influence of the temperature of co2 rich springs on their aluminium and rare earth element contents abstract in a set of thermomineral waters of about constant major element composition al fe and rare earth element ree concentrations are strongly dependent on the spring temperature al and ree concentrations are not affected by co2 degassing at the outflow of the waters al concentrations vary by one order of magnitude between the coldest and the hottest waters this change in total concentration is related to a change in the speciation fluoride complexes mainly alf03 are the dominant species in cold waters hydroxide or fluoro hydroxide complexes are more important at higher temperature ree patterns vary smoothly as a function of the atomic number from a regular decrease for the hottest water ce yb 30 to a large increase from ce to dy followed by a slight decrease from dy to yb for the coldest waters ce yb 0 3 ce dy 0 15

226 ra excess ba growth rates and u th ra ba systematic of baltic mn fe crusts abstract we analyzed 238u 234u 232th 230th and 226ra by thermal ionization mass spectrometry tims and ba by inductively coupled plasma optical emission spectrometry icp oes on eight mn fe crusts from the mecklenburg bay sw baltic and on one from the bothnian bay n baltic to test the 226raex ba ratio as potential geochronometer 226raex ba ratios decrease as a function of depth within the concretions in all analyzed profiles calculated diffusion coefficients are relatively low 9 10 7 cm2 yr for ra and 5 10 7 cm2 yr for ba and suggest that diffusion is negligible for the ra and ba record in addition 226raex ba ages are consistent and independent from the growth rate and growth direction within a crust thus the decline in 226raex ba ratio is most likely due to radioactive decay of 226raex although the influence of varying oxic conditions has still to be evaluated 226raex ba growth rates range from 0 021 to 0 0017 mm yr and tend to be lower than those calculated and based on stratigraphic methods 1 to 0 013 mm yr 226raex ba ages of concretions from shallow water environment 20 m depth mecklenburg bay sw baltic cover a time interval from 990 140 yr to 4310 310 yr bp corresponding to the stabilization of the sea level close to the present position about 5500 to 4500 yr ago one sample from greater depth 70 m bothnian bay n baltic showed a higher 226raex ba age of 6460 520 yr bp

transport of u and th series nuclides in a baltic shield watershed and the baltic sea the transport of th ra and 210 pb from a continental source region and through an estuarine environment was investigated unlike previous studies here both short and long lived nuclide data were obtained for river inputs river water and estuarine waters the mire rich kalix river drainage basin was chosen as a typical northern shield area because this river may represent typical waters flowing into the arctic and northern seas groundwaters from bedrock and glacial tills have comparable th isotope concentrations and do not exhibit significant th isotopic shifts relative to host rocks the extensive peat deposits of the basin receive groundwater discharges and concentrate th and u but not ba and ra which cause high 230 th 232 th ratios in mire waters however mire outflows do not have a significant impact on th and ra isotopic compositions of the river overall weathering characteristics for the basin are obtained from the river data the 230 th 232 th 228 ra 226 ra and 226 ra ba river ratios are comparable to those of source rocks consistent with similar release rates of these nuclides from u th and ba bearing minerals river ratios of 230 th 238 u ar and 226 ra 238 u ar are 1 so that th and possibly ra are accumulating in the weathering regions and the weathering profile is still evolving low 228 ra 232 th ar and 226 ra 230 th ar ratios indicate that th is preferentially retained over ra river 234 th 238 u ar ratios are greater than 230 th 238 u ar ratios and suggest that in systems where river inputs are well characterized these ratios can be used to calculate th transit times through the watershed filtration data indicate that although a dominant fraction of the th is transported in the river on particles the rest is almost entirely carried by colloids the kalix river discharges into the baltic sea model calculations for the transport of th and ra isotopes in the baltic sea show that the high ratios of 234 th 238 u ar found here reflect long th residence times relative to particle scavenging of 50 d the water column 232 th budget is dominated by eolian inputs the 226 ra concentrations may be higher than those of water inflows with 60 derived from underlying sediments a greater fraction of 228 ra is derived from sediments to balance the decay of 228 ra within the water column during the 35 yr residence time of water in the baltic the baltic 228 ra 226 ra ar ratios which are relatively constant over a range of salinities are fortuitously similar to those of the river inflows

assessing the potential consequences of co2 leakage to freshwater resources a batch reaction experiment towards an isotopic tracing tool abstract the assessment of the environmental impacts of co 2 geological storage requires the investigation of potential co 2 leakages into fresh groundwater particularly with respect to protected groundwater resources the geochemical processes and perturbations associated with a co 2 leak into fresh groundwater could alter groundwater quality indeed some of the reacting minerals may contain hazardous constituents which might be released into groundwater since the geochemical reactions may occult direct evidence of intruding co 2 it is necessary to characterize these processes and identify possible indirect indicators for monitoring co 2 intrusion the present study focuses on open questions can changes in water quality provide evidence of co 2 leakage which parameters can be used to assess impact on freshwater aquifers what is the time scale of water chemistry degradation in the presence of co 2 the results of an experimental approach allow selecting pertinent isotope tracers as possible indirect indicators of co 2 presence opening the way to devise an isotopic tracing tool the study area is located in the paris basin france which contains deep saline formations identified as targets by french national programs for co 2 geological storage the study focuses on the multi layered albian fresh water aquifer confined in the central part of the paris basin a major strategic potable groundwater overlying the potential co 2 storage formations an experimental approach batch reactors was carried out in order to better understand the rock water co 2 interactions with two main objectives the first was to assess the evolution of the formation water chemistry and mineralogy of the solid phase over time during the interaction the second concerned the design of an isotopic monitoring program for freshwater resources potentially affected by co 2 leakage the main focus was to select suitable environmental isotope tracers to track water rock interaction associated with small quantities of co 2 leaking into freshwater aquifers in order to improve knowledge on the albian aquifer and to provide representative samples for the experiments solid and fluid sampling campaigns were performed throughout the paris basin albian groundwater is anoxic with high concentrations of fe a ph around 7 and a mineral content of 0 3 g l 1 macroscopic and microscopic solid analyses showed a quartz rich sand with the presence of illite smectite microcline apatite and glauconite a water mineral co 2 interaction batch experiment was used to investigate the geochemical evolution of the groundwater and the potential release of hazardous trace elements it was complemented by a multi isotope approach including 13 c dic and 87 sr 86 sr here the evolution of the concentrations of major and trace elements and isotopic ratios over batch durations from 1 day to 1 month are discussed three types of ion behavior are observed type i features ca sio 2 hco 3 f po 4 na al b co k li mg mn ni pb sr zn which increased after initial co 2 influx type ii comprises be and fe declining at the start of co 2 injection then type iii groups element with no variation during the experiments like cl and so 4 the results of the multi isotope approach show significant changes in isotopic ratios with time the contribution of isotope and chemical data helps in understanding geochemical processes involved in the system the isotopic systems used in this study are potential indirect indicators of co 2 water rock interaction and could serve as monitoring tools of co 2 leakage into an aquifer overlying deep saline formations used for c sequestration and storage

osmium in the rivers there is a large uncertainty in our understanding of the behavior of osmium during weathering and transport into deep oceans and the osmium budget of the oceans the problem stems chiefly from the lack of osmium data on the dissolved load in the rivers and in the estuaries in this study the concentration and isotopic composition of osmium have been determined in three north american rivers the mississippi the columbia and the connecticut and one river draining central europe and flowing into the baltic sea the vistula osmium concentration in the mississippi and the vistula is about 45 femto mol kg 1 it is about 14 and 15 femto mol kg 1 for the connecticut and the columbia respectively the 187 os 186 os ratios estimated for the mississippi and the vistula are 10 4 and 10 7 respectively for the connecticut and the columbia 187 os 186 os 8 8 and 14 4 respectively of all the rivers examined the mississippi is by far the largest supplying 1 6 of the total annual world river flow its osmium isotopic composition is identical to the upper mississippi valley loesses esser and turekian 1993a indicating 1 congruent dissolution of the bedrock and 2 little or no impact of anthropogenic sources on the osmium isotopic composition of the dissolved load the latter observation indicates that the upper limit of the anthropogenic input in the dissolved osmium load of the mississippi outflow is about 250 g yr 1 while the osmium concentration of the vistula is high the isotopic composition does not appear to have been affected by substantial pollution the river data can be used to put limits on the mean residence time of osmium in the oceans t os and on the osmium budget of the oceans if the bulk river influx of dissolved osmium into the oceans is similar to that of the mississippi we get a value for the net riverine inflow of osmium of 1680 mol yr 1 if there were no sequestering of osmium in the estuaries this would give a value of t os of 1 3 10 4 years as the estuaries may trap a significant amount of river osmium this is a lower limit so that t os 1 3 x 10 4 years using the iridium data by anbar et al 1996 the os ir ratio for the vistula is 2 8 we infer that there is no large fractionation between osmium and iridium during the transport of these elements from the continents into the oceans it follows that the high os ir ratio 22 observed in seawater must be related to the different rain out mechanisms of these elements in the estuaries or in the oceans

quantitative modelisation of differential erosion between cristalline and sedimentary area of a french basin by isotopic analysis of strontium in river waters

microbial control on the precipitation of modern ferrihydrite and carbonate deposits from the cezallier hydrothermal springs massif central france abstract actively precipitating hydrous iron oxides and carbonates are commonly associated with cool co2 rich spring waters in the massif central france chemical isotopic and mineralogical analyses and thermodynamic calculations were undertaken to elucidate the processes involved in the formation of these deposits hydrous iron oxide particles rich in al si ca and as are the first to form in the springs accompanying the iron oxides are layered carbonate deposits composed mainly of well crystallised calcite sem examination of both oxides and carbonates sampled at the outlet of the springs shows that they basically consist of grape shaped agglomerates of small 300 nm to 1 m anhedral crystals light acid etching of these agglomerates reveals colonies of spherical nannobacteria water trace partitioning between oxide and carbonate favours the hydrous oxide with as pb zn th concentration the microscopic features of both types of deposit indicate that microbial mediation probably contributes to their formation

surface water groundwater interactions in an alluvial plain chemical and isotopic systematics our work on the loire river forms part of a french national research program dedicated to wetlands and aims to better understand the global functioning of the system from the hydrological geochemical ecological and sociological aspects the present study using a coupled hydrological and geochemical stable and sr isotopes approach focuses on the soulangy site with its secondary anastomosing channels just below the confluence of the loire and allier rivers and also on the dorna nt site with two unconnected oxbow lakes 50 km upstream of the confluence the stable isotopes of water 18o 2h show that the alluvial or riverbank aquifer feeds the loire river during the summer but is not recharged by the river during flood periods in the winter the alluvial groundwater thus has a purely local origin from precipitation the major elements reveal an anthropogenic input of cl and more importantly of no3 especially near farms the 87sr 86sr isotopes identify different groundwater layers in the alluvium i e an upper and a lower alluvial aquifer and a perched aquifer at dornant that have relatively complex relationships with the surface water the two main rivers loire and allier present distinct geochemical characteristics reflecting the different lithologies that they drain upstream in addition the secondary channels lying parallel to the loire main stream at the soulangy site give different geochemical signatures which shows that they are not fed by the same overflows of the loire they are more or less well connected to the upper level of the alluvial plain and a longitudinal study of one of these channels has revealed a loire river influence progressively replaced by a water contribution from the upper alluvial aquifer similarly the two oxbow lakes at the dornant site are not supplied by the same water during the summer months a conceptual scheme of the loire hydrosystem based on 18o and 87sr 86sr suggests that the isotopic variations of the loire river can be related to a massif central surface water supply for the loire and allier main streams and to a groundwater supply from the alluvial plains

