mid ocean ridge and island arc affinities in ophiolites from iran palaeographic implications complementary reference abstract fifty six samples of ophiolitic rocks from various late cretaceous eocene suture zones in iran have been analyzed for major and trace elements in order to assess their petrogenetic affinity and to determine their original tectonic setting in both southern baluchestan i e between the makran range and the lut block the fanuj maskutan sequence and northeastern baluchestan i e in the east iranian ranges the tchehel kureh sequence the ophiolitic complexes are well developed the rocks display affinities with mid ocean ridge tholeiites the basaltic rocks are comparable to respectively transitional fanuj maskutan and normal tchehel kureh morb in contrast the sequence along the zagros the sahneh sequence appears to have formed in an island arc setting in iranshar i e in southeastern baluchestan ophiolites are dismembered into a melange which includes cumulate intrusives similar to those from fanuj maskutan and lavas with island arc tholeiitic affinity a similar island arc origin may be inferred for the sabzevar ophiolitic sequence north of the lut block studied by other authors the chemical data thus help to elucidate the development of the jigsaw puzzle of microplates of gondwanian origin that during the mesozoic were intermediate in position between afro arabia india and eurasia and that now constitute the middle east ophiolite obduction in iran occurred during arc basin continent or ocean continent collisions in the late cretaceous early paleogene largely predating the final suturing between arabia and india with eurasia to which the intermediate microplates were already attached which did not take place before the neogene

meso tethyan oceanic sutures and their deformation abstract on the basis of comparative stratigraphie and paleontologic analysis supported by some key paleomagnetic data and interpretations it is shown that during the mesozoic and the cenozoic the eurasian continent grew by accretion of microcontinents these microcontinents separated basins with oceanic crust from the main ocean during the late cretaceous and the early cenozoic the collision of the microcontinents with eurasia resulted in the closure of the basins and meso tethyan oceanic sutures originated in the region under consideration from the carpathians to tibet there are two main meso tethyan sutures the carpathian lesser caucasus and the afghan tibet suture the above mentioned main structures also had branches which remained as sutures of small basins the kamennopotock interpontide nain baft basins and others in the west carpathians the carpathian lesser caucasus suture is overlain by a widespread gemeric tatric allochton from the west carpathians the suture passes through the pannonian basin into the vardar ophiolite zone and farther to the ophiolites of the izmir ankara zone being displaced along the north anatolian right lateral strike slip fault the main suture passes from the eastern pontides into the lesser caucasus where it is marked by ophiolites of the amasia area the shirak bozum and zangezur ridges sunsequently it can be observed through the iranian qara dagh mountains to lake urumiyeh and the north anatolian strike slip fault being again shifted along the strike slip fault the carpathian lesser caucasus meso tethyan suture ends in the western zagros near the cenozoic neo tethyan suture the afghan tibet meso tethyan suture is situated in the pamirs in the rushan pshart zone the east prolongation of the suture has been displaced along the pamir karakorum right lateral strike slip fault in tibet west of the pamirs this suture is also displaced along strike slip faults and continues in the farahrud zone in afghanistan and than passes through the zabol baluch and daz murian ophiolite zones and approaches the neo tethyan suture the paleomagnetic data allow us to reconstruct the location of those sutures in the late cretaceous early cenozoic if one compares the present position of the carpathian lesser caucasus and afghan tibet meso tethyan sutures with the late cretaceous early cenozoic reconstructions of these sutures it is possible to trace the inner deformation of the alpine belt according to these data the carpathian lesser caucasus suture moved northwards over 1200 km ahead of the arabian turkish syntaxis with the displacement direction across the fold belt at the border of the dinarides and hellenides the displacement decreases to 400 500 km and its direction is along the fold belt the amplitude of the suture displacement increases in the pannonian region and again decreases towards the eastern alps the displacement of the afghan tibet suture was 2000 km during the alpine deformation a great ensemble of cenozoic nappes folds and structural arcs of the pamir punjab and arabian turkish syntaxes and carpathian loop is the result of lateral shortening of the alpine belt through the collision

seawater ph pco2 and co2 3 variations in the caribbean sea over the last 130 kyr a boron isotope and b ca study of planktic foraminifera abstract here a new analytical methodology is described for measuring the isotopic composition of boron in foraminifera using multicollector inductively coupled plasma mass spectrometry mc icpms this new approach is fast 10 samples analysed in duplicate per analytical session and accurate to better than 0 25 at 95 confidence with acceptable sample size requirements 1 3 mg of carbonate a core top calibration of several common planktic and two benthic species from geographically widespread localities shows a very close agreement between the isotopic composition measured by mc icpms and the isotopic composition of b oh 4 in seawater as predicted using the recently measured isotopic equilibrium factor of 1 0272 at the depth of habitat a down core and core top investigation of boron concentration b ca ratio shows that the partition coefficient is influenced by co2 3 complicating the application of this proxy nevertheless it is demonstrated that these two proxies can be used to fully constrain the carbonate system of surface water in the caribbean sea odp site 999a over the last 130 kyr this reconstruction shows that during much of the holocene and the last interglacial period surface water at site 999a was in equilibrium with the atmosphere with respect to co2 during the intervening colder periods although the surface water pco2 was lower than the holocene it was a minor to significant source of co2 to the atmosphere possibly due to either an expansion of the eastern equatorial atlantic upwelling zone or a more local expansion of coastal upwelling in the southern caribbean such reorganisation of the oceanic carbonate system in favour of a larger source of co2 to the atmosphere from the equatorial ocean may require mechanisms responsible for lowering atmospheric co2 during glacial periods to be more efficient than previously supposed

orbital control on carbon cycle and oceanography in the mid cretaceous greenhouse we established a new high resolution carbonate carbon isotope record of the albian interval of the marne a fucoidi formation central apennines italy which was deposited on the southern margin of the western tethys ocean bulk carbonate sampled with 10 15 cm spacing was used for the construction of a continuous carbon isotope curve through the albian stage spectral analyses reveal prominent 400 kyr cyclicity in the 13c curve which correlates with milankovitch long eccentricity changes cycles occurring in our record resemble those observed in several cenozoic 13c records suggesting that a link between orbital forcing and carbon cycling existed also under mid cretaceous greenhouse conditions based on comparisons with cenozoic eccentricity carbon cycle links we hypothesize that 400 kyr cycles in the mid cretaceous were related to a fluctuating monsoonal regime coupled with an unstable oceanic structure which made the oceanic carbon reservoir sensitive to orbital variations in the tethys these oceanographic conditions lasted until the late albian and then were replaced by a more stable circulation mode less sensitive to orbital forcing

evolutionary driven of gephyrocapsa coccolith isotopic vital effects over the past 400 ka abstract coccolithophores play important roles in marine biochemistry due to the processes of calcification and photosynthesis coccoliths are produced intracellularly and cells produce coccoliths with stable isotopes distinct from theoretically precipitated inorganic calcite due to the influences of coccolithophore physiology which are the so called vital effects the coccolith isotopic vital effects show large variations between species and hamper the use of coccolith isotopes in paleoceanography in addition learning the coccolith isotopic vital effects can help to better understand the carbon fractionation in coccolithophore cell so as to provide a new insight in reconstructing sea water carbonate system e g from alkenone 13 c or directly from coccolith 13 c in geological past in the present study we investigated the morphological parameters growth rate and coccolith stable isotope compositions of gephyrocapsa the most universal alkenone producing coccolithophore across the pleistocene these data allow us to estimate the influences of gephyrocapsa morphology as well as the growth rate on coccolith vital effects the results showed that gephyrocapsa morphology as well as coccolith isotopes varied with species and morphotype changes which were evolutionarily forced over the past 400 ka the small gephyrocapsa morphotypes g caribbeanica and gephyrocapsa

