isotope hydrology and geothermometry of the thermal springs damavand volcanic region iran abstract the chemo isotopic characteristics geothermal activity and water origin of the 5 thermal and 7 non thermal springs have been investigated in damavand volcanic region northern iran the damavand thermal waters are characterized by outlet temperature values of 23 to 65 c and the ca cl or ca so4 water types stable isotope values of 49 monthly precipitation samples from 5 stations at 2500 to 3200 m elevations were also measured in the study area and damavand meteoric water line dmwl was drawn as d 7 64 18o 8 93 r2 0 98 n 49 it has a lower slope and intercept than the global meteoric water line gmwl due to isotope kinetic fractionation effects during precipitation the 18o 0 0018 h m a s l 3 12 equation was derived based on precipitation data the reservoir temperature was estimated to be 110 135 c based on different geothermometers damavand volcano can be considered as the main heat source for the thermal springs in the region the conductive process along with the mixing of thermal waters with shallow cold groundwaters is the main cooling mechanisms almost all the thermal waters fall near the lmwl and within prediction interval area indicating meteoric origin and no significant effect of water rock interaction the damavand geothermal reservoir is fed by local meteoric water from altitudes of 2500 to 4100 m and circulates at least 500 m deep near the magma chamber

uranium series ages of travertines and timing of the last glaciation in the northern yellowstone area wyoming montana uranium series age determinations by mass spectrometric methods were done for travertines and associated carbonate veins related to clastic deposits of the last glaciation pinedale in the northern yellowstone area dramatic variations in the hydrologic head are inferred from variations in the elevation of travertine deposition with time and are consistent with the expected hydrologic effects of glaciation we determine the following chronology of the pinedale glaciation with the key assumption that travertine deposits and associated carbonate veins perched high above present thermal springs were deposited when glaciers filled the valley below these perched deposits 1 the early pinedale outlet glacier advanced well downvalley between 47 000 and 34 000 yr b p 2 the outlet glacier receded to an interstadial position between 34 000 and 30 000 yr b p 3 an extensive pinedale ice advance occurred between 30 000 and 22 500 yr b p 4 a major recession occurred between 22 500 and 19 500 yr b p 5 a minor readvance deckard flats culminated after 19 500 yr b p and 6 recession from the deckard flats position was completed before 15 500 yr b p this chronology is consistent with the general trend of climatic changes in the northern hemisphere as revealed by recent high resolution ice core records from the greenland ice sheet

the mutual interaction between continental scale ice sheets and atmospheric stationary waves the great continental ice sheets of the pleistocene represented significant obstacles to the northern hemisphere midlatitude westerlies they must therefore have forced large changes in the atmospheric circulation and consequently also in the patterns of accumulation and melting over the ice sheets themselves a simplified threedimensional coupled ice sheet stationary wave model is developed in order to understand the ice sheet s response to the circulation changes that it induces consistent with ice age climate simulations the ice sheet topography induces an anticyclonic circulation over the ice sheet causing a slight warming over the western slopes and a stronger cooling over the remainder the modeled feedbacks significantly affect the ice sheet configuration with the most important influences being the patterns of summer temperature and the topographically induced precipitation field the time evolution of the ice sheet is also changed by the atmospheric feedbacks and the results suggest the possibility of multiple equilibrium solutions

stable chlorine isotopes in the palo duro basin texas evidence for preservation of permian evaporite brines experimental evaporation of seawater yields brines with 37cl from 0 0 initial to 0 9 in the palo duro basin brines with 37cl values overlapping the 0 1 to 0 4 range of halite evaporite can be generated by a set of processes including dissolution of halite in meteoric water such brines occur above and below an evaporite aquitard brines with 37cl values of 0 4 to 1 0 in the evaporite aquitard and in a deep brine aquifer cannot be generated by dissolution of halite considered with br and cl content d and noble gas content the 37cl data indicate that such brines originated as evapoconcentrated seawater high br evaporite brine formed directly from seawater on the eastern side of the basin whereas low br evaporite brines on the western side formed after an influx of meteoric water at the time of evaporite formation there has not been detectable vertical flow of meteoric water across the evaporite aquitard strata beneath the evaporite contain compartments that have been isolated geochemically since the permian

the behavior of lithium and its isotopes in oilfield brines evidence from the heletz kokhav field israel twenty four brine samples from the heletz kokhav oilfield israel have been analyzed for chemical composition and li isotope ratios the chemical composition of the brines together with geological evidence suggests derivation from messinian seawater by evaporation that proceeded well into the gypsum stability field but failed to reach the stage of halite crystallization the present salinity of the samples 18 47 g cl l was achieved by dilution of the original evaporitic brine by local fresh waters like brines from other sedimentary basins the li cl ratios in the heletz kokhav samples show a prominent li enrichment five fold to eight fold relative to modern seawater the isotopic ratios of li expressed in the 6 li notation vary from 26 3 to 17 9 all values being significantly higher than that of modern seawater 32 irrespective of their corresponding li concentration 1 0 2 3 mg l the isotopic composition of li and the li cl ratio in the oilfield brines were acquired in two stages a the original evaporated seawater gained isotopically light li during the diagenetic interaction between the interstitial messinian brine and the basin sediments a parent brine with an elevated li cl ratio was formed the brine was later diluted in the oilfields b the 6 li values of the final brines were determined during epigenetic interaction with the heletz kokhav aquifer rocks at the same time the li cl ratio inherited from stage a remained largely unchanged this work represents the first use of lithium isotopic composition to elucidate the origin and evolution of formation waters in sedimentary basins copyright 2002 elsevier science ltd

isotope geochemistry of fluid inclusions in permian halite with implications for the isotopic history of ocean water and the origin of saline formation waters abstract d and 18o values have been determined for fluid inclusions in 45 samples of permian halite the inclusions are enriched in 18o relative to the meteoric water line but are depleted in d relative to ocean water inclusions with the more positive values coincide with the isotopic composition expected for evaporating sea water which follows a hooked trajectory on a d 18o diagram inclusions with more negative values may represent more highly evaporated sea water but probably reflect synsedimentary or diagenetic mixing of meteoric water with evaporite brines the isotope systematics in these inclusions are sufficiently similar to those of a modern evaporite pan to indicate that permian sea water was isotopically similar to modern sea water connate evaporite brines can have negative values because of the probable hooked isotope trajectory of evaporating sea water and or synsedimentary mixing of evaporite brines with meteoric waters subsurface formation waters composed of mixtures of remnant primary evaporite brines and later meteoric waters may be more common than previous isotopic evidence has suggested

age budget and dynamics of an active salt extrusion in iran the hormuz salt of kuh e namak iran began rising through its phanerozoic cover in jurassic times and had surfaced by cretaceous times in miocene times the still active zagros folds began to develop and the salt is still extruding to feed a massive topographic dome and two surface flows of salt which have previously been called salt glaciers but are here called namakiers two crude but independent estimates for the rate of salt extrusion and loss are shown to balance the salt budget if the current salt dynamics are assumed to be in steady state first to replace the extrusive salt likely to be lost in solution in the annual rainfall the salt must rise at an average velocity of about 11 cm a second the foliation pattern shows that the extruding and partially dissolved salt column spreads under its own weight the maximum height of the salt dome is consistent with a viscous fluid with a viscosity of 2 6 x 1017 poises extruding from its orifice at a rate of almost 17 cm a k both estimates are consistent in indicating that salt can extrude onto the surface 42 85 times faster than the average long term rate at which salt diapirs rise to the surface the structure fabrics textures and deformation mechanisms of the impure halite all change along the path of the extrusive salt from the dome down the length of both namakiers such changes tend to occur when the flowing salt encounters changes in its boundary conditions and the recognition of buried namakiers is discussed in the light of such observations episodes of salt flow at a rate of 0 5 m per day have been measured along the margin of the n namakier after significant rain showers such brief episodes of rapid flow alternate with long periods when the namakier is dry and stationary the shape of the colour bands cropping out on the n namakier indicate that the flow over the surface of impure salt with a mylonitic texture obeys a power law with n 3 although the reported annual rainfall has the potential of dissolving both namakiers in about 2000 years a superimposed thin marine cover may protect static parts of them for as long as 30 000 to 300 000 years

varied climatic and topographic influences on late pleistocene mountain glaciation in the western united states the timing of late pleistocene mountain glacier fluctuations varied widely across the western united states glaciers in the maritime olympic mountains reached local maxima 125 60 ka and 34 31 ka and were far less extensive during the global last glacial maximum lgm glaciers in the cascade mountains showed a similar general pattern but with contrasts in detailed timing most mountain glacier systems further inland exhibited maximum ice extent during marine isotope stage mis 2 in the wallowa wind river and possibly the sawtooth mountains maximum ice extent occurred ca 20 23 ka mountain glacier systems of the cordilleran ice sheet puget lobe greater yellowstone region and uinta mountains reached maximum extent ca 19 16 ka and those in the wallowa sawtooth and wind river ranges were at near maximum positions ca 17 ka the variable timing of maximum and near maximum ice advances appears to be related to climatic setting and glacier mass balance characteristics mountain glacier systems under the strongest maritime influences reached maximum extent at times of strong westerly atmospheric flow olympic and cascades glaciers appear to have been negatively influenced by weakened westerly flow at the time of the global lgm perhaps associated with ice sheet induced anticyclonic flow glacier systems with maximum advances correlative with the global lgm appear to have responded more strongly to depressed temperature the ca 17 ka ice advances of several glacier systems are broadly correlative with heinrich event 1 in the north atlantic region and imply a cooling event and reinvigoration of moisture transport into the region post lgm advances of uinta mountain glaciers appear to have arisen from moisture influences of pluvial lake bonneville copyright 2008 john wiley sons ltd

hydrochemical and isotopic δ18o δ2h 87sr 86sr δ37cl and δ81br evidence for the origin of saline formation water in a gas reservoir abstract the permo triassic kangan gasfield in southern iran is composed of an aquifer the kangan aquifer ka and an overlying gas reservoir it is located in the kangan and dalan formations and consists predominantly of limestone and dolomite the kangan gasfield is exploited from 36 wells at depths from 2300 to 2860 m the quality of the produced formation waters pfw varies from fresh to saline with salinities of up to 60 000 mg l the present study aims to identify the origin of the salinity of the pfws the concentration of major ions li sr and br as well as 18o d 87sr 86sr 37cl and 81br isotope compositions of the ka water and pfw samples a fresh and a brine spring and the persian gulf water were all measured the suite of isotopic 37cl and 81br and hydrochemical data li cl and br concentrations and cf index in this study indicates that the salinity origin of the pfws is evaporated seawater which could be either the ka water or the intergranular saturated brine in the kangan gas reservoir kgr both derived from permo triassic evaporated seawater 18o and 87sr 86sr data exclude the ka water as the source of the saline pfw leaving the intergranular brine of the kgr as the most likely source although further isotopic and geochemical tests are needed to verify this this work also proposes for the first time the use of a li cl versus br cl diagram to distinguish between evaporate formation water water modified by halite dissolution and fresh water it is recommended to apply these comprehensive methods to deep brine aquifers especially related to gasfields

