natural uranium and strontium isotope tracers of water sources and surface water groundwater interactions in arid wetlands pahranagat valley nevada usa summary near surface physical and chemical process can strongly affect dissolved ion concentrations and stable isotope compositions of water in wetland settings especially under arid climate conditions in contrast heavy radiogenic isotopes of strontium 87sr 86sr and uranium 234u 238u remain largely unaffected and can be used to help identify unique signatures from different sources and quantify end member mixing that would otherwise be difficult to determine the utility of combined sr and u isotopes are demonstrated in this study of wetland habitats on the pahranagat national wildlife refuge which depend on supply from large volume springs north of the refuge and from small volume springs and seeps within the refuge water budgets from these sources have not been quantified previously evaporation transpiration seasonally variable surface flow and water management practices complicate the use of conventional methods for determining source contributions and mixing relations in contrast 87sr 86sr and 234u 238u remain unfractionated under these conditions and compositions at a given site remain constant differences in sr and u isotopic signatures between individual sites can be related by simple two or three component mixing models results indicate that surface flow constituting the refuge s irrigation source consists of a 65 25 10 mixture of water from two distinct regionally sourced carbonate aquifer springs and groundwater from locally sourced volcanic aquifers within the refuge contributions from the irrigation source and local groundwater are readily determined and depend on proximity to those sources as well as water management practices

chemistry of rainwater in the massif central france a strontium isotope and major element study atmospheric aerosols sea salt crustal dust and biogenic aerosols are the primary source of dissolved species in rainwater as well as one of the sources of dissolved species in river water chemical weathering studies require quantification of this atmospheric input the crustal component of atmospheric input can have various origins both distant and local the proportions of the various inputs marine distant or local are determined in this study strontium isotope ratios and ca na k mg al cl so4 no3 and sr concentrations were measured in rainwater samples collected in the massif central france over a period of one year each sample collected automatically represents a monthly series of rain events chemical composition of the rainwater samples varied considerably and the 87sr 86sr ratios ranged between 0 709198 and 0 713143 using na as an indicator of marine origin and al for the crustal input in rain samples the proportion of marine and crustal elements was estimated from elemental ratios a marine origin of 4 to 100 of cl of 0 6 to 20 of the so4 of 1 to 10 of ca 1 to 40 of k 4 to 100 of mg and 1 to 44 of sr was determined strontium isotopes were used to characterize the crustal sources the 87sr 86sr ratios of the crustal sources varied considerably from 0 7092 to 0 71625 and indicate the occurrence of multiple sources for the crustal component in the analysed rainwaters

geochemical characteristics of biotite from felsic intrusive rocks around the sisson brook w mo cu deposit west central new brunswick an indicator of halogen and oxygen fugacity of magmatic systems abstract the sisson brook w mo cu deposit was formed by hydrothermal fluids likely related to the nashwaak granites muscovite biotite granite group i and biotite granite group ii and related dykes biotite granitic dykes group iii and a feldspar biotite quartz porphyry dyke group iv chemical data obtained using epma and la icp ms data of primary magmatic biotites were used to investigate magmatic processes and associated hydrothermal fluids trace element features of biotite in the group i two mica granite suggest other magmatic processes along with a simple fractional crystallization the k rb ratios and compatible elements cr ti co v and ba in biotite from groups ii iii and iv decrease whereas incompatible elements including ta tl ga cs li and sn increase with magma fractionation no correlation of cu w and mo with k rb ratios is evident suggesting that partitioning of cu w and mo into biotite may not be entirely controlled by magma fractionation halogen fugacity of the parental magma of the nashwaak granites and related dykes calculated from zircon saturation temperature shows that group i has high f hf f cl ratios broadly higher than 0 similar to the plutons at the henderson porphyry mo deposit the f hf f cl ratios of the other groups are generally lower than 0 comparable to the santa rita porphyry cu deposit the f h 2 o f hcl and f h 2 o f hf ratios inferred from biotite in the nashwaak granites and related dykes range from 3 to 5 and from 4 to 5 respectively the inferred oxygen fugacity shows that the dyke phases groups iii and iv have the oxygen fugacity around the nickel nickel oxide buffer the plutonic phases groups i and ii have the oxygen fugacity around the quartz fayalite magnetite qfm buffer at high temperatures and oxidized to nickel nickel oxide buffer at lower temperatures this oxidation process in the plutonic phases groups i and ii could be caused by h 2 release at or near h 2 o vapor saturation at high h 2 o fe 2 the magma associated with the biotite dykes group iii is more likely the source of the hydrothermal fluids at the sisson brook deposit since it has the highest differentiation degree and seems to have formed in an oxidized setting necessary for mo to concentrate in the late stage fluids

effect of calcite precipitation on stable strontium isotopic compositions insights from riverine and pool waters in a karst cave abstract radiogenic and stable sr isotope ratios 87 sr 86 sr 88 86 sr serve as potential tracers for evaluation of weathering sources and associated physicochemical processes in terrestrial environments despite carbonate weathering sourcing two thirds of the total continental sr flux to the ocean however few attempts have been aimed at studying stable sr isotope fractionation in carbonate dominated aquifers here we present a monthly resolved monitoring dataset of major ion concentrations and sr isotope ratios for karst riverine and pool waters at the luofang cave in the central china to understand the potential controls responsible for water 88 86 sr compositions under various climatic conditions with the exception of some pool waters in the dry period significantly heavier 88 86 sr were detected in the riverine and pool waters 0 20 to 0 42 compared to bedrock 88 86 sr 0 24 to 0 28 which can t be interpreted solely by lithology a sequential leaching experiment of the local soils suggests limited stable sr isotope fractionation during incongruent silicate mineral dissolution local plant utilization and biological activity in the soil overlying the cave are possible processes for causing the observed heavier 88 86 sr in cave water however air partial pressure of co 2 in cave monitoring water ph and sr isotopic mass balance calculations suggest that plant utilization is unlikely to be the primary control on the heavier water 88 86 sr on the other hand significant stable sr isotope fractionation was found between the cave dripping waters and calcite precipitates and the 88 86 sr car aq was estimated to be 0 15 0 07 2sd precipitation of secondary calcites might be a potential process responsible for the heavier 88 86 sr in the waters the negative correlation between 88 86 sr and sr na ratios in the cave waters is consistent with a scenario of preferential incorporation of the light sr isotope by solid phase furthermore by combining the calcite saturation states and water ph our results suggest that calcite precipitation is the most likely process controlling 88 86 sr compositions in cave water we demonstrate that secondary calcite precipitation in carbonate dominated catchments could be important in controlling the riverine water 88 86 sr compositions

radiogenic and stable sr isotope ratios 87 sr 86 sr δ 88 86 sr as tracers of riverine cation sources and biogeochemical cycling in the milford sound region of fiordland new zealand this study reports radiogenic sr isotope ratios 87sr 86sr stable sr isotope ratios 88 86sr and major ion concentrations for river rock sediment soil and plant samples collected from the cleddau and hollyford catchments in the milford sound region of fiordland new zealand the catchments primarily drain gabbro but some tributaries access limestone and volcanogenic sediments the goal of the study was to understand controls on riverine 88 86sr values in a landscape with multiple factors that may influence chemical weathering including dense vegetation high rainfall and abundant freshly eroded holocene fluvio glacial and landslide debris rivers draining gabbro have higher 88 86sr values than bedrock by as much as 0 14 and the 88 86sr values strongly correlate with molar ca sr ratios r2 0 69 leaching of rocks and sediment reveals no evidence for the preferential dissolution of minerals having high 88 86sr values and ca sr ratios in stream sr isotope fractionation seems unlikely because comparison against 87sr 86sr and ca sr ratios demonstrates that riverine 88 86sr values conservatively trace water mass mixing the riverine data are best explained by the input of soil water which is distinct from potential bedrock end members i e silicates and carbonates based on 88 86sr but indistinguishable in terms of ca sr and 87sr 86sr while strontium isotope fractionation during secondary mineral formation and pedogenesis is possible clay mineral formation is minor and most soils are poorly developed instead soil water 88 86sr values more likely reflect plant uptake plant samples yielded a wide range of 88 86sr values but on average they are lower than those for bedrock consistent with the expectation that plants preferentially incorporate lighter sr isotopes mass balance constraints together with 87sr 86sr ratios indicate that soil water 88 86sr values are 0 30 higher than bedrock 88 86sr values and mixing calculations show that the plant fractionated soil water pool contributes 27 of the riverine sr for tributaries accessing limestone and volcanogenic sediments ca sr and 87sr 86sr ratios appear consistent with two component mixing between silicate and carbonate weathering but 88 86sr values reveal a third contribution from soil water inputs similar to gabbro catchments the results of this study suggest that sr isotopes behave conservatively during water mass mixing and stream transport but non conservatively in soil where plant uptake can elevate soil water 88 86sr values relative to bedrock plant uptake or related biogeochemical processes such as ion exchange on organic matter surfaces also appear to modify soil water ca sr ratios many studies use 87sr 86sr and ca sr ratios to apportion riverine solutes between silicate and carbonate weathering but ca sr ratios may be non conservative in densely vegetated areas the stable sr isotope tracer shows promise for resolving riverine cation sources as well as effects from biological cycling