strontium dissolved and particulate loads in fresh and brackish waters the baltic sea and mississippi delta a study was conducted of the isotopic composition and concentration of sr and of major elements in dissolved and suspended loads of fresh and brackish waters the purpose was to establish the contributions of different parent rocks and minerals to sr during weathering and transport and to identify the role of fe mn oxyhydroxides in the redistribution of sr in the water column during the sedimentary cycle studies were conducted on a profile across an oxic anoxic boundary in the baltic and on rivers covering behavior over an annual cycle in general the 87sr 86sr ratios differ between particulate and dissolved loads with more radiogenic sr in the particulate loads these differences are attributed to differential weathering of minerals where high rb sr minerals dominate the particulate load and low rb sr the dissolved load there is broad correlation of 87 sr 86 sr with k al in the suspended load the differences in 87 sr 86 sr between suspended and dissolved load are highly variable and are related to the fe or mn concentration on the particulates in samples with high fe al the difference becomes small a good correlation was found between sr al and fe al or mn al in the particulates both in brackish and fresh waters sr is removed from solution both in rivers and in the baltic sea whenever there is formation of fe mn oxyhydroxide particulates this precipitation greatly diminishes the difference in isotopic composition of the dissolved and suspended loads as the particles containing fe mn oxyhydroxides settle they dissolve in anoxic zones and release sr this provides a mechanism for sr redistribution in the water column sr is thus only quasi conservative in environments where fe mn oxyhydroxides form or dissolve from consideration of the isotopic differences in sr between dissolved and suspended loads it follows that the net sr input depends upon weathering characteristics of the contributing mineral phases changes in weathering mechanisms due to climate change may cause sr isotopic shifts in the marine environment

geochemistry and water dynamics of a medium sized watershed the herault southern france abstract the aim of this study of the herault watershed is to constrain the river groundwater relations with a global geochemical investigation major and trace elements radiogenic isotopes sr pb and stable isotopes oxygen deuterium among the six sampling campaigns in high and low flows this paper focuses on the first one march 1995 sampled during a low flow period for major and trace elements and sr isotopes on both dissolved and particulate loads a companion paper will focus on the river karst relations in a dynamical scheme over a complete hydrological cycle the objective of this paper is to constrain the spatial organisation of the different water reservoirs to show the relations between surficial and groundwaters and to assess the mechanical and chemical weathering in this low flow period the herault main stream successively drains a palaeozoic basement a karstified mesozoic cover and a tertiary and quaternary alluvial plain the different tributaries also drain these lithologies this watershed is also impacted by ancient mining and agricultural activities especially in the southern part major element concentrations generally reflect the drained lithologies the chemistry of the herault main stream is mainly controlled by silicate and carbonate endmembers whereas the karstic springs show clearly a mixture of limestones and dolomitic limestones major elements point out some specific characteristics of some karstic springs and sr isotopes are used to check previous underground circulation hypotheses and sometimes reveal strong connections with overlying surface waters mixing phenomena between the herault river and its tributaries can be quantified in the 87 sr 86 sr vs 87 rb 86 sr diagram based on a simple two component scheme and agree within 10 with the real discharge measurements as in large basins the suspended matter presents more variable and more radiogenic 87 sr 86 sr than the dissolved load due to the more important contribution of silicate particles which are less soluble than carbonate dissolved ca fluxes were estimated to be 36 51 and 38 kg km 2 day 1 in the palaeozoic basement the mesozoic cover and the alluvial plain respectively this implies a chemical erosion estimated to be 20 m year in the palaeozoic basement and 58 m year in the mesozoic cover similar to values calculated for large basins

a spring and wooded habitat at flk zinj and their relevance to origins of human behavior the 1959 discovery of the hominin fossil zinjanthropus boisei brought the world s attention to the rich records at olduvai gorge tanzania subsequent excavations of archaeological level 22 flk zinj bed i uncovered remains of homo habilis and a high density collection of fossils and oldowan stone tools the occurrence of this unusual collection of bones and tools at this specific location has been controversial for decades we present paleoecological data that provide new insights into the origin of flk zinj our recent excavations 200 m north of the site uncovered a 0 5 m thick tufa mound draped by tuff ic in the same stratigraphic horizon as level 22 stable isotope analyses indicate that the carbonates were deposited by a freshwater spring phytolith analysis of the waxy clay under tuff ic revealed abundant woody dicotyledon and palm phytoliths indicating that the site was wooded to densely wooded the time equivalency and close physical proximity of the two environments indicate the two are related this study has provided the first documented evidence of springs in bed i and these data have important implications for the interpretation of hominin behavior in meat acquisition and the ongoing debate on scavenging versus hunting

new excavations at the flk zinjanthropus site and its surrounding landscape and their behavioral implications renewed excavations at flk zinj and its surrounding landscape have yielded valuable information regarding its paleoecological situation and the prehistoric behavioral function of the site the density of materials at the main cluster of the site excavated by leakey contrasts with the bone and lithic scatters surrounding the site the location of flk zinj situated a few hundred meters away from a freshwater spring would have enabled hominins access to water plants and game the appeal of the spot for hominins also explained by the presence of a wooded habitat is confirmed by inferences of its redundant use prior and during the formation of the flk zinj paleosol as witnessed by materials accumulated both under and on the waxy clay deposit that constitutes the flk zinj stratum the single cluster nature of the site indicates central place behavior and evidence is provided that hominins occupied the site at a time of very low predation hazards in the area

strontium isotopic constraints on the origin of ore forming fluids of the viburnum trend southeast missouri abstract we have measured 87 sr 86 sr and rb and sr concentrations in several minerals primarily sulfides spanning the paragenesis of hydrothermal mineralization in the viburnum trend in southeast missouri separate measurements were made for fluid inclusions opened by crushing or thermal decrepitation and for the solids for comparison measurements were also made on samples of probable local aquifers the bonneterre formation and the lamotte sandstone for some of the samples concentrations of k ca cl na and mg are also reported in several cases 87 sr 86 sr ratios are different higher in the solids than in the fluid inclusions we have investigated the possibility that either type of sample gives spurious results e g that the fluid inclusions are secondary or contaminated by host dolomite or that sr in the solids reflects a detrital rather than an authigenic source consideration of mass balance overall solute chemistry and examination of non sulfide dissolution residue however suggests that both types of sample reflect primary fluid sr composition we thus adopt the working hypothesis that sr isotopic composition in fluids at the time of hydrothermal mineralization was highly variable the observed results for the viburnum trend do not conform well to expected trends for mississippi valley type mvt mineralization based primarily on analyses of gangue carbonates barite and fluorite fluid inclusion sr in some of the viburnum trend samples is more radiogenic than in the host dolomite but only moderately so in other samples notably main stage octahedral galena fluid inclusion sr composition is within the range observed for the host dolomite in contrast sr in some of the sulfides is very radiogenic much more so than previously reported for mvt minerals and is very radiogenic early in the paragenesis pyrite chalcopyrite sphalerite less radiogenic during main stage ore deposition and again more radiogenic in later paragenetic stages

hydrogeochemistry and strontium isotopes in the arno river basin tuscany italy constraints on natural controls by statistical modeling summary in this paper the chemistry of major and trace elements and for the first time strontium isotopic ratios measured in running waters from the arno river basin tuscany central northern italy and thermal springs discharging in the same hydrographic system are presented and discussed classical graphical methods e g mixing diagrams have here been improved to identify in a correct statistical sample space extreme chemical compositions attributable to the action of geochemical processes and or inherited from specific lithologies namely contributions or components 1 2 and 3 to be used in inverse modeling procedures due to the absence of clear end members a linear least squares problem with non negativity constraints and distances as required for compositional data convex linear mixing was solved by considering the contribution of the most discriminant variables given by the 87 sr 86 sr isotopic ratios and the concentration of ca 2 mg 2 sr and rb following such approach it can be assumed p 2 mg 2 hco 3 radiogenic rich 87 sr 86 sr 0 71274 rb sr 0 039 represents a dominant feature at basin scale with a weight ranging from 69 to 100 much lower percentages are related to component 2 represented by a ca 2 mg 2 so 4 2 facies with intermediate 87 sr 86 sr 0 70874 and low rb sr 2 8 10 4 ratios and component 3 identified by ca 2 hco 3 facies with less radiogenic 87 sr 86 sr 0 70827 and low mg 2 ca 2 0 011 ratios these components are mainly dominated by the dissolution of evaporitic rocks and or mixing with thermal waters in the southern part of the arno river basin and by dissolution of the carbonatic fraction kinetically favored with respect to that of the silicatic minerals in the upper reaches of the main course and its tributaries respectively

the flk zinj paleolandscape reconstruction of a 1 84 ma wooded habitat in the flk zinj amk ptk ds archaeological complex middle bed i olduvai gorge tanzania abstract we have analyzed the phytolith content of 37 samples from the paleosol capped by tuff ic dated 1 84 ma within middle bed i at olduvai gorge tanzania samples were obtained from different trenches sampling an area of about 25 ha to document the paleovegetation associated with the abundant faunal remains and hominin artifacts in flk amk ptk and ds sites the analysis reveals the abundance of globular granulate and forest indicator phytoliths from 3 to 86 relative to the total number of phytoliths in the assemblages attributed to woody plants and of short cell grass phytoliths up to 22 the presence of palm phytoliths up to 57 attests for meso haline soils in the area in agreement with the presence of the saline alkaline olduvai paleolake and one or more groundwater discharge areas freshwater springs and or wetland phytoliths provide botanical evidence for a mixed paleovegetation dominated by forest and woodland with patches of open spaces occupied by grasses prior to the deposition of tuff ic the presence of fern phytoliths in some assemblages suggest shaded and humid habitat which supports the presence of freshwater watercourses or springs that might have attracted hominins and other animals yet we have found that our phytolith extractions residues also include micrometric zeolites chabazite clinoptilolite phillipsite which attest that the phytolith signal in the zinj paleosols is certainly affected by dissolution this study completes the spatial analysis of the area and reveals that the wooded area extends north south and west of flk zinj with palm trees preferentially located in the periphery like the zinj amk and ds sites the phytolith inferred distribution of plants does not support the hypothesis that topography was influential in the location of these sites particularly given that trees and or shrubs were dominant all over rather it is the presence of freshwater ponds that seem to have been the attractive factor for hominins at this particular place and time

les eaux thermales des granites de galice espagne des eaux carbogazeuses aux eaux alcalines thermal waters from granites of galicia spain from co2 rich to high ph waters abstract thermal waters from galicia spain range from co 2 rich low ph to high ph sulfide rich waters going through intermediate waters in order to explain the variations of their chemical composition we present a discussion of the major factors governing the water composition we eiscuss especially the isochemical recrystallization of a granite it is shown that the equilibrium mineral association of the water alkali granite system is unique for chalco alkaline granites two different associations are possible depending on the chemical composition of the granite the effect of an addition of co 2 is also discussed some criteria allowing a distinction between fully equilibrated and non equilibrated waters are presented finally the composition of galician waters is explained by different initial co 2 contents and by different values of the degree of the granite water reaction progress

the transport of osmium and strontium isotopes through a tropical estuary abstract we have determined the concentration and isotopic composition of os and sr in the estuarine waters from the godavari delta in peninsular india additionally we have obtained the concentration and isotopic composition of os and al concentration in selected suspended particulate matter recovered on 0 45 m filters the na k mg and ca concentrations of water samples obtained along salinity gradients from two distributary channels in the delta display a general two component mixing between river and sea water the data also reveal that al behaves non conservatively and is affected by interactions with suspended particulates the 87 sr 86 sr ratio of the riverine end member is 0 716303 and shows a linear decrease with salinity to seawater value and sr isotope systematics indicate that its behavior is conservative in the estuary the 187 os 188 os ratio of the godavari river end member is 1 24 and within error of the average eroding upper continental crust the concentration and isotopic composition of os through the two salinity transects shows that its behavior in the godavari estuary is complex and non conservative by comparing the al os ratios and os isotopes in the waters with those of the suspended particulate we find that both os gains and losses occur in the water column however in one of the distributaries vasishta the os concentration of suspended load increases and that of dissolved load decreases with increasing salinity towards the bay of bengal end member we infer that there is removal of seawater os at higher salinities the estimated mean residence time of os in the oceans is 37 14 2 kyr a comparison of the os concentration of the bay of bengal and the indian ocean waters indicates that the rainout rate of os in bay of bengal is 30 faster than that in the open ocean and suggests that the observed discrepancy between the mean residence time calculated from mass balance considerations and that estimated from the relaxation of the os isotopic ratio in marine record may not be real as the relaxation time experiments likely estimate the residence time for a basin sub basin and not for the entire ocean

surface deformations associated with the 2001 mw 7 8 kunlun earthquake northern tibet geomorphic growth features along a major strike slip fault