hydrogen oxygen helium and strontium isotopic constraints on the formation of oilfield waters in the western qaidam basin china abstract surveys and exploration for oil and gas have revealed many oil field brines in the tertiary strata of the western qaidam basin china the source and formation of these brines are unclear brine samples collected from petroleum wells in the oilfield area were analyzed for their general chemical composition and for hydrogen oxygen strontium and helium isotopes in order to trace their origin formation and resource distribution results show that the concentrations of resources such as k b sr br and li are unusually enriched in oil field brines and have excellent potential for development and utilization in future the geology h o sr and he isotopic composition the chemical composition and the geophysical measurements all show that the tertiary oil field brines predominantly originated from the deep mixture of formation water and magmatic residual fluids in the western qaidam basin the tectonic geology intense and frequent magmatic hydrothermal activity as well as high 3he 4he ratio indicate that the magmatic fluids possibly originate from the upper mantle derived magmatic fluids thus according to our interpretation of the formation and evolution of the oilfield brine this source is adequate for the volume and composition to be explored and utilized latterly

a loess paleosol record of climate and glacial history over the past two glacial interglacial cycles 150 ka southern jackson hole wyoming abstract loess accumulated on a bull lake outwash terrace of marine oxygen isotope stage 6 mis 6 age in southern jackson hole wyoming the 9 m section displays eight intervals of loess deposition loess 1 to loess 8 oldest each followed by soil development our age depth model is constrained by thermoluminescence meteoric 10 be accumulation in soils and cosmogenic 10 be surface exposure ages we use particle size geochemical mineral magnetic and clay mineralogical data to interpret loess sources and pedogenesis deposition of mis 6 loess was followed by a tripartite soil thin loess complex soils 8 7 and 6 apparently reflecting the large climatic oscillations of mis 5 soil 8 mis 5e shows the strongest development loess 5 accumulated during a glacial interval 76 69 ka mis 4 followed by soil development under conditions wetter and probably colder than present deposition of thick loess 3 43 51 ka mis 3 was followed by soil development comparable with that observed in soil 1 loess 1 mis 2 accumulated during the pinedale glaciation and was followed by development of soil 1 under a semiarid climate this record of alternating loess deposition and soil development is compatible with the history of yellowstone vegetation and the glacial flour record from the sierra nevada

regional trends in water chemistry smackover formation southwest arkansas geochemical and physical controls we present results on regional geochemical analyses of formation waters from jurassic carbonate strata of the upper smackover formation from the southwest arkansas shelf gulf coast basin these formation waters have been noted in earlier studies for their exceptional salinities and abnormally br rich composition our detailed and regionally extensive database shows that chemical heterogeneities occur on a relatively small scale and have spatial relations to faults which may act as pathways for fluid migration from deeper and hotter portions of the stratigraphic section one of the most pronounced heterogeneities in water chemistry is an h 2 s rich anomaly in the center of the shelf enrichments in h 2 s are accompanied by large increases in alkali elements li k and b and b which could be produced by higher temperature diagenesis of clay minerals and feldspars in deeper seated siliciclastic strata bromide enrichments in all smackover formation waters are apparent from relations between br and cl contents as well as br and divalent cation carpenter function values as suggested by earlier studies of these waters evaporatively concentrated seawater expelled from associated thick monomineralic evaporite sections may be an important source of br cl and na whereas ca mg and sr concentrations have been modified by carbonate mineral recrystallization and dolomitization mineral equilibria exert significant controls on concentrations of ca mg sr and so 4 in these brines br enrichment likely was produced by halite recrystallization in fluids already enriched in br from seawater evaporation elevated cl br ratios occur in regional association with lower salinity water near t e south arkansas fault system consistent with halite dissolution during meteoric water recharge thus despite relatively uniform reservoir lithology and simple structural setting processes on small spatial scales have resulted in significant heterogeneity in water chemistry within a small area of the gulf coast sedimentary basin although movement of fluids along these fault systems is not demonstrated in our study the regional trends in geochemistry are strongly suggestive of their important role in controlling chemical heterogeneities in smackover formation waters

latest pleistocene glacial chronology of the uinta mountains support for moisture driven asynchrony of the last deglaciation abstract recent estimates of the timing of the last glaciation in the southern and western uinta mountains of northeastern utah suggest that the start of ice retreat and the climate driven regression of pluvial lake bonneville both occurred at approximately 16 cal ka to further explore the possible climatic relationship of uinta mountain glaciers and the lake and to add to the glacial chronology of the rocky mountains we assembled a range wide chronology of latest pleistocene terminal moraines based on seventy four cosmogenic 10be surface exposure ages from seven glacial valleys new cosmogenic exposure ages from moraines in three northern and eastern valleys of the uinta mountains indicate that glaciers in these parts of the range began retreating at 22 20 ka whereas previously reported cosmogenic exposure ages from four southern and western valleys indicate that ice retreat began there between 18 and 16 5 ka this spatial asynchrony in the start of the last deglaciation was accompanied by a 400 m east to west decline in glacier equilibrium line altitudes across the uinta mountains when considered together these two lines of evidence support the hypothesis that lake bonneville influenced the mass balance of glaciers in southern and western valleys of the range but had a lesser impact on glaciers located farther east regional scale variability in the timing of latest pleistocene deglaciation in the rocky mountains may also reflect changing precipitation patterns thereby highlighting the importance of precipitation controls on the mass balance of pleistocene mountain glaciers

gisp2 oxygen isotope ratios the gisp2 oxygen isotope record with its high resolution detail yields crucial information on past climate change the glacial 18o oscillations of the gisp2 core with their very fast onsets are templates of a prototype oscillation of variable duration with an amplitude of 3 9 the halfway mark of the cold warm transition is reached in 2 years the top is reached in 50 years the 18o time gradient of the leading front is about 7 8 per 100 yr after reaching the top 18o slowly declines by 0 14 per 100 yr the duration of 18o decline varies from a couple of centuries for fast oscillations to about 4000 yr for slower ones the subsequent 18o downturn during the warm cold transition has a 18o time gradient of 3 2 per 100 yr and lasts about 80 yr

origin and chemical evolution of formation waters from silurian devonian strata in the illinois basin usa abstract a suite of formation water samples from silurian devonian reservoirs in the illinois basin has been analyzed for major minor and trace element concentrations and for h o and sr isotopic compositions in order to interpret origin of salinity and geochemical evolution of brine compositions in this evaporite and shale poor cratonic basin although chloride concentrations range from 2000 to 137 000 mg l cl br ratios 291 18 are consistent with those of seawater or seawater evaporated short of halite saturation cl br 292 thus during silurian devonian time subaerially evaporated penesaline brine entered the subsurface where it was chemically modified through brine rock interactions cation br ratios and mineralogy of associated strata indicate that na and k were depleted through interaction with clay minerals ca was enriched and mg depleted by dolomitization and sr was enriched as a result of caco3 recrystallization and dolomitization although significant dilution of the modified brine with meteoric water is supported by d 18o covariance original marine waters have not been completely expelled from silurian devonian strata hydrogen and oxygen isotopes exhibit covariant relations with cation and anion concentrations implying that isotopic exchange between h2o and minerals has not greatly influenced the d 18o trend brine 87 sr 86 sr ratios range from 0 7092 to 0 7108 when these ratios are plotted versus 1 sr a two component mixing trend is suggested although sr concentrations have experienced local diagenetic modification a 87sr enriched fluid may have accompanied petroleum migration from new albany shales into adjacent silurian devonian carbonates where it mixed with remnant evaporated seawater this event probably preceded the influx of meteoric water as gdd and 18o are not correlated with sr isotopic compositions of formation waters

an integrated modelling approach to reconstruct complex solute transport mechanisms cl and δ37cl in pore water of sediments from a former brackish lagoon in the netherlands abstract a one dimensional transport model was developed to reconstruct historical conservative transport of chloride and 37 cl in pore water of sediments from a former brackish lagoon in the netherlands an area now covered by the freshwater lakes ijssel and marken knowledge of the mechanism of historical solute transport in the sediments and environmental conditions during transport is critical in understanding observed pore water chemistry and will form a basis for simulating effects of changing environmental climate change conditions the model synthesizes present knowledge of geology and historical information on storm surges in the area and takes into account processes such as erosion of sediments mixing of pore water sedimentation and diffusion emsd the chemistry of pore water from one particular boring in the area was found to be mainly controlled by alternating seawater and freshwater diffusion models with a constant averaged porosity 0 55 and tortuosity factor 0 3 showed similar results as models incorporating the measured bulk porosity variations 0 4 0 8 and variable tortuosity factors calculated with archie s law the relatively small tortuosity factor either results from anion exclusion or from the heterogeneous build up of the profile in which a peaty layer in the middle part may obstruct diffusion diffusion of 35 cl was found to be 1 0017 times faster than of 37 cl seawater diffusion into the sediments started at least 400 years ago and refreshening took place since the lagoon was isolated from the sea by a dam in 1932

chemistry and isotopic composition of rotliegend and upper carboniferous formation waters from the north german basin abstract element concentrations and isotopic composition d 18 o 15 n of ammonium 87 sr 86 sr have been determined in highly saline formation waters from the rotliegend altmark gasfield and the upper carboniferous husum schneeren gasfield in the north german basin both reservoirs have been covered by huge zechstein evaporite caps since the late permian formation waters from the altmark gasfield are characterized by high total dissolved solids and are enriched in 18 o relative to meteoric waters and either show positive or negative d values which typically follow the proposed d vs 18 o paths for seawater evaporation formation waters stored in upper carboniferous sandstones show much more variable element concentrations and 18 o and d values than the rotliegend formation waters the br vs cl concentrations of the brines suggest seawater evaporation being the principal source of salinity at both sites the ammonium concentrations in the analyzed brines are highly variable and the 15 n isotopic composition of dissolved ammonium is controlled either by the isotopic composition of the gas in the reservoir rotliegend or that of the host rocks upper carboniferous at both sites early formation waters interacted with the sedimentary host rocks after deposition 87 sr 86 sr ratios suggest that re equilibration between fluids and their host rocks occurred in pre triassic times there is no chemical or isotopic evidence that original formation waters which occur in sandstone below the overlying zechstein evaporites were flushed out or mixed by later meteoric water as has been documented in deep seated mesozoic and other paleozoic aquifers of the north german basin