origin of calcium in pedogenic carbonate nodules from silicate watersheds in the far north region of cameroon respective contribution of in situ weathering source and dust input significant amounts of pedogenic ca carbonate nodules have been observed in the far north region of cameroon in the carbonate free watershed of the mayo tsanaga thus a priori not favourable for carbonate nodules accumulations these nodules are associated with a clay rich parent material crpm covering either a granitic upstream or a greenstone bedrock downstream in this peculiar context the amount of pedogenic carbonate nodules represents large quantities of ca and c therefore determining the ca sources for pedogenic carbonate nodules is a key point regarding the mechanisms leading to carbonate nodule precipitation and their role in the biogeochemical cycle of ca three sites two on granite and one on greenstone were studied by combining sr et nd isotope systematics in order to assess the ca sources of carbonate nodules and the origin of the crpm associated with nodules carbonate nodules have a distinct sr isotopic composition in each profile pointing to the contribution of a local source for ca sr isotopic compositions of plagioclases and carbonate nodules display a concomitant variation in each profile indicating that plagioclases acted as a sr and thus ca source for the carbonate nodules nevertheless carbonate nodules have a higher sr isotopic signature than plagioclases implying the contribution of another more radiogenic sr source sr and nd isotope data from the crpm show that it is a mixture of weathered bedrock compounds and saharan dust this result highlights two other potential sr and ca sources biotite and saharan dust calculations of their respective contributions demonstrate that in situ weathering significantly adds to the ca source of nodules this result contrasts with many other studies from similar settings that highlight the importance of allochthonous marine aeolian inputs this conclusion points out that a substantial part of ca is transferred from the local bedrock to the carbonate nodules this mechanism seems to have been possible as peculiar edaphic conditions preserved the primary ca sources making in situ weathering a significant process for providing ca

stable sr isotope sr ca mg ca li ca and mg li ratios in the scleractinian cold water coral lophelia pertusa the aragonitic skeletons of scleractinian cold water corals can serve as valuable archives in paleoceanographic studies the potential of 88 86sr sr ca mg ca li ca and mg li ratios of the cold water coral lophelia pertusa to record intermediate water mass properties has been investigated here we used samples from several locations along the european continental margin spanning a large temperature range from 6 to 14 c stable strontium isotope measurements were carried out with the recently developed double spike tims technique and our results differ from those obtained with less precise methods in contrast to the strong positive relationship with temperature of previous studies our results suggest that 88 86sr measured in scleractinian cold water corals is not controlled by seawater temperature but reflects the sr isotopic composition of seawater with an offset of 88 86sr 0 196 as found in previous studies the elemental ratios sr ca li ca and mg li measured in corals are significantly related to water temperature and do not correlate with salinity moreover sr ca ratios in l pertusa display the expected inverse correlation with temperature however the variance in the sr ca data severely limits the accuracy of paleotemperature estimates the li ca and mg ca ratios reveal other influences besides temperature such as ph and or growth or calcification rate however corresponding mg li ratios in l pertusa are more tightly related to temperature as they remove these secondary effects in particular the mg li ratio in l pertusa may serve as a new promising paleotemperature proxy for intermediate water masses our dataset represents the most extensive geochemical examination of l pertusa to date revealing a temperature sensitivity of 0 015 mol mmol c for mg li however using this temperature dependence and the precision of 5 3 2sd only temperature variations larger than 1 5 c can be resolved with 95 confidence

geochemistry and u pb geochronology of the wagone and hermyingyi a type granites southern myanmar implications for tectonic setting magma evolution and sn w mineralization abstract tin tungsten associated granites occur widely in the dawei region of the southeast asian tin belt in this contribution we present a detailed study of zircon u pb geochronology and whole rock and zircon elemental geochemistry for the wagone and hermyingyi granites in southern myanmar with the aim of determining their petrogenesis mineralization associations and tectonic setting these granitic rocks which belong to the high k calc alkaline series a2 type granites are characterized by high concentrations of sio2 75 2 82 5 rb 264 927 ppm th 18 4 58 3 ppm u 10 4 18 3 ppm and y 33 5 212 ppm but low contents of tfeo 0 57 3 45 cao 0 23 0 86 mgo 0 02 0 19 mno 0 01 0 38 tio2 0 01 0 10 p2o5 0 003 0 012 ba 3 162 ppm and sr 4 3 34 4 ppm hydrothermal zircons from the mineralized wagone pluton show an anomalous lack of zoning and vermicular spongy internal structures and they contain high concentrations of ti y u and light rees but low th u ratios mostly

characterising the stable δ88 86sr and radiogenic 87sr 86sr isotopic composition of strontium in rainwater rainwater plays a major role in determining the transfer of elements and pollutants to soils and hydrological catchments with compositional variations reflecting the extent of mixing between marine sea salt terrestrial dust and vegetation and anthropogenic aerosols while the radiogenic strontium isotope system 87sr 86sr is often used to help constrain the different sources of atmospheric sr the degree of variability in the stable strontium isotope system 88 86sr remains unresolved in order to determine how atmospheric sr affects the 88 86sr composition of water entering the hydrological cycle this study analysed a suite of rainwater samples collected over the course of a year in central paris rainwater 88 86sr compositions were found to range from 0 13 to 0 32 with 87sr 86sr ratios varying between 0 70796 and 0 71093 no seasonality was observed in 88 86sr whereas 87sr 86sr ratios were observed to be generally more radiogenic in the summer and less radiogenic in the winter strontium enrichment factors significantly above seawater implied a predominantly terrestrial non sea salt origin of sr in rainwater with the 88 86sr and 87sr 86sr composition of this terrestrial fraction consistent with a mixture of sr derived from carbonate dust and agricultural fertiliser evidence for a 0 1 decrease in the 88 86sr composition of the river seine as it passes through paris suggests that anthropogenic pollutants may contribute to significant regional variations in the composition of sr in the hydrological cycle together these results demonstrate that there is significant potential for both temporal and spatial variations in the 88 86sr and 87sr 86sr composition of rainwater that need to be taken into consideration when studying 88 86sr variations in localised catchments

weathering rates and 87sr 86sr ratios an isotopic approach the 87sr 86sr ratios of precipitation throughfall groundwater streamwater and mineral matter were analyzed precipitation strontium ratios are around 0 71 throughfall which is affected by strontium from the mineral soil has ratios of 0 72 0 73 and shallow groundwater in a drug well and runoff have ratios around 0 73 0 74 there is a tendency for this relationship to be reversed for discharge higher ratios are associated with lower discharges water from a fracture zone gave the highest value 0 78 approaching the value of the bedrock around 0 85 a calcium budget which reflects the mean conditions over a few years has been calculated this budget indicates that weathering should be of the order of 8 kg ca ha 1yr 1 to maintain the pool of exchangeable calcium at a constant level the major anion in the runoff is suphate which has entered the system in the form of acid rain sulphur deposition has been rather constant over the last two decades if acidification had an effect on weathering of silicates this would have shown up in a tendency of the strontium isotope ratios toward higher values in the soil pool and in runoff water thus its seems from the observed ratios that at least a major portion of the excess calcium export resulting from sulphur deposition is taken from the soil pool resulting in a gradual acidification of the soil