reevaluation of the oxygen isotopic composition of planktonic foraminifera experimental results and revised paleotemperature equations cultured planktonic foraminifera orbulina universa symbiotic and globigerina bulloides nonsymbiotic are used to reexamine temperature 18o relationships at 15 25 c relationships for both species can be described by linear equations equations for o universa grown under low light ll and high light hl share a slope of 4 80 0 21 c 1 with a hl ll offset of 0 33 due to symbiont photosynthetic activity the effect of co32 on o universa is 0 002 mol 1 kg 1 and is insensitive to temperature for g bulloides ontogenetic effects produce size related trends in temperature 18o whereby larger shells are enriched in 18o relative to smaller specimens the o universa temperature 18o relationships are more accurate than previously published equations for describing plankton tow data our equations do not explain planktonic core top data with the same precision but provide a good fit to benthic cibicidoides data below 10 c temperature 18o relationships for g bulloides provide good agreement with field data for this species from the northeast pacific

millennial scale evolution of the southern ocean chemical divide abstract the chemical properties of the mid depth and deep southern ocean are diagnostic of the mechanisms of abrupt changes in the global ocean throughout the late pleistocene because the regional water mass conversion and mixing help determine global ocean gradients here we define continuous time series of southern ocean vertical gradients by differencing the records from two high deposition rate deep sea sedimentary sequences that span the last several ice age cycles the inferred changes in vertical carbon and oxygen isotopic gradients were dominated by variability on the millennial scale and they followed closely the abrupt climate events of the high latitude northern hemisphere in particular the stadial events of at least the last 200 kyr were characterized by enhanced mid deep gradients in both 13 c dissolved inorganic carbon and 18 o temperature interstadial events conversely featured reduced vertical gradients in both properties the glacial terminations represented exceptions to this pattern of variability as the vertical carbon isotopic gradient flattened dramatically at times of peak warmth in the southern ocean surface waters and with little or no corresponding change 18 o gradient the available evidence suggests that properties of the upper layer of the southern ocean antarctic intermediate water were influenced by an atmospherically mediated teleconnection to high latitude northern hemisphere

block rotation by strike slip faulting structural and paleomagnetic evidence geometric analysis shows that motion of sets of strike slip faults should cause block rotation otherwise the distorted fault domain would not fit with its surrounding the sense of the block rotation depends on the sense of fault slip and the spacing and orientation of the faults all of which can be obtained from structural data the predictions of the geometric model can then be independently tested by paleomagnetic measurements the model was tested in northern israel structural data reveal several domains of contemporaneous right and left lateral strike slip faults paleomagnetic measurements show that in a domain of nnw trending left lateral faults blocks rotated 23 3 8 2 clockwise and in a domain of right lateral faults blocks rotated 22 4 9 0 anticlockwise these results are in agreement with the prediction of the geometric analysis of the structure the combined results of the heterogenous deformation of the area resembles a pure shear which allows n s extension by about 1 3 in other domains rotations of 34 6 9 1 and 53 1 11 0 were found in their original orientation the left and right lateral faults intersected at angles of 60 70 enclosing the principal axis of shortening in accordance with theories of brittle failure as a result of block rotations this angle is now larger and may reach 110 the results demonstrate large block rotations in different senses in domains of strike slip faults the independent structural and paleomagnetic data can be interpreted within the framework of a simple geometric model northern israel is considered to be a good model for this efficient mechanism of intraplate deformation which is expected to occur in similar tectonic settings elsewhere

coccolith chemistry reveals secular variations in the global ocean carbon cycle the mismatch between the 100 and 400 k y components of pleistocene climate and the relative power of those terms from the eccentricity of the earth s orbit remains a challenge to the milankovitch hypothesis coccolithophores have the potential to respond to parameters of orbital forcing other than insolation and as a critical component of the ocean carbon cycle can act to modify the climate response the first direct comparison of coccolith fraction sr ca alkenone abundance and automated coccolithophore counts shows that cf sr ca is largely driven by changing production of bloom species with unusually high sr ca ratios the periods of high cf sr ca and high bloom production mark periods of high global coccolithophore production which correlate inversely with the low amplitude 100 and higher amplitude 400 k y eccentricity orbital frequency 400 k y cycles of coccolithophore bloom production correspond to periods of enhanced carbonate accumulation in some parts of the ocean deep ocean dissolution in others positive shifts in global ocean 13c and acmes of gephyrocapsa caribbeanica and emiliania huxleyi the link between production of coccolithophore blooms and eccentricity may be due to orbital control of silica leakage from the southern ocean to the orbitally defined inverse correlation between insolation and growing season length and the asymptotic growth response to these parameters or to changes in nutrient input from weathering during the pleistocene the eccentricity induced coccolithophore acmes have no apparent influence on atmospheric carbon dioxide pco2 due to the shift towards small bloom coccolithophores or to coupling with increased diatom productivity or the ballast effect of the calcium carbonate rain such that pleistocene climate has no significant variance at the largest amplitude eccentricity forcing of 400 k y coccolithophores and their influence on the carbon cycle may act as a filter between the incident orbital forcing and resultant climate

isotopic record of pleistocene glacial interglacial cycles in pelagic carbonates revisiting historical data from the caribbean sea the glacial interglacial cycles of the pleistocene were first recognised by variations in the oxygen isotopic composition of planktonic foraminifera from cores in the caribbean sea since this pioneering work by emiliani this proxy has been extensively applied to a variety of carbonate biominerals over the entirety of the meso cenozoic however palaeoceanographic studies have overwhelmingly focused on foraminifera compared to other calcifying microorganism fossils such as the coccoliths in this study i revisit coccolith stable isotopic data obtained from the classic p6304 4 core in light of recent developments in the biogeochemistry of coccolithophores in particular i show that the coccolith stable isotope record of the last 13 marine isotope stages 480 kyrs is significantly biased by large vital effects the magnitude of coccolith carbon and oxygen isotope vital effects is not uniform but shows remarkable co variance with the vostok co2 ice record during periods of relatively elevated co2 interstadials the expression of the vital effect is relatively small whereas it can as high as 3 for the oxygen isotopes during glacial stadials which i argue is a result of enhanced co2 limitation of coccolithophores using this paradigm i propose that coccolithophore vital effects are not a complicating factor but rather the signal of interest as the magnitude of the coccolith vital effect is shown to scale with pco2 coccolith carbon and oxygen isotopes may be used in conjunction with foraminifera data to reconstruct and refine aqueous co2 concentrations in the past

origin of structural arcs of the carpathian balkan region burtman vs 1986 origin of structural arcs of the pat an balkan region in l p zonenshain editor tectonics of the eurasian fold belts tectonophysics 127 245 260 the late cretaceous reconstruction shows that the inner zones of the west east and south carpathians were adjacent to the dinarides and hellenides at that time forming together with them a linear fold system with bilateral vergence this fold system had a northwest strike in paleogene early miocene times the general deformation of the given part of the alpine belt took place it was caused by rotation of its asia minor balkan part relative to the more northern part of the belt this rotation 30 40 counter clockwise was accompanied by a shortening of the considered segment of the alpine belt by 30 hence exfoliation of the carpathian pontide and dinaric tauride branches of the alpine belt from each other and their disharmonious plastic deformation resulted in the formation of the aegean and tauride structural arcs and the carpathian structural loop during formation of the carpathian loop the gemeric tatric tectonic block moved northwards along the pemrinic oceanic substratum and rotated over 90 counter clockwise relative to the eastern alps