isotopic and trace element constraints on the origin and evolution of saline groundwaters from central missouri na ca cl groundwaters with salinities of 1 to 30 discharge from natural springs and artesian wells in mississippian carbonates and ordovician sandstones and carbonates in central missouri carbonate saturation and quartz supersaturation are maintained throughout the salinity range major and trace element and isotopic variations in the waters are used to place constraints on models for rock water interaction and regional hydrology the groundwaters have d values that range from 108 to 45 and 18 o values that range from 14 7 to 6 5 smow these data lie approximately along the meteoric water line ranging from values similar to local recharge in missouri to significantly lower values that are similar to 18 o and d for meteoric recharge in high altitude and high latitude regions of north america the more saline samples have the lowest 18 o and d contents a trend that is opposite to that observed in most other studies of saline waters the h o isotopic correlation and the range in salinity and several major and trace element concentrations in central missouri groundwaters are readily explained by a saline dilute water mixing model 87sr 86sr ratios for the groundwaters range from 0 7155 to 0 7161 these values are significantly higher than previously published values for 1 estimates of 87 sr 86 sr in phanerozoic seawater 0 7068 0 7092 and 2 carbonates of the mississippian burlington keokuk fm 0 7075 0 7105 through which some of the waters migrate as they pass to the surface nd 0 values in the groundwaters range from 10 9 to 8 1 and 147 sm 144 nd ratios range from 0 108 to 0 128 these values are similar to or lower than previously published analyses of carbonates and other authigenic phases from the burlington keokuk fm mean nd 0 7 8 0 8 1 mean 147 sm 144 nd 0 141 the h o sr and nd isotopic data and the results of model calculations preclude 1 models involving the modification of ancient seawater for the origin of the saline waters and 2 extensive interaction between the groundwaters and their host carbonates the waters apparently acquired their 18 o and d values as meteoric recharge and their 87sr 86sr and rare earth element signatures from extraformational crustal sources high 87 sr 86 sr low nd 0 low 147sm 144nd and largely preserved these isotopic signatures during subsequent migration through the carbonates chemical exchange via rock water interaction is required for isotopic exchange to occur therefore the present state of chemical equilibrium between the groundwaters and carbonate aquifer minerals may serve to limit rock water interaction and hence preserve the extraformational isotopic signatures in the waters the integration of geochemical isotopic and hydrologic data on a local and regional scale suggests a history for the central missouri groundwaters involving 1 meteoric recharge in the front range of colorado 2 dissolution of permian halite in the subsurface of kansas 3 interaction with predominantly silicate mineral assemblages in paleozoic strata and possibly precambrian basement with aquisition of crustal sr and ree signatures 4 dilution and migration to shallow aquifer levels in central missouri and 5 mixing with local meteoric recharge through mississippian carbonates with no significant change of the isotopic signatures acquired in stage 3

strontium isotope evidence on the history of oilfield brines mediterranean coastal plain israel abstract the isotopic composition of sr in oil field brines from the mediterranean coastal plain was determined in 18 drillholes 13 of which are oil producing wells the brines are characterized by salinities ranging from 35 to 93 g l tds sr from 28 to 350 mg l sr ca molar ratios from 0 011 to 0 053 and 87 sr 86 sr ratios from 0 7075 to 0 7090 e a 0 7081 0 0004 2 the brines are classified into two groups 1 a mavqi im group brines with relatively high 87 sr 86 sr ratios 0 7087 and 0 7090 sampled from elastics dolomites and anhydrites of upper miocene age 2 b heletz group brines with relatively low 87 sr 86 sr ratios 0 7075 to 0 7081 sampled from sandstones and dolomites of lower cretaceous age equations were derived to show the relations between 87 sr 86 sr ratio of the brines and the processes through which they evolved dolomitization and dissolution reprecipitation it is suggested that both groups of brines originated from mediterranean evaporated seawater during the messinian desiccation the strontium isotope composition of the seawater is reflected in that of both groups of brines the mavqi im group containing the original 87 sr 86 sr ratio 0 7088 the heletz group evolved later on through exchange reactions of those primary brines with a carbonate sequence of cretaceous age and consequently new 87 sr 86 sr ratios 0 7078 could have been developed the effect of the dissolution reprecipitation reactions on the carbonate rocks is estimated to be very slight only around 1 by weight

the strontium isotope budget of the warta river poland between silicate and carbonate weathering and anthropogenic pressure abstract the sr isotope composition 87 sr 86 sr and sr content of waters of the warta river central western poland and its tributaries were used to fingerprint water sources and their interactions in space and time dissolved sr in river water of the warta is characterized by a relatively narrow range of the 87 sr 86 sr values from 0 7090 to 0 7105 which contrasts with a strong variation in isotopic signatures of the tributaries from 0 7080 to 0 7121 with the exception of three streams which include inputs of mine waters the waters of tributaries are more enriched in 87 sr than the master stream the overall sr budget of the warta watershed is determined by the relative contributions of carbonate dissolution and silicate weathering it can be accounted for by mixing between waters from three reservoirs 1 groundwater charged with sr through interaction with sr bearing clay minerals 2 groundwater related to weathering dissolution of carbonate rocks and 3 atmospheric waters charged with sr from the near surface weathering and wash out of quaternary glaciogenic deposits superimposed on the natural sr isotope systematics is impact of mine waters and fertilizers the former providing non radiogenic sr from the permian mesozoic aquifers constitutes an important anthropogenic element of the sr budget whereas the impact of the latter is presumably common but of minor importance the present day sr isotope systematics of the warta is temporary and different from that of the pre industrial times

a model for the exchange of water and salt between the baltic and the skagerrak abstract a model for the exchange of salt and water between the baltic and the sea the skagerrak is presented because of strong inter basin interactions in the baltic entrance area the model must include the kattegat and the belt sea these are modeled by horizontally homogeneous two layer sub models the most prominent dynamical properties of the sub models are wind driven entrainment flows and rotational baroclinic hydraulic controls the model is driven by a meteorologically forced barotropic transport qh calculated from the freshwater supply to the baltic qf and the sea level fluctuations in the kattegat and turbulent entrainment flows coupled to the wind speed w and in the belt sea also to the barotropic transport the most important bathymetric features of the basins are included the model equations are integrated numerically for a test period of 1 years the stratification in the kattegat as well as in the belt sea is quite well predicted it is found that approximately one half of

continental scale transport of sediments by the baltic ice stream elucidated by coupled grain size and nd provenance analyses abstract we introduce a methodology for determining the transport distance of subglacially comminuted and entrained sediments we pilot this method on sediments from the terminal margin of the baltic ice stream the largest ice stream of the fennoscandian ice sheet during the last glacial maximum a strong correlation r2 0 83 between the end and latitudes of circum baltic river sediments enables us to use end as a calibrated measure of distance the proportion of subglacially transported sediments in a sample is estimated from grain size ratios in the silt fraction

freshwater limestone in an arid rift basin a goldilocks effect abstract the olduvai basin 3 s situated just west of the east african rift system in northern tanzania contains a two million year record of paleoclimate and paleoenvironmental change as well as a rich archive of vertebrate paleontology including hominins milankovitch precession cycles 20 kyr regulate the mean annual precipitation 250 700 mm yr and the 2500 mm yr evapotranspiration results in a negative hydrologic balance despite persistent aridity extensive deposits of freshwater limestone punctuate the stratigraphic record between 2 and 1 ma lake olduvai occupied the basin and its sediments are a proxy for climate driven cycles three limestones 1 84 1 80 and 1 36 ma in age which formed within lake margin floodplains adjacent to the lake were studied to determine their depositional environment using field relations sedimentary structures fossils petrography and stable isotope and major element geochemistry the three limestones are similar in that they contain peloidal micrite siliciclastic detrital grains and rhizoconcretions abundant faunal remains gastropods ostracods charaphytes and fish indicate that ponded water was relatively fresh and alkaline geochemical and stable isotope data indicate two types of groundwater sourced carbonate producing waters a deeper sourced fluid that was enriched in iron and manganese due to extended water rock interactions and a shallower groundwater that traveled through alluvial fan deposits regional faults tapped the deeper groundwater producing carbonate at spring sites while seeps associated with basinward changes in alluvial fan slopes drew on shallower groundwater sources isotope compositions indicate that fault related waters experienced some evaporation as water moved away from the spring sites while compositions of the seep related carbonate remained relatively constant pedogenic alteration and meteoric calcite cementation affected the carbonate when the spring and seep sites dried out secondary strontium rich dolomite precipitated within the limestones during burial under paleo lake olduvai sediments and fluids during periods of lake expansion integrating these data within the geological context of regional paleoclimatic and local environmental change indicates that the freshwater carbonates formed periodically when the conditions were just right i e a goldilocks effect carbonates near the basin center formed from groundwater flowing under a hydraulic head from faults or fractures during the falling limbs of milankovitch cycles when the lake was in recession carbonates near the basin margin formed from an increased rate of groundwater seepage that occurred only on the rising limbs of cycles in both contexts the continuous flow of groundwater with surface evaporation and co2 degassing optimizes the conditions for limestone formation in this arid environment these results help explain the formation of freshwater limestones in the rift basin link the carbonates to specific portions of milankovitch cycles and document that localized sources of potable water were present for use by hominins in olduvai gorge during an important period of human evolution

strontium and neodymium isotopes in hot springs on the east pacific rise and guaymas basin we have determined the concentrations and isotopic compositions of sr and nd in hydrothermal fluids from 21 n east pacific rise and guaymas basin gulf of california the purest solutions analyzed from 21 n exhibit a small range in sr concentration between individual vents from 5 8 to 8 7 ppm close to normal seawater sr concentrations they exhibit a small range in 87 sr 86 sr from e sr 0 13 4 to 17 7 corresponding to e sr 0 18 2 in the pure hydrothermal end member these results indicate extensive but not complete isotopic exchange with sr in the depleted oceanic crust e sr 0 31 8 and suggest that sr concentrations in these solutions are buffered in contrast the concentration and isotopic composition of nd in solutions show large variations between vents the concentration of nd ranges from 20 to 336 pg g 6 100 times seawater nd concentrations the isotopic composition ranges from e nd 0 3 6 similar to pacific seawater to 7 9 many samples show substantial contributions from morb but all have e nd 0 well below morb at this locality e nd 0 9 7 in spite of very large enrichments in nd concentrations while complete isotopic exchange with water rock 2 or exchange with anomalous oceanic crust can explain the sr data the nd data require exchange with a reservoir having e nd 0 pacific seawater low temperature reactions with metalliferous sediments on the ridge flanks may provide such a source both sr and nd in the guaymas basin solution are very different from21 n e sr 0 11 0 and e nd 0 11 4 and are consistent with the fluid exchanging sr and nd with heated sediments having a substantial component of old continental detritus some irregularities in the nd isotopic data reported here indicate that there must be a problem of contamination for some ultra low level trace elements during sample collection and processing which requires further attention using a simple box model the estimates for hydrothermal nd fluxes are compared with fluxes which would be required to maintain the relatively radiogenic value of e nd 0 3 in the pacific against the influx of more negative antarctic waters e nd 0 9 it is shown that the hydrothermal flux of nd from mid ocean ridges falls far short of that necessary to maintain the isotopic balance this indicates that weathered material from volcanic terranes e nd 0 7 is the most reasonable major source of radiogenic nd in the pacific

isotopic composition of neodymium in waters from the drake passage the isotopic composition of neodymium has been determined in seawaters from the drake passage the antarctic circumpolar current which controls interocean mixing flows through this passage the parameter e nd 0 which is a function of the ratio of neodymium 143 to neodymium 144 is found to be uniform with depth at two stations with a value which is intermediate between the values for the atlantic and the pacific and indicates that the antarctic circumpolar current consists of about 70 percent atlantic water cold bottom water from a site in the south central pacific has the neodymium isotopic signature of the waters in the drake passage by using a box model to describe the exchange of water between the southern ocean and the ocean basins to the north together with the isotopic results an upper limit of approximately 33 million cubic meters per second is calculated for the rate of exchange between the pacific and the southern ocean concentrations of samarium and neodymium were also determined and found to increase approximately linearly with depth these results suggest that neodymium may be a valuable tracer in oceanography and may be useful in paleo oceanographic studies

groundwater in the earth s critical zone relevance to large scale patterns and processes although we have an intuitive understanding of the behavior and functions of groundwater in the earth s critical zone at the scales of a column atmosphere plant soil bedrock along a toposequence ridge to valley and across a small catchment up to third order streams this paper attempts to assess the relevance of groundwater to understanding large scale patterns and processes such as represented in global climate and earth system models through observation syntheses and conceptual models evidence are presented that groundwater influence is globally prevalent it forms an environmental gradient not fully captured by the climate and it can profoundly shape critical zone evolution at continental to global scales four examples are used to illustrate these ideas 1 groundwater as a water source for plants in rainless periods 2 water table depth as a driver of plant rooting depth 3 the accessibility of groundwater as an ecological niche separator and 4 groundwater as the lower boundary of land drainage and a global driver of wetlands the implications to understanding past and future global environmental change are briefly discussed as well as critical discipline scale and data gaps that must be bridged in order for us to translate what we learn in the field at column hillslope and catchment scales to what we must predict at regional continental and global scales