origin and mixing history of brines palo duro basin texas u s a formation waters in the palo duro basin texas u s a fall into four major groups based on integrated chemical and isotopic characteristics 1 interbed brines within the major permian evaporite aquitard these are the most chemically concentrated and18o rich fluids in the basin and are interpreted as evaporatively concentrated sea water which has been hydrologically isolated since the permian 2 brines below the salt on the eastern side of the basin have clbr divalent cation and isotopic systematics indicating a mixture of evaporatively concentrated sea water and meteoric water of d 20 3 brines below the salt on the western side of the basin have chemical and isotopic systematics suggesting a mixture of two pulses of meteoric water one with d 20 and the other with d 55 and 4 waters above the salt have the isotopic composition of meteoric waters diagenetic alteration of the cation chemistry has occurred for brines within and below the salt aquifers below the salt on the eastern side are interpreted as having been charged with dense permian evaporite brines which subsequently mixed in various amounts with a basin wide pulse of triassic meteoric water on the western side the descending triassic meteoric waters became saline by dissolution of halite and are currently mixing with a tertiary pulse of meteoric water initiated by the laramide uplift to the west the hydrochemistry suggests flow on the western side of the basin and static conditions on the eastern side an unrecognized approximately n s permeability restriction or discontinuity in the potentiometric flow surface is inferred for major aquifers in the central area of the basin

regional stratigraphy of the zagros fold thrust belt of iran and its proforeland evolution the latest neoproterozoic through phanerozoic stratigraphy of the zagros fold thrust belt of iran has been revised in the light of recent investigations the revised stratigraphy consists of four groups of rocks each composed of a number of unconformity bounded megasequences representing various tectonosedimentary settings in the lowest group ranging in age from latest precambrian to devonian the uppermost neoproterozoic to middle cambrian rocks constitute a megasequence of evaporites siliciclastic deposits and interlayered carbonates which were deposited in pull apart basins that developed by the najd strike slip fault system this megasequence is overlain by a second one middle to late cambrian in age which consists of shallow marine siliciclastic and carbonate rocks representing deposition in an epicontinental platform the overlying shales siltstones and partly volcanogenic sandstones of ordovician silurian and devonian age are local remnants of stratigraphic units that were extensively eroded during development of several major unconformities the second group consists of two megasequences one permian and the other triassic composed of widespread transgressive basal siliciclastic rocks and overlying evaporitic carbonates of an equatorial epi pangean very shallow platformal sea the third group is composed of four megasequences formed of shallow and deep water carbonates with some siliciclastic and evaporite deposits which accumulated on a neo tethyan continental shelf during earliest jurassic through late turonian time the fourth group comprises siliciclastic and carbonate deposits of a largely underfilled nw to se trending forward and backward migrating late cretaceous to recent proforeland basin which has evolved as an integral part of the zagros orogen this last group consists of three megasequences ix x and xi with distinctive lateral and vertical facies variations which reflect specific tectonic events megasequence ix comprises uppermost turonian to middle maastrichtian prograding and retrograding siliciclastic and carbonate deposits whose accumulations reflect emplacement obduction of ophiolite slivers and subsequent collisional events in the zagros orogen megasequence x consists of uppermost maastrichtian to upper eocene siliciclastic and carbonate rocks which deposited first progradationally in front of the zagros orogenic wedge with reduced contractional tectonic activity and then retrogradationally due to intensified thrust stacking in the interior parts of the orogen megasequence xi consists of oligocene and lower miocene carbonate strata deposited retrogradationally shortly after a period of intensified late eocene thrust faulting in the deformational wedge and an overlying succession of upward coarsening northeasterly derived siliciclastic deposits of lower miocene to recent age which are composed of erosional byproducts of the southwest vergent zagros thrust sheets

origin and evolution of formation water at the jujo tecominoacan oil reservoir gulf of mexico part 1 chemical evolution and water rock interaction abstract the origin and evolution of formation water from upper jurassic to upper cretaceous mudstone packstone dolomite host rocks at the jujo tecominoacan oil reservoir located onshore in se mexico at a depth from 5200 to 6200 m b s l have been investigated using detailed water geochemistry from 12 producer wells and six closed wells and related host rock mineralogy saline waters of cl na type with total dissolved solids from 10 to 23 g l are chemically distinct from hypersaline cl ca na and cl na ca type waters with tds between 181 and 385 g l bromine cl and br na ratios suggest the subaerial evaporation of seawater beyond halite precipitation to explain the extreme hypersaline components while less saline samples were formed by mixing of high salinity end members with surface derived low salinity water components the dissolution of evaporites from adjacent salt domes has little impact on present formation water composition geochemical simulations with harvie m ller weare and phrqpitz thermodynamic data sets suggest secondary fluid enrichment in ca hco3 and sr by water rock interaction the volumetric mass balance between ca enrichment and mg depletion confirms dolomitization as the major alteration process potassium cl ratios below evaporation trajectory are attributed to minor precipitation of k feldspar and illitization without evidence for albitization at the jujo tecominoacan reservoir the abundance of secondary dolomite illite and pyrite in drilling cores from reservoir host rock reconfirms the observed water rock exchange processes sulfate concentrations are controlled by anhydrite solubility as indicated by positive si values although anhydrite deposition is limited throughout the lithological reservoir column the chemical variety of produced water at the jujo tecominoacan oil field is related to a sequence of primary and secondary processes including infiltration of evaporated seawater and original meteoric fluids the subsequent mixing of different water types and the formation of secondary minerals by water rock interaction a best fit between measured and calculated reservoir temperatures was obtained with the mg li geothermometer for high salinity formation water tds 180 g l whereas na k na ka ca and quartz geothermometers are partially applicable for less salinite water tds

geochemistry of formation waters from the lower silurian clinton formation albion sandstone eastern ohio waters of the petroleum bearing clinton formation albion sandstone of eastern ohio are highly concentrated brines with average total dissolved solids tds of 250 000 ppm sodium calcium and chloride account for 97 of the tds distribution of divalent metal chlorides mcl 2 allows inference of an up dip paleoflow direction although present day flow is probably down dip solute distribution may have been emplaced during early basin development it thus provides a snapshot of paleoflow formation structure alone can not explain mcl 2 trends they probably also are controlled by regional variation in salt thickness major constituent data do not indicate that membrane filtration affected the waters high bromide content mean 1860 ppm of the waters indicates that they originated from evaporating seawater they probably are related genetically to the salina evaporite group calculations show that several subsequent diagenetic reactions can account for the observed major ion composition recrystallization of aragonite and dolomitization of calcite probably occurred as the waters moved through the big lime and or the packer shell carbonates cation exchange and chlorite formation probably altered water composition during interaction with shales of the cabot head formation and within the clinton minor constituents of the waters appear to be controlled by reactions with clays

history and dynamics of the greater yellowstone glacial system during the last two glaciations abstract the greater yellowstone glacial system gygs covered about 20 000 km2 at its maximum pleistocene extent the initiation culmination and ultimate decay of the gygs involved complex interactions between several coalescent ice masses flowing from glacial source areas adjoining and including the yellowstone plateau here we present an updated review of the history and dynamics of the gygs during the penultimate bull lake and last pinedale glaciations drawing upon an integration of glacial geologic mapping with 130 cosmogenic 10be and 3he exposure ages bull lake glacial deposits in greater yellowstone are dated to ca 150 140 ka and correlate with marine isotope stage 6 the bull lake glaciation extended well beyond the pinedale along the southern and western gygs margins but pinedale glaciers overrode bull lake ice limits on the north and east sides the northeastward shift of the center of ice mass from bull lake to pinedale time may be explained by uplift on the leading edge of the yellowstone hotspot and subsidence on the trailing margin in early pinedale time 22 18 ka ice buildup culminated in the high terrain of the beartooth uplift and high absaroka range glaciers from these source regions flowed onto the northeastern margin of the yellowstone plateau and advanced to terminal moraines beyond clarks fork canyon and in jackson hole by middle pinedale time 18 16 ka the yellowstone plateau ice cap surface had risen above the equilibrium line altitude stimulating orographic glacial buildup nourished by storms funneled eastward through the snake river plain the plateau ice cap eventually thickened to 1000 m and joined glaciers from the beartooth uplift and gallatin range to form the northern yellowstone outlet glacier terrain east and downwind of the ice cap crest was placed in a precipitation shadow resulting in glacial recession in these regions during the late pinedale 16 13 ka the plateau ice cap prograded southwestward toward the direction of moisture supply leading to advances along the southern and western margins of the gygs northern sectors of the plateau ice cap were nearly stagnant at this time the yellowstone region experienced widespread deglaciation ca 15 14 ka in response to warming climate unloading of the 1 km thick plateau ice cap and consequent release of pressure on the magmatic system beneath yellowstone was not accompanied by volcanism indicating that the magma chamber was not primed to erupt via decompression during the last deglaciation

using δ87 sr values to identify sources of salinity to a freshwater aquifer greater aneth oil field utah usa salinity increases in water from the freshwater navajo aquifer in the aneth area have been documented in recent years previous studies during the 1980s in the aneth area suggested that brines associated with oil production and their subsequent re injection were the probable source of salinity in the navajo aquifer differences in the delta strontium 87 87sr composition of ground water samples from southeastern utah were used to determine if oil field brine or water from the upper paleozoic aquifer is a plausible source of salinity to the navajo aquifer the 87sr values of the oil field brine samples mean 0 95 range 1 06 to 0 79 n 5 are substantially more negative than the values in water samples from wells completed in the navajo aquifer mean 0 73 range 0 85 to 2 02 n 48 indicating that oil field brine is not a source of salinity the 87sr values in water samples from wells completed in the upper paleozoic aquifer mean 0 801 range 0 34 to 1 10 n 4 are similar to the mean isotopic composition of the more saline water from the navajo aquifer the 87sr values in water from the navajo aquifer confirm that two distinct flow areas are present mixing models using the 87sr values and sr concentrations of non saline water from the navajo aquifer and saline water from the upper paleozoic aquifer indicate that water from the upper paleozoic aquifer is a plausible source of saline water to the navajo aquifer most navajo aquifer wells that contain water with a 87sr signature similar to water from the upper paleozoic aquifer are located within or adjacent to an area where the hydraulic gradient is favorable for upward movement of water from the upper paleozoic aquifer into the navajo aquifer

strontium isotopic compositions and potassium and rubidium contents of formation waters in sedimentary basins clues to the origin of the solutes abstract strontium isotopic compositions of formation waters in sedimentary basins relate primarily to sr from dissolution replacement of alkali feldspar minerals dissolution recrystallization precipitation of marine carbonate and sulfate minerals and illitization formation waters in sedimentary basins are often depleted in k but enriched in rb relative to evaporated seawater and have k rb ratios commonly between 200 and 2000 the k and rb characteristics of formation waters suggest that deep burial conversion of smectite to illite has a major influence on the evolutionary history of these solutes

