new 26al 10be and u th he constraints on the age of the upland complex central mississippi river valley abstract the upland complex is a widespread terrace of the ancestral mississippi river it has played a central role in studies of the pliocene mississippi river drainage as well as uplift and seismicity in the central mississippi river valley previous efforts to date the upland complex have yielded a range of age estimates spanning the miocene through pleistocene we dated gravels and fe oxide cements from quarries of the upland complex in arkansas kentucky mississippi and tennessee using 26al 10be burial dating and u th he geochronology our 26al 10be burial dates revealed possible pliocene to pleistocene depositional ages while u th he dating showed that the onset of weathering dates to at least the pliocene taken together the 26al 10be and u th he age constraints demonstrate that the upland complex is at least pliocene in age and likely formed during a prolonged period of base level stability that preceded pleistocene glaciations

a new technique for sampling water and gas from deep drill holes a new technique for sampling water and gas from deep 500 1500 m drill holes is described the principle of the technique is to raise a continuous column of water inside a thin polyamide tube with a back pressure valve at the lower end and with shutoff valves every 50 m the equipment is easily assembled from standard parts sampling can be performed by three people without mechanical apparatus descent to 1000 m takes 2 hours and retrieval 1 hour the method makes it possible to obtain a practically undisturbed continuous water profile from a drill hole dissolved gases remaining inside the tube can be sampled at the surface to demonstrate the efficiency of the technique selected results from the deepest drill hole in finland having a vertical depth of 1100 m are presented

equilibrium oxygen hydrogen and carbon isotope fractionation factors applicable to geologic systems as demonstrated by the chapters in this short course stable isotope techniques are an important tool in almost every branch of the earth sciences central to many of these applications is a quantitative understanding of equilibrium isotope partitioning between substances indeed it was harold urey s 1947 thermodynamically based estimate of the temperature dependence of 18o 16o fractionation between calcium carbonate and water and a recognition of how this information might be used to determine the temperatures of ancient oceans that launched the science of stable isotope geochemistry the approach pioneered by urey has since been used to estimate temperatures for a wide range of geological processes e g emiliani 1955 anderson et al 1971 clayton 1986 valley this volume in addition to their geothermometric applications equilibrium fractionation data are also important in the study of fluid rock interactions including those associated with diagenetic hydrothermal and metamorphic processes baumgartner and valley this volume shanks this volume finally a knowledge of equilibrium fractionation is a necessary first step in evaluating isotopic disequilibrium a widespread phenomenon that is increasingly being used to study temporal relationships in geological systems cole and chakraborty this volume in the fifty four years since the publication of urey s paper equilibrium fractionation data have been reported for many minerals and fluids of geological interest these data were derived from 1 theoretical calculations following the methods developed by urey 1947 and bigeleisen and mayer 1947 2 direct laboratory experiments 3 semi empirical bond strength models and 4 measurement of fractionations in natural samples each of these methods has its advantages and disadvantages however the availability of a variety of methods for calibrating fractionation factors has led to a plethora of calibrations not all of which are in agreement in this chapter we evaluate the major methods for determining fractionation factors

large scale erosion rates from in situ produced cosmogenic nuclides in european river sediments abstract we have calculated long term erosion rates of 20 100 mm kyr from quartz contained 10be in the bedload of middle european rivers for catchments ranging from 102 to 105 km2 these rates average over 10 40 kyr and agree broadly with rock uplift incision and exhumation rates historic soil erosion rates and erosion rates calculated from the measured sediment loads of the same rivers moreover our new erosion rate estimates correlate well with lithology and relief however in the regen neckar loire and meuse catchments cosmogenic nuclide derived erosion rates are consistently 1 5 4 times greater than the equivalent rates derived from measured river loads this may be due to the systematic under representation of high magnitude low frequency transport events in the gauging records which cover less than a century alternatively the discrepancy may derive from spatially non uniform erosion and preferential tapping of deeper sections of the irradiation profile a third explanation relates the high cosmogenic nuclide derived erosion rates to inheritance of an elevated pleistocene erosion signal uncertainties associated with the cosmogenic nuclide derived erosion rate estimates are not greater than the potential errors in conventional estimates therefore the cosmogenic nuclide approach is an effective tool for rapid catchment wide assessment of time integrated rates of bedrock weathering and erosion and we anticipate its fruitful application to the quaternary sedimentary record

implications for the late pleistocene climate in finland and adjacent areas from the isotopic composition of mammoth skeletal remains nine samples of subfossil bone and teeth remains from woolly mammoth mammuthus primigenius discovered in finland russian karelia and western russia were analyzed for the oxygen isotope composition of the phosphate fraction and the carbon and oxygen isotope composition of the carbonate fraction in skeletal apatite the samples have been radiocarbon dated in previous studies and are of late middle weichselian to late weichselian age the preservation of the samples was tested analyzing the chemical composition and checking the isotopic equilibrium between the phosphate and carbonate components in skeletal apatite according to these tests five out of the nine samples were determined to have retained their original isotopic composition these samples were used to estimate late pleistocene climatic conditions in finland and neighboring areas based on the best preserved enamel samples the isotopic composition of oxygen in late pleistocene precipitation was 1 3x lower than that in the mean annual precipitation in southern and central finland today using the relationship between the isotopic composition of precipitation and the ambient temperature it can be estimated that the mean temperatures during the middle weichselian ice free period were 2 6 8c lower compared to the present day values d 2005 elsevier b v all rights reserved

geochemistry and origin of saline groundwaters in the fennoscandian shield chemical and isotopic analyses of water from drill holes and mines throughout the fennoscandian shield show that distinct layers of groundwater are present an upper layer of fresh groundwater is underlain by several sharply differentiated saline layers which may differ in salinity relative abundance of solutes and o h sr and s isotope signature saline groundwater can be classified into four major groups based on geochemistry and presumed origin brackish and saline waters from 50 200 m depth in coastal areas around the baltic sea exhibit distinct marine chemical and isotopic fingerprints modified by reactions with host rocks these waters represent relict holocene seawater inland three types of saline groundwater are observed an uppermost layer of brackish and saline water from 300 900 m depth saline water and brines from 1000 2000 m depth and superdeep brines which have been observed to a depth of at least 11 km in the drill hole on the kola peninsula u s s r electrical and seismic studies in shield areas suggest that such brines are commonly present at even greater depths the salinity of all inland groundwaters is attributed predominantly to water rock interaction the main solutes are cl ca na and mg in varying proportions depending on the host rock lithology the abundance of dissolved gases increases with depth but varies from site to site the main gas components are n2 ch4 up to 87 vol and locally h2 the 13c value for methane is highly variable 25 to 46 and it is suggested that hydrothermal or metamorphic gases trapped within the surrounding rocks are the most obvious source of ch4 the uppermost saline water has meteoric oxygen hydrogen isotopic compositions whereas values from deeper water plot above the meteoric water line indicating considerably longer mean residence time and effective low temperature equilibration with host rocks geochemical and isotopic results from some localities demonstrate that the upper saline water cannot have been formed through simple mixing between fresh water and deep brines but rather is of independent origin the source of water itself has not been satisfactorily verified although superdeep brines at least may contain a significant proportion of relict precambrian hydrothermal or metamorphic fluids

