that have gained increasing interest recently since modeling landscape geochemical response can be applied to various environmental stress situations such as acidification by rain and forest harvesting rock type may be the main factor explaining the large differences between watersheds in fact variability of cation removal in the temperate zone is probably most closely related to flow paths of water investigations at different scales from entire watersheds to slopes to individual pedons highlight the problem in the catamaran brook watershed new brunswick water chemistry is explained by a mix of groundwater and soil solution from the horizons at the base of the floodplain soils geochemical mass balances based on net outputs give little information on the weathering reactions of primary minerals the weathering products or on the nature of the weathering processes that provide the dissolved load of streams mineralogic and petrographic analysis of selected soil pedons are necessary to determine weathering reactions and their role as sources or sinks for bases silica aluminum and iron in the various compartments through which water percolates before it reaches the stream

petroleum geology of the black sea abstract the black sea comprises two extensional basins formed in a back arc setting above the northward subducting tethys ocean close to the southern margin of eurasia the two basins coalesced late in their post rift phases in the pliocene forming the present single depocentre the western black sea was initiated in the aptian when a part of the moesian platform now the western pontides of turkey began to rift and move away to the south east the eastern black sea probably formed by separation of the mid black sea high from the shatsky ridge during the palaeocene to eocene subsequent to rifting the basins were the sites of mainly deep water deposition only during the late miocene was there a major sea level fall leading to the development of a relatively shallow lake most of the margins of the black sea have been extensively modified by late eocene to recent compression associated with closure of the tethys ocean gas chromatography mass spectrometry and carbon isotope analysis of petroleum and rock extracts suggest that most petroleum occurrences around the black sea can be explained by generation from an oil prone source rock of most probably late eocene age although a wider age range is possible in the basin centres burial history modelling and source kitchen mapping indicate that this unit is currently generating both oil and gas in the post rift basin a palaeozoic source rock may have generated gas condensate in the gulf of odessa in bulgarian waters the main plays are associated with the development of an eocene foreland basin kamchia trough and in extensional structures related to western black sea rifting the latter continue into the romanian shelf where there is also potential in rollover anticlines due to gravity sliding of neogene sediments in the gulf of odessa gas condensate has been discovered in several compressional anticlines and there is potential in older extensional structures small gas and oil discoveries around the sea of azov point to further potential offshore around the central azov high in offshore russia and georgia there are large culminations on the shatsky ridge but these are mainly in deep water and may have poor reservoirs there are small compressional structures off the northern turkish coast related to the pontide deformation these may include eocene turbidite reservoirs the extensional fault blocks of the andrusov ridge mid black sea high are seen as having the best potential for large hydrocarbon volumes but in 2200 m of water

regional compensation of the greater caucasus mountains based on an analysis of bouguer gravity data abstract teleseismic and geological observations of the continent continent collision zone in the greater caucasus mountains of the southwestern soviet union indicate that the range is presently being underthrust primarily from the south since the onset of alpide deformation tectonic activity has been concentrated along the southern slope of the mountains but ongoing deformation along the northern slope in the eastern part of the range may be associated with thrusting of the mountains northward over the scythian platform in this area to understand the present day plate interactions in the caucasian region and the mode of compensation of the greater caucasus mountains we analyze bouguer gravity anomaly data using both spectral coherence and admittance calculations and traditional spatial domain forward modeling techniques as a whole the range appears to be in regional isostatic equilibrium with compensation by flexure of an elastic plate of approximately 40 km thickness d 6 10 23 nm loaded strongly from the bottom as well as the top subsurface loads corresponding to stacking of thrust sheets uplifts of basement rocks active volcanic zones and thick sequences of basin sediments play an important role in improving the fit between observed and calculated bouguer values closer examination of the individual tectonic provinces which make up the range yields results consistent with support by a 40 50 km thick plate in the eastern and central parts of the greater caucasus mountains and by a plate with no flexural rigidity in the western part of the range coupled with the active volcanism and the relative lack of seismicity in the western part of the greater caucasus region these results indicate the presence of hot thermally altered lithosphere in this area contrasting to the colder more brittle and more elastic lithosphere of the seismically active eastern region

geochemistry of dissolved inorganic carbon in a coastal plain aquifer 1 sulfate from confining beds as an oxidant in microbial co2 production a primary source of dissolved inorganic carbon dic in the black creek aquifer of south carolina is carbon dioxide produced by microbially mediated oxidation of sedimentary organic matter groundwater chemistry data indicate however that the available mass of inorganic electron acceptors oxygen fe iii and sulfate and observed methane production is inadequate to account for observed co2 production although sulfate concentrations are low approximately 0 05 0 10 mm in aquifer water throughout the flow system sulfate concentrations are greater in confining bed pore water 0 4 20 mm the distribution of culturable sulfate reducing bacteria in these sediments suggests that this concentration gradient is maintained by greater sulfate reducing activity in sands than in clays calculations based on fick s law indicate that possible rates of sulfate diffusion to aquifer sediments are sufficient to explain observed rates of co2 production about 10 5 mmoll 1 year 1 thus eliminating the apparent electron acceptor deficit furthermore concentrations of dissolved hydrogen in aquifer water are in the range characteristic of sulfate reduction 2 6 nm which provides independent evidence that sulfate reduction is the predominant terminal electron accepting process in this system the observed accumulation of pyrite and calcite cemented sandstones at sand clay interfaces is direct physical evidence that these processes have been continuing over the history of these sediments

a record of temperature and monsoon intensity over the past 40 kyr from groundwater in the north china plain abstract the well known temperature dependence of noble gas solubilities in water enables the determination of absolute paleotemperature records from radiocarbon dated groundwater an advantage of the noble gas paleothermometer is that noble gas temperatures ngts can directly be related to stable isotope ratios from the same groundwater archive in order to calibrate the stable isotope thermometer over long time scales our record from heavily used aquifers of the north china plain constitutes a unique combined ngt and stable isotope data set from the region affected by the east asian monsoon in addition to providing a reliable estimate for the glacial interglacial temperature change the data enable the separation of the effects of temperature and precipitation monsoon strength on the stable isotopes although the record extends from modern waters to near the limit of the radiocarbon dating range at about 40 kyr bp the last glacial maximum is not represented probably because arid conditions limited groundwater recharge during that period the coldest observed period at about 30 kyr bp was 4 6 1 2 c cooler than the holocene whereas ngts show no systematic variation during the holocene the 18 o values increased by about 1 between the early and late holocene a similar increase of 18 o has been observed before in speleothems and ascribed to decreasing monsoon strength in response to decreasing insolation during the holocene our results confirm that the holocene trend in stable isotopes is not related to temperature in contrast 18 o and ngt are correlated within the pleistocene group of samples indicating a 18 o ngt slope of 0 18 0 05 c 1 similar to the temperature effect in modern precipitation of the region thus of the overall increase of 18 o by about 2 between 30 kyr bp and the late holocene about half is due to a temperature increase whereas the other half is due to a decrease of monsoon strength