chemical evolution of a gas capped deep aquifer southwest of iran the kangan aquifer ka is located below a gas reservoir in the crest of the kangan anticline southwest of iran this aquifer is composed of permo triassic limestone dolomite sandstone anhydrite and shale it is characterized by a total dissolved solid of about 332 000 mg l and na ca cl type water a previous study showed that the source of the ka waters is evaporated seawater chemical evolution of the ka is the main objective of this study the major minor and trace element concentrations of the ka waters were measured the chemical evolution of ka waters occurred by three different processes evaporation of seawater water rock and water gas interactions due to the seawater evaporation process the concentration of all ions in the ka waters increased up to saturation levels in comparison to the evaporated seawater the higher concentrations of ca li sr i mn and b and lower concentrations of mg so4 and na and no changes in concentrations of cl and k ions are observed in the ka waters based on the chemical evolution after seawater evaporation the ka waters are classified into four groups 1 no evolution cl k ions 2 water rock interaction na ca mg li and sr ions 3 water gas interaction so4 and i ions and 4 both water rock and water gas interactions mn and b ions the chemical evolution processes of the ka waters include dolomitization precipitation ion exchange and recrystallization in water rock interaction bacterial reduction and diagenesis of organic material in water gas interaction also occur a new type of chart caexcess versus mgdeficit is proposed to evaluate the dolomitization process

stable chlorine isotopes in hydrothermal processes abstract values of 37cl can now be routinely measured with an analytical precision of 0 2 as reported herein on fluid inclusion leachates from the elmwood gordonsville mississippi valley type deposit and formation waters from its host formation basin brines from the gulf coast and palo duro basins and fluid inclusion leachates and biotites from the bingham silver bell and panguna porphyry copper deposits isotopic measurements are not affected by reaction yield in the range 85 100 or by generation of free i2 during sample preparation in the elmwood gordonsville deposit five successive paragenetic stages of ore and gangue sphalerite fluorite calcite 2 barite and calcite 3 each yielded multiple 37cl measurements ranges of 37cl vary in alternating fashion between stages with more negative values sphalerite calcites 2 and 3 and those with more positive values fluorite barite an interface between two brine systems with 37 cl and 0 0 appears to have moved back and forth across the zone of mineralization brines from the gulf coast and palo duro basins are apparently bimodal in 37cl with modes near 0 9 and 0 0 consistent with the variation in 37cl observed in fluid inclusion leachates from elmwood gordonsville biotite in the bingham deposit has 37cl values up to 1 7 and chlorine isotopes that are fractionated with respect to salt rich hydrothermal fluid hydrothermal fluids in all three porphyry copper deposits studied have a 37cl range of 0 1 to 0 4 with the one exception of a 0 5 value at bingham loss of low 37 cl chloride in vapor may balance chloride with a net 37 cl 0 in the porphyry deposits

origin of groundwater salinity in the fasa plain southern iran hydrogeochemical and isotopic approaches the study area the fasa plain is situated in the semiarid region of fars province in the south of iran the salloo diapir is a salt dome that crops out in the northwest of the study area isotopic and hydrochemical analyses were used to examine the water and how the origin of salinity and the diapir affect the quality of the groundwater quality in the study area groundwater was sampled from 31 representative pumping wells in alluvial aquifer and five springs in order to measure their stable isotope compositions bromide ion concentration and physical and chemical parameters the alluvial aquifer was organized into two main groups based on the chemistry with group 1 consisting of low salinity well samples 544 1744 s cm with water type ca mg hco3 so4 which were taken in the center and north of the area and group 2 consisting of high salinity samples 2550 4620 s cm with water type ca mg cl so4 which were taken from the wells in the south and southwest of the area a saline spring near the salt dome with an ec of 10 280 s cm has water type na cl while the compositions of the water in the other karstic springs is comparable to the fresh groundwater samples all groundwater samples are undersaturated with respect to gypsum anhydrite and halite and are supersaturated with respect to calcite and dolomite stable isotopes 18o and 2h differentiated four water types saline springs freshwater spring fresh groundwater and saline groundwater the results indicate that meteoric water is the main origin of these water resources halite dissolution from the salt dome was identified as the origin of salinity the na cl and cl br ratios confirmed the results groundwater compositions in the southwestern part of the area are affected by the intrusion of saltwater from the salt dome the average saltwater fraction in the some water wells is about 0 2 in the south and southwestern part of the area the saltwater fraction is positive in mixed freshwater saltwater group 2 different processes interact together to change the hydrochemical properties of fasa s alluvial aquifer the main processes that occur in the aquifer are mixing gypsum dissolution and calcite precipitation

using 81kr and noble gases to characterize and date groundwater and brines in the baltic artesian basin on the one million year timescale abstract analyses for 81 kr and noble gases on groundwater from the deepest aquifer system of the baltic artesian basin bab were performed to determine groundwater ages and uncover the flow dynamics of the system on a timescale of several hundred thousand years we find that the system is controlled by mixing of three distinct water masses interglacial or recent meteoric water 18 o 10 4 with a poorly evolved chemical and noble gas signature glacial meltwater 18 o 18 with elevated noble gas concentrations and an old high salinity brine component 18 o 4 5 90 g cl l with strongly depleted atmospheric noble gas concentrations the 81 kr measurements are interpreted within this mixing framework to estimate the age of the end members deconvoluted 81 kr ages range from 300 ka to 1 3 ma for interglacial or recent meteoric water and glacial meltwater for the brine component ages exceed the dating range of the atta 3 instrument of 1 3 ma the radiogenic noble gas components 4 he and 40 ar are less conclusive but also support an age of 1 ma for the brine based on the chemical and noble gas concentrations and the dating results we conclude that the brine originates from evaporated seawater that has been modified by later water rock interaction as the obtained tracer ages cover several glacial cycles we discuss the impact of the glacial cycles on flow patterns in the studied aquifer system

geochemistry of metal rich brines from central mississippi salt dome basin u s a abstract oil field brines are the most favored ore forming solutions for the sediment hosted mississippi valley type ore deposits detailed inorganic and organic chemical and isotope analyses of water and gas samples from six oil fields in central mississippi one of the very few areas with high metal brines were conducted to study the inorganic and organic complexes responsible for the high concentrations of these metals the samples were obtained from production zones consisting of sandstone and limestone that range in depth from 1900 to 4000 m 70 120 c and in age from late cretaceous to late jurassic results show that the waters are dominantly bittern brines related to the louann salt the brines have extremely high salinities that range from 160 000 to 320 000 mg l total dissolved solids and are na ca cl type waters with very high concentrations of ca up to 48 000 mg l and other alkaline earth metals but with low concentrations of aliphatic acid anions the concentrations of metals in many water samples are very high reaching values of 70 mg l for pb 245 mg l for zn 465 mg l for fe and 210 mg l for mn the samples with high metal contents have extremely low concentrations 2 s samples obtained from the smackover formation limestone have low metal contents that are more typical of oil field waters but have very high concentrations up to 85 mg l of h 2 s computations with the geochemical code solmineq 87 give the following results 1 both pb and zn are present predominantly as aqueous chloride complexes mainly as pbcl 4 2 and zncl 4 2 respectively 2 the concentrations of metals complexed with short chained aliphatic acid anions and reduced s species are minor 3 organic acid anions are important in controlling the concentrations of metals because they affect the ph and buffer capacity of the waters at subsurface conditions and 4 galena and sphalerite solubilities control the concentrations of pb and zn in these waters

milankovitch paced termination ii in a nevada speleothem 1 the devils hole dh calcite record from the great basin nevada provided the first radiometrically dated time series of late pleistocene climate fluctuations in doing so dh suggested that the penultimate deglaciation termination ii t ii occurred at 142 3 ka which is 10 kyr before the associated rise in summer insolation helping to launch the causality problem for milankovitch the interpretation of the dh record has been subject to considerable discussion ever since we present the first attempt to reproduce the dh record of an early t ii in the great basin based on a stalagmite from lehman caves nevada which is 400 km northeast of devils hole our speleothem records at least the latter part of t ii over its period of growth from 133 129 ka which appears to disagree with the early timing of t ii in dh dh also exhibits important differences from many other paleoclimate records over the past two deglaciations though these are reduced somewhat after ice volume correcting dh 18o we suggest that the climatic signal in the dh record remains to be fully explained

postglacial slip rate increase on the teton normal fault northern basin and range province caused by melting of the yellowstone ice cap and deglaciation of the teton range along the eastern front of the teton range wyoming prominent fault scarps offset pinedale deposits by up to 30 m and document that multiple earthquakes ruptured the range bounding teton normal fault after the last glacial period paleoseismological data suggest that 70 of the postglacial slip on the southern teton fault accumulated during or shortly after deglaciation before 8 ka here we use a three dimensional fi nite element model to show that melting of the yellowstone ice cap and the valley glaciers in the teton range may have caused the postglacial slip rate increase on the teton fault during deglaciation slip on our model fault accelerates by a factor of 6 with respect to the long term rate our model further shows that the impact of the melting yellowstone ice cap on fault slip increases along strike of the fault from south to north and is everywhere larger than the effect of the former valley glaciers in the teton range the results demonstrate that postglacial slip on faults in glaciated regions may not have been uniform through time rather a signifi cant fraction of slip may have accumulated within a few thousand years after the last glaciation we hypothesize that the rebound caused by the yellowstone ice cap has also triggered clusters of earthquakes on other normal faults in the surrounding basin and range province

chlorine stable isotope studies of old groundwater southwestern great artesian basin australia abstract stable cl isotope ratios 37 cl 35 cl were measured in groundwater samples from the southwestern flow system of the great artesian basin australia to gain a better understanding of the cl sources and transport mechanisms 37 cl values range from 0 to 2 5 smoc and are inversely correlated with cl concentration along the inferred flow direction the cl isotopic compositions in conjunction with other geochemical parameters suggest that cl in groundwaters is not derived from salt dissolution mixing of the recharge water with saline groundwater cannot explain the relationship between 37 cl and cl concentration measured marine aerosols deposited via rainfall and subsequent evapotranspiration appear to be responsible for the cl concentrations observed in wells that are close to the recharge area and in groundwaters sampled along the southern transect 37 cl values measured in the leachate of the bulldog shale suggest that the aquitard is the subsurface source of cl for the majority of groundwater samples studied diffusion is likely the mechanism through which cl is transported from the pore water of the bulldog shale to the aquifer however a more detailed study of the aquitard rocks is required to verify this hypothesis