saline groundwaters in the canadian shield a first overview abstract the chemical and isotopic compositions of saline groundwaters and brines in the canadian shield are described the occurrence of such waters is very widespread not related to any specific rock type or mineralization and generally can be expected at depths below 1 km the most saline brines have salinities exceeding 200 g l 1 dissolved solids and their chemistries tend to suggest that in the past saline waters penetrated the canadian shield the original chemistry of these solutions was subsequently modified through strong rock water interactions and it appears that their final chemical compositions are independent of the original chemistries stable isotope analyses indicate that these waters are not simple evaporated seawater sedimentary basin brines hydrothermal solutions or residual ore forming fluids although any of these could be a precursor of the brines secondary isotope exchange reactions and the hydration of primary silicates accompanied by the formation of clay minerals could have modified not only the primary isotopic composition but may have also profoundly influenced the chemistries of these brines to be effective these processes would have had to occur in closed systems

late quaternary ice sheet history of northern eurasia the maximum limits of the eurasian ice sheets during four glaciations have been reconstructed 1 the late saalian 140 ka 2 the early weichselian 100 80 ka 3 the middle weichselian 60 50 ka and 4 the late weichselian 25 15 ka the reconstructed ice limits are based on satellite data and aerial photographs combined with geological field investigations in russia and siberia and with marine seismic and sediment core data the barents kara ice sheet got progressively smaller during each glaciation whereas the dimensions of the scandinavian ice sheet increased during the last ice age the barents kara ice sheet attained its maximum size as early as 90 80 000 years ago when the ice front reached far onto the continent a regrowth of the ice sheets occurred during the early middle weichselian culminating about 60 50 000 years ago during the late weichselian the barents kara ice sheet did not reach the mainland east of the kanin peninsula with the exception of the nw fringe of taimyr a numerical ice sheet model forced by global sea level and solar changes was run through the full weichselian glacial cycle the modeling results are roughly compatible with the geological record of ice growth but the model underpredicts the glaciations in the eurasian arctic during the early and middle weichselian one reason for this is that the climate in the eurasian arctic was not as dry then as during the late weichselian glacial maximum

mid pliocene shorelines of the us atlantic coastal plain an improved elevation database with comparison to earth model predictions abstract for nearly a century the atlantic coastal plain acp of the united states has been the focus of studies investigating pliocene and pleistocene shorelines however the mapping of paleoshorelines was primarily done by using elevation contours on topographic maps here we review published geologic maps and compare them to paleoshoreline locations obtained through geomorphometric classification and satellite data we furthermore present the results of an extensive field campaign that measured the mid pliocene 3 3 2 9 ma shorelines of the atlantic coastal plain using high accuracy gps and digital elevation models we compare our new dataset to positions and elevations extracted from published maps and find that the extracted site information from earlier studies is prone to significant error both in the location and more severely in the elevation of the paleoshoreline we also investigate using geophysical modeling the origin of post depositional displacement of the shoreline from georgia to virginia in particular we correct the elevation of our shoreline for glacial isostatic adjustment gia and then compare the corrected elevation to predictions of mantle flow induced dynamic topography dt while a subset of these models does reconcile the general trends in the observed elevation of the mid pliocene shoreline local discrepancies persist these discrepancies suggests that either i the dt and gia models presented here do not capture the full range of uncertainty in the input parameters and or ii other influences such as sediment loading and unloading or local fault driven tectonics may have contributed to post depositional deformation of the mid pliocene shoreline that are not captured in the above models in this context our field measurements represent an important observational dataset with which to compare future generations of geodynamic models improvements in models for dt gia and other relevant processes together with an expanded geographically distributed set of shoreline records will ultimately be the key to obtaining more accurate estimates of eustatic sea level not only in the mid pliocene but also earlier in the cenozoic

abiotic and biotic controls on methane formation down to 2 5 km depth within the precambrian fennoscandian shield abstract despite a geological history characterised by high temperature and pressure processes and organic carbon deprived crystalline bedrock large amounts of hydrocarbons are found in deep groundwaters within precambrian continental shields in many sites methane comprises more that 80 of the dissolved gas phase reaching concentrations of tens of mmol l 1 in this study we used isotopic methods to study the carbon isotope systematics and sources of crustal methane within the fennoscandian shield the main study sites were the outokumpu deep drill hole and the pyhasalmi mine in finland both of which allow groundwater sampling down to 2 5 km depth and have been previously studied for their groundwater chemistry and microbiology we show that the differences in the amount and isotopic composition of methane are related to the availability of carbon sources as well as processes behind the incorporation of hydrogen and carbon via abiotic and biotic pathways into hydrocarbon molecules supported by previously reported occurrences and isotopic data of deep groundwater methane in lithologically different locations in finland and sweden we show that methane formation is controlled by microbial methanogenesis and abiotic reactions as well as lithology with the metasedimentary environments being the most favourable for methane occurrence rather than a thermogenic relic crustal methane within the fennoscandian shield is more likely the result of low temperature formation from ancient organic compounds or their inorganic intermediates such as graphite such crustal gases are characterised by the lack of major amounts of c 2 hydrocarbons and 13 c rich methane further microbiological and isotopic geochemical evidence suggest that microbial methane is more common at depths shallower than 1 5 km

delineating ophiolite derived host rocks of massive sulfide cu co zn deposits with 2d high resolution seismic reflection data in outokumpu finland abstractseismic reflection data was applied to a study of the upper crustal structures in the outokumpu mining and exploration area in eastern finland the cu co zn sulfide ore deposits of the outokumpu area are hosted by palaeoproterozoic ophiolite derived altered ultrabasic rocks serpentinite skarn rock and quartz rock and black schist within turbiditic mica schist mining in the outokumpu area has produced a total of 36 mt of ore from three historical and one active mine seismic data comprises 2d vibroseis data surveyed along a network of local roads the seismic sections provide a comprehensive 3d view of the reflective structures acoustic rock properties from downhole logging and synthetic seismograms indicate that the strongly reflective packages shown in the seismic data can be identified as the host rock environments of the deposits reflectors show excellent continuity along the structural grain of the ore belt which allows correlating reflectors with surface geology magnetic map and dri