sr isotope stratigraphy of the upper jurassic of central portugal lusitanian basin based on oyster shells strontium isotope stratigraphy was performed on oyster shells from the late jurassic of the lusitanian basin central portugal this represents the first approach to obtain numerical ages for these strata the new chronostratigraphic data provide a more precise age determination of several units after a basin wide hiatus sedimentation in the late jurassic is proven in the cabo mondego and cabacos formations to resume as early as the middle oxfordian the alcobaca formation can be placed in the latest late oxfordian to late kimmeridgian while data from the upper part of the abadia formation indicate an early to late kimmeridgian age the farta pao formation ranges from the latest kimmeridgian to the latest tithonian the largely synchronous sobral arranho i and arranho ii members are overlain by the late early to late tithonian freixial member the brief local carbonate incursion of the arranho i member marks the kimmeridgian tithonian boundary oysters are shown once more to be suitable for strontium isotope studies their calcitic shells are often unaffected by diagenesis in particular for marginal marine jurassic and cretaceous strata where belemnites are usually absent oysters may serve as a valuable tool for isotope stratigraphy

paleoenvironmental reconstruction of a paleosol catena the zinj archeological level olduvai gorge tanzania abstract paleosols record paleoclimatic processes in the earth s critical zone and are archives of ancient landscapes associated with archeological sites detailed field micromorphologic and bulk geochemical analysis of paleosols were conducted near four sites at olduvai gorge tanzania within the same stratigraphic horizon as the zinjanthropus paranthropus boisei archeological site paleosols are thin

87sr 86sr in waters from the lincolnshire limestone aquifer england and the potential of natural strontium isotopes as a tracer for a secondary recovery seawater injection process in oilfields the sr isotope composition of formation waters is a sensitive indicator of diagenetic processes in the host sediments mixing processes between different bodies of water and the connectivity of hydrological systems the87sr 86sr ratio of present seawater is constant worldwife while formation waters in hydrocarbon reservoirs have various values depending on the aforementioned effects in most cases different from modern seawater this forms the basis of anatural tracer technique for seawater injection projects involving characterization of the87sr 86sr ratios and sr contents of formation waters in the reservoir before injection commences followed by monitoring of these parameters in the produced water as injection proceeds this method is best suited to reservoirs in which the formation waters have low sr concentrations and87sr 86sr ratios much higher or lower than seawater available data for reservoir formation waters suggest that breakthrough recognition could be expected at 10 seawater in many sandstone reservoirs while the method would be less sensitive in carbonate reservoir or situations where the formation waters had interacted with evaporites as the associated waters tend to have high sr contents in heterogeneous but well mapped reservoirs it may be possible to obtain information about flow paths mechanismsbefore breakthrough combination with other chemical and isotopic tracers creates a very powerful tool the sr method acting as a safeguard should the batch of water containing the conventional tracers be overtaken by subsequently injected seawater the sr method could also be used for injection projects that were begun without the addition of tracers a natural analogue of a water injection process is found in the jurassic lincolnshire limestone aquifer in england where rapidly moving fresh meteoric water mixes progressively with an older saline formation water the87sr 86sr data enable quantitative modelling of this mixing process the infiltrating fresh water becomes progressively modified by dissolution of detrital carbonate and calcite cement in the limestone with depth becoming increasingly dominated by sr derived from the more soluble detrital components the saline formation water contains water molecules of meteoric origin and an87sr 86sr ratio much higher than jurassic seawater or marine carbonate the solute content has been influence by interaction of the water with non carbonate phases

biogeochemical characterization of a lithified paleosol implications for the interpretation of ancient critical zones abstract modern soils are characterized by an array of physical chemical mineralogical and biological laboratory analyses of samples taken from horizons of pedogenic profiles in contrast fossil soils paleosols are typically characterized from assays of whole rock molecular oxides because of sample lithification where element sources are unconstrained here we for the first time subject a lithified paleosol to an array of modern soil analytical techniques and new pedotransfer functions providing a glimpse into the colloidal world of an ancient critical zone as an analog to research conducted on a network of modern critical zones this methodology provides a framework for decoding a previously unknown archive of terrestrial biogeochemical information at multiple temporal and spatial scales application to a paleosol within an early paleocene critical zone reveals that many biogeochemical properties have been preserved since burial that are similar to modern clay rich vertisols the measured and calculated physical properties of this paleosol include clay content and mineralogy bulk density and water retention available water capacity and coefficient of linear extensibility shrink swell potential the chemical properties include cation exchange capacity exchangeable cations base saturation and exchangeable sodium percentage the solution properties electrical conductivity and ph seem reasonable but are interpreted with less confidence because of their greater vulnerability to alteration from fluid flow new pedotransfer functions to reconstruct pre burial organic carbon and nitrogen contents provide invaluable information of organically derived nutrient content the sum of the measured properties of the early paleocene paleosol in context of reconstructed regional environmental conditions indicate the presence of a mid successional hardwood forest in a humid climate with high water holding capacity high nutrient retention and rapid flux of elements through biogeochemical cycling

87sr 86sr and sr ca investigation of jurassic mollusks from scotland implications for paleosalinities and the sr ca ratio of seawater measurements of 87 sr 86 sr sr ca 18 o and 13 c were performed on molluskan fos sils from the great estuarine group scot land to deduce paleosalinity patterns and hydrodynamic environments in this classic jurassic marginal marine succession fos sils are found as winnowed accumulations in shell beds that bear low diversity assem blages consistent with deposition in a la goonal paleoenvironment previous studies have concluded that estuarine mixing of seawater and freshwater took place based on correlated trends in 18 o and 13 c most notably in the mussel praemytilus strathair densis from the kildonnan member this interpretation is shown to be incorrect based on 87 sr o 13 c and the sr ca ratio this is consistent with a lagoonal hydrology controlled more by seasonal changes in evaporation precipitation and flooding than by direct inputs of seawater or river ine water transported over large distances lagoons containing the oyster praeexogyra in the duntulm formation have similar in ferred o and c isotope characteristics but based on their 87 sr 86 sr ratios they have a higher proportion of seawater than the praemytilus lagoons of the kildonnan member the data thus far suggest that many of the lagoonal environments in the great es tuarine group were nearly hydrologically closed at least over the interval represent ing the molluskan invasion of these habi tats rendering o and c isotopes unreliable proxies of paleosalinity because strontium isotopes are not directly affected by evap oration of the lagoons knowledge of marine and freshwater 87 sr 86 sr ratios along with estimates of sr concentration are used to calculate the proportion of seawater in the brackish water mixture unio is nearly al ways the most radiogenic taxon compared to other genera in closely adjacent sedimen tary strata confirming its freshwater affin ity the purported marine brackish bivalve tancredia yields a low paleosalinity of 4 only slightly more saline than unio and praemytilus at 1 3 the oyster praeexo gyra hebridica yields paleosalinities between 2 and 26 attesting to the wide salinity tolerance of this species thus far only neomiodon from the dun tulm and staffin bay formations show co variant relationships between 87 sr 86 sr and ca sr ratio that can be reconciled with a dynamic response to seawater freshwater mixing the slopes of these trends converge at 0 7068 which is close to the early cal lovian seawater composition of 0 7069 us ing values of dsr from modern aragonite se creting mollusks the sr ca ratio of middle jurassic seawater is constrained from the best correlated mixing line to be 5 4 0 6 millimoles mole in contrast sr ca ratios in the great estuarine group lagoons and continental watershed range from 5 4 to 19 0 these are much higher than the av erage value of 2 3 for modern rivers but typical of sr ca ratios in rivers draining arid climate regions the semirestricted hy drodynamic regime inferred from the high seawater like 18 o values and high but uni form sr ca ratios in many of the great es tuarine group mollusks is consistent with a seasonally dry mediterranean style climate for the middle jurassic of britain

neodymium isotopes and concentrations in caribbean seawater tracing water mass mixing and continental input in a semi enclosed ocean basin we present the first full water column nd isotope end and concentration data for caribbean seawater as well as for stations close to the orinoco river mouth and in the florida straits the surface inflow into the southeastern caribbean via the guyana current is characterized by an endsignature of 10 9 which is a consequence of the mixing of relatively unradiogenic endsignatures 13 6 supplied by the orinoco river with contributions from the amazon river 10 despite the proximity to land sub surface and intermediate waters within the caribbean largely retain the endsignatures of their source water masses in the atlantic in contrast the deep waters of the caribbean show endsignatures at least 3 endunits more radiogenic than the inflowing upper north atlantic deep water unadw a endshift from 13 to 9 7 can be explained by addition of radiogenic nd to the deep caribbean through weathering inputs from land however in order to balance such large shifts in endwith at the same time modest increases in nd concentrations nd must also be removed from seawater within the basin it is suggested that the long residence time of deep waters in the caribbean allows significant interaction of seawater with sinking particles and seafloor sediments resulting in more radiogenic values these findings have implications for the use of endas a proxy for paleocirculation in restricted basins in which the residence times of the deep waters are long

tectonics fracturing of rock and erosion 1 we argue that by fracturing rock not by raising it relative to base level tectonics plays its most important role in causing rapid incision of valleys and rapid erosion of hillslopes tectonic deformation riddles the upper crust with fractures which not only provide avenues for water flow and thus promote weathering and further disintegration of rock but also fragment bedrock into debris that is readily extracted and transported by surface processes bends in active faults require straining of adjacent rock masses aftershocks that occur subsequent to slip on primary faults reflect penetrative brittle deformation of the upper crust at least some aftershocks must nucleate or lengthen cracks which contribute to the comminution of these rock masses scaling rules suggest that dimensions of ruptures for very small m 2 earthquakes can be meters or less the gutenberg richter recurrence relationship implies that such earthquakes are common as high magnification seismographs in low noise environments confirm moreover large differences among fault plane solutions for aftershocks show that the small faults on which they occur are not parallel to one another some faults must intersect thus the upper crust in tectonically active regions should be fragmented into blocks down to the scale of boulders or smaller dismembered rock arrives at the earth s surface already prepared to be transported away as a corollary both deeply exhumed lower crust and posttectonic igneous rock never deformed under brittle conditions and not deformed recently should be less susceptible to detachment and subsequent transport than fractured rock

sr isotopes of the shells of the euryhaline gastropod potamides lamarcki from the oligocene of the french massif central and paris basin a clue to its habitats euryhaline mollusks are adapted to large ranges of salinities in their life environment but are not reliable indicators of the marine or non marine origin of dissolved ions many palaeogeographical controversies based on such ambiguous organisms are long lasting questions this is the case for the some rupelian deposits of the french massif central in these deposits the presence of a gastropod potamides lamarcki has been considered to reflect various palaeoenvironments from marine or marginal lagoons or marine ingressions to continental brackish to saline lakes as a marginal or marine fossil it was used to reconstruct oligocene seaways in the european cenozoic rift system the application of sr isotope ratio of well preserved aragonitic fossils of p lamarcki from rupelian deposits in the massif central and in the paris basin is tested as a method of solving this problem these data confirm the reliability of sr isotopes in discriminating between euryhaline gastropods of marine origin in the paris basin and of continental origin in the french massif central the potamides lamarcki shells of the paris basin rupelian gulf have 87sr 86sr ratios from 0 707744 18 to 0 707949 11 i e close to the oligocene seawater range 0 70780 0 70820 mcarthur et al 2001 in contrast the p lamarcki shells collected in the oligocene deposits of the french massif central have high 87sr 86sr ratios ranging from 0 713231 16 in the limagne basin to 0 715205 13 in the aurillac basin these are very distinct from contemporaneous seawater and reflect the sr isotopic compositions of local continental waters in these basins during the rupelian it is suggested that the potamides lamarcki of the french massif central basins lived in intracontinental saline lakes rather than in lagoons with connection to seawater accordingly the presence of p lamarcki and of other euryhaline fossils cannot be taken as evidence of seawater influence in the distinct grabens of this region during the oligocene and palaeogeographical reconstructions of the western part of the european rift system should be reviewed