northern hemisphere forcing of southern hemisphere climate during the last deglaciation changes in ocean circulation are the most plausible explanation for the early southern hemisphere deglacial warming and its lead over northern hemisphere temperature milankovitch theory which was developed to explain the relationship between earth s movement and the climate holds that glacial cycles are ultimately controlled by variations in northern hemisphere summer insolation exposure to the sun s rays spectral analyses of palaeoclimate records support this theory but a mechanistic test has been elusive other lines of evidence also show that climate changes in the southern hemisphere may have led those in the northern hemisphere casting doubt on the main theory here feng he and colleagues use a coupled ocean atmosphere model to show that the last deglaciation was indeed triggered by northern hemisphere insolation changes amplified by albedo co2 and ocean circulation changes according to the milankovitch theory changes in summer insolation in the high latitude northern hemisphere caused glacial cycles through their impact on ice sheet mass balance1 statistical analyses of long climate records supported this theory but they also posed a substantial challenge by showing that changes in southern hemisphere climate were in phase with or led those in the north2 although an orbitally forced northern hemisphere signal may have been transmitted to the southern hemisphere3 insolation forcing can also directly influence local southern hemisphere climate potentially intensified by sea ice feedback4 5 6 suggesting that the hemispheres may have responded independently to different aspects of orbital forcing signal processing of climate records cannot distinguish between these conditions however because the proposed insolation forcings share essentially identical variability7 here we use transient simulations with a coupled atmosphere ocean general circulation model to identify the impacts of forcing from changes in orbits atmospheric co2 concentration ice sheets and the atlantic meridional overturning circulation amoc on hemispheric temperatures during the first half of the last deglaciation 22 14 3 kyr bp although based on a single model our transient simulation with only orbital changes supports the milankovitch theory in showing that the last deglaciation was initiated by rising insolation during spring and summer in the mid latitude to high latitude northern hemisphere and by terrestrial snow albedo feedback the simulation with all forcings best reproduces the timing and magnitude of surface temperature evolution in the southern hemisphere in deglacial proxy records8 9 amoc changes associated with an orbitally induced retreat of northern hemisphere ice sheets10 is the most plausible explanation for the early southern hemisphere deglacial warming and its lead over northern hemisphere temperature the ensuing rise in atmospheric co2 concentration provided the critical feedback on global deglaciation9 11

cosmogenic 3he and 10be chronologies of the late pinedale northern yellowstone ice cap montana usa cosmogenic 3 he and 10 be ages measured on surface boulders from the moraine sequence deposited by the northern outlet glacier of the yellowstone ice cap indicate that the outlet glacier reached its terminal position at 16 5 6 0 4 3 he ka and 16 2 6 0 3 10 be ka respectively concordance of these ages supports the scaled production rates used for 3 he 118 6 6 6 6 atoms g 21 y r 21 and 10 be 5 1 6 0 3 atoms g 21 y r 21 62s at high latitudes at sea level two recessional moraines upvalley from the terminal moraine have mean ages of 15 7 6 0 5 10 be ka and 14 0 6 0 4 10 be ka respectively and a late glacial flood bar was deposited at 13 7 6 0 5 10 be ka these cosmogenic chronologies identify a late pinedale glacial maximum in northern yellowstone that is significantly younger than previously thought and they suggest deglaciation of the yellowstone plateau by 14 10 be ka

chlorine isotope distribution in formation waters texas and louisiana theoretically the chlorine isotope ratio 37cl 35cl can aid in identifying chloride sources and in distinguishing chloride transport mechanisms among formation waters if ratio differences exist among samples we measured the chlorine ratios of 18 formation water samples from oil fields along the texas louisiana gulf coast representing depths between 2 016 and 4 267 m chloride concentrations of samples ranged from 4 to 94 874 g l the chlorine ratios ranged from 1 24 to 0 58 pmil with respect to standard mean ocean chloride or smoc precision 0 12 pmil and enrichment of 37cl correlates with increasing concentration we also compared the isotope ratios of samples from within the weeks island salt dome with adjacent formation waters in louisiana all ratio measurements on the salt are between 0 1 and 0 3 pmil and for the formation waters are between 0 0 and 0 22 pmil the probability that the salt measurements differ from the waters is 99 we conclude that significant chlorine isotope ratio differences exist among formation waters and between the waters and potential sources in the gulf coast region and that the chlorine ratio will be a valuable tool in interpreting chloride geochemistry in this region

a cross calibration of chlorine isotopic measurements and suitability of seawater as the international reference material abstract a collection of 24 seawaters from various worldwide locations and differing depth was culled to measure their chlorine isotopic composition 37cl these samples cover all the oceans and large seas atlantic pacific indian and antarctic oceans mediterranean and red seas this collection includes nine seawaters from three depth profiles down to 4560 mbsl the standard deviation 2 of the 37cl of this collection is 0 08 which is in fact as large as our precision of measurement 0 10 thus within error oceanic waters seem to be an homogeneous reservoir according to our results any seawater could be representative of standard mean ocean chloride smoc and could be used as a reference standard an extended international cross calibration over a large range of 37cl has been completed for this purpose 13 geological fluid samples of various chemical compositions and a manufactured ch3cl gas sample with 37cl from about 6 to 6 have been compared data were collected by gas source isotope ratio mass spectrometry irms at the paris reading and utrecht laboratories and by thermal ionization mass spectrometry tims at the leeds laboratory comparison of irms values over the range 5 3 to 1 4 plots on the y x line showing a very good agreement between the three laboratories on 11 samples the trend line between paris and reading universities is 37clreading 1 007 0 009 37clparis 0 040 0 025 with a correlation coefficient r2 0 999 tims values from leeds university have been compared to irms values from paris university over the range 3 0 to 6 0 on six samples the agreement between these two laboratories using different techniques is good 37clleeds 1 052 0 038 37clparis 0 058 0 099 with a correlation coefficient r2 0 995 the present study completes a previous cross calibration between the leeds and reading laboratories to compare tims and irms results anal chem 72 2000 2261 both studies allow a comparison of irms and tims techniques between 37cl values from 4 4 to 6 0 and show a good agreement 37cltims 1 039 0 023 37clirms 0 059 0 056 with a correlation coefficient r2 0 996 our study shows that for fluid samples if chlorine isotopic compositions are near 0 their measurements either by irms or tims will give comparable results within less than 0 10 while for 37cl values as far as 10 either positive or negative from smoc both techniques will agree within less than 0 30

cosmogenic exposure age chronologies of pinedale and bull lake glaciations in greater yellowstone and the teton range usa abstract we have obtained 69 new cosmogenic 10be surface exposure ages from boulders on moraines deposited by glaciers of the greater yellowstone glacial system and teton range during the middle and late pleistocene these new data combined with 43 previously obtained 3he and 10be ages from deposits of the northern yellowstone outlet glacier establish a high resolution chronology for the yellowstone teton mountain glacier complexes boulders deposited at the southern limit of the penultimate ice advance of the yellowstone glacial system yield a mean age of 136 13 10be ka and oldest ages of 151 157 10be ka these ages support a correlation with the bull lake of west yellowstone with the type bull lake of the wind river range and with marine isotope stage mis 6 end moraines marking the maximum pinedale positions of outlet glaciers around the periphery of the yellowstone glacial system range in age from 18 8 0 9 to 16 5 1 4 10be ka and possibly as young as 14 6 0 7 10be ka suggesting differences in response times of the various ice cap source regions moreover all dated pinedale terminal moraines in the greater yellowstone glacial system post date the pinedale maximum in the wind river range by 4 6 kyr indicating a significant phase relationship between glacial maxima in these adjacent ranges boulders on the outermost set and an inner set of pinedale end moraines enclosing jenny lake on the eastern teton front yield mean ages of 14 6 0 7 and 13 5 1 1 10be ka respectively the outer jenny lake moraines are partially buried by outwash from ice on the yellowstone plateau hence their age indicates a major standstill of an expanded valley glacier in the teton range prior to the younger dryas followed closely by deglaciation of the yellowstone plateau these new glacial chronologies are indicative of spatially variable regional climate forcing and temporally complex patterns of glacier responses in this region of the rocky mountains during the pleistocene

asynchronous maximum advances of mountain and continental glaciers the last maximum glacier advance in many mountain ranges appears to have predated the last maximum advance of the wisconsinan continental ice sheets 20 000 years b p published evidence from widely spaced localities in north and south america europe asia and hawai i suggests that some mountain glaciers extended farther during one or more stades early in the last glaciation roughly 115 000 30 000 years b p than at its end when low global temperature and high precipitation presumably were most favorable for the growth of glaciers variations in the timing of glacier advances in different mountain ranges suggest that alpine glaciers are dependent on regional climate as well as global conditions their study might provide sensitive tests for theories of global climate change glacial deposits are often used as time markers in neotectonic and geomorphic studies and their ages sometimes are inferred from distant measurements or from proxy histories of global climate change undated geomorphic features such as moraines sharply incised streams and river terraces which commonly have been associated with the last maximum glacier advance 20 000 years b p or last deglaciation 13 000 years b p may actually be older by a factor of 2 to 4 or more conversely deposits assigned to the maximum advances of the penultimate global glaciation 130 000 years b p may actually date from early in the most recent glacial cycle and be younger by a comparable factor rates of faulting or folding estimated from displacements or deformation and the assumed ages of such geomorphic features might be too great or too small by corresponding factors

factors controlling li concentration and isotopic composition in formation waters and host rocks of marcellus shale appalachian basin in this study water and whole rock samples from hydraulically fractured wells in the marcellus shale middle devonian and water from conventional wells producing from upper devonian sandstones were analyzed for lithium concentrations and isotope ratios 7li the distribution of lithium concentrations in different mineral groups was determined using sequential extraction structurally bound li predominantly in clays accounted for 75 91 wt of total li whereas exchangeable sites and carbonate cement contain negligible li 3 up to 20 of the li is present in the oxidizable fraction organic matter and sulfides the 7li values for whole rock shale in greene co pennsylvania and tioga co new york ranged from 2 3 to 4 3 similar to values reported for other shales in the literature the 7li values in shale rocks with stratigraphic depth record progressive weathering of the source region the most weathered and clay rich strata with isotopically light li are found closest to the top of the stratigraphic section diagenetic illite smectite transition could also have partially affected the bulk li content and isotope ratios of the marcellus shale in greene co southwest pennsylvania the upper devonian sandstone formation waters have 7li values of 14 6 1 2 2sd n 25 and are distinct from marcellus shale formation waters which have 7li of 10 0 0 8 2sd n 12 these two formation waters also maintain distinctive 87sr 86sr ratios suggesting hydrologic separation between these units applying a temperature dependent illitilization model to marcellus shale we found that li concentration in clay minerals increased with li concentration in pore fluid during diagenetic illite smectite transition samples from north central pennsylvania show a much smaller range in both 7li and 87sr 86sr than those in southwest pennsylvania spatial variations in li and 7li values show that marcellus formation waters are not homogeneous across the appalachian basin marcellus formation waters in the northeastern pennsylvania portion of the basin show a much smaller range in both 7li and 87sr 86sr suggesting long term cross formational fluid migration in this region assessing the impact of potential mixing of fresh water with deep formation water requires establishment of a geochemical and isotopic baseline in the shallow fresh water aquifers and site specific characterization of formation water followed by long term monitoring particularly in regions of future shale gas development