hydrochemical properties of transition zone between fresh groundwater and seawater in karst environment of the adriatic islands croatia eastern coast of the adriatic sea consists of karstified carbonates it belongs to the well known dinaric karst region the coast is extremely indented and there are 718 islands with numerous rock crags and reefs some of the inhabited islands use their own water resources for public water supply or plan to do it in the future since karst rocks are extremely permeable the seawater intrudes into underground water resources thereby forming the wedge a wide transition zone occurs between this seawater wedge and fresh water aquifers consequently island groundwater reserves turn brackish to a certain extent in this study 77 water samples were collected from a wide variety of water resources comprehensive statistical and mathematical multivariate analysis of these data was performed simple statistical approach showed several useful correlations among some parameters and more complex multivariate techniques extracted three factors in connection with three natural processes 1 mixing with the seawater 2 carbonate dissolution and 3 human influence pollution and nitrogen transformation processes the results of this study demonstrate that in situ measurement of electrical conductivity is adequate for the very rough field estimation of numerous parameters

corroborating ecological depth preferences of planktonic foraminifera in the tropical atlantic with the stable oxygen isotope ratios of core top specimens 1 past variability in upper ocean thermocline depth is commonly estimated from the abundance of different species of planktonic organisms or the difference in oxygen isotopic composition between two species of planktonic foraminifera one that lives in the mixed layer and one that lives in or near the thermocline to test the latter relationships we measured the oxygen isotopic composition of eight species of planktonic foraminifera pink and white varieties of globigerinoides ruber globigerinoides sacculifer without the final chamber orbulina universa pulleniatina obliquiloculata globorotalia menardii neogloborotalia dutertrei and globorotalia tumida in surface sediment samples from 31 tropical atlantic deep sea sediment cores bayesian analysis was used to compare measured oxygen isotopic compositions with their predictions based on modern data sets of annual temperatures and oxygen isotopic composition of ocean water in the upper 500 m at the core sites posterior probability densities for predictive model parameters were computed probability distributions of calcification depth for analyzed species corroborated their ecological preferences inferred from net tow and sediment trap data robustness of the habitat signals in core top specimens suggests that reconstructions of the entire upper ocean temperature profiles not just their thermocline depth or temperature might be possible

biomineralization in perforate foraminifera in this paper we review the current understanding of biomineralization in perforate foraminifera ideas on the mechanisms responsible for the flux of ca2 and inorganic carbon from seawater into the test were originally based on light and electron microscopic observations of calcifying foraminifera from the 1980s onward tracer experiments fluorescent microscopy and high resolution test geochemical analysis have added to existing calcification models despite recent insights no general consensus on the physiological basis of foraminiferal biomineralization exists current models include seawater vacuolization transmembrane ion transport involvement of organic matrices and or ph regulation although the magnitude of these controls remain to be quantified disagreement between currently available models may be caused by the use of different foraminiferal species as subject for biomineralization experiments and or lack of a more systematic approach to study dis similarities between taxa in order to understand foraminiferal controls on element incorporation and isotope fractionation and thereby improve the value of foraminifera as paleoceanographic proxies it is necessary to identify key processes in foraminiferal biomineralization and formulate hypotheses regarding the involved physiological pathways to provide directions for future research

constraints on the vital effect in coccolithophore and dinoflagellate calcite by oxygen isotopic modification of seawater in this study we show that there are independent controls of 18o 16o and 13c 12c fractionation in coccolithophore and dinoflagellate calcite due to the contrasting kinetics of each isotope system we demonstrate that the direction and magnitude of the oxygen isotope fractionation with respect to equilibrium is related to the balance between calcification rate and the replenishment of the internal pool of dissolved inorganic carbon dic as such in fast growing cells such as those of emiliania huxleyi and gephyrocapsa oceanica forming the so called heavy group calcification of the internal carbon pool occurs faster than complete isotopic re adjustment of the internal dic pool with h2o molecules hence coccoliths reflect the heavy oxygen isotope signature of the co2 overprinting the whole dic pool conversely in large and slow growing cells such as coccolithus pelagicus ssp braarudii complete re equilibration is achieved due to limited influx of co2 leading to coccoliths that are precipitated in conditions close to isotopic equilibrium equilibrium group species exhibiting the most negative oxygen isotope composition such as calcidiscus leptoporus light group precipitate coccolith under increased ph in the coccolith vesicle as previously documented by the carbonate ion effect we suggest that for the carbon isotope system any observed deviation from isotopic equilibrium is only apparent as the carbon isotopic composition in coccolith calcite is controlled by a rayleigh fractionation originating from preferential incorporation of 12c into organic matter therefore species with low pic poc ratios as e huxleyi and g oceanica are shifted towards positive carbon isotope values as a result of predominant carbon fixation into the organic matter by contrast cells with higher pic poc as c braarudii and c leptoporus maintain to some extent the original negative isotopic composition of the co2 the calcareous dinoflagellate thoracosphaera heimii exhibits different behaviour for both isotopic systems in particular with respect to its very negative carbon isotope composition owing to coeval intra and extracellular biomineralisation in this group in this study we also investigate the sensitivity of 18o 16o fractionation to varying ambient oxygen isotope composition of the medium for inorganic coccolithophore and dinoflagellate calcite precipitated under controlled laboratory conditions the varying responses of different taxa to increased oxygen isotope composition of the growth medium may point to a potential bias in sea surface temperature reconstructions that are based on the oxygen isotopic compositions of sedimentary calcite especially during times of changing seawater oxygen isotopic composition overall this study represents an important step towards establishing a mechanistic understanding of the vital effect in coccolith and dinoflagellate calcite and provides valuable information for interpreting the geochemistry of the calcareous nannofossils in the sedimentary record at both monospecific and interspecies levels

the influence of kinetics on the oxygen isotope composition of calcium carbonate paleotemperature reconstructions rely on knowledge of the equilibrium separation of oxygen isotopes between aqueous solution and calcium carbonate although oxygen isotope separation is expected on theoretical grounds the temperature dependence remains uncertain because other factors such as slow exchange of isotopes between dissolved co2 species and water can obscure the temperature signal this is problematic for crystal growth experiments on laboratory timescales and for interpreting the oxygen isotope composition of crystals formed in natural settings we present results from experiments in which inorganic calcite is precipitated in the presence of 0 25 m dissolved bovine carbonic anhydrase ca the presence of dissolved ca accelerates oxygen isotope equilibration between the dissolved carbon species co2 h2co3 hco3 co32 and water thereby eliminating this source of isotopic disequilibrium during calcite growth the experimental results allow us to isolate for the first time kinetic oxygen isotope effects occurring at the calcite water interface we present a framework of ion by ion growth of calcite that reconciles our new measurements with measurements of natural cave calcites that are the best candidate for having precipitated under near equilibrium conditions our findings suggest that isotopic equilibrium between calcite and water is unlikely to have been established in laboratory experiments or in many natural settings the use of ca in carbonate precipitation experiments offers new opportunities to refine oxygen isotope based geothermometers and to interrogate environmental variables other than temperature that influence calcite growth rates