contrasting geochemical cycling of hafnium and neodymium in the central baltic sea the central baltic sea is a marginal brackish basin which comprises anoxic bottom waters and is surrounded by geological source terrains with a wide variety of compositions and ages this allows the investigation of water mass mixing using radiogenic isotope compositions of nd and hf as well as their geochemical cycling across varying redox conditions in the water column in this study we present the distribution of nd and hf concentrations and their isotopic compositions for 6 depth profiles and 3 surface water sites obtained during a cruise in the central baltic sea onboard the rv oceania as a part of the international geotraces program the results obtained indicate that nd isotopes effectively trace the mixing between more radiogenic saline waters from the south and unradiogenic fresh waters from the north which helps to understand the reliability of nd isotopes as water mass tracer in the open ocean in surface waters nd shows higher concentrations and less radiogenic isotope compositions at the northern stations which are progressively diluted and become more radiogenic to the south consistent with the counterclockwise circulation pattern of central baltic sea surface waters in contrast to the variable nd concentrations hf shows much less variability at the gotland deep station the nd concentrations of the euxinic waters are higher by a factor 10 than those of the overlying oxygen depleted waters whereas hf only shows small concentration variations this indicates faster removal of hf from the water column than nd moreover the dissolved hf isotope signatures document great variability but no consistent mixing trends our explanation is that hf has a lower residence time than nd and also that the hf isotope signatures of the sources are highly heterogeneous which is attributed to their differing magmatic and tectonic histories as well as incongruent post glacial weathering around the central baltic sea

controls over the strontium isotope composition of river water abstract strontium concentrations and isotope ratios have been measured in river and ground waters from the ganges orinoco and amazon river basins when compared with major element concentrations the data set has allowed a detailed examination of the controls over the strontium isotope systematics of riverine input to the oceans in the following environments 1 1 typical drainage basins containing limestones evaporites shales and alumino silicate metamorphic and igneous rocks 2 2 shield terrains containing no chemical or biogenic sediments and 3 3 the floodplains that constitute the largest areas of many large rivers the strontium concentration and isotope composition of river waters are largely defined by mixing of strontium derived from limestones and evaporites with strontium derived from silicate rocks the strontium isotope composition of the limestone endmember generally lies within the phanerozoic seawater range which buffers the 87 sr 86 sr ratios of major rivers a major exception is provided by the rivers draining the himalayas where widescale regional metamorphism appears to have led to an enrichment in limestones of radiogenic strontium derived from coexisting silicate rocks the strontium isotope systematics of rivers draining shield areas are controlled by the intense transportlimited nature of the weathering reactions and thereby limits variations in the strontium flux from these terrains floodplains are only a minor source of dissolved strontium to river waters and precipitation of soil salts in some floodplains can reduce the riverine flux of dissolved strontium to the oceans the most effective mechanisms for altering the isotope ratio and flux of riverine strontium to the oceans are increased glaciation and large scale regional metamorphism of the type produced during continental collision both mechanisms provide a means for increasing the 87 sr 86 sr ratio of the global riverine flux

geochemistry u pb zircon geochronology and sm nd isotopes of the xincai banded iron formation in the southern margin of the north china craton implications on neoarchean seawater compositions and solute sources abstract banded iron formations bifs that are distal from submarine volcanic activity and generally lack direct relationships with volcanic rocks have been extensively used as proxies to infer the chemical composition of ancient seawater and trace the effects of continental weathering at the time of their deposition here we discuss the major and trace elements and sm nd isotopic geochemistry of the poorly studied xincai bif located west of the superior type huoqiu bif along a nw se trending supracrustal belt in the southern margin of the north china craton to understand the compositions and solute sources of seawater during the xincai bif precipitation u pb zircon dating of granitic intrusive rock and biotite schist interlayer of the bif constrains the depositional age of the xincai bif to 2 5 2 7 ga for the first time indicating that the xincai bif could be part of the huoqiu bif or consist of contemporaneous sediments formed in a similar tectonic depositional environment shale normalized rare earth element and yttrium rey patterns of the bulk and individual band samples display features that are characteristic of other archean bifs with light ree depletion relative to heavy ree positive lasn gdsn and ysn anomalies indicative of pure chemical sedimentation the marine origin of these samples is further supported by their super chondritic y ho ratios average y ho 47 the very low al ti and high field strength element contents of the xincai bif indicate an essentially detritus free component the bulk bif samples show a narrow range of end t values from 1 5 to 1 0 and most of the samples have negative end t values 0 3 on average which is different from archean bifs with mantle derived depleted nd isotopes deviations toward negative end t values of the iron bands 0 5 to 0 1 and the silica bands 4 7 to 0 5 further indicate a continental nd contribution in addition positive eusn anomalies that were found in all of the bulk and individual band samples indicate that a high t hydrothermal input also contributed to their rey signatures it is considered that both high t hydrothermal fluids and ambient seawater with solutes from erosion and weathering of a nearby landmass can provide their rey signatures

rare earth elements neodymium and strontium isotopic systematics in mineral waters evidence from the massif central france abstract rare earth elements rees and sr and nd isotope distributions have been studied in mineralized waters from the massif central france the co 2 rich springs are characterized by a neutral ph 6 7 associated with total dissolved solids tds from 1 to 7 g l 1 the waters result from the mixing of very mineralized water pools thought to have equilibrated at a temperature of around 200 c with superficial waters these two mineral water pools evidenced by sr isotopes and dissolved rees could reflect 2 different stages of water rock interaction and an equilibrium with different mineral assemblages the concentrations of individual dissolved rees and total dissolved rees ree in the mineral waters examined vary over several orders of magnitude but are not dependent on the main parameters of the waters tds t c ph total organic c the dissolved ree concentrations presented as upper continental crust normalized patterns show hree enrichment in most of the samples the time evolution of ree patterns does not show significant fluctuations except in 1 borehole located in the limagne d allier area which was sampled on 16 occasions over an 18 month period ten samples are hree enriched whereas 6 samples show flat patterns the aqueous speciation of rees shows that co 2 3 complexes dominate 80 over the free metal f so 2 4 and hco 3 complexes the detailed speciation demonstrates that the fractionation of rees i e the hree enrichment in co 2 rich and ph neutral fluids is due essentially to the predominance of the co 2 3 complexes the sr isotopic composition of the mineral waters in the massif central shows different mixing processes in the cezallier area at least 3 end member water types exist the most dilute end member is likely to originate as poorly mineralized waters with minimal groundwater circulation two other mineralized end members are identified although the link between the geographical location of spring outflow and the mixing proportion between the 2 end members is not systematic the range in nd 0 for mineralized waters in the massif central correlates well with that of the known parent rocks except for 4 springs one way to explain the nd 0 in these instances is a contribution from drainage of volcanic rocks the isotopic systematics help to constrain the hydrogeological models for this area

buried paleoindian age landscapes in stream valleys of the central plains usa abstract a systematic study of late quaternary landscape evolution in the central plains documented widespread deeply buried paleosols that represent paleoindian age landscapes in terrace fills of large streams 5th order in alluvial fans and in draws in areas of western kansas with a thick loess mantle alluvial stratigraphic sections were investigated along a steep bio climatic gradient extending from the moist subhumid forest prairie border of the east central plains to the dry subhumid and semi arid shortgrass prairie of the west central plains radiocarbon ages indicate that most large streams were characterized by slow aggradation accompanied by cumulic soil development from ca 11 500 to 10 000 14c yr b p in the valleys of some large streams such as the ninnescah and saline rivers these processes continued into the early holocene the soil stratigraphic record in the draws of western kansas indicates slow aggradation punctuated by episodes of landscape stability and pedogenesis beginning as early as ca 13 300 14c yr b p and spanning the pleistocene holocene boundary the development record of alluvial fans in western kansas is similar to the record in the draws slow aggradation was punctuated by multiple episodes of soil development between ca 13 000 and 9000 14c yr b p in eastern kansas and nebraska development of alluvial fans was common during the early and middle holocene but evidence shows fan development as early as ca 11 300 14c yr b p buried soils dating between ca 12 600 and 9000 14c yr b p were documented in fans throughout the region in stream valleys across the central plains rapid alluviation after ca 9000 14c yr b p resulted in deeply buried soils that may harbor paleoindian cultural deposits hence the paucity of recorded stratified paleoindian sites in the central plains is probably related to poor visibility i e deep burial in alluvial deposits instead of limited human occupation in the region during the terminal pleistocene and early holocene the thick dark cumulic a horizons of soils representing buried paleoindian age landscapes are targets for future archaeological surveys

c4 plant productivity and climate co2 variations in south central texas during the late quaternary abstract a continuous record of organic carbon 13c from a buried soil sequence in south central texas demonstrates 1 strong coupling between marine and adjacent continental ecosystems in the late pleistocene as a result of glacial meltwater entering the gulf of mexico and 2 ecosystem decoupling in the holocene associated with a reduction of meltwater and a shift in global circulation patterns in the late pleistocene reduction in c4 plant productivity correlates with two well documented glacial meltwater pulses 15 000 and 12 000 14c yr b p indicating a cooler than present adjacent continental environment increased c4 production between 11 000 and 10 000 14c yr b p suggests that the younger dryas was a warm interval responding to the diversion of glacial meltwater away from the mississippi river with waning meltwater flow c4 productivity generally increased throughout the holocene culminating in peak warm intervals at 5000 and 2000 14c yr b p shifts in the abundances of c3 c4 plants through the late quaternary show no correlation to ecophysiological responses to atmospheric co2 concentration

strontium isotopic composition of the po river dissolved load insights into rock weathering in northern italy abstract strontium isotopic composition 87sr 86sr of river water provides insight on the nature of rocks involved in the weathering processes and important constraints for reconstructing silicate versus carbonate weathering in large scale basins new data presented in the context of a geochemical map of the po river basin highlight that the po river water evolves from the upper part of the catchment where 87sr 86sr approaching 0 7097 relates to the weathering of igneous and metamorphic silicate rocks to the middle part where less radiogenic compositions 87sr 86sr 0 7089 are driven by the confluence of the tributaries draining mesozoic carbonate rocks of the south alpine domain and from inflow of apennine streams characterized by less radiogenic sr signatures due to weathering of marly sediments and mafic magmatic rocks down flow the sr isotopic compositions of po river water rises at 0 7091 either by the confluence of the last apennine tributary panaro 87sr 86sr 0 7095 and or by the possible contribution from hyporheic exchanges po river isotopic signatures reveal slightly more radiogenic 87sr 86sr in comparison to other important alpine river systems e g danube rhine and rhone likely suggesting that silicate rocks are comparatively contributing more weathering byproducts in the po basin

the last glacial termination a major puzzle of paleoclimatology is why after a long interval of cooling climate each late quaternary ice age ended with a relatively short warming leg called a termination we here offer a comprehensive hypothesis of how earth emerged from the last global ice age a prerequisite was the growth of very large northern hemisphere ice sheets whose subsequent collapse created stadial conditions that disrupted global patterns of ocean and atmospheric circulation the southern hemisphere westerlies shifted poleward during each northern stadial producing pulses of ocean upwelling and warming that together accounted for much of the termination in the southern ocean and antarctica rising atmospheric co2 during southern upwelling pulses augmented warming during the last termination in both polar hemispheres

formation waters from mississippian pennsylvanian reservoirs illinois basin usa chemical and isotopic constraints on evolution and migration we have analyzed a suite of seventy four formation water samples from mississippian and pennsylvanian carbonate and siliciclastic strata in the illinois basin for major minor and trace element concentrations and for strontium isotopic composition a subset of these samples was also analyzed for boron isotopic composition data are used to interpret origin of salinity and chemical and sr isotopic evolution of the brines and in comparison with a similar data set from an earlier study of basin formation waters from silurian devonian reservoirs systematics of cl br na show that present mississippian pennsylvanian brine salinity can be explained by a combination of subaerial seawater evaporation short of halite saturation and subsurface dissolution of halite from an evaporite zone in the middle mississippian st louis limestone along with extensive dilution by mixing with meteoric waters additional diagenetic modifications in the subsurface interpreted from cation br ratios include k depletion through interaction with clay minerals ca enrichment and mg depletion by dolomitization and sr enrichment through caco3 recrystallization and dolomitization ste genevieve limestone middle mississippian formation waters show 87sr86sr ratios in the range 0 70782 0 70900 whereas waters from the siliciclastic reservoirs are in the range 0 70900 0 71052 inverse correlations between 87sr86sr and b li and mg concentrations suggest that the brines acquired radiogenic 87sr through interaction with siliciclastic minerals completely unsystematic relations between 87sr86sr and 1 sr are observed sr concentrations in ste genevieve and aux vases middle mississippian waters appear to be buffered by equilibrium with respect to srso4 although there are many similarities in their origin and evolution these formation waters are distinguished from silurian devonian brines in the basin by elevated clbr and nabr ratios and by unsystematic sr isotope relationships thus waters from these two major segments of the illinois basin stratigraphic column form distinct geochemical regimes which are separated by the new albany shale group devonian mississippian regional aquitard geochemical evolution appears to have been influenced significantly by paleozoic and mesozoic hydrologic flow systems in the basin