quaternary downcutting rate of the new river virginia measured from differential decay of cosmogenic 26al and 10be in cave deposited alluvium the concentrations of the cosmogenic radionuclides sup 26 al and sup 10 be in quartz can be used to date sediment burial here we use sup 26 al and sup 10 be in cave deposited river sediment to infer the time of sediment emplacement sediment burial dates from a vertical sequence of caves along the new river constrain its quaternary downcutting rate to 27 3 4 5 m m y and may provide evidence of regional tectonic tilt 32 refs 3 figs 1 tab

geomorphological and geochemistry changes in permafrost after the 2002 tundra wildfire in kougarok seward peninsula alaska geomorphological and thermo hydrological changes to tundra caused by a wildfire in 2002 on the central seward peninsula of alaska were investigated as a case study for understanding the response from ice rich permafrost terrain to surface disturbance frozen and unfrozen soil samples were collected at burned and unburned areas and then water isotope geochemistry and cryostratigraphy of the active layer and near surface permafrost were analyzed to investigate past hydrological and freeze thaw conditions and how this information could be recorded within the permafrost the development of thermokarst subsidence due to ice wedge melting after the fire was clear from analyses of historical sub meter resolution remote sensing imagery long term monitoring of thermo hydrological conditions within the active layer in situ surveys of micro relief and geochemical signals recorded in the near surface permafrost the resulting polygonal relief coincided with depression lines along an underground ice wedge network and cumulative subsidence to 2013 was estimated as at least 10 1 to 12 1 cm 0 9 1 1 cm year eleven year average profiles of water geochemistry in the ground indicated mixing or replenishment of older permafrost water with newer meteoric water as a consequence of the increase in active layer thickness due to wildfire or past thaw event our geocryological analysis of cores suggests that permafrost could be used to reconstruct the permafrost degradation history for the study site distinct hydrogen and oxygen isotopic compositions above the global meteoric water line were found for water from these sites where permafrost degradation with geomorphological change and prolonged surface inundation were suggested

svecofennian detrital zircon ages implications for the precambrian evolution of the baltic shield metasediments intruded by 1 90 1 87 ga old plutonic rocks form the oldest major proterozoic crustal component in the svecofennian domain of the baltic fennoscandian shield their ndtdm model ages and conventional multigrain zircon u pb ages between 2 4 and 2 1 ga have previously been interpreted either as mixing ages between 1 9 ga old juvenile materials and a minor archaean component or as actual rock and protolith ages to resolve the ensuing controversy 120 individual detrital zircons from svecofennian metasediments in sweden and finland were analysed using the shrimp ion microprobe the oldest materials in this array are a 3 44 ga old zircon from the tampere schist belt in finland and a 3 32 ga old crystal from southeastern sweden about 30 of the analysed crystals are 2 97 2 60 ga old while 65 have ages between 2 12 and 1 88 ga thus there is no evidence of 2 6 2 1 ga old protoliths but the age range of the proterozoic zircons indicates that a major area of 2 1 1 9 ga old crust was in erosional position 1 9 ga ago this implies that the formation of palaeoproterozoic crust in the baltic shield or its one time close neighbourhood must have commenced 100 200 ma earlier than hitherto assumed in conjunction with previously obtained isotopic data the youngest detritus ages of the present study constrain the age of svecofennian sedimentation it can also be concluded that the archaean zircons found in quartzites from southern sweden may have been derived from source areas to the southwest of the central svecofennian marine depositional basin the so called bothnian basin separating southern sweden from the archaean craton in the northeastern part of the shield

sr isotopes in natural waters applications to source characterisation and water rock interaction in contrasting landscapes strontium isotopes 87sr 86sr are routinely measured in hydrochemical studies to determine sources and mixing relationships they have proved particularly useful in determining weathering processes and quantifying end member mixing processes a number of routine case studies are presented which highlight that sr isotopes represent a powerful tool in the geochemists toolbox helping to constrain weathering reactions weathering rates flow pathways and mixing scenarios differences in methodologies for determining the weathering component in natural environments inherent differences in weathering rates of different minerals and mineral heterogeneity often cause difficulties in defining the weathering component of different catchments or aquifer systems nevertheless sr isotopes are useful when combined with other hydrochemical data to constrain models of water rock interaction and mixing as well as geochemical processes such as ion exchange this paper presents a summary of recent work by the authors in constraining the sources of waters and weathering processes in surface catchments and aquifers and indicates cases where sr isotopes alone are insufficient to solve hydrological problems

weathering geochronology by u th he dating of goethite nine samples of supergene goethite feooh from brazil and australia were selected to test the suitability of this mineral for u th he dating measured he ages ranged from 61 to 8 ma and were reproducible to better than a few percent despite very large variations in u and th in all samples with internal stratigraphy or independent age constraints the he ages corroborated the expected relationships these data demonstrate that internally consistent he ages can be obtained on goethite but do not prove quantitative 4he retention to assess possible diffusive he loss stepped heating experiments were performed on two goethite samples that were subjected to proton irradiation to produce a homogeneous distribution of spallogenic 3he the 3he release pattern indicates the presence of at least two diffusion domains one with high helium retentivity and the other with very low retentivity at earth surface conditions the low retentivity domain which accounts for 5 of 3he contains no natural 4he and may represent poorly crystalline or intergranular material which has lost all radiogenic 4he by diffusion in nature diffusive loss of 3he from the high retentivity domain is independent of the macroscopic dimensions of the analyzed polycrystalline aggregate so probably represents diffusion from individual micrometer size goethite crystals the 4he 3he evolution during the incremental heating experiments shows that the high retentivity domain has retained 90 95 of its radiogenic helium this degree of retentivity is in excellent agreement with that independently predicted from the helium diffusion coefficients extrapolated to earth surface temperature and held for the appropriate duration considering both the high and low retentivity domains these data indicate that one of the samples retained 90 of its radiogenic 4he over 47 5 ma and the other retained 86 over 12 3 ma thus while diffusive loss corrections to supergene goethite he ages are required these initial results indicate that the corrections are not extremely large and can be rigorously quantified using the proton irradiation 4he 3he method