determination of 88sr 86sr mass dependent isotopic fractionation and radiogenic isotope variation of 87sr 86sr in the neoproterozoic doushantuo formation abstract we measured both mass dependent isotope fractionation of 88sr 88sr 86sr and radiogenic isotopic variation of sr 87sr 86sr for the neoproterozoic doushantuo formation that deposited as a cap carbonate immediately above the marinoan related nantuo tillite the 88sr and 87sr 86sr compositions showed three remarkable characteristics 1 high radiogenic 87sr 86sr values and gradual decrease in the 87sr 86sr ratios 2 anomalously low 88sr values at the lower part cap carbonate and 3 a clear correlation between 87sr 86sr and 88sr values these isotopic signatures can be explained by assuming an extreme greenhouse condition after the marinoan glaciation surface seawater mixed with a large amount of freshwater from continental crusts with high 87sr 86sr and lighter 88sr ratios was formed during the extreme global warming after the glacial event high atmospheric co2 content caused sudden precipitation of cap carbonate from the surface seawater with high 87sr 86sr and lighter 88sr ratios subsequently the mixing of the underlying seawater with unradiogenic sr isotope compositions and normal 88sr ratios probably caused gradual decrease of the 87sr 86sr ratios of the seawater and deposition of carbonate with normal 88sr ratios the combination of 87sr 86sr and 88sr isotope systematics gives us new insights on the surface evolution after the snowball earth

88sr 86sr fractionation in inorganic aragonite and in corals conflicting results have been reported for the stable sr isotope fractionation specifically with respect to the influence of temperature in an experimental study we have investigated the stable sr isotope systematics for inorganically precipitated and biogenic coral aragonite natural and laboratory cultured inorganic aragonite precipitation experiments were performed from natural seawater using the co2 diffusion technique the experiments were performed at different temperatures and different carbonate ion concentrations 88sr 86sr of the inorganic aragonite precipitated in the experiments are 0 2 lighter than seawater but showed no correlation to the water temperature or to co32 concentration similar observations are made in different coral species cladocora caespitosa porites sp and acropora sp with identical fractionation from the bulk solution and no correlation to temperature or co32 concentration the lack of 88sr 86sr variability in corals at different environmental parameters and the similarity to the 88sr 86sr fractionation in inorganic aragonite may indicate a similar sr incorporation mechanism in corals skeleton and inorganic aragonite and therefore the previously proposed rayleigh based multi element model gaetani et al 2011 cannot explain the process of sr incorporation in the coral skeletal material it is proposed that the relatively constant 88sr 86sr fractionation in aragonite can be used for paleo reconstruction of seawater 88sr 86sr composition the seawater 88sr 86sr ratio reconstruction can be further used in calcite samples to reconstruct paleo precipitation rates

stable strontium isotopes δ88 86sr in cold water corals a new proxy for reconstruction of intermediate ocean water temperatures abstract zooxanthellate scleractinian corals are known as archives for temporal variations of climate variables such as sea surface temperature salinity or productivity the use of azooxanthellate cold water corals as potential archives for intermediate water mass properties and climate variability was tested recently however the correlation of established proxies such as 18o and 13c with temperature is difficult since there is no direct temperature equation applicable as in shallow water corals other temperature proxies such as sr ca mg ca and u ca are influenced by the complex microstructure of the aragonite skeleton the rate of calcification and other vital effects observed for coral species for the first time we show that the stable strontium isotope ratio 88 86sr incorporated in the skeletons of the cold water coral species lophelia pertusa portrays the ambient seawater temperature the temperature sensitivity from live samples collected along the european continental margin covering a temperature range from 6 to 10 c is 0 026 0 003 c 2 standard error which is a sensitivity similar to the tropical shallow water coral record of pavona clavata this indicates a similar fractionation process of strontium for both zooxanthellate and azooxanthellate corals for coral aragonite the 88 86sr ratio may serve as a new paleo temperature proxy and introduces new perspectives in paleoceanography with respect to intermediate water dynamics

evidence for stable sr isotope fractionation by silicate weathering in a small sedimentary watershed in southwestern taiwan abstract radiogenic sr isotopes 87 sr 86 sr are robust for provenance identification in hydrology affected mainly by the age of background lithologies and the degree of chemical weathering however there is limited knowledge concerning the fractionation mechanism of stable sr isotopes 88 sr 86 sr in rivers in this study river water was collected on a weekly to monthly basis throughout dry and wet seasons furthermore to study the variations of radiogenic and stable sr isotopes during intense weathering a major flooding event 2000 mm precipitation in three days typhoon morakot water was captured within a small drainage catchment system 161 km 2 along the hou ku river in southwestern taiwan for a better constraint on the end member compositions bedload sediments suspended particles and several host rocks were sampled for a systematic investigation the carbonate and silicate phases of these solids were chemically separated dissolved major elements indicate that the watersheds were predominated by silicate weathering stable sr isotopes show no significant variation 88 sr 0 24 0 31 temporally and spatially with an average of 0 28 additionally all solids showed lower 88 sr values than the river water while the host rocks had higher 88 sr values 88 sr 0 20 0 26 than the residual weathering products 88 sr 0 08 0 22 indicating preferential leaching of heavy sr into the hydrosphere and leaving light sr in the residual solids results of laboratory acid leaching experiments reveal that dissolution of high 88 sr value minerals occurred at an early stage of weathering the variation of weathering intensity does not alter stable sr isotopes in silicate weathering dominated river water which contains higher stable sr isotopes than the associated sediments the silicatic sedimentary rocks preferentially released higher stable sr isotopes into the hydrosphere during chemical weathering thus leaving lower stable sr isotopes in the residual solids

the origin and migration of mud volcano fluids in taiwan evidence from hydrogen oxygen and strontium isotopic compositions abstract mud volcanoes are important gateways for deep fluids to migrate upward and provide windows for studying fluid sediment interaction at depth fluids emitted from 40 terrestrial mud volcanoes were collected in southern and eastern taiwan to study their chemical compositions including h o and sr isotopes 87sr 86sr and 88 86sr relative to seawater the mud volcano fluids are depleted in cl mg so42 and d and are elevated in b ba li and 18o possibly due to water rock interaction and clay dehydration mainly smectite to illite transformation in the source region the distribution of sr in mud volcano fluids shows patterns associated with their localities and geological settings most fluids have higher 87sr 86s than seawater indicating water rock interaction at depth the low na 87sr 86s and high ca fluids emitted from eastern taiwan imply intense interaction with igneous basement most fluids have higher sr cl and lower 88sr than seawater except mud volcanoes in the northern chu kou fault which emit low sr cl and extremely high 88sr up to 0 82 fluids we performed laboratory carbonate precipitation experiments that indicate that these high sr isotope ratios are caused by co precipitation of carbonates from high alkalinity fluids mud volcano fluids in taiwan originate at depth and their chemical compositions are controlled by the host rock degrees of water rock interaction and clay dehydration but also are masked by retrograde progresses such as carbonate precipitation during migration our results show that an approach combining water isotopes d and 18o and strontium isotopes 87sr 86sr and 88 86sr provides a robust tool for tracing fluid sources and migration pathways in accretionary prisms