behaviour of major elements and some trace elements li rb cs sr fe mn w f in deep hot waters from granitic areas abstract analyses of selected hot springs in more than sixty areas in granites from europe are presented concentrations of major elements and of some trace elements li rb cs sr fe mn w f in high ph waters are not significantly affected by processes during uprise from the deep reservoir to the surface re equilibrations mixing with surficial waters normalized to k or na concentrations of all other elements are related to the aquifer temperature the knowledge of aquifer temperature and total electric charge of mobile elements cl s possibly f allows us to predict both major elements within 50 and trace elements within a factor 2 or 3 concentrations in alkaline waters from granites

rare earth elements and sr and nd isotopic compositions of dissolved and suspended loads from small river systems in the vosges mountains france the river rhine and groundwater abstract the aim of this study is to characterize the evolution of the rare earth elements ree in non mature streams from small catchment areas in the vosges mountains downstream to more mature plain rivers including the river rhine the dissolved load ree distribution patterns of the low ph vosges streams are very different from those of high ph plain rivers indicating that different physico chemical parameters control ree transport in these different water systems the plain rivers and groundwater show similar ree distribution patterns with a strong negative ce anomaly and heavy rare earth element hree enrichment in addition the river rhine has a positive gd anomaly which is of anthropogenic origin similar to the world s major rivers the light rare earth element lree enrichment in the plain rivers is mainly ph controlled their sm nd and 143 nd 144 nd isotope ratios are close to average continental crust values this is not the case for the less evolved non mature and low ph vosges streams their high sm nd and 143 nd 144 nd ratios but low 87 sr 86 sr ratios suggest that chemical alteration of accessory middle rare earth element mree enriched minerals such as apatites from rocks in the catchment area control the ree abundances of these waters a comparison of the dissolved load ree distribution patterns with those of the principal lithologies in the corresponding drainage basins illustrates that especially the eu anomalies of the vosges streamlets are strongly lithology dependent leaching experiments indicate that the suspended load is isotopically very inhomogeneous the ree distribution patterns of the suspended load leachates have no similarities with those of the corresponding dissolved load indicating that the leachable reservoir not only contains adsorbed ree but also ree from leachable mineral phases their 143 nd 144 nd sm nd and 87 sr 86 sr ratios support this suggestion being always higher and lower respectively than those of their corresponding dissolved loads they rather point to the presence of relic primary apatite in the leachable portion of the suspended load the flat paas normalized ree distribution patterns the high 87 sr 86 sr and low 143 nd 144 nd isotopic ratios of the corresponding residues suggest secondary silicate phases such as clay minerals in the residual phase of the suspended load leachates and corresponding residual phases define alignments in the sm nd isochron diagram whose slopes define ages ranging between 200 and 390 ma indicating that the mineral phases in the suspended load retain some memory of their primary precursor minerals in the hercynian granitic source rocks

comparison of the sr isotopic signatures in brines of the canadian and fennoscandian shields abstract a synthesis of sr isotope data from shallow and deep groundwaters and brines from the fennoscandian and canadian shields is presented a salinity gradient is evident in the water with concentrations varying from approximately 1 75 g l 1 below 1500 m depth in the fennoscandian shield and from 10 up to 300 g l 1 below 650 m depth in the canadian shield strontium isotope ratios were measured to assess the origin of the salinity and evaluate the degree of water rock interaction in the systems in both shields the sr concentrations are enriched relative to cl defining a positive trend parallel to the seawater dilution line and indicative of sr addition through weathering processes the depth distribution for sr concentration increases strongly with increasing depth in both shields although the variation in sr isotope composition does not mirror that of sr concentrations strontium isotope compositions are presented for surface waters and groundwaters in several sites in the fennoscandian and canadian shields numerous mixing lines can be drawn reflecting water rock interaction a series of calculated lines links the surface end members surface water and shallow groundwater and the deep brines these mixing lines define a range of 87 sr 86 sr ratios for the deep brines in different selected sites all sites show a specific 87 sr 86 sr signature and the occurrence of large 87 sr 86 sr variations is site specific in both shields in canadian shield brines the sr isotope ratios clearly highlight large water rock interaction that increases the 87 sr 86 sr ratio from water that could have been of marine origin in contrast to the canadian shield groundwater does not occur in closed pockets in the fennoscandian and the well constrained 87 sr 86 sr signatures in deep brines should correspond to a large well mixed and homogeneous water reservoir whose sr isotope signature results from water rock interaction

paleoseismic evidence for multiple mw 6 earthquakes in the eastern tennessee seismic zone during the late quaternary abstract the eastern tennessee seismic zone etsz is the second most active seismic zone in the eastern united states but it has not generated an earthquake larger than m w 4 8 in historic time earthquakes are sourced deep in autochthonous basement and there are no known faults originating at this depth that break the surface as a result until recently there has been virtually no fieldwork to identify quaternary paleoseismic features in the etsz we present new results from paleoseismic investigations of coseismic features that indicate the etsz generated m w 6 earthquakes during the late quaternary detailed geologic mapping and trenching near dandridge tennessee record a northeast trending zone of seismically generated features optically stimulated luminescence ages delimit timing for the formation of paleoseismic features crosscutting quaternary alluvium and alluvium filled fissures including a thrust fault with 1 m displacement collectively this zone of faults and fissures provides significant evidence that the etsz has produced at least three large earthquakes during the late pleistocene and at least one that exceeded m w 6

an isochron method for cosmogenic nuclide dating of buried soils and sediments we describe an improved method for dating buried paleosols using measurements of the cosmic ray produced radionuclides 10be and 26al in quartz grains and apply it to a sequence of intercalated tills and paleosols in central missouri usa that record plio pleistocene advances of the laurentide ice sheet a buried paleosol implies a period of surface exposure and nuclide accumulation followed by burial and a halt to nuclide production if the paleosol is formed in a sedimentary unit such as till this unit may also have been emplaced with unknown 26al and 10be concentrations inherited from past surface exposure if the inherited nuclide concentrations are the same at all depths in the soil as is true for well mixed sediments such as till then the 26al and 10be concentrations at different depths in the paleosol will show a linear relationship the slope of this line depends on the duration of burial of the paleosol but not on the inherited nuclide concentrations or on the sample depths thus one can date strata overlying buried paleosols by measuring 26al and 10be at multiple depths in the paleosol and calculating the burial age of the paleosol from the resulting isochron we focus on applying this approach to till paleosol sequences but the basic idea of forming an 26al 10be burial isochron with a set of samples that share the same burial age but differ in other aspects of their exposure history applies to other stratigraphic settings as well the method yields ages for four tills in missouri that are stratigraphically consistent agree with paleomagnetic age constraints and show that ice advanced into missouri near 1 25 ma near 0 8 ma and twice between ca 0 4 and 0 2 ma

evidence for slowly changing 87sr86sr in runoff from freshwater limestones of southern france abstract 87 sr 86 sr ratios have been determined in modern rivers and freshwater limestones dating from 65 ma to the present over an area extending from the pyrenees to the massif central southern france about 40 ma ago the alpine mountain range of the pyrenees was strongly uplifted by the alpine orogenic activity and its pre hercynian basement dominated by schists gneisses and granites was rapidly exposed from beneath its blanket of mesozoic marine limestones meanwhile the 87 sr 86 sr ratio of the rivers has remained remarkably constant in both space with the exception of the very few northernmost samples and time in this area extreme variations through the orogenic period are small with 87 sr 86 sr lying between 0 7073 and 0 7084 at 55 65 ma and 0 7077 0 7096 for the last 30 ma river sr is controlled by a nearly binary mixing of silicate 3 4 and 1 4 end members with negligible influence of evaporites it is inferred that the silicate sediment contribution ratio of the world average rivers to seawater sr changes at a very slow rate even taking major basaltic events into account does not alter this conclusion as their contribution to the river sr is very subordinated to other components it is inferred that the seawater 87 sr 86 sr secular main trend over the phanerozoic is controlled by hydrothermal alteration of oceanic basalts and slow variation of the limestone silicate contribution ratio to the riverine sr oceanic events changes in organic productivity and carbonate compensation depth ccd may produce intense short term variations but recovery of steady state seawater 87 sr 86 sr is delayed by 40 80 ma through diagenetic sr remobilization in carbonate sediments

paleo critical zones windows into the changing life and landscapes during the quaternary period the critical zone cz as visualized in 1998 was a way to integrate the research of the four scientific spheres lithosphere hydrosphere biosphere and atmosphere at the surface of earth and to study the linkages feedbacks and record of processes rather than closeting studies by a variety of disciplines into their respective pigeonholes the cz perspective provides the symbiotic framework from which the tendrils of improved understanding can radiate outward to new disciplines and or feedback into the component disciplines during the last 2 decades cz research has been limited to the modern environment knowledge gained from the modern and the focus on interpreting ancient records allows for the development of paleo czs pczs pczs provide a powerful tool for improved understanding of the landscapes during the quaternary period and the response of this thin skin to glaciations sea level fluctuations and evolving life case studies from hominins in east africa and homo sapiens in the americas provide examples of the rich records stored in pczs as we move into the space age the cz can provide a platform from which to guide future exploration of the proto critical zones on the rocky planets and asteroids of our solar system

impact of carbo gaseous saline waters registered by soils abstract the impact of carbo gazeous saline spring waters rich in ca fe as and p and chemically stable through time on the chemistry major and trace elements and mineralogy of soils developed from anatexite is presented the soils developed beyond the influence of the spring are typical of a granite pedogenesis on a granitic bedrock with ca loss si al and k conservation the soils influenced by the springs are enriched in ca and fe respectively precipitated as carbonates and oxides in such soils the presence of two ca enrichment peaks may be explained by the occurrence of two distinct precipitation mechanisms for the carbonates 1 related to degassing of the carbo gaseous waters upon emergence at the surface and 2 in the water unsaturated zone related to capillary rise and evaporation processes the precipitation of iron oxides is related to a change in the redox potential of the mineral waters following their emergence at the surface the simultaneous association of as p with fe as evidenced by principal components analysis and in the patterns in concentrations vs depth observed in soils can be explained by adsorption and or coprecipitation of as and p during iron oxide formation while the as and p enrichments and the carbonate formation are independent the extent of the spring influence was studied the soil enrichments in ca and particularly fe sharply decrease with increasing distance from the spring on a metric scale

a strontium isotopic study of mineral and surface waters from the cezallier massif central france implications for mixing processes in areas of disseminated emergences of mineral waters abstract surface and mineral waters from a geothermal area cezallier in the centre of the massif central france were analysed for sr isotopes sr and major elements in order to use sr isotopes to investigate the discharge of a mineralised water area especially in the case of disseminate mineralised water emergences the 87 sr 86 sr ratios of mineralised waters ranged from 0 715541 to 0 716773 the variation in 87 sr 86 sr values was small for the 5 mineral springs sampled over two periods 5 10 6 14 10 6 regarding the reproductivity of the 87 sr 86 sr ratio measurements no differences can be seen and the 87 sr 86 sr ratio of mineral waters can be considered to be constant with time the 87 sr 86 sr ratios of surface waters collected along the zagat river ranged from 0 705303 to 0 715091 the lowest values were always observed in the headwaters the difference in the 87 sr 86 sr ratios between the two sampling periods was 22 10 4 and can be related to the hydrological situation low or high flow the 87 sr 86 sr ratios of surface waters collected in the drain ranged from 0 715072 to 0 716585 the difference in the 87 sr 86 sr ratios between the two sampling periods is 11 10 4 for the drain headwaters and 13 10 5 at the outlet of this area likewise these variations can also be related to the hydrological situation plots of 87 sr 86 sr vs 1 sr ratios show two distinct binary mixing trends and the existence of at least four end members a mixing parameter f giving the proportions of the two components can be estimated for assumed 87 sr 86 sr ratio and sr content values of the pure end members an estimate of the mineral water discharge can be calculated using the results of the mixing model and the measured flow in the drain area the mixing model gives an estimate 0 5 1 l s 1 or 10 13 of mineral water in the total flow a similar calculation was done for the river where the mineral water flow was 0 96 l s 1 3 5 m3 h 1 100 m downstream from the bridge in april 1994 and 6 m3 h 1 20 m downstream from the bridge in september 1994