characterisation and isotopic evolution of saline waters of the outokumpu deep drill hole finland implications for water origin and deep terrestrial biosphere abstract the isotopic composition of water and dissolved sr as well as other geochemical parameters at the 2516 m deep outokumpu deep drill hole finland were determined the drill hole is hosted by palaeoproterozoic turbiditic metasediments ophiolite derived altered ultramafic rocks and pegmatitic granitoids sodium ca cl and ca na cl rich waters total dissolved solids up to ca 70 g l 1 containing significant amounts of gas mainly ch 4 up to 32 mmol l 1 n 2 up to 10 mmol l 1 h 2 up to 3 1 mmol l 1 and he up to 1 1 mmol l 1 discharge from fracture zones into the drill hole this water is distinct from the shallow fresh groundwater of the area and has an isotopic composition typical of shield brines that have been modified during long term water rock interaction based on water stable isotopes and geochemistry the drill hole water profile can be divided into five water types each discharging from separate fracture systems and affected by the surrounding rocks the 2 h varies from 90 to 56 vsmow and 18 o from 13 5 to 10 4 vsmow plotting clearly above the global and local meteoric water lines on a 2 h vs 18 o diagram the 87 sr 86 sr ratios range between 0 72423 and 0 73668 simple two component mixing between 2 h and 18 o rich end member brine and meteoric water cannot explain the water stable isotopic composition and trends observed instead hydration of silicates by ancient groundwaters recharged under different climatic conditions warmer than at present is the most likely mechanism to have caused the variation of the 2 h and 18 o values water types correlate with changes in microbial communities implying that different ecosystems occur at different depths the different water types and microbial populations have remained isolated from each other and from the surface for long periods of time probably tens of millions of years

sr isotopic evidence for discrete saline components in stratified ground waters from crystalline bedrock outokumpu finland the authors present a continuous sr isotope depth profile of waters sampled in situ in the deepest borehole in finland approx 1 1 km the waters all with a meteoric oxygen and hydrogen isotope signature are compositionally stratified a recent fresh water zone 0 05 mg l sr sup 87 sr sup 86 sr 0 730 approx 400 m thick is underlain by two saline water zones the upper with approx 25 mg l sr and sup 87 sr sup 86 sr 0 724 the lower with 45 mg l sr and sup 87 sr sup 86 sr 0 723 the sr isotope data show that the stratification is not due merely to upward dilution of saline water by fresh surface waters two discrete saline waters are present the two saline water components are homogeneous in composition apparently unaffected by local variations in rock composition either within the borehole or between neighboring boreholes the implication is that the saline waters did not develop in isolated pockets but rather in large well mixed bodies most likely salinization mechanisms involve breakdown of low rb sr minerals e g plagioclase feldspar and or leaching of fluid inclusions

origin and stability of a permafrost methane hydrate occurrence in the canadian shield abstract relatively little attention has been given to the stability of methane hydrates formed during periods of past climate change currently in areas of continuous permafrost although a large portion of the canadian arctic is underlain by crystalline rocks the occurrence phase and origin of alkanes in crystalline rocks under thick permafrost conditions 500 m have not been reported for the first time composition and isotopic data for gases from a crystalline shield environment currently under permafrost conditions are presented gas and water samples were collected from exploration boreholes and seeps between 890 and 1130 m depths in the lupin gold mine nunavut canada gases were methane dominate 64 87 with nitrogen 10 37 the next largest component and smaller amounts of ethane propane and carbon dioxide pressure and temperature measurements indicated gas hydrates were stable at the site prior to mining operations a conclusion supported by noble gas and salinity determinations gas hydrate stability over the last 120 kyr glacial cycle was demonstrated by calculating transient subsurface pressure and temperature conditions utilizing the memorial university university of toronto glacial systems model mun uoft gsm and the hydrogeosphere groundwater flow model model results also indicated glacial loading increased subsurface pressures resulting in increased hydrate stability fields during glacial periods subglacial groundwater recharge would be limited by any significant formation of gas hydrates gas composition combined with carbon and hydrogen isotopic determinations on methane 56 to 42 vpdb and 349 to 181 vsmow carbon dioxide 55 to 15 vpdb ethane 37 to 27 vpdb and 330 to 228 vsmow and propane 34 to 27 vpdb and 196 to 172 vsmow indicated formation of natural gases by thermogenic processes mixed with bacteriogenic gas reasonable given site geologic history methane hydrate formation affected gas composition and gas 2 h values complicating the interpretation gas production is not a modern process at this location and the overall contribution to the global carbon budget is small glacial groundwater recharge models need to account for methane hydrate formation and dissipation due to changes in subsurface stability fields during glaciation and the effect of methane hydrate on hydraulic conductivity

40ar 39ar and u th he 4he 3he geochronology of landscape evolution and channel iron deposit genesis at lynn peak western australia u th he geochronology of authigenic goethite cements from the lynn peak channel iron deposit cid hamersley province western australia reveals a history of mineral precipitation ranging from ca 33 to 14 ma massive goethites from nearby weathering profiles at roy hill north a possible source of detrital material during the aggradation of the lynn peak channels yield u th he results as old as ca 64 ma the combination of u th he geochronology with incremental outgassing 4he 3he studies on proton irradiated samples reveals that lynn peak goethites host radiogenic 4he in low retentivity lrd and high retentivity hrd domains and that the hrds account for most of the sample mass and have lost very little of their original 4he over geologic time such high retentivity is especially notable given the goethites were collected from the surface where they were subject to significant heating by solar irradiation minor contamination by detrital fragments of potentially 4he rich primary phases e g rutile ilmenite zircon occurs in some samples fortunately the 4he 3he method permits characterization of this extraneous 4he component which is small 10 wt of the total 4he in the goethite and can be corrected out in estimating the goethite formation age these results indicate that the lynn peak channel was already aggraded and undergoing goethite cementation by ca 33 ma the history of aggradation and channel cementation independently measured through 40 ar 39 ar geochronology is consistent with that obtained from the u th he and 4he 3he record laser incremental heating 40 ar 39 ar geochronology of detrital and authigenic mn oxides primarily cryptomelane kmn 8o 16 xh 2o from the same locality in the lynn peak channel reveals that detrital oxides are older than ca 44 ma and as old as ca 65 ma and authigenic oxides are younger than ca 35 ma and as young as ca 16 ma authigenic cryptomelane precipitation and channel cementation occurred throughout the miocene with a particularly strong period at around 20 ma the 40 ar 39 ar geochronological results suggest that regional weathering profiles developed before 44 ma and possibly as early as ca 65 ma were incised and partially eroded in the 44 35 ma interval semi arid conditions promoted the transport of large volumes of sediments aggrading the regional drainage system metasomatic reactions in the aggraded channels caused the ferruginization and in some places manganese replacement of the cids goethite and k mn oxide cementation continued throughout the oligocene and miocene post miocene aridification contributed to the preservation of the cemented channel sediments forming some of the largest readily mineable iron ore deposits on earth