near synchronous interhemispheric termination of the last glacial maximum in mid latitudes isotopic records from polar ice cores imply globally asynchronous warming at the end of the last glaciation however 10be exposure dates show that large scale retreat of mid latitude last glacial maximum glaciers commenced at about the same time in both hemispheres the timing of retreat is consistent with the onset of temperature and atmospheric co2 increases in antarctic ice cores we suggest that a global trend of rising summer temperatures at the end of the last glacial maximum was obscured in north atlantic regions by hypercold winters associated with unusually extensive winter sea ice

fossil brines preserved in the st lawrence lowlands quebec canada as revealed by their chemistry and noble gas isotopes abstract brines in cambrian sandstones and ordovician dolostones of the st lawrence lowlands at becancour quebec canada were sampled for analysis of all stable noble gases in order to trace their origin and migration path in addition to quantifying their residence time major ion chemistry indicates that the brines are of na ca cl type possibly derived from halite dissolution 87 sr 86 sr ratios and ca excess indicate prolonged interactions with silicate rocks of the proterozoic grenville basement or the cambrian potsdam sandstone the brines constrain a 2 3 contribution of mantle 3 he and large amounts of nucleogenic 21 ne and 38 ar and radiogenic 4 he and 40 ar 4 he 40 ar and 21 ne 40 ar ratios corrected for mass fractionation during incomplete brine degassing are identical to their production ratios in rocks the source of salinity halite dissolution plus the occurrence of large amounts of 40 ar in brines constrain the residence time of becancour brines as being older than the cretaceous evaporites in the st lawrence lowlands likely existed only during devonian silurian time brines might result from infiltration of devonian water leaching halite penetrating into or below the deeper cambrian ordovician aquifers during the devonian the basin reached temperatures higher than 250 c allowing for thermal maturation of local gas prone source rocks utica shales and possibly facilitating the release of radiogenic 40 ar into the brines the last thermal event that could have facilitated the liberation of 40 ar into fluids and contributed to mantle 3 he is the cretaceous monteregian hills magmatic episode for residence times younger than the cretaceous it is difficult to find an appropriate source of salinity and of nucleogenic radiogenic gases to the becancour brines

assessing climatic and nonclimatic forcing of pinedale glaciation and deglaciation in the western united states new 10 be surface exposure ages from adjacent valleys in the upper arkansas river basin colorado united states indicate that pinedale maxima culminated asynchronously at 22 4 1 4 19 2 0 2 17 8 0 6 and 15 8 0 4 ka but that deglaciation initiated synchronously between ca 16 and 15 ka these data are combined with published glacial chronologies across the western united states and indicate that although the ages of pinedale terminal moraines vary within individual ranges as well as regionally most western united states glaciers remained near their pinedale termini until ca 16 ka at which time widespread deglaciation commenced we hypothesize that the near synchronous demise of glaciers across the western u s between ca 15 and ca 13 ka was driven by the first major northern hemisphere warming following the last glacial maximum but that some differences in pinedale culmination ages can be explained by nonclimatic factors intrinsic to individual valleys these results suggest the need for caution in focusing exclusively on climate forcings to explain apparent asynchrony in pinedale maxima

numerical simulations of hurricane generated currents abstract the work described here involves the application of a three dimensional numerical circulation model to the hindcasting of currents generated during two storms tropical storm delia and hurricane anita reasonably high quality current and other data were collected during these two storms and are reported in the literature the hindcasted results of the two storms are used to assess the accuracy of the model and to explore the relative importance of the forcing mechanisms which affect water circulation during a tropical storm event the observed currents from both data sets indicate that the bottom shear stress is much larger than the surface shear stress during the storms implying that a forcing mechanism other than the local wind is important in driving flow during the storm two possible mechanisms have been suggested in the literature flow driven by pressure gradients and unsteady flow effects created by wind waves the circulation model is used to study the first mechanism and the results indi

preferential diffusion of 35cl relative to 37cl in sediments of kau bay halmahera indonesia kau bay a 470 m deep basin is separated from the pacific ocean by a shallow 40 m deep sill during the last glaciation this sill was above sea level and the bay turned into a freshwater lake after glaciation the sea level rose and the bay turned saline again since then chloride from the newly formed saline sediments diffused into the freshwater sediments as the sedimentation rate was constant throughout the holocene it is relatively easy to model the chloride concentration in the sediment pore water the diffusion coefficient of 35cl is slightly higher than the diffusion coefficient of 37cl thus variations in 37cl were expected in the pore water because the pore water history of kau bay is well known it was possible to use 37cl variations to determine the diffusion coefficient ratio d35d37 for the two stable isotopes of chlorine it was found that this ratio is 1 0023 in the pore water from sediments in this bay

geochemistry of hco 3 na thermal water from the gudian slope insights into fluid origin formation mechanism and circulation in the yitong basin northeast china abstract the goal of this paper is to systematically analyze the geochemical and isotopic characteristics 18o d t 13chco3 and doc of a hco3 na thermal water to determine its origin formation mechanism and circulation pattern in the gudian slope yitong basin northeast china schoeller diagrams and isotope data indicate that this thermal water is not connected to groundwater or river water and that its recharge source is immature water with low 18o and d values that originates from the changbaishan area this result was also confirmed by its doc 13c value approximately 24 which indicates that the c originates from c3 plants the analysis of na k mg diagrams indicates that the thermal waters except for one sample sjxk are fully equilibrated this observation combined with the results of the analysis for 18o d t and cation geothermometry data for the thermal water indicates that no water underwent mixing with cold water before arriving at the surface instead high temperature immature water flowed up from a deep reservoir and mixed with old formation water approximately 35 4 in the eocene reservoir these data indicate the occurrence of an interesting phenomenon in which the thermal water samples of the gd area exhibit a regression line with a negative slope and similar 18o values potentially due to the fractionation of co2 gas and a buffer of high hco3 concentrations rather than their short circulation times the high so4 cl b cl f cl and hco3 cl ratios and 13chco3 values ranging from 0 84 to 1 24 of these samples imply that magmatic volatiles have been dissolved in the thermal water however we cannot ignore the contributions of 13c from the leaching of limestone with a13c value of approximately 3 4 which is further supported by the br cl and hco3 cl ratios thus we analyzed the geological background and data collected from well chang 27 and deduced that a limestone stratum exists below the study area magmatic volatiles flow up through the lithospheric faults along the northwestern and southeastern edges of the basin encounter changbaishan area recharge water in the limestone reservoir form hot water with high concentrations of hco3 and then recharged into the eocene sandstone reservoir long term mineral hydrolysis and transformation reactions in the reservoir cause the concentrations of na to increase and lead to the formation of hco3 na water

extracting a climate signal from 169 glacier records i constructed a temperature history for different parts of the world from 169 glacier length records using a first order theory of glacier dynamics i related changes in glacier length to changes in temperature the derived temperature histories are fully independent of proxy and instrumental data used in earlier reconstructions moderate global warming started in the middle of the 19th century the reconstructed warming in the first half of the 20th century is 0 5 kelvin this warming was notably coherent over the globe the warming signals from glaciers at low and high elevations appear to be very similar

beryllium 10 dating of the duration and retreat of the last pinedale glacial sequence accurate terrestrial glacial chronologies are needed for comparison with the marine record to establish the dynamics of global climate change during transitions from glacial to interglacial regimes cosmogenic beryllium 10 measurements in the wind river range indicate that the last glacial maximum marine oxygen isotope stage 2 was achieved there by 21 700 700 beryllium 10 years and lasted 5900 years ages of a sequence of recessional moraines and striated bedrock surfaces show that the initial deglaciation was rapid and that the entire glacial system retreated 33 kilometers to the cirque basin by 12 100 500 beryllium 10 years

deep water circulation at the northern pyrenean thrust implication of high temperature water rock interaction process on the mineralization of major spring water in an overthrust area abstract in an overthrust context of the northern pyrenean area groundwater is affected by high mineralization sources a multi isotopic approach was used to track the origin of mineralization in a complex multilayer aquifer system through the study of a major regional spring the oeillal spring water osw which shows a not yet investigated geochemical singularity the aims of this study are to understand the hydrogeochemical evolution and the mineralization mechanisms of groundwater in a large scale aquifer extending over the northern pyrenean overthrust oriental corbieres based on an adequate set of geochemical and isotopic tracers including cosmogenic stable and radiogenic isotopes we have revealed complex hydrogeochemical processes that cannot be tracked with traditional hydrochemical and isotopic tracers the high 87 sr 86 sr ratios of the osw associated with relatively high concentrations in trace elements cs rb sr b li suggest the influence of brine from the triassic deposits containing saliferous clay orsaline fluids from the fractured basement the basement hypothesis may be considered regarding the hydro geochemical fingerprint of the paleozoic basement as demonstrated in previous study and further data would be required to validate the contribution of basement fluids contrasting with marine primary brine and current seawater the relatively high 37 cl 0 22 and 0 39 of osw attests the non marine origin of the chloride ion 36 cl cl shows that the osw is issued from a mixing process between recently recharged water lightly mineralized and significantly marked in 36 cl by the thermonuclear bomb pulse and a saline deep end member at secular equilibrium this indicates that cl in these springs is primarily derived from subsurface non meteoric sources the osw s low br cl molar ratio suggests the influence of simple dissolution of halite and or the contribution of more complex secondary brine the deep saline water may results from meteoric infiltration into the lower jurassic aquifer in contact with triassic deposits or deeper high temperature promotes water rock interaction enhancing leaching of mg k rich saliferous clay this is supported by environmental scanning electron microscopy esem analyses showing that i cl is found in accessory minerals from the kcl mgcl 2 h 2 o system of the triassic deposits and ii cs rb molar ratio is similar to that of osw ranging between 0 13 and 0 7 and from 0 13 to 0 4 respectively laboratory experiments carried out on triassic material show that high temperature water rock interaction is suitable to explain the relatively high 87 sr 86 sr observed in groundwater such process can be investigated to confirm the deep origin of the osw and to explain the signature of deep brines in contact with the triassic deposits under high temperature conditions basement fluid contribution may also be considered regarding the hydro geochemical fingerprint of the paleozoic basement as shown in previous studies further data would be required to validate this hypothesis