on the potential role of marine calcifiers in glacial interglacial dynamics 1 ice core measurements have revealed a highly asymmetric cycle in antarctic temperature and atmospheric co2 over the last 800 kyr both co2 and temperature decrease over 100 kyr going into a glacial period and then rise steeply over less than 10 kyr at the end of a glacial period there does not yet exist wide agreement about the causes of this cycle or about the origin of its shape here we explore the possibility that an ecologically driven oscillator plays a role in the dynamics a conceptual model describing the interaction between calcifying plankton and ocean alkalinity shows interesting features i it generates an oscillation in atmospheric co2 with the characteristic asymmetric shape observed in the ice core record ii the system can transform a sinusoidal milankovitch forcing into a sawtooth shaped output and iii there are spikes of enhanced calcifier productivity at the glacial interglacial transitions consistent with several sedimentary records this suggests that ecological processes might play an active role in the observed glacial interglacial cycles

modifications of the c37 alkenone and alkenoate composition in the water column and sediment possible implications for sea surface temperature estimates in paleoceanography 1 the literature pertaining to c37 alkenone and c37 and c38 alkenoate production and diagenesis has been reviewed and evaluated for issues that might jeopardize their usefulness in paleotemperature estimation we also examined the use of the c37 alkenones as paleoproductivity indicators the stability of their 13c isotopic compositions and their incorporation into the nonsolvent extractable organic matter fraction biological transformation of organic matter by bacteria and zooplankton does not appear to cause significant changes to the ratio of c37 2 and c37 3 alkenones but there are major alterations in the relative composition of alkenoates studies of water column processes and postdepositional sedimentary changes indicate overall stability in the c37 2 c37 2 c37 3 ratio leading to effective preservation of the paleotemperature signal this is not the case for alkenoates and there also appear to be some doubts about the dependence between sea surface temperature and the sedimentary abundance of the c37 4 alkenone c37 alkenones may provide useful qualitative estimates of marine paleoproductivity although these compounds are apparently only derived from haptophycea changes in their quantitative composition might reflect changes in nutrient availability that on sedimentary timescales should also be generally significant of other algal species one caveat is that in highly productive upwelling systems productivity may be expressed mostly in diatom growth and thus not measurable by the c37 alkenones no changes in 13c c37 alkenone composition are observed upon zooplankton ingestion although this is expected from a theoretical perspective further studies are encouraged in order to fully assess the stability of the isotopic signal during c37 alkenone diagenesis finally alkenones bound in the nonextractable fraction of sedimentary organics have not been adequately studied and further work is required to clarify any possible correspondence with a temperature signal

conditions for shallow geothermal energy utilization in dinaric karst terrains in croatia hydrogeological and thermogeological properties of the shallow subsurface in the dinaric karst area of croatia were investigated in the context of its utilization for ground and water source heat pumps gshps and wshps the research encompassed four 100 m deep boreholes with gshp installations in both coastal and inland dinaric karst different limestones and evaporitic rocks at one location and a set of six exploratory boreholes abstraction and reinjection wells for wshp heating and cooling using seawater on the coast fractured and karstified limestones it was determined that rock thermal conductivities are favourable for gshp utilization but dependent on the wider rock mass characteristics which are hard to predict size of karst voids and their saturation status in addition wells with high enough yield and stabile seawater or groundwater temperatures for wshp utilization can be designed in appropriate structural settings tensional fractures and fracture set intersections advantages and disadvantages of the utilized methodology have been pointed out as well as methods which should prove useful in the future especially if larger systems are planned hydrogeological geotechnical and thermal risks expected during the drilling installation and operational phases have also been identified presented case studies have given the insight into heat pump installation options and conditions in croatian part of the dinarides but can be useful to other researchers and engineers both in the dinarides and in similar karst regions

on the fidelity of shell derived δ18oseawater estimates article i nfo 18 oseawater a robustproxyforsurfacesalinity we assessthe fidelity of shell derived 18 oseawater estimates for the surface dwelling foraminifer globigerinoides ruber white using an atlantic meridional coretop transect spanning basin scale temperature and salinity gradients shell derived and observed 18 oseawater values are well correlated r 2 0 77 but a large systematic bias is observed shell mg ca ratios are significantly elevated above values expected from observed and isotopic calcification temperatures in the saline subtropical gyres of both hemispheres this temperature independent shell mg ca ratio variability termed excess mg ca i s highly correlated with surface salinity r 2 0 77 and the observed salinity dependence 27 4 is much higher than indicated by culture studies 6 2 our coretop data are used to develop new atlantic basin temperature and salinity calibration equations that are accurate 1 1 c and 0 20 respectively precise r 2 0 82 and 0 81 respectively and verifiable using previously published data these results are valid for the relatively high salinities of the subtropical atlantic 35 5 37 3 we discover that inclusion of other published data from lower salinity regions b35 indicates little or no excess mg ca taken together these results point to a strongly non linear positive salinity effect on shell mg ca ratios that significantly affects the accuracy of sst and 18

isotopic and biostratigraphical records of calcareous nannofossils in a pleistocene core knowledge of the species composition is essential for the isotopic record of polyspecific coccolith assemblages in deep sea sediments to be interpreted properly we have determined the carbon and oxygen isotopic composition as well as the relative abundance of coccolith species on the 3 25 m fractions of the caribbean core p6304 4 the dominant taxon in all samples is well preserved gephyrocapsa spp oxygen isotope variations clearly define glacial interglacial oscillations except in the upper part of the core carbon isotopic compositions are not related to the oxygen isotope stratigraphy the occurrence of three coccolith datum levels in the core correlates almost exactly with globally synchronous horizons1 the amplitude of the coccolith 18o record 2 4 is significantly greater than that for the planktonic foraminifera globigerinoides sacculifer in p6304 4 and adjacent cores2 4 we suggest here that selective dissolution or deep calcification during interglacials reduced the amplitudes of g sacculifer in these cores and that the coccolith record is a more reliable indicator of temperature and 18o changes in surface seawater

parameter estimation for a karst aquifer with unknown thickness using the genetic algorithm method the thickness of an aquifer b is a critical hydrogeologic parameter in understanding groundwater system especially in a karst aquifer where the high heterogeneity in this parameter brings more uncertainty to the evaluation of groundwater resources in this study the genetic algorithm ga method was used to estimate b as well as five other parameters including k r horizontal hydraulic conductivity k z vertical hydraulic conductivity s storativity s y specific yield and delayed coefficient of a karst aquifer based on a pumping test the search bounds of the six parameters for the ga method were obtained from numerous hypothetic numerical tests the feasibility of the ga method for parameter estimation was verified by the results obtained from the gradient method in terms of a pumping test conducted in the platte river valley in nebraska then this approach was used to estimate the hydraulic parameters in a karst aquifer with unknown aquifer thickness based on a pumping recovery test conducted in the houzhai karst basin southwestern china the results show that the k r k z and the anisotropy ratio of k r to k z are strongly affected by b the differences between the estimated parameter values at two observation wells indicate the existence of high heterogeneity in the karst aquifer the parameter b has the highest absolute normalized sensitivity among these variables implying that the estimated b may be more reliable as compared to other parameters this study demonstrates that the ga method is an alternative method of parameter estimation with the unknown aquifer thickness