noble gas residence times of saline waters within crystalline bedrock outokumpu deep drill hole finland abstract noble gas residence times of saline groundwaters from the 2516 m deep outokumpu deep drill hole located within the precambrian crystalline bedrock of the fennoscandian shield in finland are presented the accumulation of radiogenic 4 he 40 ar and nucleogenic 21 ne noble gas isotopes in situ together with the effects of diffusion are considered fluid samples were collected from depths between 180 and 2480 m below surface allowing us to compare the modelled values with the measured concentrations along a vertical depth profile the results show that while the concentrations in the upper part are likely affected by diffusion there is no indication of diffusive loss at or below 500 m depth furthermore no mantle derived gases were found unequivocally previous studies have shown that distinct vertical variation occurs both in geochemistry and microbial community structuring along the drill hole indicating stagnant waters with no significant exchange of fluids between different fracture systems or with surface waters therefore in situ accumulation is the most plausible model for the determination of noble gas residence times the results show that the saline groundwaters in outokumpu are remarkably old with most of the samples indicating residence times between 20 and 50 ma although being first order approximations the ages of the fluids clearly indicate that their formation must predate more recent events such as quaternary glaciations isolation within the crust since the eocene miocene epochs has also direct implications to the deep biosphere found at outokumpu these ecosystems must have been isolated for a long time and thus very likely rely on energy and carbon sources such as h 2 and co 2 from groundwater and adjacent bedrock rather than from the ground surface

the preglacial pliocene mississippi river abstractlate neogene upland gravels of the mississippi river valley are interpreted to be terrace deposits of the pliocene mississippi and tennessee rivers previous investigators have identified large wavelength paleo meanders in these gravels in the state of mississippi that indicate a paleo discharge six to eight times greater than that of the modern mississippi river suggesting that the drainage basin of the preglacial mississippi river may have extended into canada this study explores the extent of the preglacial mississippi river by mapping upland gravels from 97 wells in illinois 80 gravel locations from geologic quadrangles in illinois northeastern arkansas and southeastern missouri and 557 gravel wells in eastern arkansas western kentucky and western tennessee the distribution of these gravels indicates that during the pliocene the mississippi river flowed near its modern course a longitudinal profile of a 50 m thick pliocene mississippi river floodplain was constructed from northern i

origin and residence time of salinity in the aspo groundwater system abstract the origin of salinity within the aspo groundwater system is investigated by combining interpretations of conservative dissolved ions and of stable isotope ratios in water the interpretation concludes that the groundwater salinity results from a mixing between baltic sea water intrusion and a deep seated saline groundwater of marine origin this conclusion supports the geochemical model developed for the aspo site the residence time of the deep salinity is assessed by comparing the 36 cl content of dissolved salt at different depths and the secular equilibrium value of the host rock the 36 cl of deepest levels corresponding to the highest salinity is in equilibrium with rock suggesting a penetration of the deep salinity into the host rock more than 1 5 ma ago

exotic stable isotope compositions of saline waters and brines from the crystalline basement the overwhelming majority of groundwaters reported in literature show isotopic compositions that place them on or right of the meteoric water line mwl in a 2h vs 18o diagram a closer look to the steadily increasing data from the deeper crystalline basement reveals nevertheless that points left of the mwl are not so unusual as has been suggested during the last decades their supposed rareness seems to be due to a bias of sampling the concerned fluids develop only at greater depths and in low permeability environments which makes access to them so difficult paradoxically exotic stable isotope compositions may be the rule in a restricted depth zone in all crystalline basements with slow groundwater movements but not too high temperatures the present study takes stable isotope data on saline fluids from the deep french granitic basement as a starting point in order to situate the french data from the vienne region in a more general context a literature review has been undertaken assembling more than 1300 stable isotope analyses of waters and brines in crystalline rocks from stable cratons and mountain belts world wide the french fluids show some particular features with respect to the majority of other studies as their major ion composition close to seawater or a significant isotopic shift at relatively low salinities detailed knowledge on the hydrological and chemical history of the site allowed to develop a conceptual model of isotopic evolution by interaction of fracture fluids with fracture minerals this model considers interactions of the last fluids flushing the system marine water unaltered evaporated or diluted with previously precipitated mineral phases and the neoformation of the last generation of fracture minerals the model has been tested quantitatively for several combinations of dissolution precipitation reactions involving formation of carbonates clay minerals and fe hydroxides most of the modelled scenarios would leave the residual liquid phase depleted in 18o and either enriched or depleted in 2h and produce waters with isotopic signatures corresponding to the observed 2h vs 18o correlation it is therefore suggested that the general phenomenon of an isotopic shift in deep fissured silicate rocks which seems to be rather independent of lithology may result from a combination of different reaction mechanisms implying not solely the rock matrix but also the different generations of fracture minerals

new constraints for the source characteristics deposition and age of the 2 1 1 9 ga metasedimentary cover at the western margin of the karelian province abstract the paleoproterozoic cover sequence at the 100 150 km wide western margin of the archean karelian province is dominated by deep water lower and upper kaleva metasediments we present here an interpretation of sm nd isotope and geochemical data on 36 samples tims multi grain u pb zircon analyses on nine samples and ca 100 sims analysis of detrital zircon grains from four upper kaleva and one lower kaleva samples the lower kaleva is characterized by autochthonous parautochthonous lithologically heterogeneous metaturbidites showing common enrichment in quartz all the analysed detrital zircons are of a local neoarchean source but tdm variation up to 2 4 ga combined with geochemical data indicate abundant mixing of paleoproterozoic mafic material presumably from 2 1 ga plateau lavas and dykes in most of the lower kaleva samples the upper kaleva is dominantly allochthonous with tectonically enclosed fragments of ophiolite bodies and it is characterized by lithological and geochemical isotopic homogeneity geochemical isotopic and detrital zircon data favour material derived from an orogenic domain comprising both archean and proterozoic units followed by effective mixing during the transport the archean zircon grains 25 are mostly neoarchean the paleoproterozoic grains lack zircons at 2 5 2 2 ga and plot dominantly 92 between 1 92 and 2 05 ga the indicated maximum deposition ages vary from 1 95 1 94 ga to 1 92 ga the main source area proposed is the himalaya type lapland kola orogen now in the northeast which experienced mountain building and erosion at 1 95 1 91 ga the western margin of the karelian province shows evidence of rifting and lithosphere thinning from 2 1 to 1 95 ga but it is still under debate whether the craton breakup occurred at 2 06 ga in a volcanic or later at 1 95 ga in a non volcanic margin setting one hypothesis is that the onset of collision in the northeast changed plate motion and lead to a new spreading within the pre existing passive margin at 1 97 1 95 ga thus both a volcanic margin at 2 06 ga and a non volcanic margin at ca 1 95 ga could have been operated at the western margin of the karelian province