geochemistry and origin of formation brines from the paris basin france 2 saline solutions associated with oil fields abstract oil fields from the paris basin are located in three geological levels dogger middle jurassic rhaetian and keuper upper triassic the origin of water and dissolved salts in saline solutions associated with oil is investigated using the hypothesis that cl and br are conservative in solution in a diagram of cl br ratios vs cl the points of the dogger and the keuper aquifers lie in the zone of primary brines whereas those of the rhaetian are located in the zone of secondary brines the na cl ratio is very high in all of the saline solutions suggesting either a relatively poorly evolved brine at the beginning of halite deposition or some halite dissolution all of the saline solutions especially those from the dogger aquifer are clearly diluted dilution by meteoric waters would not alter the cl br ratio high concentrations of lithium rubidium and boron are attributed to the presence of an extremely evolved brine of marine origin in mixtures of secondary brines formed by dissolution of halite and small amounts of sylvite and ca sulphate mass balance calculations of the excess of cl with respect to na k allows the fraction x of water derived from the primary brine to be calculated assumptions are that all na and k is derived from the secondary brine and that the cl content of the primary brine is constrained by bischofite saturation at 11 000 mmol kg 1 the typical proportion of water from the primary brine waters is 0 7 in the dogger formation and 2 4 in the keuper values of the concentration factor cf expressed as the ratio of the molal concentration of a conservative ion in the evolved brine to its concentration in seawater have been calculated for lithium solutions from the dogger and keuper aquifers have cfli values of 1 8 103 and of 7 7 103 respectively in the rhaetian aquifer the linear relationship between heavy isotope contents of the brine 2h and 18o and the cl content indicates a mixture of two water sources the first one is meteoric water as defined by the intersection of the formation water line with the global meteoric water line 2 h 65 18 o 9 3 the other end member is enriched in heavy isotopes and in cl and is attributed to seawater that has dissolved evaporites mainly halite however the presence of small amounts of an extremely evolved brine is required to account for the bromide lithium rubidium and boron contents of the formation brine from the rhaetian aquifer as this contribution is very limited in amount it cannot affect the heavy isotope content of the formation water mass balance equations are solved for ternary mixtures of meteoric water seawater and brine the same constraints as above no na and k supplied by the primary brine and clbrine 11 000 mmol kg 1 are applied it is also assumed that the seawater component has the same ionic contents as modern seawater and that the salt content of the meteoric component is negligible the fraction of primary brines is x 1 4 according to the cl balance this estimate agrees with that obtained from the lithium balance assuming that the primary brine component was the same as that of the keuper formation water mass balance calculations also indicate that the so42 content of the rhaetian formation water is exclusively due to the secondary brine component in the three saline solutions the very high ca2 contents and high ca 2 mg 2 ratios may be attributed to reaction of the very evolved brine free of so2 4 with gypsum or anhydrite the result is an exchange of mg2 for ca2 which causes a release of ca2 to the solution and a precipitation of secondary mg sulphate this process can also account for the high strontium contents of the analysed samples values of the ratio 87 sr 86 sr are very high in the keuper formation water due to close contact of the solutions with the granitic basement or with granite derived detrital deposits values in the rhaetian and dogger aquifers equal those of upper triassic marine deposits the stable isotope 34s and 18o content of the dissolved aqueous so2 4 indicates a triassic origin for the bulk of sulphate involved in the evolution of formation waters from the rhaetian and from the dogger all geochemical indicators thus show a vertical migration of triassic brines however aqueous so2 4 from the keuper has a permian isotopic signature suggesting a reworking in solution of salts from this period

strontium isotopic composition of oil field and gas field waters japan abstract the87sr 86sr ratios of 10 formation waters in petroleum and natural gas reservoirs along the western coast of northeastern honshu japan ranged from 0 7052 to 0 7084 and are distinctly lower than the ratio in seawater this forms a marked contrast to oil field brines from the u s a which have higher87sr 86sr ratios taking into consideration that petroleum and natural gas in japan accumulate in volcanic rocks derived from intense submarine volcanism in the middle miocene the87sr 86sr ratios of the water samples are explained in terms of the isotope exchange between waters containing seawater sr and reservoir rocks with lower ratios

thermomineral waters of ca chloride composition review of diagnostics and of brine evolution ca chloride waters are defined as those in which q rca r so4 hco3 1 rna rcl 0 80 rmg rca 0 5 and wcl wbr 286 r meq l 1 and w mg l 1 throughout the last 50 years different models for the formation of such waters have been suggested these models include 1 filtration through semipermeable membranes under conditions of highly compacted argillaceous sediments 2 deaquation of seawater by evaporation and or by freezing followed by dolomitization 3 hydrolysis of plagioclase and biotites in igneous metamorphic rock masses 4 radiolytic modification of residual metamorphic fluids and 5 dissolution of chalks followed by ion exchange on smectites the better understanding of processes and of natural environments leading to the evolution and natural occurrence of such brines is imperative for the prospection and further sustained exploitation of such waters

deglaciation and postglacial environmental changes in the teton mountain range recorded at jenny lake grand teton national park wy abstract sediments contained in lake basins positioned along the eastern front of the teton mountain range preserve a continuous and datable record of deglaciation and postglacial environmental conditions here we develop a multiproxy glacier and paleoenvironmental record using a combination of seismic reflection data and multiple sediment cores recovered from jenny lake and other nearby lakes age control of teton lake sediments is established primarily through radiocarbon dating and supported by the presence of two prominent rhyolitic tephra deposits that are geochemically correlated to the widespread mazama 7 6 ka and glacier peak 13 6 ka tephra layers multiple glacier and climate indicators including sediment accumulation rate bulk density clastic sediment concentration and flux organic matter concentration flux 13c 15n and c n ratios and biogenic silica track changes in environmental conditions and landscape development sediment accumulation at jenny lake began centuries prior to 13 8 ka and cores from three lakes demonstrate that teton glacier extents were greatly reduced by this time persistent ice retreat in cascade canyon was slowed by an interval of small glacier activity between 13 5 and 11 5 ka prior to the end of glacial lacustrine sedimentation 11 5 ka the transition to non glacial sediments marks the onset of holocene conditions at jenny lake and reflects a shift toward warmer summers increased vegetation cover and landscape stability in the tetons we discuss the teton lake sediment records within the context of other regional studies in an effort to construct a comprehensive overview of deglaciation and postglacial environmental conditions at grand teton national park

dating fluvial terraces by 230th u on pedogenic carbonate wind river basin wyoming abstract reliable and precise ages of quaternary pedogenic carbonate can be obtained with 230th u dating by thermal ionization mass spectrometry applied to carefully selected milligram size samples datable carbonate can form within a few thousand years of surface stabilization allowing ages of quaternary deposits and surfaces to be closely estimated pedogenic carbonate clast rinds from gravels of glacio fluvial terraces in the wind river basin have median concentrations of 14 ppm u and 0 07 ppm 232th with median 230th 232th 270 making them well suited for 230th u dating horizons as thin as 0 5 mm were sampled from polished slabs to reduce averaging of long 105 yr and sometimes visibly discontinuous depositional histories dense translucent samples with finite 230th u ages preserve within rind stratigraphic order in all cases ages for terraces wr4 167 000 6 400 yr and wr2 55 000 8600 yr indicate a mean incision rate of 0 26 0 05 m per thousand years for the wind river over the past glacial cycle slower than inferred from cosmogenic nuclide dating terrace wr3 which formed penecontemporaneously with the final maximum glacial advance of the penultimate rocky mountain bull lake glaciation has an age of 150 000 8300 yr indicating that it is broadly synchronous with the penultimate global ice volume maximum

origin and evolution of formation water at the jujo tecominoacan oil reservoir gulf of mexico part 2 isotopic and field production evidence for fluid connectivity abstract the chemical and isotopic characterization of formation water from 18 oil production wells extracted from 5200 to 6100 m b s l at the jujo tecominoacan carbonate reservoir in se mexico and interpretations of historical production records were undertaken to determine the origin and hydraulic behavior of deep groundwater systems the infiltration of surface water during late pleistocene to early holocene time is suggested by 14c concentrations from 2 15 to 31 86 pmc and by 87sr 86sr ratios for high salinity formation water 0 70923 0 70927 that are close to the composition of holocene to modern seawater prior to infiltration the super evaporation of seawater reached maximum tds concentrations of 385 g l with lowest 18o values characterizing the most hypersaline samples minor deviations of formation water and dolomite host rocks from modern and jurassic 87sr 86sr seawater composition respectively suggest ongoing water rock interaction and partial isotopic equilibration between both phases the abundance of 14c in all sampled formation water 87sr 86sr ratios for high salinity water close to holocene present seawater composition a water salinity distribution that is independent of historic water cut and a total water extraction volume of 2 037 mmm3 1 83 4 07 excludes a connate oil leg origin for the produced water of the jurassic cretaceous mudstone dolomite sequence temporal fluctuations of water chemistry in production intervals the accelerated migration of water fronts from the reservoir flanks and isotopic mixing trends between sampled wells confirms the existence of free aquifer water below oil horizons vertical and lateral hydraulic mobility has probably been accelerated by petroleum extraction the combination of interpreting historical fluctuations of salinity and water percentage in production wells with chemical isotopic analysis of formation water resulted in a successful method to distinguish four groundwater bodies stratified vertically within the jujo tecominoacan reservoir two with low tds from 10 to 23 g l are preserved in the upper reservoir section mainly in lower cretaceous and kimmeridgian strata for the deeper part of the reservoir 87sr 86sr trends indicate an affiliation of most samples to two independent mixing trends between intermediate saline tds 200 g l and hypersaline 350 g l groundwater end members

reconciliation of the devils hole climate record with orbital forcing the driving force behind quaternary glacial interglacial cycles and much associated climate change is widely considered to be orbital forcing however previous versions of the iconic devils hole nevada subaqueous calcite record exhibit shifts to interglacial values 10 000 years before orbitally forced ice age terminations and interglacial durations 10 000 years longer than other estimates our measurements from devils hole 2 replicate virtually all aspects of the past 204 000 years of earlier records except for the timing during terminations and they lower the age of the record near termination ii by 8000 years removing both 10 000 year anomalies the shift to interglacial values now broadly coincides with the rise in boreal summer insolation the marine termination and the rise in atmospheric co2 which is consistent with mechanisms ultimately tied to orbital forcing