a review of possible eustatic isostatic and tectonic contributions in eight late holocene relative sea level histories from the mediterranean area abstract this paper consists of a comparison between eight late holocene sea level histories investigated by the author in different mediterranean areas and sea level predictions in the same areas made by global isostatic models the areas include three regions that are generally considered as tectonically relatively stable 1 the southern coast of france 2 sardinia and 3 the southern coasts of tunisia where late holocene evidence may be either of submergence or of emergence also considered are 4 a subsidence region in the northern adriatic and actively uplifting areas 5 in calabria and 6 in nisyros island greece lastly case studies in areas affected by repeated coseismic vertical displacements include 7 western crete and antikythira island in the hellenic arc and 8 the levant coasts of turkey syria and the lebanon in each case the question of whether the evidence available may or may not be consistent with gradual isostatic or eustatic displacements has been explored it appears that in non tectonic areas the hydro isostatic effects have been overestimated sardinia or underestimated southern tunisia by the same models in the northern adriatic the closest mediterranean area to the former scandinavian ice sheet glacio eustatic effects are suspected to be almost absent our analysis failed to quantify isostatic effects in areas of rapid tectonic uplift calabria and nisyros but rejected predictions of significant isostatic subsidence in the hellenic arc and on the levant coast finally several data from tectonic and non tectonic areas are consistent with nearly stable global eustasy since 6000 bp thus challenging the assertion of significant additional melting of antarctica after the complete melting of the former northern hemisphere ice caps

western caribbean sea surface temperatures during the late quaternary 1 mg ca ratios in the planktonic foraminifera globigerinoides ruber from colombian basin core odp 999a suggest that caribbean sea surface temperatures ssts were from 2 1 to 2 7 c colder than the present during the last three glacial maximums in comparison faunal derived ssts simmax method show that august ssts in the caribbean varied 2 c over the past 360 kyr whereas february ssts varied between 21 0 c and 26 5 c changes in the mg ca sst record contain a strong 23 kyr periodicity suggesting the mg ca sst record reflects a warm season weighted sst average rather than an annual mean sst combining several dissolution indices we identify brief periods of decreased carbonate preservation in our record and show that mis 11 stands out as the most intensive dissolution cycle in the caribbean over the last 460 kyr comparison of caribbean sst change with a similar estimate of tropical sst variability in the western pacific over the past 360 kyr reveals shifts in the east west tropical sst gradient that are coeval with glacial interglacial climate change and consistent both with a southward migration of the glacial itcz and with a glacial el nino like mode of tropical circulation

glacial interglacial surface water variations in the caribbean sea during the last 300 ky based on calcareous nannofossil analysis abstract quantitative and qualitative analyses of nannofossil assemblages from odp site 999 in the caribbean sea were performed to reveal changes in upper seawater structures and implications for climatic changes during the last 300 000 years overall there is an inverse relationship in stratigraphic fluctuations between the absolute abundance aa of a lower photic taxon florisphaera profunda and 18 o this fluctuation pattern is considered to represent climatic changes in the subtropical under water suw in the caribbean cross spectral analysis demonstrates that the suw was characterized by nutrient rich water during interglacials changes in orbitally driven gyre circulation system strongly affected fluctuations in the suw in the caribbean conversely the surface water was enriched in nutrients during glacials as the result of increased terrigenous materials and shallowing of the thermocline based on changes of the n ratio abundance of reticulofenestrids relative to f profunda and results of cross spectral analysis between them and 18 o the relationship between the thermocline variation and the ice volume fluctuation suggests that changes in the subtropical gyre circulation system in the north atlantic have had stronger influences on the caribbean thermocline variations and there may be a little contribution of climatic fluctuations that originated in the southern ocean to the caribbean sea a large floral turnover in nannofossil assemblages between oxygen isotope stages 6 and 5 was observed in hole 999a which corresponds to termination ii on the basis of floral compositions photosynthetic primary productions had been more active than today before termination ii

rapid least squares inversion of apparent resistivity pseudosections by a quasi newton method1 a fast inversion technique for the interpretation of data from resistivity tomography surveys has been developed for operation on a microcomputer this technique is based on the smoothness constrained least squares method and it produces a two dimensional subsurface model from the apparent resistivity pseudosection in the first iteration a homogeneous earth model is used as the starting model for which the apparent resistivity partial derivative values can be calculated analytically for subsequent iterations a quasi newton method is used to estimate the partial derivatives which reduces the computer time and memory space required by about eight and twelve times respectively compared to the conventional least squares method tests with a variety of computer models and data from field surveys show that this technique is insensitive to random noise and converges rapidly this technique takes about one minute to invert a single data set on an 80486dx microcomputer

control of ambient ph on growth and stable isotopes in phytoplanktonic calcifying algae the present work examines the relationship between ph induced changes in growth and stable isotopic composition of coccolith calcite in two coccolithophore species with a geological perspective these species gephyrocapsa oceanica and coccolithus pelagicus with differing physiologies and vital effects possess a growth optimum corresponding to average ph of surface seawater in the geological period during their first known occurrence the ancestral c pelagicus has much wider ph tolerance in terms of growth rates than the more recently evolved g oceanica diminished growth rates are explained by the challenge of proton translocation into the extracellular environment at low ph and enhanced aqueous co2 limitation at high ph reducing the cell dynamics in this way leads to a lower degree of oxygen isotopic disequilibrium in g oceanica in contrast the slower growing species c pelagicus which typically precipitates near equilibrium calcite does not show any modulation of oxygen isotope signals with changing ph overall carbon and oxygen isotope compositions are best explained by the degree of utilization of the internal dissolved inorganic carbon dic pool and the dynamics of isotopic reequilibration inside the cell thus the carbonate ion effect may not apply to coccolithophores this difference with foraminifera can be traced to different modes of dic incorporation into these two distinct biomineralizing organisms from a geological perspective these findings have implications for refining the use of oxygen isotopes to infer more reliable sea surface temperatures ssts from fossil carbonates and contribute to a better understanding of how climate relevant parameters are recorded in the sedimentary archive

multispecies approach to reconstructing eastern equatorial pacific thermocline hydrography during the past 360 kyr 1 stable isotope data from eastern equatorial pacific eep core tr163 19 2 15 n 90 57 w 2348 m are presented for the surface dwelling foraminifers globigerinoides ruber and g sacculifer and thermocline dwelling globorotalia menardii and neogloboquadrina dutertrei using species specific normalization factors derived from experimental and plankton tow data we reconstruct a 360 kyr record of water column hydrography across the past three glacial cycles we demonstrate that g ruber maintains a mixed layer habitat throughout the entire record while g sacculifer records a mixture of thermocline and mixed layer conditions and g menardii and n dutertrei record thermocline properties we conclude that g sacculifer is not appropriate for paleoceanographic applications in regions with steep vertical hydrographic gradients results suggest that this region of the eep had a thicker mixed layer and deeper 13cdic boundary between the surface and equatorial undercurrent during the last two glacial periods a shift in n dutertrei and g sacculifer geochemistry prior to 185 kyr suggests water column structure and chemocline gradients changed possibly due to a shift in the position of the undercurrent relative to this site the timing and magnitude of glacial interglacial 13c variations between species indicates that near surface carbon chemistry is controlled by changes in productivity atmospheric circulation and advected intermediate water sources north of the antarctic polar front these results demonstrate that when properly calibrated for species differences multispecies geochemical data sets can be invaluable for reconstructing water column structure and properties in the past

temperature sensitivity of planktic foraminifera and its influence on the oxygen isotope record abstract we used oxygen isotope measurements from holocene surface sediments to infer optimum temperature and temperature sensitivity of the planktic foraminiferal species globigerinoides ruber pink and globigerinoides sacculifer the isotopic optimum temperature of g ruber pink is close to 27 c g sacculifer seems to have optimum vital conditions around 22 c and is less temperature sensitive than g ruber pink our estimations of optimum temperature and temperature sensitivity are in good accordance with laboratory and field investigations two simple experiments show that the temperature sensitivity of planktic foraminifera determined from oxygen isotopes can influence phase and amplitude of oxygen isotope records if the temperature distribution at the sea surface changes through time to use this distortion for paleoceanography we suggest to derive an isotopic transfer function which allows the calculation of average temperature temperature variability and the isotopic composition of seawater if the oxygen isotope differences between at least three species are known