hydrogeochemistry groundwater ages and sources of salts in a granitic batholith on the canadian shield southeastern manitoba abstract the hydrogeochemistry of the lac du bonnet granitic batholith has been determined for the region of the whiteshell research area wra in southeastern manitoba canada this work forms part of the geosciences studies performed for the canadian nuclear fuel waste management program over the period 1980 1995 by atomic energy of canada limited aecl knowledge of the variation of groundwater chemistry and its causes is useful in assessing the performance and safety of a nuclear fuel waste vault located at depths of up to 1000 m in a crystalline rock formation of the canadian shield groundwaters and matrix pore fluids have been obtained by standard sampling methods from shallow piezometers in clay rich overburden from packer isolated borehole zones intersecting fractures or fault zones in the bedrock and from boreholes in unfractured rock in aecl s underground research laboratory url eighty six individual fracture groundwaters have been sampled and analysed from permeable zones in 53 boreholes drilled to depths of up to 1000 m in the lac du bonnet batholith in addition 28 groundwaters from piezometers in a large wetland area near the url have been sampled and analysed to determine the influence of clay rich overburden on the bedrock hydrogeochemistry analyses have been made for major and minor ions ph eh trace metals and stable and radioactive isotopes to characterise these groundwaters and relate them to their hydrogeologic regimes shallow groundwaters in the fractured bedrock are generally dilute tds 500 m na ca cl so4 waters of increasing salinity up to 50 g l with depth are found and in some fractures the waters have evolved to a ca na cl composition isotopic data indicate that these waters are warm climate and pre glacial in origin with residence times of over 1 ma pore fluids observed to drain from the unfractured rock matrix in the url facility are almost pure ca cl in composition 90 g l salinity and have a 2h 18o composition displaced well to the left of the global meteoric water line about which all other wra groundwaters lie this information indicates that these pore fluids have undergone prolonged water rock interaction and have residence times of 101 103 ma most of the deeper fracture groundwaters and pore fluids have low br cl ratios and moderate to high 34s values of dissolved so4 which indicates that their salinity could be derived from a marine source such as the basinal sedimentary brines and evaporites to the west of the batholith these fluids may have entered the batholith during early paleozoic times when sedimentary rocks were deposited over the granite and were driven by a hydraulic gradient resulting from higher ground in western canada the hydrogeochemical data and interpretations show that below 500 m in the wra fracture hosted groundwaters are very saline reducing and old and are therefore indicative of stagnant conditions over the period of concern for nuclear waste disposal 1 ma the intact rock matrix at these depths is extremely impermeable as indicated by the presence of pore fluids with unusual geochemical and isotopic characteristics the pore fluids may represent basinal brines that have evolved geochemically and isotopically to their current composition over periods as long as 103 ma

hydrography and mollusc faunas of the baltic and the white sea north sea seaway in the eemian abstract palynologically dated mollusc and cirriped faunas from a region extending from the north sea through the baltic and karelia to the arkhangelsk region show that the hydrography of the baltic was very different from the holocene for 2 2 5 ka in the early eemian a seaway existed from the barents to the north sea through karelia until it was severed at the present continental watershed to the north of lake onega after this the ladoga onega trough remained an arm of the baltic for several millennia the benthic faunas are comparable to the holocene but their boundaries were displaced much further into the baltic notable differences from the holocene are the absence or rarity of the macoma balthica biocoenosis and the presence of cold portlandia dominated biocoenoses in karelia in the belt sea and western baltic winter sea surface temperatures and salinity were higher than now by ca 6 c and 15 and the distinctly brackish top layer was missing at the same time cold bottom water 2 5 c with a tendency to anoxia characterised the karelian arm of the baltic water exchange through this area was inhibited by the constriction to the north of lake onega and the basin and threshold bathymetry water transport through the white sea baltic seaway was too sparse to play an active role in the north atlantic surface circulation or climatic change in the region the high salinity and temperature in the belt sea and western baltic persisted throughout the eemian and are explained by wider and deeper passage from the north sea to kattegat wider straits through denmark higher salinity in the north sea higher evaporation as well as more dispersed fresh water supply the advection of oceanic water into the baltic culminated in the early eemian before the carpinus zone and probably resulted in an oceanic climate in the baltic region while at the same time cold winters produced cold bottom water in the karelian arm

reconstructions of the continents around the north atlantic at about the 60th parallel abstract late carboniferous early tertiary apparent polar wander apw paths 300 40 ma for north america and europe have been tested in various reconstructions these paths demonstrate that the 500 fathom bullard et al fit is excellent from late carboniferous to late triassic times but the continental configuration in northern pangea changed systematically between the late triassic ca 214 ma and the mid jurassic ca 170 ma due to pre drift extension best fit north atlantic reconstructions minimize differences in the late carboniferous early jurassic and late cretaceous tertiary segments of the apw paths but an enigmatic difference exists in the paths for most of the jurassic whereas for the early cretaceous the data from europe are nearly non existent greenland s position is problematic in a bullard et al fit because of a late triassic early jurassic regime of compression 300 km that would be inherently required for the norwegian shelf and the barents sea but which is geologically not defensible we suggest a radically new fit for greenland in between europe and north america in the early mesozoic this fit keeps greenland locked to europe for the late paleozoic early mesozoic and maintains a reconstruction that better complies with the offshore geological history of the norwegian shelf and the barents sea pre drift a24 extension amounted to approximately 450 km on the mid norwegian shelf but with peak extension in the late cretaceous

an example of neotectonism in a continental interior thebes gap midcontinent united states abstract some of the most intense neotectonic activity known in the continental interior of north america has been recently discovered on a fault zone in the thebes gap area missouri and illinois this faulting almost assuredly was accompanied by large earthquakes the zone is located approximately 30 km north of the new madrid seismic zone and consists of complex north northeast to northeast striking steeply dipping faults that have had a long lived history of reactivation throughout most of the phanerozoic geophysical studies by others suggest that the faults are rooted in the deeply buried late proterozoic and early cambrian reelfoot rift system quaternary deposits are cut by at least four episodes of faulting two of which occurred during the holocene the overall style of neotectonic deformation is interpreted as right lateral strike slip faulting at many locations however near surface displacements have stepped from one fault strand to another and produced normal and oblique slip faults in areas of transtension and high angle reverse faults thrust faults and folds in areas of transpression there is evidence of reactivation of some near surface fault segments during the great 1811 1812 new madrid earthquakes quaternary faulting at thebes gap demonstrates that there are additional seismic source zones in the midcontinent u s other than new madrid and that even in the absence of plate margin orogenesis intense neotectonic activity does occur over long time periods along crustal weaknesses in continental interiors