variability of carbonate diagenesis in equatorial pacific sediments deduced from radiogenic and stable sr isotopes the recrystallisation dissolution precipitation of carbonate sediments has been successfully modelled to explain profiles of pore water sr concentration and radiogenic sr isotope composition at different locations of the global ocean however there have been few systematic studies trying to better understand the relative importance of factors influencing the variability of carbonate recrystallisation here we present results from a multi component study of recrystallisation in sediments from the integrated ocean drilling program iodp expedition 320 321 pacific equatorial age transect peat where sediments of similar initial composition have been subjected to different diagenetic histories the peat sites investigated exhibit variable pore water sr concentrations gradients with the largest gradients in the youngest sites radiogenic sr isotopes suggest recrystallisation was relative rapid consistent with modelling of other sediment columns as the 87sr 86sr ratios are indistinguishable within 2 uncertainties from contemporaneous seawater 87sr 86sr ratios bulk carbonate leachates and associated pore waters of site u1336 have lower 87sr 86sr ratios than contemporaneous seawater in sediments older than 20 2 ma most likely resulting from the upward diffusion of sr from older recrystallised carbonates it seems that recrystallisation at site u1336 may still be on going at depths below 102 5 rmcd revised metres composite depth suggesting a late phase of recrystallisation furthermore the lower sr ca ratios of bulk carbonates of site u1336 compared to the other peat sites suggest more extensive diagenetic alteration as less sr is incorporated into secondary calcite compared to the other peat sites u1336 has an inferred greater thermal gradient and a higher carbonate content the enhanced thermal gradient seems to have made these sediments more reactive and enhanced recrystallisation in this study we investigate stable sr isotopes from carbonate rich deep sea sediments for the first time pore water 88 86sr increases with depth from 0 428 to values reaching up to 0 700 at site u1336 documenting an isotope fractionation process during recrystallisation secondary calcite preferentially incorporates the lighter sr isotope 86sr leaving pore waters isotopically heavy the 88 86sr values of the carbonates themselves show more uniform values with no detectable change with depth carbonates have a much higher sr content and total sr inventory than the pore waters meaning pore waters are much more sensitive to fractionation processes than the carbonates the 88 86sr results indicate that pore water stable sr isotopes have the potential to indicate the recrystallisation of carbonate sediments

ca sr and ba stable isotopes reveal the fate of soil nutrients along a tropical climosequence in hawaii abstract nutrient biolifting is an important pedogenic process in which plant roots obtain inorganic nutrients such as phosphorus p and calcium ca from minerals at depth and concentrate those nutrients at the surface here we use soil chemistry and stable isotopes of the alkaline earth elements ca strontium sr and barium ba to test the hypothesis that biolifting of p has been an important pedogenic process across a soil climosequence developed on volcanic deposits at kohala mountain hawaii the geochemical linkage between these elements is revealed as generally positive site specific relationships in soil mass gains and losses particularly for p ba and ca using the ratio of immobile elements titanium and niobium ti nb to link individual soil samples to a restricted compositional range of the chemically and isotopically diverse volcanic parent materials at sites where p is enriched in surface soils relative to abundances in deeper soils the isotope compositions of exchangeable ca sr and ba in the shallowest soil horizons 10 cm depth at those sites is consistently heavier than the volcanic parent materials the isotope compositions of exchangeable ca and sr trend toward heavier compositions with depth more gradually reflecting increasing leakiness from these soils in the order ba

tropical atlantic sst history inferred from ca isotope thermometry over the last 140ka exploring the potentials of new methods in palaeothermometry is essential to improve our understanding of past climate change here we present a refinement of the published 44 40ca temperature calibration investigating modern specimens of planktonic foraminifera globigerinoides sacculifer and apply this to sea surface temperature sst reconstructions over the last two glacial interglacial cycles reproduced measurements of modern g sacculifer collected from surface waters describe a linear relationship for the investigated temperature range 19 0 28 5 c 44 40ca 0 22 0 05 sst c 4 88 thus a change of 44 40ca of 0 22 0 05 corresponds to a relative change of 1 c the refined 44 40camodern calibration allows the determination of both relative temperature changes and absolute temperatures in the past this 44 40camodern calibration for g sacculifer has been applied to the tropical east atlantic sediment core geob1112 for which other sst proxy data are available comparison of the different data sets gives no indication for significant secondary overprinting of the 44 40ca signal long term trends in reconstructed sst correlate strongly with temperature records derived from oxygen isotopes and mg ca ratios supporting the methods validity the observed change of sst of approximately 3 c at the holocene last glacial maximum transition reveals additional evidence for the important role of the tropical atlantic in triggering global climate change based on a new independent palaeothermometer

introducing δ88 86sr analysis in archaeology a demonstration of the utility of strontium isotope fractionation in paleodietary studies abstract isotopic methods are widely used in archaeology to investigate paleodiet here we present a new method to identify trophic level in archaeological human populations and to investigate paleodiet we demonstrate that strontium isotope compositions reported as 88 86sr vary in a mass dependent manner with increasing trophic level and can elucidate paleodiet in archaeological human populations we present new mass dependent strontium isotope data from tooth enamel and bone from individuals buried during the late intermediate period c ad 1000 1300 in the large cemeteries of chiribaya alta chiribaya baja san geronimo and el yaral in the ilo and moquegua valleys of southern peru we compare these data to radiogenic strontium isotope data 87sr 86sr and light stable isotope data 15ncol and 13ccol from the same individuals to investigate geologic variability in strontium sources as well as marine food consumption among the chiribaya our results demonstrate the utility of measurements of strontium isotope fractionation as a new tool for archaeological investigation of paleodiet importantly this new technique can be used to generate paleodietary 88 86sr and paleomobility 87sr 86sr data from the same specimen minimizing destructive analyses of invaluable archaeological material and provides a new way to examine paleodiet through hydroxyapatite which is particularly important when collagen is poorly preserved

determination of temperature dependent stable strontium isotope 88sr 86sr fractionation via bracketing standard mc icp ms stable strontium isotopes here 88sr 86sr are introduced as a new member of the nontraditional stable isotopes we have developed a bracketing standard method for the determination of 88 86sr using an axiom mc icp ms and normalizing to strontium srm nbs987 for individual measurements the external reproducibility is better than about 25 ppm 1 rsd for the iapso seawater standard a 88 86sr value of 0 381 0 010 2sem was determined for the first time a temperature dependent strontium isotope fractionation during calcium carbonate precipitation could be shown aragonite samples inorganically precipitated under temperature control between 10 and 50 c revealed a 88 86sr temperature dependency of 0 0054 5 c r2 0 987 in contrast for natural coral samples pavona clavus from a proxy calibration study 23 to 27 c we did determine 0 033 5 c r2 0 955 the processes causing this sixfold stronger temperature dependency for the natural coral samples have to be studied in more detail in future studies in a first approach the different slopes can be interpreted as effects of kinetic fractionation of strontium ions with or without a hydrate shell of 22 to 29 water molecules

geology and geochemistry of the burnthill granite and related w sn mo f mineral deposits central new brunswick several significant w sn mo f bearing hydrothermal mineral deposits occur in the miramichi highlands of central new brunswick these deposits are spatially and temporally related to a group o

natural variations of δ30si ratios during progressive basalt weathering hawaiian islands abstract silicon stable isotopes can be used to trace the biogeochemical pathways of si as it moves from its continental sources to its sink in ocean sediments along the way si is incorporated into clay minerals taken up by plants where it forms plant opal and leached into rivers the major land to ocean conduit compared to igneous rocks the waters that drain continents are enriched in heavy si isotopes but the mechanisms that control fractionation have not been elucidated we studied si isotope fractionation along a 4 million yr basaltic soil chronosequence on the hawaiian islands using the natural context of these samples in combination with laboratory experiments we demonstrate that the isotopic composition of dissolved si in weathering systems is determined by the combined effects of rock disintegration clay mineral neosynthesis and si biocycling weathering preferentially releases 28si into solution whereas secondary mineral formation preferentially removes 28si from solution in humid environments leached soils have lost large amounts of this soluble si thus creating a net loss of 30si from the entire soil system as soils develop and greater fractions of si reside in neoformed clay minerals 30sibulk soil values change progressively toward more negative values basalt 30si values are about 0 5 but older soils have 30si values up to 2 5 the difference between the solid and solution 30si values remains more or less constant with progressive weathering and therefore soil water from older soils has a more negative 30si composition in the upper horizons of the hawaiian soils this weathering driven 30si shift is modified by the addition of unweathered primary minerals via dust carrying 30si values of about 0 5 and by biocycling of si via plants producing negative 30si values in phytoliths and positive 30si values in soil solutions derived from upper horizons due to the high concentrations of dissolved si in these near surface layers rivers have more positive 30si values than predicted based on the weathering status of the lower horizons when combined with published 30si values from large rivers worldwide we find that the results from hawaii point to weathering control of si isotopes delivered to the oceans and thus to an important continent ocean linkage that warrants further investigation