gas water rock interactions in frio formation following co2 injection implications for the storage of greenhouse gases in sedimentary basins to investigate the potential for the geologic storage of co2 in saline sedimentary aquifers 1600 t of co2 were injected at 1500 m depth into a 24 m thick sandstone section of the frio formation a regional brine and oil reservoir in the u s gulf coast fluid samples obtained from the injection and observation wells before co2 injection showed a na cacl type brine with 93 000 mg l total dissolved solids tds at near saturation with ch4 at reservoir conditions following co2 breakthrough samples showed sharp drops in ph 6 5 5 7 pronounced increases in alkalinity 100 3000 mg l as hco3 and fe 30 1100 mg l and significant shifts in the isotopic compositions of h2o dissolved inorganic carbon dic and ch4 geochemical modeling indicates that brine ph would have dropped lower but for the buffering by dissolution of carbonate and iron oxyhydroxides this rapid dissolution of carbonate and other minerals could ultimately create pathways in the rock seals or well cements for co2 and brine leakage dissolution of minerals especially iron oxyhydroxides could mobilize toxic trace metals and where residual oil or suitable organics are present the injected co2 could also mobilize toxic organic compounds environmental impacts could be major if large brine volumes with mobilized toxic metals and organics migrated into potable groundwater the d 18 o values for brine and co2 samples indicate that supercritical co2 comprises 50 of pore fluid volume 6 mo after the end of injection postinjection sampling coupled with geochemical modeling indicates that the brine gradually will return to its preinjection composition

stable chlorine isotopes in halite and brine from the gulf coast basin brine genesis and evolution stable chlorine isotope data used in conjunction with other geochemical parameters are useful in determining the origin of solute in formation waters with salinity different from that of seawater jurassic salt in the gulf coast basin has 37cl ranges of 0 5 to 0 3 bedded and 0 0 to 0 5 diapiric the values for bedded salt are consistent with a 37cl value of 0 0 for jurassic seawater chloride as in modern oceans the slightly higher values for diapiric salt are possibly caused by incongruent solution of halite formation waters have a 37cl range of 1 9 to 0 7 waters with 37cl 0 2 low salinity water from geopressured aquifers appears to have resulted from shale dewatering low 37cl values in such water are related to low mcl mna a parameter indicating dewatering but show no general relationship to cl br they are consistent with diffusion of chloride from allochthonous brine diffusion can generate domains of water with negative 37cl on a scale of hundreds of meters in 104 106 years and may also generate positive 37cl chloride in residual source brine

chemical and isotope composition of the oilfield brines from mishrif formation southern iraq diagenesis and geothermometry abstract this paper focuses on the geochemical composition and isotope geochemistry of brines in the cenomanian turonian carbonate mishrif reservoir of southern iraq main dissolved constituents trace elements 2h and 18o 87sr 86sr mineral saturation indices and thermodynamic calculations were investigated in formation waters from the mishrif formation to obtain a better understanding of brine evolution and diagenetic effects over geological time previous published 11b data were also reinterpreted as a geothermometer tool the results are compared with previous published data for local oilfields and coeval formations in the arabian gulf the mishrif brine has a marine origin and is diagenetically modified to ca excess and na deficit formation waters are quartz supersaturated and are in equilibrium with chalcedony and calcite dolomite in the temperatures range of 50 75 c which is also confirmed by calcite water oxygen isotope fractionation and 11b geothermometer the potential role of clays in conditioning brine chemistry during diagenetic processes was highlighted by activity diagrams in particular their adsorption exchange effect on sodium could explain the lower temperature obtained by the na li geothermometer 42 6 c the 2h and 18o values show that oxygen isotope composition of the brines was isotopically more affected by interaction with limestone during diagenesis than seawater evaporation the main effect is an 18o enrichment on the brine starting from the smow value locally dilution by present day meteoric water was also detected rumaila south which is shifted towards the local meteoric water line the strontium isotope ratios range from 0 707713 to 0 707749 and correspond to a marine strontium of late cenomanian early maastrichtian age except for the majnoon sample which shows a more radiogenic value 0 708043 radiogenic strontium and gypsum and anhydride saturation indices of the majnoon sample could indicate the contribution of calcium and sulphate from the strontium rich sulphate minerals of the cambrian salt domes occurring in the oilfields of southern iraq the higher manganese concentration 4 mg l and the slightly higher temperature inferred by geothermometers up to 74 c in comparison with present day could indicate that the majnoon brine is a hot fluid probably related to a deeper structure such as the zagros foredeep fault

hydrodynamic behavior of kangan gas capped deep confined aquifer in iran the kangan aquifer ka is located beneath the kangan gas reservoir kgr 2 885 m below the ground surface the gas reservoir formations are classified into nine non gas reservoir units and eight gas reservoir units based on the porosity water and gas saturation lithology and gas production potential using the logs of 36 production wells the gas reservoir units are composed of limestone and dolomite whereas the non gas reservoir units consist of compacted limestone and dolomite gypsum and shale the lithology of ka is the same as kgr with a total dissolved solid of 333 000 mg l the source of aquifer water is evaporated seawater the static pressure on the gas water contact gwc was 244 atm before gas production but it has continuously decreased during 15 years of gas production resulting in a 50 m uprising of the gwc and the expansion of ka water and intergranular water inside the gas reservoir the general flow direction of the ka is toward the northern coast of the persian gulf due to the migration of water to the overlying formations via a trust fault the ka is a gas capped deep confined aquifer gcdca with special characteristics differing from a shallow confined aquifer the main characteristics of a gcdca are unsaturated intergranular water below the confining layers no direct contact of the water table gwc with the confining layers no vertical flow via the cap rock permanent uprising of the gwc during gas production and permanent descend of gwc during water exploitation

late pleistocene glaciation and deglaciation in the crestone peaks area colorado sangre de cristo mountains usa chronology and paleoclimate abstract cosmogenic 10be surface exposure dating and numerical glacier modeling are used to reconstruct glacial chronology and climate in the colorado sangre de cristo mountains during the local last glacial maximum llgm and the subsequent deglaciation twenty two surface exposure ages on moraine boulders and polished bedrock outcrops in the willow creek valley and ten in two adjacent valleys indicate that glaciers were at or near their maxima from 21 ka until 17 16 ka and then retreated rapidly nearly deglaciating the willow creek valley entirely by 14 ka coupled energy mass balance and flow modeling of two of the glaciers indicates that if changing ice extent was driven only by temperature and insolation changes temperature depressions of 5 0 and 5 1 c from modern conditions with an uncertainty of approximately 1 5 1 0 c would have sustained the glaciers in mass balance equilibrium at their llgm extents doubling or halving of modern precipitation during the llgm would have been associated with 2 7 3 0 c and 6 9 7 0 c temperature depression respectively approximately half of the subsequent llgm to modern climate change was accomplished by 14 ka if the rapid main phase of deglaciation between about 16 ka and 14 ka was driven solely by temperature and insolation changes it would have been associated with a temperature rise of about 2 5 c at a mean rate of approximately 1 1 c ky this new chronology of the last glaciation is generally consistent with others developed recently in the colorado rocky mountains the numerical modeling however suggests a lesser llgm temperature depression from modern conditions than have most previous studies in colorado

strontium isotope evolution of late permian and triassic seawater the 87sr 86sr values based on brachiopods and conodonts define a nearly continuous record for the late permian and triassic intervals minor gaps in measurements exist only for the uppermost brahmanian lower part of the upper olenekian and middle norian and only sparse data are available for the late permian these 219 measurements include 67 brachiopods and 114 conodont samples from the tethyan realm as well as 37 brachiopods and one conodont sample from the mid european middle triassic muschelkalk sea the late permian lower triassic interval is characterized by a steep 1 3 10 3 rise from 0 7070 at the base of the dzhulfian to 0 7082 in the late olenekian a rate of change comparable to that in the cenozoic in the mid triassic anisian and ladinian the isotope values fall to 0 7075 followed again by a rise to 0 7081 in the middle late norian the 87sr 86sr values decline again in the late norian sevatian and rhaetian to 0 7076 the sharp rise in the 87sr 86sr values during the late permian early triassic was coincident with widespread clastic sedimentation because of the paucity of tectonic uplifts the enhanced erosion may have been due to intermittent humid phases during mainly an arid interval coupled with the absence of a dense protective land plant cover following the mass extinction during the latest permian the apex of the 87sr 86sr curve at the olenekian anisian boundary coincides with cessation of the large scale clastic sedimentation and also marks the final recovery of land vegetation as indicated by the renewed onset of coal formation in the middle triassic the rising 87sr 86sr values from the middle carnian to the late norian coincide with the uplift and erosion of the cimmeride indosinian orogens marking the closure of the palaeotethys the subsequent rhaetian decline that continues into jurassic pliensbachian toarcian boundary on the other hand coincides with the opening of the vardar ocean and its eastern continuation in the izmir ankara ophiolitic belt samples from the upper muschelkalk are more radiogenic than the global trend this may reflect separation of the basin from the open ocean due to strong meteoric influx from a large land mass in the north the germanic basin became increasing brackish up section in the north and east but because of the high evaporation rates the salt content was not much reduced in the southern and central basin where a rich but increasingly endemic marine fauna survived

evolution and origin of deep reservoir water at the activo luna oil field gulf of mexico mexico petroleum wells of the activo de produccion luna oil field at the mexican gulf coast are partially invaded by formation water at a production depth between 5000 and 6000 m measured 14c activities between less than 0 9 and 13 7 modern carbon reflect a homogenous late pleistocene early holocene age 40 10 ka for the regional infiltration of meteoric and marine water into the reservoir before infiltration both components were partially affected by atmospheric evaporation which explains the hypersaline composition of some formation waters very positive d18o values up to 12 5 of the formation waters are caused by strong secondary water rock interaction processes and reflect close to equilibrium conditions between the carbonate host rock and the fluids the formation of biogenic and or thermocatalytic methane in some parts of the petroleum reservoir is indicated by d13c values up to 20 4 southwest northeast directed hydraulic migration of the deep aquifer between camps sen and escuintle pijije caparroso is indicated by interference tests and pressure drawdown characteristics whereas northwest southeast trending thrust faults restrict communication toward the luna and tizon camps in the most northeastern part of the oil field on a local scale vertical zonation trends of the fluids with decreasing salinity toward upper parts of the common aquifer are related to separation processes by gravity and or by the rising of condensed vapor the migration of the fluids is mainly related to southwest northeast trending fractures and microfractures whereas northwest southeast and northeast southwest trending reverse and normal faults respectively behave irregularly as barrier or as flow conduits recently the extraction of petroleum caused an increased mobilization of the hydrodynamic aquifer system begin page 458

variable responses of western u s glaciers during the last deglaciation cosmogenic 10 be exposure ages from moraines in the wallowa mountains oregon identify two maximal late pleistocene glaciations at 21 1 6 0 4 ka and 17 0 6 0 3 ka and a minor glacial event at 10 2 6 0 6 ka our new high resolution chronology integrated with other well dated glacial records from the western united states demonstrates sub stantial differences in the synoptic responses of western u s glaciers to climate forcing associated with the global last glacial maximum and subsequent millennial scale events originating in the north atlantic region these variable synoptic glacier responses identify large changes in the relative contributions of regional to global controls on the climate of the western united states that accompanied the deglaciation