a review of the history of the baltic sea 13 0 8 0 ka bp abstract the dynamic history of the baltic sea during the millennia following the last deglaciation has been one of the main topics for many generations of quaternary geologists around the baltic sea based on the present state of knowledge and certain hypotheses a model for the development during the baltic ice lake yoldia sea and ancylus lake stages are presented the oresund strait was the threshold of the initial stage of the baltic ice lake and was eroded down to bedrock as a result of the isostatic uplift the emerging threshold forced the baltic ice lake to rise above sea level at ca 12 0 ka bp this gradual up damming ended at ca 11 2 ka bp when the large glacial lake was lowered 5 10m by possible subglacial drainage at mt billingen a glacial readvance during the younger dryas ended a ca 400 year long land bridge between sweden and the continent by blocking the former drainage route once again the baltic ice lake had to rise above sea level to be drained over the oresund strait at ca 10 5 ka bp a gradual ice recession began and 200 years later when the receding ice sheet could not withhold the up dammed water masses the final drainage of the baltic ice lake occurred which rapidly lowered the water level within the baltic basin with ca 25 m and ended the baltic ice lake stage the next stage the yoldia sea was characterized by a complex pattern of relative sea level changes with large differences within the baltic basin a very restricted baltic sea in the south and thus an extensive landbridge at ca 9 9 ka bp a short 100 200 years saline ingression is seen in the baltic sediment records from stockholm in the north to the southernmost parts of the yoldia sea the gradually shallower strait in south central sweden the narke strait ended the saline influence 300 400 years later the two remaining outlets west of lake vanern gota alv and otteid steinselva had become too shallow to swallow the outflowing yoldia sea waters at this stage the baltic lake vanern level could thus not fall in pace with the relative sea level fall outside the outlet areas this was the isolation of lake vanern and the baltic from the sea and the beginning of the ancylus lake since the water depth of the larger gota alv outlet had to be more or less maintained the ancylus lake level had to rise in pace with the uplift of the outlet region this caused a significant and rapid transgression 10 30 m in ca 300 years in the southern baltic which flooded large areas with recently immigrated pine forests since the oresund strait during the yoldia sea stage had been uplifted more than southerly areas the ancylus transgression ended with a new drainage pathway at ca 9 2 ka bp through the darss sill area in the southern baltic and northwards through the store belt strait this so called dana river had cut off the former large land bridge the quaternary deposits of this new threshold were eroded and a fairly rapid regression set in at ca 9 0 ka bp the dana river had eroded down to the sea level which isolated lake vanern from the ancylus lake and created a land bridge between southern sweden and northwards ca 800 years later when the sea level rose above the oresund threshold marine water could enter the baltic and at ca 8 0 ka bp brackish water characterized the southern baltic this marks the end of the ancylus lake

possible relict meanders of the pliocene mississippi river and their implications abstractalthough the late quaternary history of the mississippi river the largest north american river has been intensely studied its pliocene history is largely unknown we assert that large relict meander bends oxbows of the pliocene mississippi river are preserved as arcuate valleys of local streams in the northwest area of the state of mississippi these arcuate valleys are within the pliocene upland complex stratigraphic unit that occurs as a high level alluvial terrace along the lower mississippi river valley outside these arcuate valleys the upland complex is a braided river gravel deposit that shows southward downvalley paleoflow directions interiors of the arcuate valleys are occupied by upland complex point bar deposits with large scale cross bedding showing a range of paleoflow directions commonly upvalley flow indicative of a meandering regime we used measurements of the radii of the putative relict meander bends and of their paleochannel widths to estimate paleodischarge of the pl

the correlation between 18o 16o ratios of meteoric water and surface temperature its use in investigating terrestrial climate change over geologic time abstract correlations between mean annual temperature mat and the weighted average oxygen isotope composition of yearly precipitation 18opt are well known but the utility of modern relations to make reliable estimates of temperature change over geological time is uncertain this question has been addressed by using seasonal subsets of the global data base of temperature and isotopic measurements to represent two different climate modes a comparison of middle to high latitude 18opt temperature relations for each climate mode reveals 1 a significant offset between them and 2 a difference in the strength of their correlations the offset in relations is due to differences in temperature and water vapor budget in the tropics and can lead to serious underestimates of temperature change differences in the strength of correlations arise from the influence of climate mode specific non temperature factors on 18opt the overall result is that no single relation can be used in all cases to make unambiguous temperature estimates using a temporal record of 18opt values one way to overcome these problems is to reconstruct 18opt temperature relations for the time periods being investigated if an appropriate proxy for 18opt is available it may also be possible to estimate temperature without relying on 18opt temperature relations a promising alternative to these options is to use records of 18opt to test predictions of global climate models an approach that may allow a reliable and more complete reconstruction to be made of climate change over geologic time

saline ground waters and brines in the canadian shield geochemical and isotopic evidence for a residual evaporite brine component abstract saline ca na cl type groundwaters and brines sampled in deep mines over an extensive area of the canadian precambrian shield have elevated br cl ratios which may indicate that the chlorinity of these waters was derived from the infiltration of residual evaporitic brines remnants of the great marine incursions of the paleozoic era boron concentrations in these waters are generally low i e 11 b 10 b ratios of these waters are significantly greater than the average value for continental crustal rocks with the highest values 4 19 approaching that of present day seawater 4 20 moreover the boron isotopic ratios generally trend to higher values with increasing chlorinity which supports the conclusion from the br cl relationship that most of the chloride in shield brines is of marine origin rather than a product of water rock interactions if this is correct crystalline rocks must then be sufficiently permeable on a regional scale to have allowed the brine to infiltrate to depths of several kilometers where it now resides