88 sr 86 sr fractionation and calcite accumulation rate in the sea of galilee abstract this study used the sea of galilee lake kinneret northern israel as a natural laboratory to investigate the fractionation of the stable sr isotope ratio 88 sr 86 sr during precipitation of inorganic primary calcite from the lake s water it was found that the absolute value of the 88 sr 86 sr fractionation factor 88 86 sr increases as a function of calcite accumulation rate 88 86 sr 0 05 to 0 042 log r mol m 2 d 1 where r is the accumulation rate furthermore the 87 sr 86 sr and 88 sr 86 sr ratios in the freshwater and brines that enter the lake were used to calculate the contributions of these sources to the lake sr budget the 87 sr 86 sr and 88 sr 86 sr ratios were measured in primary calcite aragonite shells of live melanopsis lake water and various water sources to the lake while the lake s 87 sr 86 sr ratios are determined by the mixture of freshwater of the jordan river and saline springs the 88 sr 86 sr ratios of the lake reflect a more complex mass balance that includes the effect of isotopic fractionation associated with the precipitation of primary calcite data analysis suggests that long term accumulation of inorganic calcite depleted in the heavy isotope 88 sr results in an increase of the 88 86 sr value of the lake water by 0 05 in contrast to the primary inorganic calcite biogenic aragonite of the melanopsis shells show a rather constant 88 sr 86 sr water caco 3 fractionation of 88 86 sr 0 21 similar 88 86 sr values were reported for the precipitation of coralline and inorganic aragonite from seawater and the precipitation of inorganic calcite from various continental waters the 88 86 sr value of inorganic calcite is modulated by the rate of carbonate precipitation as noted above and shown by precipitation experiments massive precipitation of primary calcite with a wide spread of accumulation rates occurs during the spring phytoplankton bloom in lake kinneret the bloom dictates the degree of calcite saturation in the lake and hence the stable sr isotopic composition of the precipitating calcite the correlation between 88 sr 86 sr and the calcite accumulation rate can be therefore used as a tool to reconstruct environmental and ecological variations in the historical lake by analyzing the 88 sr 86 sr ratio in the primary caco 3 recovered from the lake s sedimentary archives

barium isotopes in cold water corals abstract recent studies have introduced stable ba isotopes 138 134 ba as a novel tracer for ocean processes ba isotopes could potentially provide insight into the oceanic ba cycle the ocean s biological pump water mass provenance in the deep ocean changes in activity of hydrothermal vents and land sea interactions including tracing riverine inputs here we show that aragonite skeletons of various colonial and solitary cold water coral cwc taxa record the seawater sw ba isotope composition thirty six corals of eight different taxa from three oceanic regions were analysed and compared to 138 134 ba measurements of co located seawater samples sites were chosen to cover a wide range of temperature salinity ba concentrations and ba isotope compositions seawater samples at the three sites exhibit the well established anti correlation between ba concentration and 138 134 ba furthermore our data set suggests that ba ca values in cwcs are linearly correlated with dissolved ba in ambient seawater with an average partition coefficient of dcwc sw 1 8 0 4 2sd the mean isotope fractionation of ba between seawater and cwcs 138 134bacwc sw is 0 21 0 08 2sd indicating that cwc aragonite preferentially incorporates the lighter isotopes this fractionation likely does not depend on temperature or other environmental variables suggesting that aragonite cwcs could be used to trace the ba isotope composition in ambient seawater coupled ba and 138 134 ba analysis on fossil cwcs has the potential to provide new information about past changes in the local and global relationship between ba and 138 134 ba and hence about the operation of the past global oceanic ba cycle in different climate regimes

s type granites and their probable absence in southwestern north america criteria that have been and still are used to characterize s type granites of the lachlan fold belt lfb of southeastern australia are reviewed and comparisons are made with various peraluminous granites of southwestern north america some of which have been classified as s types on the basis of insufficient data virtually all of the vast volume of s type granites in the lfb are near surface batholithic granites that are commonly associated with s type volcanics and are not associated with regional metamorphic rocks and migmatites they are strongly peraluminous as shown by the presence of cordierite granites with primary muscovite are rare all are low in na ca and sr as a result of chemical weathering during formation of the sedimentary sources peraluminous granites of various ages in southwestern north america are distinctly different they rarely contain cordierite a mineral characteristic of lfb s types but some are highly evolved such that fe mn rich garnet has crystallized they are dominantly two mica granites indicating crystallization at higher water fugacities and greater depths than most peraluminous granites of the lfb cordierite bearing volcanics s types have not been reported sodium is generally high in the peraluminous granites of southwestern north america some of these rocks have trondhjemitic affinities the parent magmas seem more likely to have been produced by partial melting of altered basaltic rocks locally some peraluminous rocks marginal to metaluminous types may owe their compositions to high level contamination of i types these are not s type rocks no compelling evidence has been presented that any of the peraluminous granites of southwestern north america are s types

geochemistry of large river suspended sediments silicate weathering or recycling tracer this study focuses on the major and trace element composition of suspended sediments transported by the world s largest rivers its main purpose is to answer the following question is the degree of weathering of modern river borne particles consistent with the estimated river dissolved loads derived from silicate weathering in agreement with the well known mobility of elements during weathering of continental rocks we confirm that river sediments are systematically depleted in na k ba with respect to the upper continental crust for each of these mobile elements a systematics of weathering indexes of river borne solids is attempted a global consistency is found between all these indexes important variations in weathering intensities exist a clear dependence of weathering intensities with climate is observed for the rivers draining mostly lowlands however no global correlation exists between weathering intensities and climatic or relief parameters because the trend observed for lowlands is obscured by rivers draining orogenic zones an inverse correlation between weathering intensities and suspended sediment concentrations is observed showing that the regions having the highest rates of physical denudation produce the least weathered sediments finally chemical and physical weathering are compared through the use of a simple steady state model we show that the weathering intensities of large river suspended sediments can only be reconciled with the silicate derived dissolved load of rivers by admitting that most of the continental rocks submitted to weathering in large river basins have already suffered previous weathering cycles a simple graphical method is proposed for calculating the proportion of sedimentary recycling in large river basins finally even if orogenic zones produce weakly weathered sediments we emphasize the fact that silicate chemical weathering rates and hence co2 consumption rates by silicate weathering are greatly enhanced in mountains simply because the sediment yields in orogenic drainage basins are higher hence the parameters that control chemical weathering rates would be those that control physical denudation rates

accuracy and precision of 88sr 86sr and 87sr 86sr measurements by mc icpms compromised by high barium concentrations barite baso4 is a widely distributed mineral that incorporates strontium sr during formation mass dependent fractionation of sr isotopes occurs during abiotic precipitation of barite and formation of barite associated with biological processes e g bacterial sulfide oxidation sr isotopes in barite can provide provenance information as well as potentially reconstruct sample formation conditions e g saturation state temperature biotic versus abiotic incomplete separation of ba from sr has complicated measurements of sr isotopes by mc icpms in this study we tested the effects of ba in sr sample solutions and modified extraction chromatography of sr using eichrom sr spec eichrom technologies llc usa resin to enable rapid accurate and precise measurements of 88sr 86sr and 87sr 86sr ratios from ba rich matrices sr isotope ratios of sample solutions doped with ba were statistically indistinguishable from ba free sample solutions below 1 ppm ba deviations in both 87sr 86sr and 88 86sr occurred above 1 ppm ba an updated extraction chromatography method tested with barite and ba doped seawater produces sr sample solutions containing 10 100 ppb levels of ba the practice of zr spiking for external mass discrimination correction of 88sr 86sr ratios was also evaluated and it was confirmed that variable zr levels do not have adverse effects on the accuracy and precision of 87sr 86sr ratios in the zr concentration range required to produce accurate 88 86sr values