the sources and transport of sr and nd isotopes in the baltic sea we have determined the concentration and isotopic composition of sr and nd in waters from the baltic sea the baltic sea is an intracontinental stratified brackish water estuarine like system and the rivers emptying into it drain a suite of terranes ranging from proterozoic archean in the north to phanerozoic in the south the sampled brackish waters range in salinity from seawater sw at 35 289 to a minimum of 2 460 at the surface in the innermost part of the gulf of bothnia the sr concentrations show generally conservative behavior indicating a simple two component mixing however small deviations 3 70 from a perfect mixing line reveal that the imprints from rivers with different sr concentrations are preserved in the blending strontium concentrations from a depth profile across the redoxcline in the baltic proper indicate that vertical particle transport alters the sr concentration in the water our estimated concentration of sr in the average freshwater input to the baltic is 0 03 ppm which is only about 0 4 of the sw concentration the sr isotopic data range from e sr sw 0 in seawater to e sr bw sw 7 8 in the least saline baltic water bw sample in the gulf of bothnia the isotopic composition of sr versus 1 sr in the baltic sea follows an almost perfect mixing line which shows that seawater sr is mixed with much more radiogenic components calculated end member values of e sr sw for each sample show that the riverine input into the gulf of bothnia has e sr sw 120 200 and 10 50 e units in the baltic proper these values are in general agreement with direct measurements of river waters in each region however the calculated values in the gulf of bothnia are lower than the measured river water input in this region which indicates the presence of less radiogenic sr presumably originating from the river waters draining the southern part of the basin which are partially transported northward and mixed with sr from the gulf of bothnia rivers the nd concentration in the baltic sea is not conservative varying between 5 and 45 ppt with the highest concentrations in the bottom waters due to vertical particulate transport a plot of e nd o in baltic water yields a good correlation with the calculated freshwater end member e sr sw the data show that it is possible to unravel the different freshwater sources into the baltic and to identify the zones of particulate removal of both non conservative species such as the ree and of quasi conservative species such as sr the use of isotopic tracers in this estuarine environment may provide a much better insight into mixing and element transport it should also be possible to trace lateral movements of freshwater inputs

paleoenvironmental reconstruction and water balance of a mid pleistocene pluvial lake dakhleh oasis egypt mid pleistocene lacustrine sediments exposed as erosional remnants in dakhleh oasis in the western desert of egypt provide evidence for a more humid climate than that which persists today the sediments range in facies from palustrine to fully lacustrine and generally reflect an increase in water depth upward through the strata ironstone spring deposits associated with the lacustrine sediments and modern artesian discharge in the oasis indicate that nubian aquifer water was probably an important component of the water balance but the high carbonate content of the lake sediments requires the input of surface drainage derived from the nearby limestone capped libyan plateau although definitive shorelines have not been observed a maximum lake size of 1735 km2 is derived from extrapolation of the elevations of the deposits onto the modern deflated topography theoretical water balance modeling suggests that in addition to the discharge derived from the nubian aquifer 410 860 mm yr of rainfall would be required over the dakhleh oasis drainage basin in order to maintain the lake at hydrologic steady state the persistence of climatic and hydrologic conditions amenable to maintaining a shallow freshwater lake would have allowed the region to be inhabited by a savanna fauna as well as early human groups

sulfate and strontium water source identification by o s and sr isotopes and their temporal changes 1997 2008 in the region of freiberg central eastern germany abstract various waters bulk atmospheric precipitation groundwater river water flowing mine water mine drainage galleries and flooding mine water were studied in the region of freiberg to achieve an improved understanding of sources and mixing processes in the hydrological cycle and to specify the main sources that determine the isotope composition of dissolved sulfate and strontium 18 o so 4 34 s so 4 and 87 sr 86 sr in river water the combined use of isotope and chemical data led to identification of three major sulfate sources i sulfate from groundwater ii sulfate from the oxidation of local ore sulfides that remained in unflooded und flooded parts after mine decommissioning and iii industrial sulfate released from abundant waste slag and tailing deposits left behind after a long mining and industrial history of the region the same three components groundwater pore water from oxidation of residual ores and industry source were identified by analyzing sr isotope ratios however the sr isotopes pointed out a fourth yet unrecognized source that contributed to water of the flooded mine section the data show that the isotope composition of water of the river freiberger mulde was mainly determined by uncontaminated groundwater diluted with atmospheric precipitation whereas the other two end members played only a minor role for this river water however for the river triebisch the isotope compositions of dissolved sulfate and strontium record a strong impact of end members ii and iii after recharging the flooding water into the river a twelve year monitoring 1997 2008 revealed a strong decrease of 18 o so 4 values of water from bulk atmospheric precipitation as of 2006 2008 7 compared to 1997 14 while 34 s so 4 values remained constant 5 this isotope shift was probably caused by a lower contribution of primary sulfates to atmospheric precipitation in recent years groundwater and river water freiberger mulde also showed decreasing 18 o so 4 values albeit to a lower degree by 4 5 a decrease of 18 o so 4 values was again found in flowing mine water by 5 6 mainly affected by end member i uncontaminated groundwater the flood event in august 2002 likely washed out large parts of older groundwater and thus enabled the relatively large oxygen isotope decrease 18 o so 4 of groundwater and river water within a few years the previously high input from the industrial source waste and slag deposits decreased from 1997 to 2002 in some drainage galleries and flooding water that discharge their water into local rivers this led to lower 18 o and 34 s values of dissolved sulfates in these waters accompanied by a concentration decrease of several elements cl na and mg however no further decrease of the impact of this source could be detected after the storm and flood event in august 2002

87sr 86sr values in groundwaters of the east bull lake pluton superior province ontario canada abstract the east bull lake pluton is a 2 48 ga old layered mafic intrusion located on the southern margin of the superior province precambrian shield in ontario canada the groundwaters have been studied as part of a detailed geological mapping and geochemical study of the pluton for the canadian nuclear fuel waste management program all groundwater samples are dilute the most concentrated na cl type water contains 3 1 g l total dissolved solids present day87sr 86sr values of the rock samples varies from 0 705 to 0 714 and the groundwaters from 0 711 to 0 720 the ca hco3 recharge waters show the greatest range in values in contrast to the deeper na hco3 and deep na cl waters where a narrow range of 0 712 0 713 is found fracture filling laumontite calcite and gypsum have the same isotopic signature as the deep water the ca hco3 water is the youngest component of the groundwater system and its spread in isotopic values reflects local conditions at the surface the na cl water is considered to be the oldest component and its sr isotopic ratio value indicates equilibration with silicate fracture mineral phases the isotopic data suggest that laumontite calcite and gypsum fracture phases have either crystallized from this water or are currently controlling its isotopic composition by dissolution no age can be assigned to the deep waters except that the na cl component may date from the early paleozoic based on geological arguments or more likely be 104 106 years old based on kinetic studies of rock water interaction and other isotopic data if seawater was one component of the na cl water history there is no record of this in the87sr 86sr ratios

late quaternary systematic stream offsets caused by repeated large seismic events along the kunlun fault northern tibet abstract the kunlun fault is one of the largest strike slip faults in northern tibet china in this paper we focus upon the kusai lake kunlun pass segment of the fault to understand the geomorphic development of offset streams caused by repeated large seismic events based on tectono geomorphic analysis of high resolution satellite remote sensing images combined with field studies the results indicate that systematic left lateral stream offsets appear at various scales across the fault zone lateral offsets of small gullies caused by the 2001 m w 7 8 kunlun earthquake vary typically from 3 m to 6 m meanwhile streams with cumulative offsets of 10 m 25 30 m 50 70 m 250 300 m and 750 1400 m have resulted from repeated large seismic events during the late quaternary an average slip rate of 10 1 mm year has been estimated from the lateral stream offsets and 14 c ages of alluvial fan surfaces incised by the streams a three dimensional model showing tectono geomorphic features along a left lateral strike slip fault is also presented the kusai lake kunlun pass segment provides an opportunity to understand the relationship between geomorphic features produced by individual large seismic events and long term geomorphic development caused by repeated large seismic events along a major strike slip fault

assessing the role of submarine groundwater discharge as a source of sr to the mediterranean sea abstract submarine groundwater discharge sgd has been identified as an important source of sr to the ocean and the sgd driven sr flux to the global ocean has been recently re evaluated beck et al 2013 however the uncertainty of this value is still high because of the uncertainties related to the determination of sgd flow rates and the paucity of 87 sr 86 sr data in sgd end members as carbonates have high sr concentrations and are subjected to intense heightened weathering they might significantly influence the sgd input of sr to the ocean here we present data on sr concentrations and 87 sr 86 sr ratios in three carbonate dominated sites of the western area of the mediterranean sea a semi enclosed basin characterized by abundant coastal carbonates the 87 sr 86 sr ratios in groundwater were lower compared to modern seawater 0 70916 as expected for areas dominated by carbonate lithologies concentrations of sr and 87 sr 86 sr ratios in groundwater showed conservative mixing in the studied subterranean estuaries by using sgd flow rates reported in the literature for the study areas a flow weighted fresh sgd end member characterized by a sr concentration of 27 30 m and a 87 sr 86 sr ratio of 0 707834 0 708020 was calculated for the eastern coast of the iberian peninsula integrating these sr data with literature data i e values of sr concentration and 87 sr 86 sr ratio from other lithologies as well as sgd flow rates we also calculated the fresh sgd driven sr flux to the entire mediterranean sea obtaining a value of 0 34 0 83 10 9 mol y 1 with a 87 sr 86 sr of 0 7081 0 7086 thus for the entire mediterranean basin sgd is globally a source of sr less radiogenic compared to seawater the sgd sr flux to the mediterranean sea represents 5 6 of the sgd sr flux to the global ocean and the mediterranean sgd end member has higher sr concentration 5 12 m than the global sgd end member 2 9 m this confirms the significant role of carbonate lithologies on sgd driven sr fluxes to seawater the fresh sgd driven sr flux to the mediterranean sea is about 20 50 of the riverine sr input and significantly higher than the input through atmospheric dust deposition therefore sgd should be considered as an important continental source of sr to the basin

isotopic compositions of ce nd and sr in ferromanganese nodules from the pacific and atlantic oceans the baltic and barents seas and the gulf of bothnia abstract ferromanganese nodules from the pacific and atlantic oceans the barents and baltic seas and the gulf of bothnia were analyzed for the isotopic compositions of ce nd and sr and the abundances of ree ba and sr ree patterns of barents baltic and bothnian samples show no ce anomaly or even a negative one in contrast to the positive anomaly observed for the pacific and atlantic samples moreover the baltic and bothnian samples have distinctly low end values average end values of the four regions are as follows pacific 5 barents 10 atlantic 11 and baltic inclusive of gulf of bothnia 19 the characteristic low end values of the baltic samples are indicative of the influence of precambrian rocks from the baltic shield of particular interest is the feature of the ce isotopic composition that ece values of the samples from the pacific are negative and those from the other three regions positive this novel finding might suggest a difference in sources of ce between the pacific and other regions these results demonstrate that ce isotopic ratios can be a useful tracer in marine geochemistry in combination with isotopic compositions of nd and sr