a core top assessment of proxies for the ocean carbonate system in surface dwelling foraminifers we have assessed the reliability of several foraminifer hosted proxies of the ocean carbonate system 11b b ca and u ca using holocene samples from the atlantic and pacific oceans we examined chemical variability over a range of test sizes for two surface dwelling foraminifers globigerinoides sacculifer and globigerinoides ruber measurements of 11b in g ruber show no significant relationship with test size in either atlantic or pacific sites and appear to provide a robust proxy of surface seawater ph likewise there is no significant variability in the 11b of our atlantic core top g sacculifer but we find that 11b increases with increasing test size for g sacculifer in the pacific these systematic differences in 11b are inferred to be a consequence of isotopically light gametogenic calcite in g sacculifer and its preferential preservation during postdepositional dissolution the trace element ratio proxies of ocean carbonate equilibria u ca and b ca show systematic increases in both g ruber and g sacculifer with increasing test size possibly as a result of changing growth rates this behavior complicates their use in paleoceanographic reconstructions in keeping with several previous studies we find that mg ca ratios increase with increasing size fraction in our well preserved atlantic g sacculifer but not in g ruber in contrast to previous interpretations we suggest that these observations reflect a proportionally larger influence of compositionally distinct gametogenic calcite in small individuals compared to larger ones as with 11b this influences g sacculifer but not g ruber which has negligible gametogenic calcite

estimating recharge thresholds in tropical karst island aquifers barbados puerto rico and guam the hydrology and geochemistry of groundwater in tropical island aquifers such as barbados guam and puerto rico are significantly influenced by tropical climatic conditions recharge to these aquifers is the product of regional and local climate patterns that control rainfall oxygen isotopes can be used to estimate the amount and timing of recharge on these islands because seasonal fluctuations of rainwater oxygen isotopic compositions are related to the amount of rainfall the karst aquifers on barbados guam and puerto rico have similar rainwater and groundwater oxygen isotopic compositions comparison of groundwater and rainwater oxygen isotopic compositions in the three aquifers indicates that 1 recharge occurs by rapid infiltration with little evaporation prior to recharge and 2 recharge is associated with similar monthly rainfall thresholds of 190 200 mm these rainfall thresholds are remarkably similar for three aquifers in different geographic locations differences between the spatial variations of groundwater oxygen isotopic compositions on barbados and puerto rico can be attributed to the more complex groundwater flow system on puerto rico the surprising similarities of hydrologic conditions under which recharge will take place can be attributed to similarities in climate and geologic conditions such as soils and limestone bedrock that exist on the three islands we therefore speculate that similar recharge rainfall thresholds may be observed in other tropical karst aquifers q 2003 elsevier science b v all rights reserved

vital effects in coccolith calcite cenozoic climate pco2 drove the diversity of carbon acquisition strategies in coccolithophores 1 coccoliths calcite plates produced by the marine phytoplankton coccolithophores have previously shown a large array of carbon and oxygen stable isotope fractionations termed vital effects correlated to cell size and hypothesized to reflect the varying importance of active carbon acquisition strategies culture studies show a reduced range of vital effects between large and small coccolithophores under high co2 consistent with previous observations of a smaller range of interspecific vital effects in paleocene coccoliths we present new fossil data examining coccolithophore vital effects over three key cenozoic intervals reflecting changing climate and atmospheric partial pressure of co2 pco2 oxygen and carbon stable isotopes of size separated coccolith fractions dominated by different species from well preserved paleocene eocene thermal maximum petm 56 ma samples show reduced interspecific differences within the greenhouse boundary conditions of the petm conversely isotope data from the plio pleistocene transition ppt 3 5 2 ma and the last glacial maximum lgm 22 ka show persistent vital effects of 2 ppt and lgm data show a clear positive trend between coccolith cell size and isotopic enrichment in coccolith carbonate as seen in laboratory cultures on geological timescales the degree of expression of vital effects in coccoliths appears to be insensitive topco2 changes over the range 350 ppm pliocene to 180 ppm lgm the modern array of coccolith vital effects arose after the petm but before the late pliocene and may reflect the operation of more diverse carbon acquisition strategies in coccolithophores in response to decreasing cenozoic pco2

an assessment of hydrogeological parameters on the karstic island of dugi otok croatia summary extensive explorations have been performed in the northern part of the island of dugi otok in the adriatic sea croatia with the purpose of extraction of fresh and or brackish water the island is predominantly composed of karstified carbonate rocks of the cretaceous age the explorations included geological and hydrogeological mapping of the area geophysical surveys by means of the geoelectric tomography method electrical resistivity sounding and surface seismic refraction exploratory core drilling hydrochemical in situ and laboratory explorations and the pumping test with the calculation of rock mass parameters based on the obtained results it was concluded that it is possible to exploit the groundwater with a pumping quantity of 5 l s without intrusion of salt water into the fresh water lens choosing a pumping regime based on the parameters of the aquifer rock mass hydraulic conductivity order of magnitude 10 4 10 6 m s and knowing the parameters of the well as well as the tidal efficiency should reduce the possibility of intrusion to the minimum because of the systematic quality of the performed explorations and obtained results the island of dugi otok can serve as a typical example for such kinds of exploration works on other karstic islands hydrogeological composition behaves partly according to ghyben herzberg s law but because of the nature of the karstic hydrogeological system such a statement needs to be accepted approximately because of the highly complicated relationships

engineering characterization of hydraulic properties in a pilot rock cavern for underground lng storage abstract feasibility of storing lng in a lined rock cavern was evaluated using a pilot cryogenic rock cavern constructed in daejeon korea the pilot program included hydrogeological and engineering characterization of the rock mass around the cavern design and construction of a drainage system and pilot operation of the cryogenic cavern an appropriate drainage system is most important to protect the containment system of lng from thermal shocks due to ice lenses and hydrostatic pressure of groundwater as a part of the pilot program this study focused on the evaluation of hydraulic and engineering properties of the rock mass around the cavern for this purpose engineering logging of the rock cores single and cross hole hydraulic tests and recharge drainage tests were performed using seven drilled holes with different trends and plunges three main joint sets were found from the logging of the rock cores acoustic borehole televiewer and window mapping the orientations of the three major joint sets were 60 209 40 171 and 29 331 which can provide the main groundwater flow paths mean rqd values ranged from 56 to 88 which were classified as fair and good although varying with depth along single boreholes hydraulic conductivity from the single and cross hole hydraulic tests estimated in the order of 10 6 or 10 7 m s and corresponding transmissivity ranged between 10 5 and 10 6 m2 s permeable intervals identified from the hydraulic tests were mostly located above the cavern roof below the roof the permeable zone was difficult to observe according to the hydraulic communication tests performed for some designated intervals hydraulic connection between boreholes was highly varied with depth or location which indicated a very different distribution of water conducting joint sets along the boreholes when water was injected at r1 with constant or varying flow rates monotonous and stable seepage was observed at observation boreholes from this some stable drainage was expected even in relatively heavy rainfalls when designing the drainage system of the cavern the drainage holes should be orientated to maximize frequency of encountering the major joint sets and the permeable intervals identified from this study