sr stable isotope composition of earth the moon mars vesta and meteorites abstract high precision stable sr isotopic variations 88 sr 86 sr are reported in a variety of terrestrial samples martian and lunar meteorites hed undifferentiated primitive meteorites chondrules and refractory inclusions almost all the whole rock samples are isotopically indistinguishable at a 50 parts per million ppm level the exceptions are cv and co chondrites which are isotopically light and for which we believe that their isotopic composition is controlled by the proportion of refractory material five separated chondrules and one refractory inclusion from allende are isotopically light with 88 86 sr fractionations up to 1 73 whereas the matrix is enriched in the heavy isotopes 88 86 sr 0 66 the depletion in heavy isotopes observed in chondrules and refractory inclusions could be attributed to the condensation of a material already depleted in sr however in that case more than 60 of the original material would be unaccounted we propose instead that isotopic fractionation by electromagnetic sorting of ionized heavy sr from neutral sr in the early solar system for the origin of the fractionation observed in refractory inclusions and redistribution of sr by aqueous alteration for the origin of the fractionation observed in chondrules and matrix we conclude that cv and co chondrites are not the primary building blocks for earth and mars

the phanerozoic δ88 86sr record of seawater new constraints on past changes in oceanic carbonate fluxes the isotopic composition of phanerozoic marine sediments provides important information about changes in seawater chemistry in particular the radiogenic strontium isotope 87sr 86sr system is a powerful tool for constraining plate tectonic processes and their influence on atmospheric co2 concentrations however the 87sr 86sr isotope ratio of seawater is not sensitive to temporal changes in the marine strontium sr output flux which is primarily controlled by the burial of calcium carbonate caco3 at the ocean floor the sr budget of the phanerozoic ocean including the associated changes in the amount of caco3 burial is therefore only poorly constrained here we present the first stable isotope record of sr for phanerozoic skeletal carbonates and by inference for phanerozoic seawater 88 86srsw which we find to be sensitive to imbalances in the sr input and output fluxes this 88 86srsw record varies from 0 25 to 0 60 vs srm987 with a mean of 0 37 the fractionation factor between modern seawater and skeletal calcite 88 86srcc sw based on the analysis of 13 modern brachiopods mean 88 86sr of 0 176 0 016 2 standard deviations s d is 0 21 and was found to be independent of species water temperature and habitat location overall the phanerozoic 88 86srsw record is positively correlated with the ca isotope record 44 40casw but not with the radiogenic sr isotope record 87sr 86sr sw a new numerical modeling approach which considers both 88 86srsw and 87sr 86sr sw yields improved estimates for phanerozoic fluxes and concentrations for seawater sr the oceanic net carbonate flux of sr f sr carb varied between an output of 4 7x1010mol myr and an input of 2 3x1010mol myr with a mean of 1 6x1010mol myr on time scales in excess of 100myrs the f sr carb is proposed to have been controlled by the relative importance of calcium carbonate precipitates during the aragonite and calcite sea episodes on time scales less than 20myrs the f sr carb seems to be controlled by variable combinations of carbonate burial rate shelf carbonate weathering and recrystallization ocean acidification and ocean anoxia in particular the permian triassic transition is marked by a prominent positive 88 86srsw peak that reflects a significantly enhanced burial flux of sr and carbonate likely driven by bacterial sulfate reduction bsr and the related alkalinity production in deeper anoxic waters we also argue that the residence time of sr in the phanerozoic ocean ranged from 1myrs to 20myrs

geochemistry of the highly evolved sn w mo bearing mount douglas granite new brunswick canada implications for origin and mineralization abstract the late devonian 368 1 ma post orogenic peraluminous mount douglas granite located in southwestern new brunswick canada forms the eastern part of the saint george batholith the batholith was emplaced following the accretion of the gander and avalon zones of the northern appalachians during the neoacadian orogeny the mount douglas granite is divided into three units dmd1 dmd2 and dmd3 that formed by progressive high degrees of fractional crystallization the two most fractionated units i e dmd2 and dmd3 are locally associated with greisen sheeted veins related endogranitic sn w mo mineralization whole rock 18o values of 6 0 to 7 3 high initial 87sr 86sr ratios of 0 70550 to 0 71665 slightly positive end 368 ma values 0 3 to 1 1 and pb isotopic data indicate that the granite was derived dominantly from partial melting of juvenile avalonian crust contaminated by supracrustal rocks petrochemical features support the idea of multiple periods of fractional crystallization at lower temperatures producing compositionally more evolved magmas this is supported by estimated zircon saturation temperatures that decrease from dmd1 747 826 c dmd2 733 817 c dmd3 729 816 c the estimated crystallization pressure based on normative quartz and feldspar albite orthoclase contents also decreases with increasing silica content from 2 3 kbar 7 7 km in dmd1 to 0 3 kbar 1 km in dmd3 whole rock geochemical characteristics of this system show that unit dmd3 is the most highly evolved unit it has the highest sio2 avg 76 4 wt lile contents e g li rb cs rb sr mean 42 certain hfse ta th u including y 138 ppm and ree and has the most pronounced negative eu anomalies avg eu eu 0 08 and the lowest k rb 70 127 nb ta mean 4 9 and zr hf mean 23 5 therefore unit dmd3 with the highest content of incompatible elements is the most prospective for sn w zn bi and u mineralization and then dmd2

coupled δ44 40ca δ88 86sr and 87sr 86sr geochemistry across the end permian mass extinction event abstract we report high resolution high precision 44 40ca 88 86sr and 87sr 86sr records spanning the permian triassic boundary ptb from the meishan and dajiang carbonate successions in south china the goal of the study was to understand the behavior of ca and sr isotopes during a time period in earth history characterized by severe biological and environmental perturbations including a major mass extinction flood basalt volcanism ocean acidification and sea level fluctuations dajiang displays negative 44 40ca and 88 86sr excursions and invariant 87sr 86sr ratios in the

petrogenesis of the concordia granite gneiss and its relation to wmo mineralization in western namaqualand south africa abstract the 1 1 ga concordia granite gneiss cgg is part of the late to postorogenic spektakel suite in the western namaqualand metamorphic complex south africa it intruded synkinematically with respect to the main d2 deformation event into lower to middle crustal rocks and granite emplacement was more or less coeval with the peak of granulite facies metamorphism 800 c 5 kbar several genetically related rock types megacrystic garnet bearing granite minor aplitic leucogranites and pegmatites are distinguished all varieties are sio 2 rich 69 79 wt peraluminous granites and show subalkaline monzonitic magma characteristics geochemical differences in whole rock chemistry between megacrystic granite and aplitic leucogranites e g lower al 2 o 3 mgo cao ba zr higher k 2 o rb nb w rb sr ga al and the decrease of e g cao mgo fe 2 o 3 ba zr th u with increasing sio 2 in the megacrystic granites as well as the variation in fe mn of magmatic garnets are best explained with crystal fractionation processes fractional crystallization of plagioclase produced potassium and silica rich residual melts characterised by very high rb sr rb ba u th mn fe ratios and higher concentration of w cu and zn crystal fractionation processes also resulted in a relative lree depletion and hree enrichment megacrystic granite la lu cn 8 87 31 67 aplitic leucogranite and pegmatites la lu cn 0 71 1 44 and evolution of pronounced negative eu anomalies the crystallization sequence near solidus crystallization of biotite prior to alkali feldspar suggests that the cgg magmas were h 2 o undersaturated over a long period of their evolution water saturation during late stage crystallization is however indicated by coarse late stage eutectic mineral textures pegmatites and w mo bearing siliceous rocks furthermore the economic potential of the cgg is supported by its geochemical signature e g high u th contents which is similar to evolved high heat production hhp granites the granitic magmas are attributed to partial melting of peraluminous crustal source rocks and are tentatively interpreted as fractionated s type granites the w mo deposits represent vein type and pegmatitic deposits genetically related to a deep seated granitic system