the interglacial glacial cycle and geochemical evolution of canadian and fennoscandian shield groundwaters abstract results from cryogenic column experiments are compared with the geochemical data collected in the canadian and fennoscandian shields over the past 25 years to investigate the relative influence of the glacial interglacial cycle specifically the impact of continental glaciers permafrost and methane hydrate on the evolution of groundwater from crystalline shield environments several different geochemical indicators of freezing processes either glacial or permafrost related were utilized comparisons of na cl and br cl ratios 18 o and 2 h values and 18 o values and cl concentration during freezing fluids with different dominant cations follow distinctly different linear trends when na cl and br cl ratios are compared significantly none of the freezing trends follows the trend hypothesized by herut et al 1990 for the evolution of seawater chemistry during freezing intrusion of glacial meltwater and in situ freezing i e permafrost formation result in a similar end member when comparing 18 o values and cl concentration the geochemical influence of a freezing process on fresh brackish and some saline fluids was identified at some but not all canadian shield sites regardless of site location with respect to modern day permafrost appreciably physical and geochemical data do not support the formation of brines through any freezing process in the canadian and fennoscandian shields as hypothesized by starinsky and katz 2003 rather on all diagnostic freezing plots brines are an end member indicating a different evolutionary pathway significant depletions in 18 o with respect to modern precipitation an indication of either glacial meltwater or a freezing process were identified at depths of up to 1 km at some sites in the canadian shield and to shallower depths in the fennoscandian shield the potential of this fluid to reach such depths could be attributable to artificial gradients and mixing glacial recharge permafrost or paleo permafrost formation or methane hydrate or paleo methane hydrate formation at most locations it was not possible to distinguish between the different scenarios using the current geochemical database

analysis of 6 year fluid electric conductivity logs to evaluate the hydraulic structure of the deep drill hole at outokumpu finland over the last two decades the flowing fluid electric conductivity ffec logging method has been applied in boreholes in the well testing mode to evaluate the transmissivity hydraulic head and formation water electrical conductivity as a function of depth with a resolution of about 10 20 cm ffec profiles along the borehole are obtained under both shut in and pumping conditions in a logging procedure that lasts only 3 or 4 days a method for analyzing these ffec logs has been developed and successfully employed to obtain formation parameters in a number of field studies the present paper concerns the analysis of a unique set of ffec logs that were taken from a deep borehole reaching down to 2 5 km at outokumpu finland over a 6 year time period the borehole intersects paleoproterozoic metasedimentary granitoid and ophiolite derived rocks after the well was drilled completed and cleaned up ffec logs were obtained after 7 433 597 948 and 2036 days in analyzing these five profiles we discovered the need to account for salinity diffusion from water in the formation to the borehole analysis results include the identification of 15 hydraulically conducting zones along the borehole the calculation of flow rates associated with these 15 zones as well as the estimation of the variation of formation water electrical conductivity as a function of depth the calculated flow rates were used to obtain the tentative hydraulic conductivity values at these 15 depth levels

finite element analysis of mixed in place mip columns supporting excavations in slopes considering tension softening the use of mixed in place mip columns can be considered as an attractive alternative to sheet pile diaphragm or bored pile walls for supporting deep excavations even in difficult ground conditi

87sr 86sr of brines from the fennoscandian shield a synthesis of groundwater isotopic data from the baltic sea region high salinity ca na cl brines occur in sweden and finland the complex geological history of the fennoscandian shield is reflected by the wide range of saline waters whose chemical compositions have been explained by local water rock interaction simple evolution of relict sea water or freezing of sea water during glacial periods this study deals with the present knowledge of sr isotopes in groundwater from the fennoscandian shield to better constrain the origin of their deep saline component two different mixing trends are seen between aspo island groundwater and the baltic sea the first trend links the north sea to rivers through various dilution levels in the baltic the second trend is a simple linear relationship through aspo groundwaters agreeing with a binary mixing between a baltic end member and a highly sr concentrated fluid strontium isotope compositions are presented for precipitation in finland and sweden the baltic sea and the river waters draining the fennoscandian shield and for g

pleistocene hydrology of north america the role of ice sheets in reorganizing groundwater flow systems 1 while the geomorphic consequences of pleistocene megafloods have been known for some time it has been only in the past 2 decades that hydrogeologists and glaciologists alike have begun to appreciate the important impact that ice sheet aquifer interactions have had in controlling subsurface flow patterns recharge rates and the distribution of fresh water in confined aquifer systems across north america in this paper we document the numerous lines of geochemical isotopic and geomechanical evidence of ice sheet hydrogeology across north america we also review the mechanical thermal and hydrologic processes that control subsurface fluid migration beneath ice sheets finite element models of subsurface fluid flow permafrost formation and ice sheet loading are presented to investigate the coupled nature of transport processes during glaciation deglaciation these indicate that recharge rates as high as 10 times modern values occurred as the laurentide ice sheet overran the margins of sedimentary basins the effects of ice sheet loading and permafrost formation result in complex transient flow patterns within aquifers and confining units alike using geochemical and environmental isotopic data we estimate that the volume of glacial meltwater emplaced at the margins of sedimentary basins overrun by the laurentide ice sheet totals about 3 7 104 km3 which is about 0 2 of the volume of the laurentide ice sheet subglacial infiltration estimates based on continental scale hydrologic models are even higher 5 10 of meltwater generated these studies in sum call into question the widely held notion that groundwater flow patterns within confined aquifer systems are controlled primarily by the water table configuration during the pleistocene rather groundwater flow patterns were likely much more complex and transient in nature than has previously been thought because pleistocene recharge rates are believed to be highly variable these studies have profound implications for water resource managers charged with determining sustainable pumping rates from confined aquifers that host ice sheet meltwater

oxygen isotope values of precipitation and the thermal climate in europe during the middle to late weichselian ice age abstract the oxygen isotope compositions of 28 mammoth tooth enamel samples from estonia latvia lithuania poland and denmark provide new quantitative records of the middle to late weichselian climate in northern europe the new 18 o data was combined with records of oxygen isotope values from earlier investigations on european mammoth tooth enamel and palaeogroundwaters to study the spatial patterns and temporal variations in the oxygen isotope composition of precipitation and the thermal climate over much of europe the reconstructed geographical distribution of 18 o in precipitation during 52 24 ka reflects the progressive isotopic depletion of air masses moving northeast consistent with a westerly source of moisture for the entire region and a circulation pattern similar to that of the present day regional long term average 18 o w values were 0 6 4 1 lower than at present the largest changes recorded for the currently maritime influenced southern sweden and the baltic region the application of regionally varied t slopes estimated from palaeogroundwater data and modern correlations yield reasonable estimates of glacial surface temperatures in europe and imply 2 9 c lower long term mean annual surface temperatures during the glacial period

cenozoic deep sea temperatures and global ice volumes from mg ca in benthic foraminiferal calcite a deep sea temperature record for the past 50 million years has been produced from the magnesium calcium ratio mg ca in benthic foraminiferal calcite the record is strikingly similar in form to the corresponding benthic oxygen isotope 18o record and defines an overall cooling of about 12 c in the deep oceans with four main cooling periods used in conjunction with the benthic 18o record the magnesium temperature record indicates that the first major accumulation of antarctic ice occurred rapidly in the earliest oligocene 34 million years ago and was not accompanied by a decrease in deep sea temperatures