vital effects and beyond a modelling perspective on developing palaeoceanographical proxy relationships in foraminifera this paper primarily reviews our recent work on the biology and geochemistry of foraminifera with respect to their use as paleoceanographic proxies our approach to proxy validation and development is described primarily from a modeler s point of view the approach is based on complementary steps in understanding the inorganic chemistry inorganic isotope fractionation and biological controls that determine paleo tracer signals in organisms used in climate reconstructions integration of laboratory experiments field and culture studies theoretical considerations and numerical modeling holds the key to the method s success we describe effects of life processes in foraminifera on stable carbon oxygen and boron isotopes as well as mg incorporation into foraminiferal calcite shells stable boron isotopes will be used to illustrate our approach we show that a mechanism based understanding is often required before primary climate signals can be extracted from the geologic record because the signals can be heavily overprinted by secondary non climate related phenomena moreover for some of the proxies fundamental knowledge on the thermodynamic inorganic basis is still lacking one example is stable boron isotopes a paleo ph proxy for which the boron isotope fractionation between the dissolved boron compounds in seawater was not precisely known until recently attempts to overcome such hurdles are described and implications of our work for paleoceanographic reconstructions are discussed

fine fraction carbonate stable isotopes as indicators of seasonal shallow mixed layer paleohydrography we have measured stable isotopic compositions of miocene pelagic fine fraction 6 63 wm carbonates from oligotrophic deep sea sites in the pacific and atlantic oceans and compared them with those of coexisting foraminifers to test their utility as near sea surface indicators fine fraction carbonates primarily polyspecific nannofossils and surface dwelling planktic foraminiferal globigerinoides stable isotopes both have been considered to reflect surfacewater hydrographic conditions however our results indicate that fine fraction stable isotopes are offset from and do not correlate well with those of globigerinoides in contrast stable isotopic records of the deep dwelling planktic foraminifer globoquadrina are in good correspondence with the fine fraction records in terms of long term ca s 1 m y trends and temporal variability on the basis of a time series hydrography and flux study site in the oligotrophic subtropical north atlantic we interpret the isotopic discrepancies between fine fraction and globigerinoides as resulting primarily from season of calcification as well as possible vital effects we suggest that fine fraction stable isotope values from oligotrophic waters reflect late winter early spring relatively cool nutrient rich shallow mixedlayer conditions during the time of deep mixing i e spring bloom whereas globigerinoides stable isotope values record conditions that prevailed in the stratified surface waters in the warmer late spring fall this implies that paired analyses of fine fraction and surface dwelling planktic foraminiferal n 18 o could be applied to reconstruct paleoseasonality of the open oceans however because the fine fraction n 13 c values are not representative of the annual mean surface water n 13 c we recommend use of near surface dwelling planktic foraminiferal n 13 c as a proxy for n 13 c of stratified surface waters that are more or less in equilibrium with the atmosphere with respect to pco2

stable isotope vital effects in coccolith calcite uncertainties about the origin of the many disequilibrium or vital effects in a variety of calcifying organisms and whether these effects are constant or variable have hampered paleoceanographic application of carbon and oxygen isotopic ratios unraveling the source of these effects will improve paleoceanographic applications and may provide new information on changes in cell physiology and ecology culture of eight species of coccolithophorids a dominant marine phytoplankton group reveals a 5 array of disequilibrium or vital effects in both the carbon and oxygen isotopic composition of coccolith calcite in moderate light and nutrient replete cultures oxygen isotopic fractionation and carbon isotopic fractionation correlates directly with cell division rates and correlates inversely with cell size across a range of species however when growth rates of a single species are increased or decreased by higher or lower light levels 18o is relatively invariant likewise growth rate variations as a function of temperature do not influence coccolith 18o the slope of the 18o vs temperature relation in cultures of both gephyrocapsa oceanica and helicosphaera carteri is the same as for abiogenic carbonates this suggests a constant species specific isotopic fractionation which does not vary with cell physiology the constancy of vital effects suggests that coccolith stable isotopes will provide reliable phase for paleoceanographic reconstruction of temperature and seawater chemistry as long as monospecific fractions are analyzed or changes in nannofossil assemblages are accounted for with species specific correction factors we suspect that the cell size and its constraints on the rate of co2 diffusion relative to c fixation may be the first order influence on coccolith stable isotope vital effects a quantitative model of this process may provide important constraints on mechanisms of carbon acquisition of coccolithophorids in both modern and extinct species

the significance of isotopic and paleontologic results on quaternary calcareous nannofossil assemblages from caribbean core p6304 4 abstract the calcareous nannofossils in late quaternary caribbean core p6304 4 are examined with respect to their stable isotope composition biostratigraphy and taxonomy using relations between the various nannofossil taxa and oxygen isotopic stages a number of correlations are identified that indicate the value of nannofossils in quaternary isotope stratigraphy three globally synchronous datums previously identified are substantiated for the caribbean variations in abundances of the most common species of nannofossils are not affected by glacial interglacial changes and thus do not contribute to fluctuations seen in the oxygen isotopic record however nannofossil assemblages were more diverse during glacial stages the carbon isotopic record of nannofossils remains enigmatic eventually it may be possible to recognize the various isotopic stages of the quaternary based solely on the characteristics of the nannofossil assemblage

does sedimentary organic δ13c record variations in quaternary ocean co2 aq ocean surface water co2 aq variations based on glacial interglacial changes in sediment delta 13corg are shown to compare favorably with reconstructions based on ice core co2 in particular an approximate 80 microatmospheres increase in atmospheric pco2 during the last glacial interglacial transition is calculated to correspond to a 3 4 micromolar increase in ocean surface water co2 aq at atmospheric equilibrium a widespread marine delta 13corg decrease of 1 2 accompanied this event and was not preceded by an equivalent isotopic change in surface water total dissolved inorganic carbon these observations support the hypothesis that co2 aq influences photosynthetic isotope fractionation between marine inorganic and organic carbon pools and therefore that plankton sediment delta 13corg may serve as a proxy for surface water co2 aq

controls on stable strontium isotope fractionation in coccolithophores with implications for the marine sr cycle abstract the controls on stable sr isotope fractionation into the calcite produced by the coccolithophore species emiliania huxleyi coccolithus pelagicus spp braarudii and gephyrocapsa oceanica are investigated each species has been cultured under controlled laboratory conditions at a range of temperatures 10 25 c to test the potential of 88 86 sr as a proxy for growth rate and or sea surface temperature coccolithophores are one of the most abundant pelagic calcifiers since sr substitutes to some degree for ca in their calcite coccoliths coccolithophores represent a significant output of sr from seawater potentially influencing the 88 86 sr mass balance in the modern oceans the coccoliths are investigated for their 88 86 sr sr ca and 18 o measured as function of temperature as temperature is increased all species show a negative stable sr isotopic fractionation related to a temperature controlled growth rate we infer the shift of 88 86 sr to lighter values as indicative of a kinetic control on the isotope fractionation revealing the potential of 88 86 sr as a proxy for growth rate which in these experiments is primarily dictated by temperature the results from these experiments indicate that coccolithophore calcite incorporates sr with a very light 88 86 sr isotope composition as low as 0