characterizing nutrient pathways in quebec canada vineyards insight from stable and radiogenic strontium isotopes abstract soils are a crucial interface of earth s critical zone responsible for the biogeochemical cycling of mineral nutrients while the sources of essential nutrients such as ca and sr in plants have been widely studied the processes by which these nutrients are transferred from the soil to the plants is less clear we present new evidence for systematic nutrient fractionation between soils grapes and wines from five vineyards from the quebec terroir canada using the novel stable sr 88 86sr isotope system we coupled this approach with traditional radiogenic 87sr 86sr measurements on the same samples bulk soils labile fraction of these soils whole grapes and wines from five vineyards from the quebec terroir canada to ensure that variations in 88 86sr values were provoked by processes involved in sr transfer instead of mixing between different sources the 88 86sr values generally decrease from the bulk to the labile fractions of the soils to the grapes a decrease in the difference between the soil fractions 88 86srbulk labile with increasing 88 86sr values in the labile fraction is interpreted to reflect increasing pedogenic mineral precipitation and higher soil fertility the depleted 88 86sr values of the grapes are consistent with a preferential uptake of lighter isotopes by plants this effect is magnified in soils showing higher secondary mineral precipitation an increase in the 88 86sr values from the grapes to the wines reflects the separation of the skin seeds and the juice pulp enriched in 88sr in the winemaking process this mixing relationship is supported by a correlation between the sr concentrations and the 88 86sr values of the wines and grapes these findings suggest promising new applications of stable sr isotopes values for studying soil fertility and the impact of nutrient availability for plant growth in agricultural ecosystems as well as the impact of the maceration processes in the production of wine the overall similarity of 87sr 86sr ratios of the labile soil fractions grapes and wines from the same vineyard support the hypothesis of a same sr source from the soil solution to its transfer to the grape and wine and confirm the potential of the 87sr 86sr ratios as a proxy for geographic provenance of wine however slightly lower 87sr 86sr ratios in the grape pulps by 0 00040 on average compared to the skins and seeds suggest that the sources of nutrients available for plant uptake vary during the vegetative cycle the grape seeds and skins formed in the early growth cycle are characterized by rapid growth due to enhanced rhizosphere activity enhanced mineral dissolution providing higher nutrient levels the enhanced mineral solubility results in higher 87sr 86sr ratios in the skin and seeds derived from enhanced dissolution of 87sr enriched silicate minerals in contrast the pulp develops later in the growth cycle when rhizosphere activity and mineral solubility is reduced resulting in a lesser contribution from silicate minerals and thus reflect a higher proportion of dissolved carbonate contributing to the lower 87sr 86sr ratios of the pulps

strontium stable isotopes fractionate in the soil environments abstract this study shows that the stable isotopic composition of strontium the 88sr 86sr ratio expressed as 88 86sr value relative to the nbs987 standard varies significantly in sedimentary terrestrial environments the abundances of 86sr 88sr isotopes were analyzed by mc icp ms nu plasma all studied rocks and waters show 88 86sr values that are distinctly different from the measured nbs987 standard yielding 0 01 0 05 all errors are reported as 2 modern corals from the northern gulf of aqaba red sea yielded significantly different value than seawater 88 86sr 0 22 0 07 compared to 0 35 0 06 respectively in an excellent correlation with the 88 86sr analyses reported by fietzke and eisenhauer fietzke j eisenhauer a 2006 determination of temperature dependent stable strontium isotopes 88sr 86sr fractionation via bracketing standard mc icp ms geochm geophys geosyst 7 no 8 on other coral samples all carbonate samples that originated in the marine environment corals porites and acropora from the northern gulf of aqaba cretaceous limestone and runoff from the judea mountains as well as lacustrine evaporitic aragonite dead sea and red sea and atlantic seawater yield an average 88 86sr value of 0 26 0 1 on the other hand secondary materials products of chemical weathering from the terrestrial environment of the judea mountain such as terra rossa soil and speleothem calcite that derives its sr from the above lying soil yielded significantly lower 88 86sr value of 0 17 0 06 this indicates that strontium isotopes fractionate in the soil environment calling for a possible development of strontium isotopes as a tracer for processes of chemical weathering and pedogenesis

enrichment of 88 sr in continental waters due to calcium carbonate precipitation abstract 88 86sr data published over the last few years suggest that continental waters are enriched with 88sr as compared to the rocks in their drainage basins in an attempt to understand this phenomenon this study established the fractionation in the 88sr 86sr ratio during precipitation of continental carbonates i e carbonates precipitated on land from surface pedogenic or ground waters and evaluated the contribution of this process to the 88sr enrichment in rivers for this stable and radiogenic sr isotopes 88sr 87sr and 86sr were measured in calcite samples and their precipitating waters collected in various continental environments such as soil cave streams and groundwater the results indicate that continental carbonates are 88sr depleted relative to their precipitating waters placing them as one of the most 88sr depleted reservoirs on earth the average difference in 88 86sr values between waters and solid caco3 tufas or speleothems that they precipitate is carb water 0 218 0 014 1sd an even larger fractionation e carb water 0 285 0 02 was measured in groundwater with particularly high carbonate alkalinity and high carbonate precipitation rate that depleted 65 of the sr in the groundwater resulting in substantial 88sr enrichment in the residual dissolved sr sr 88 86 0 656 results also suggest that pedogenic carbonate precipitation in soil profile removes 50 85 of the sr from the recharging soil water thereby increasing the 88 86sr value of the soil water from 0 18 to 0 3 0 6 similar 88sr enrichment was observed in drip water from a karst cave a maximum removal flux of sr into continental carbonates of about 20 gmol sr y 1 is required to yield the reported 88sr enrichment in global rivers sr 88 86 0 32 relative to their rock sources when using the fractionation factor derived in this study carb water 0 218 and the published 88 86sr composition of marine carbonates of 0 16 this surprisingly large flux requires that 40 of the originally weathered sr should co precipitate with continental carbonates this calculation may suggest that caco3 precipitation is a significant mechanism in the continental sr cycle it is possible however that other mechanisms such as sr uptake by plants or incongruent weathering of silicates could also contribute to the riverine 88sr enrichment alternatively the average 88 86sr value of marine carbonate rock sections undergoing weathering is higher than suggested in current literature it is concluded that additional 88 86sr data on marine carbonate rock sections should be collected to resolve the enigma of the high value of riverine 88 86sr

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

lithium isotopes as a probe of weathering processes orinoco river abstract lithium isotopes have the potential to be effective tracers of weathering processes due to their large relative mass difference and therefore fractionation in this study an attempt is made to fill a major gap in the knowledge of li isotope fractionation during continental weathering and of the mechanisms involved finally the relationship between the suspended and dissolved material is made on a basin wide scale the orinoco basin provides a clear contrast in reaction limited and transport limited weathering regimes that has already been documented by a comprehensive study on its fluvial geochemistry edmond et al geochim cosmochim acta 60 1996 2949 2976 edmond et al geochim cosmochim acta 59 1995 3301 3325 conspicuous in our new results is the difference in 6li of the dissolved load between the andean 30 to 22 and shield 22 to 7 tributaries while the 6li of the suspended load is similar between the two to a first approximation during superficial weathering in high relief tectonically active terrains the dissolved load is high in li and isotopically heavy more negative 6li whereas in stable shield regions the concentrations are low and isotopically light in proportion to the increasing degree of weathering