constraining the marine strontium budget with natural strontium isotope fractionations 87sr 86sr δ88 86sr of carbonates hydrothermal solutions and river waters we present strontium sr isotope ratios that unlike traditional 87sr 86sr data are not normalized to a fixed 88sr 86sr ratio of 8 375209 defined as 88 86sr 0 relative to nist srm 987 instead we correct for isotope fractionation during mass spectrometry with a 87sr 84sr double spike this technique yields two independent ratios for 87sr 86sr and 88sr 86sr that are reported as 87sr 86sr and 88 86sr respectively the difference between the traditional radiogenic 87sr 86sr normalized to 88sr 86sr 8 375209 and the new 87sr 86sr values reflect natural mass dependent isotope fractionation in order to constrain glacial interglacial changes in the marine sr budget we compare the isotope composition of modern seawater 87sr 86sr 88 86sr seawater and modern marine biogenic carbonates 87sr 86sr 88 86sr carbonates with the corresponding values of river waters 87sr 86sr 88 86sr river and hydrothermal solutions 87sr 86sr 88 86sr hydend in a triple isotope plot the measured 87sr 86sr 88 86sr river values of selected rivers that together account for not vert similar18 of the global sr discharge yield a sr flux weighted mean of 0 7114 8 0 315 8 the average 87sr 86sr 88 86sr hydend values for hydrothermal solutions from the atlantic ocean are 0 7045 5 0 27 3 in contrast the 87sr 86sr 88 86sr carbonates values representing the marine sr output are 0 70926 2 0 21 2 we estimate the modern sr isotope composition of the sources at 0 7106 8 0 310 8 the difference between the estimated 87sr 86sr 88 86sr input and 87sr 86sr 88 86sr output values reflects isotope disequilibrium with respect to sr inputs and outputs in contrast to the modern ocean isotope equilibrium between inputs and outputs during the last glacial maximum 10 30 ka before present can be explained by invoking three times higher sr inputs from a uniquely glacial source weathering of shelf carbonates exposed at low sea levels our data are also consistent with the weathering peak hypothesis that invokes enhanced sr inputs resulting from weathering of post glacial exposure of abundant fine grained material

neodymium isotopic study of baffin bay water sources of ree from very old terranes water samples were collected from baffin bay and surrounding areas in order to evaluate this region as a potential source of nd from old continental material to atlantic water the isotopic data ranged from e nd 0 9 0 to 26 with most of the data around e nd 0 20 compared with values of north atlantic deep water nadw with e nd 0 13 5 the concentration of nd in baffin bay waters was as high as 6 10 12 g g compared with 2 5 10 12 g g for nadw the combination of low e nd and high nd concentration indicates that baffin bay may be a significant source of nd from very old crustal material a simple box model was used to evaluate the contribution to the nd budget of nadw and it was concluded that a substantial fraction of the nd from ancient crustal sources that is required to maintain the isotopic composition of nadw could be supplied by baffin bay outflow

evidence for late pleistocene climate changes from buried soils on the southern slopes of mt kilimanjaro tanzania abstract the distribution of the altitudinal vegetation zones on the slopes of mt kilimanjaro is well known but no reliable data are available about the vegetation shifts during the quaternary here i present palaeopedological results elemental biomarker stable isotope and radiocarbon analyses indicating that the frequently occurring buried black a horizons in the montane forest belt are developed under ericaceous vegetation since erica species are not abundant at this altitude nowadays but are characteristic for the sub alpine zone the palaeosols reflect palaeoclimatically driven fluctuations and changes of the vegetation zones on mt kilimanjaro the downhill descent of the ericaceous belt coincided with cold and dry periods like the late glacial and the last glacial maximum older palaeosols document that such events also took place during the marine isotope stages 3 and 4

geoarchaeology and paleoecology of the deeply stratified richard beene site medina river valley south central texas usa abstract a geoarchaeological investigation that included soil stratigraphic and paleoecological analyses was conducted at richard beene a deeply stratified open air site associated with an alluvial terrace of the medina river in south central texas the sequence of cultural and alluvial deposits at the site is one of the most complete records of holocene human occupation and sedimentation documented in north america and is very important to the interpretation of the cultural history of the inner gulf coastal plain and adjacent areas of the southern plains the most salient ecological characteristics of the site are its riparian setting and location in the ecotone between north america s western grasslands and eastern woodlands the cultural record spans the past 10 000 years and is buried in 14 m of fine grained flood deposits with multiple buried paleosols excavations totaling 730 m2 sampled 20 stratigraphically distinct archaeological components in valley fill beneath the applewhite terrace yielding more than 80 000 artifacts including flakes tools bones mussel shells and fire cracked rocks left by archaic and late pre columbian hunter gatherers seven primary stratigraphic units and five laterally traceable buried paleosols were identified at the site the oldest stratigraphic unit consists of coarse grained channel deposits that accumulated soon before 33 000 14c yr b p most of the units however consist of fine grained alluvium that accumulated between ca 10 000 and 1000 14c yr b p the 13c values of organic matter from the site s soil stratigraphic sequence indicate increased c4 production during the younger dryas 11 000 10 000 14c yr b p and c4 productivity generally increased throughout the holocene culminating in peak warm intervals at ca 5000 and 2000 14c yr b p although during relatively dry periods grasses expanded at the expense of trees a mosaic of trees and grasses i e a savannah typical of a grassland forest ecotone prevailed at the site throughout the holocene such a food rich environment characterized by an abundance of deer and geophytes as well as mussels from the medina river accounts for repetitive human occupation spanning at least 10 000 years

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

the isotopic composition of nd in a boreal river a reflection of selective weathering and colloidal transport in this study the nd concentrations cnd from 18 months of weekly sampling of filtered water 90 dominated by a colloidal phase primarily composed of organic c and fe the end 0 and 147sm 144nd only vary within a narrow range 27 1 to 24 8 and 0 103 to 0 110 respectively with no obvious relationship to cnd and discharge the end 0 and 147sm 144nd in the river water is significantly lower than in the unweathered till and average bedrock in the catchment and show a closer resemblance with the isotopic characteristics found in humic substances and plant material these data show that the isotopic composition of nd exported from a large boreal drainage basin does not directly reflect that of the bulk bedrock in the catchment the isotopic composition is controlled by selective weathering and the nd transport is dominated by organic colloidal particles

238u234u and232th230th in the baltic sea and in river water the concentration c of dissolved238u 234u 232th and230th in fresh and brackish waters from the baltic sea were determined using tims the brackish waters range in salinity from that of sea water sw to 2 5 c238u in oxygen saturated surface waters is well correlated with salinity and shows quasi conservative behavior as does sr samples from the redox water interface show depletion in c238u demonstrating that dissolved u is being removed by femn oxyhydroxides from a simple mixing relationship for the brackish water 234u 1000 was calculated for the fresh water source in the northern baltic a study of the kalixalven river over an annual cycle yields high 234u during spring and summer discharge and lower values during fall and winter showing that different sources contribute to the u load in the river during different seasons c232th and c230th in river water are governed by the discharge reflecting the importance of the increased abundance of small particles 0 45 m for the232th230th load at high discharge 232th 238u in river water is about 40 times less than in detrital material in the brackish water c232th drops 2 orders of magnitude in the low salinity region 5 reaching a value close to that of sea water at a salinity of 7 5 almost all of the riverine232th must be deposited in the low salinity regions of the estuary the230th 232th in river waters is about twice the equilibrium value for232th 238u 3 8 in the brackish waters 230th 232th is greater by a factor of 10 100 than both river water and sw the big increase in230th 232th in the baltic sea waters over the riverine input indicates that the th isotopes enter the estuary as a mixture of two carrier phases we infer that about 96 of232th in river water is carried by detrital particles whereas the other phase solution colloidal has a much higher232th 232th entering the estuary the detrital particles sediment out rapidly whereas the non detrital phase is removed more slowly causing a marked increase in230th 232th in the brackish water in sw 230th 232th is closer to river input and detrital material than in brackish water we conclude that in the deep sea 232th is almost exclusively dominated by windblown dust and can be used to monitor dust flux the230th excess in baltic rivers is produced in u rich 232th poor peatlands and trapped in authigenic particles and transported with the particles time scales for producing the230th excess are 2000 8000 yr this is younger than but comparable to the time of the latest deglaciation which ended some 9000 yr ago when the mires were forming these results have implications for the possible mobility of actinides stored in repositories

rare earth element transport in the western north atlantic inferred from nd isotopic observations the isotopic composition of nd in the water column from several western north atlantic sites and formational areas for north atlantic deep water shows extensive vertical structure at all locations in regions where a thermocline is well developed large isotopic shifts 2 to 3 units are observed across the base of the thermocline regions without a thermocline are characterized by much more gradual shifts in isotopic composition with depth in general the data reveal an excellent correlation between the nd isotopic distribution in the western north atlantic water column and the distribution of water masses identified from temperature and salinity characteristics nadw as identified from t s properties is also characterized by a well defined isotopic composition having nd 0 13 5 0 5 this signature is associated with waters identified as nadw from high latitudes near formational areas in the labrador sea down to the equatorial region the isotopic signature of nadw would appear to be formed by a blend of more negative waters originating in the labrador sea nd 0 18 and more positive waters originating in the overflows from the norwegian and greenland seas nd 0 8 to 10 and is consistent with classical theories on the formation of nadw the isotopic signature of nadw is propagated southward to the equator where it is gradually being thinned out by mixing from above and below with more radiogenic nd associated with northward spreading antarctic intermediate and bottom waters the preservation of the isotopic signature of nadw over these large distances indicate that the ree undergo extensive lateral transport the isotopic composition of nd is largely conservative over the time scales of mixing within the atlantic in spite of the intrinsic nonconservative behavior of neodymium nd concentration gradients generally show surface waters to be depleted in nd relative to deep waters which must require vertical transport processes however isotopic differences in the water column preclude the local downward transport of ree from the surface into underlying deep waters as a simple explanation of the concentration gradient the apparent decoupling of ree in nadw from overlying local surface waters and the increasing concentration with depth provide a conflict with simple vertical transport mechanisms that is not yet resolved

paleosols and paleoenvironments of early mars fluviolacustrine sediments filling gale crater on mars show two levels of former exposure and weathering that provide new insights into late noachian 3 7 0 3 ga paleoenvironments of mars diagnostic features of the two successive paleosols in the sheepbed member include complex cracking patterns of surface dilation peds and cutans a clayey surface a horizon deep sand filled cracks with vertical lamination sand wedges and replacive sulfate nodules aggregated into distinct bands gypsic by horizon above bedded sandy layers sedimentary c horizon shallow gypsic horizon periglacial sand wedges and limited chemical weathering are evidence of a hyperarid frigid paleoclimate and this alternated with wetter conditions for the lacustrine parent materials in gale crater during the late noachian depletion of phos phorus vesicular structure and replacive gypsic horizons of these martian paleosols are fea tures of habitable microbial earth soils on earth and encourage further search for definitive evidence of early life on mars

learning to read the chemistry of regolith to understand the critical zone the base of the critical zone includes the mantle of altered soil and rock regolith that changes in response to chemical physical and biological processes occurring at earth s surface these processes are recorded in the chemistry of the regolith and this long term record can often be deciphered for example on eroding ridgetops where flows are generally downward for water and upward for earth material element concentrations vary with depth to constitute depletion addition depletion enrichment and biogenic profiles models can be used to explore the records of mineral dissolution atmospheric input coupled dissolution precipitation and biolifting documented in these profiles these models enable interpretation of the effects of time climate rates of erosion and human and other biotic impacts on the profile patterns by testing quantitative models against the long term record of information in regolith we will learn to project changes arising from human and natural perturbations of the critic

co2 water mineral reactions during co2 leakage geochemical and isotopic monitoring of a co2 injection field test a shallow co2 injection experiment was performed at the co2fieldlab site near svelvik norway in sept 2011 the gas was injected through a 45 inclined well to a target depth of 20 m its aim was to test various geophysical and geochemical monitoring tools for integrated near surface leakage monitoring a total of 1 67 t of co2 was injected over a period of six days groundwater level was at 60 cm depth and a complex salinity stratification with brackish water overlying fresh and saltwater was observed at the beginning of the experiment four water sampling boreholes were located at each corner of a square configuration of 8 m with the nominal injection at the center from baseline conditions to the post co2 injection phase ph temperature and electrical conduc tivity of the groundwater were measured collecting water samples at three different depths 5 10 and 15 m for analyses of major minor and trace elements ca na so4 cl mg al ba mn ni co b li and isotopes 11b 7li 34sso4 18oso4 87sr 86sr 18oh2o 2hh2o significant changes in chemical and isotope signatures of water over the duration of the experiment indicated two processes 1 binary mixing with seawater and rainwa ter as the possible end members due to a near seashore location and 2 co2 water rock interactions enhanced by dissolved co2 causing acid conditions and favoring rock dissolution the relative contribution of those pro cesses was quantified by a mass balance model and equilibrium calculations this comprehensive geochemical and isotope approach allowed discriminating reactive mechanisms from non reactive mixing processes asso ciated with co2 leaks within an aquifer with a strong conductivity stratification and heterogeneous mineralogy and this approach seems promising for investigating co2 leaks at field scale