equatorial heat accumulation as a long term trigger of permanent antarctic ice sheets during the cenozoic abstract growth of the first permanent antarctic ice sheets at the eocene oligocene transition eot 33 7 million years ago indicates a major climate shift within long term cenozoic cooling the driving mechanisms that set the stage for this glaciation event are not well constrained however owing to large uncertainties in temperature reconstructions during the eocene especially at lower latitudes to address this deficiency we used recent developments in coccolith biogeochemistry to reconstruct equatorial atlantic sea surface temperature sst and atmospheric pco2 values from pelagic sequences preceding and spanning the eot we found significantly more variability in equatorial ssts than previously reported with pronounced cooling from the early to middle eocene and subsequent warming during the late eocene thus we show that the antarctic glaciation at the eocene oligocene boundary was preceded by a period of heat accumulation in the low latitudes likely focused in a progressively contracting south atlantic gyre which contributed to cooling high latitude austral regions this prominent redistribution of heat corresponds to the emplacement of a strong meridional temperature gradient that typifies icehouse climate conditions our equatorial coccolith derived geochemical record thus highlights an important period of global climatic and oceanic upheaval which began 4 million years before the eot and superimposed on a long term pco2 decline drove the earth system toward a glacial tipping point in the cenozoic

hydrological modeling in the karst area rižana spring catchment slovenia karst aquifers are known for their heterogeneity and irregular complex flow patterns which make them more difficult to model and demand specific modeling approaches this paper presents one such approach which is based on a conceptual model the model was applied in a karst area of the catchment of ri ana spring 200 km it is based on the mike she code and incorporates the main hydrological processes and geological features of the karst aquifer diffuse and concentrated infiltration allogenic recharge quick and slow groundwater flow shifting groundwater divides and groundwater outflow from the catchment area modeling of evapotranspiration and flow in the upper part of the unsaturated zone is more detailed for the modeling of groundwater flow in the karst aquifer a conceptual model was applied which uses drainage function for the simulation of groundwater flow through large conduits karst channels and large fissures the model was calibrated and validated against the observed ri ana spring discharge which represents a measured response of the aquifer the results of validation show that the model is able to adequately simulate temporal evolution of the spring discharge measured by nash sutcliffe coefficient 0 82 as well as overall water balance

calibration of stable isotope composition of thoracosphaera heimii dinoflagellate calcite for reconstructing paleotemperatures in the intermediate photic zone in this study we investigate the temperature dependence of oxygen isotope ratios preserved in calcite formed by the dinoflagellate thoracosphaera heimii focusing primarily on the development of a geological proxy geochemical analysis of the calcite shells produced by this species represents a valuable proxy for reconstructing environmental conditions in the intermediate photic zone calibration is based on isotopic analysis from culture experiments performed in very dilute batch conditions as well as from near monospecific t heimii assemblages separated from core top sediments results are similar for both approaches and indicate that t heimii shells have oxygen isotope compositions close to equilibrium values predicted for inorganic calcite precipitation this calibration of the isotopic composition of dinoflagellate calcite indicates that monospecific assemblages of t heimii can be used to unravel paleotemperatures in the intermediate photic zone by applying isotopic transfer functions for equilibrium calcite in culture however a 18 o offset of a1 is observed at temperatures 17 c which falls below the natural temperature range of this species culture analyses also reveal a relationship between temperature and carbon isotope composition of calcite the mechanisms behind this relationship remain to be explored but their identification may provide a better understanding of carbon isotope systematics from both biogeochemical and geological perspectives comparison of the oxygen isotope composition of t heimii shells with that of shallower dwelling organisms such as the coccolithophores represents a valuable proxy for determining temperature gradients within the photic zone and may enable reconstruction of the evolution of the depth of the thermocline

estimating recharge in a tropical karst aquifer unique constraints on seasonal and spatial variations in recharge to the pleistocene limestone aquifer of barbados are obtained from the analysis of oxygen isotopic compositions of groundwater and rainwater conventional methods of estimating recharge are based on groundwater chloride variations coastal groundwater discharge and potential evapotranspiration these methods typically yield estimates of recharge for barbados that range from 9 to 20 of average annual rainfall with significant uncertainties that arise from poorly constrained model input parameters owing to the low relief and tropical climate of barbados variations in rainwater and groundwater 18o values are primarily influenced by the amount of rainfall with negligible temperature or altitude effects composite monthly rainwater 18o values are inversely related to rainfall while groundwater 18o values show little seasonal variability rainwater 18o values are equivalent to groundwater values only at the peak of the wet season by using mass balance the difference between groundwater and weighted mean rainwater 18o values gives recharge values these values are in general agreement with estimates by conventional methods 10 20 and provide unique additional information including the following 1 recharge is restricted to the wettest 1 3 months of the year and 2 there is less recharge at higher elevations the effective shift in 18o values between contemporaneous rainwater and groundwater via recharge is a useful tool for estimating temporal and spatial variability in recharge and must be considered in paleoclimatic studies where climate inferences are based on groundwater 18o values preserved in the geologic record

trace metal mg ca and sr ca analyses of single coccoliths by secondary ion mass spectrometry here we present the first multi species comparison of modern and fossil coccolith trace metal data obtained from single liths we present both trace metal analyses sr ca mg and al and distribution maps of individual paleogene fossil coccoliths obtained by secondary ion mass spectrometry sims we use this data to determine the effects of variable coccolith preservation and diagenetic calcite overgrowths on the recorded concentrations of strontium and magnesium in coccolith calcite the analysis of coccoliths from deep ocean sediments spanning the eocene oligocene transition demonstrates that primary coccolith calcite is resistant to the neomorphism that is common in planktonic foraminifera from similar depositional environments instead where present diagenetic calcite forms distinct overgrowths over primary coccolith calcite rather than replacing this calcite diagenetic overgrowths on coccoliths are easily distinguished in sims analyses on the basis of relatively higher mg and lower sr concentrations than co occurring primary coccolith calcite this interpretation is confirmed by the comparable sims analyses of modern cultured coccoliths of coccolithus braarudii further with diagenetic calcite overgrowth being the principle source of bias in coccolith based geochemical records we infer that lithologies with lower carbonate content deposited below the palaeo lysocline are more likely to produce geochemical records dominated by primary coccolith calcite than carbonate rich sediments where overgrowth is ubiquitous the preservation of primary coccolith carbonate in low carbonate lithologies thus provides a reliable geochemical archive where planktonic foraminifera are absent or have undergone neomorphism

carbon and oxygen isotopes of bulk carbonate in sediment deposited beneath the eastern equatorial pacific over the last 8 million years to improve the understanding and utility of bulk carbonate stable carbon and oxygen isotope measurements we examine sediment from cores in the eastern equatorial pacific that span the last 8ma we measured c 13 and o 18 in 791 samples from integrated ocean drilling program site u1338 and deep sea drilling project site 573 both located close to the pacific equator in 100 samples we measured c 13 and o 18 on isolated 63 mu m and 38 mu m fractions which concentrates calcareous nannofossil carbonate and progressively excludes foraminiferal carbonate bulk carbonate c 13 and o 18 records are similar to published records from other sites drilled near the equator and seem to reflect mixed layer conditions albeit with some important caveats involving the precipitation of calcite by coccolithophores the comparatively lower c 13 and o 18 of the 63 mu m and 38 mu m fractions in sediments younger than 4 4ma is attributed to an increase in deep dwelling planktic foraminifera material in bulk carbonate shifting the bulk isotopic signals toward higher values bulk carbonate c 13 is similar over 2500km along the pacific equator suggesting covarying concentrations and c 13 of dissolved inorganic carbon within surface waters since 8ma greater bulk sediment c 13 and o 18 higher sedimentation rates and low content of coarse material suggest intensified wind driven upwelling and enhanced primary productivity along the pacific equator between 8 0 and 4 4ma although a full understanding of bulk carbonate records will require extensive future work