geochemistry of dissolved and suspended loads of the seine river france anthropogenic impact carbonate and silicate weathering this study focuses on the chemistry of the seine river system one of the major rivers in europe and constitutes the first geochemical investigation of both suspended and dissolved loads of this river the seine river drains a typical mesozoic cenozoic sedimentary basin the paris basin constituted of limestones mixed or interbedded with terrigenous sediments derived from the paleoreliefs bordering the mesozoic and cenozoic seas in the context of quantifying the global influence of carbonate and silicate weathering on atmospheric co2 consumption the seine river offers the possibility of examining weathering rates in a flat sedimentary environment under temperate climatic conditions one of the major problems associated with the seine river as with many temperate rivers is pollution we propose in this paper 2 approaches in order to correct the dissolved load of the seine river for anthropogenic inputs and to calculate weathering rates of carbonates and silicates the first uses the dissolved load of rivers and tries to allocate the different solutes to different sources a mixing model based on elemental ratios is established and solved by an inversion technique the second approach consists in using the suspended load geochemistry under steady state conditions we show that the geochemistry of suspended sediments makes it possible to estimate the amount of solutes released during the chemical weathering of silicates and thus to calculate weathering rates of silicates the total dissolved load of the seine river at paris can be decomposed into 2 of solutes derived from natural atmospheric sources 7 derived from anthropogenic atmospheric sources 6 derived from agriculture 3 derived from communal inputs and 82 of solutes derived from rock weathering during high floods the contribution of atmospheric and agriculture inputs predominates the weathering rate of carbonates is estimated to be 48 t km2 yr 25 mm 1000 yr only 10 of carbonates are transported in a solid form the rest being transported in solution co2 consumption by carbonate weathering approaches 400 103 mol km2 yr in the seine river at paris about 2 3 mg l of dissolved cations are found to originate from the chemical weathering of silicates by taking dissolved silica into accounts the total dissolved load derived from silicate weathering is about 6 7 mg l this value is minimal because biological uptake of silica probably occur in the seine river the chemical weathering rate of aluminosilicates is estimated to be 2 t km2 yr the ratio of physical over chemical weathering of silicates range between 1 and 3 and the total chemical and physical erosion rates of sedimentary silicates are about 2 3 mm kyr the co2 consumption by silicate weathering 15 24 103 mol km2 yr and is independent of dissolved silica concentration silicate consumption is thus 20 times less than carbonate consumption in the paris basin compared to the neighboring granitic areas the sedimentary region drained by the seine river has 2 to 3 times lower co2 consumption rates we attribute this difference to the cation depleted nature of the seine basin aluminosilicates which are of sedimentary origin at a world scale the chemical denudation rates found for the seine basin are very low and comparable to those given for tropical lowland rivers draining silicates such as the rivers of the congo and amazon basins in spite of huge climatic differences we attribute this similarity to the low mechanical denudation that characterizes these two types of regions

continued obliquity pacing of east asian summer precipitation after the mid pleistocene transition abstract records from natural archives show that the strength of the east asian summer monsoon easm strongly depends on the orbital configuration of the earth however the dominant orbital cycles driving easm have been found to be spatially different speleothem stable oxygen isotopic records from southern china which are believed to reflect large scale changes in the asian monsoon system are dominated by climatic precession cycles further north on the chinese loess plateau clp loess and paleosol sequences which are argued to be controlled by monsoon intensity are in pace with global ice volume changes dominated by obliquity and after the mid pleistocene transition by 100 kyr cycles to understand these critical discrepancies here we apply a novel proxy based on the trace metal compositions of pedogenic carbonate in the eolian deposits on the clp to reconstruct summer precipitation over the last 1 5 million years our reconstructions show that summer precipitation on the clp is dominantly forced by obliquity not in pace with the ice volume imprinted loess paleosol sequences before and after the mid pleistocene transition or with the precession paced speleothem oxygen isotopic records coupled with climate model results we suggest that the obliquity driven variations of summer precipitation may originate from the gradient of boreal insolation that modulates the thermal contrast between the asian continent and surrounding oceans

radiogenic and stable strontium isotopes in provenance studies a review and first results on archaeological wood from shipwrecks abstract different approaches are used to study wood provenance but most of them are based on tracers in wood that are generally controlled by climatic factors the strontium isotopic ratio 87 sr 86 sr in trees and soils is related to the signature of the local bedrock despite being used in diverse archaeological studies sr isotopes have rarely been used to trace the provenance of archaeological wood and especially wood from shipwrecks in addition recent analytical advances have allowed the detection of mass dependent fractionation of sr isotopes during biogeochemical processes as reflected in the variation of 88 86 sr values between different environmental materials the 88 86 sr values could be used in conjunction with the 87 sr 86 sr isotope ratio to improve constraints on the sources of sr in the archaeological materials being studied this paper discusses the potential and limitations of using both of these sr isotope ratios to trace the provenance of wood from shipwrecks we review the 87 sr 86 sr and 88 86 sr variations in rocks waters soils plants and other living organisms and discuss how to determine the local sr isotopic signature of potential sites we also compile a list of known wood post mortem modifications in seawater possible implications in terms of the modification of the original sr isotope ratios of wood during storage in seawater are illustrated through preliminary observations this paper points out some limitations and perspectives for using sr isotopes in provenancing wood from shipwrecks and suggests future research to test and apply this approach for tracing the origin of archaeological wood

high temperature strontium stable isotope behaviour in the early solar system and planetary bodies abstract this study presents comprehensive strontium stable isotope 88sr 86sr data measured by multiple collector inductively coupled plasma mass spectrometry mc icp ms for a suite of carbonaceous chondrites differentiated meteorites lunar martian and terrestrial samples carbonaceous chondrites comprise a mixture of refractory inclusions and chondrules that have light 88sr values between 0 35 to 0 05 and matrix material that possesses a heavy 88sr composition of 0 65 confirming the results of earlier studies consequently bulk carbonaceous chondrites are relatively heterogeneous in composition ranging from 0 12 to 0 35 most likely reflecting clast matrix variability the light 88sr compositions of the refractory inclusions are consistent with mass dependent fractionation of other refractory elements ca and eu and are most likely produced by non equilibrium fractionation undercooling in the nebula gas during condensation of hibonite from the solar nebula simon and depaolo 2010 stable calcium isotopic composition of meteorites and rocky planets earth planet sci lett 289 457 466 carbonaceous chondrites angrites and martian meteorites have indistinguishable compositions at the level of analytical uncertainty of this study however statistical analysis indicates that melts derived from the earth s mantle have heavier 88sr values than bulk carbonaceous chondrites and martian meteorites but compositions indistinguishable from eucrites 88sr 0 26 0 12 moreover terrestrial basalts and andesites have restricted 88sr values 0 30 0 07 suggesting that mantle melting delivers rather homogenous melts to the earth s surface with respect to 88sr in contrast glasses from evolved terrestrial rocks and lunar basalts extend to very light 88sr values 0 20 the sr stable isotope composition covaries with europium anomaly eu eu as an index of plagioclase fractionation and 88sr can be successfully modelled by the heavy isotopes of sr being preferentially partitioned into plagioclase with a fractionation factor of 1 0007 for 88sr 86sr our results demonstrate that sr stable isotopes may be significantly fractionated at high temperatures and their measurement can provide insights into planetary evolution and magmatic processes

s type granitoids and an i s line in the peninsular ranges batholith southern california peraluminous to metaluminous s type granitoids occur in the central and eastern parts of the peninsular ranges batholith southern california as highly deformed plutons and anatectic migmatites within metapelitic prebatholithic wallrocks of upper amphibolite fades the granitoids overlap in age with and have undergone a structural history similar to that of the early cretaceous i type granitoids that occur mainly to the west initial 87 sr 86 sr ratios greater than 0 7079 and 18 o greater than 11 8 indicate a significant metasedimentary component in the source rocks of the s type granitoids an i s line that defines the westernmost extent of these rocks lies close to gravity age isotopic and prebatholithic wallrock contrasts within the batholith and together these features probably mark a fundamental change in the mesozoic crust if the western part of the batholith represents an upper jurassic and lower cretaceous accreted tectonostratigraphic terrane then the zone that contains these features may represent a terrane boundary we propose that the s type granitoids and associated migmatites developed at midcrustal levels as a result of collision and crustal thickening and rose as diapirs some dragging an envelope of migmatite and wallrock with them the zone of intense metamorphism and deformation that now forms the axis of the batholith has been uplifted relative to the western part of the batholith possibly as a consequence of unloading

two dimensional refold interference patterns abstract when a rock undergoes two generations of folding complex three dimensional refolded structures result if such a structure is then sectioned two dimensional interference patterns result these patterns have been discussed before but the incredible variety and complexities of these patterns can be shown only with a large number of diagrams using a computer simulation various refolded structures have been sliced at every unique 30 combination of strike and dip thirty sections per structure the characteristics of the patterns observed are discussed and recurring recognizable patterns are identified

physical models of regional fold superposition the role of competence contrast abstract physical models of superposed folds demonstrate that rheologic contrast strongly controls the style of fold interference rheologic contrast affects strain partitioning between layer parallel shortening and buckling and affects the development of structural anisotropies parallel to first generation folds laminates with insignificant competence contrast are characterized by circular to elliptical domes and basins type 1 interference in addition to folding the layers accommodate shortening by layer parallel thickening preferentially in the fold culminations laminates with significant competence contrast are characterized by buckled fold hingelines and axial surfaces type 2 interference the less competent layers thicken in the hinges the more competent layers maintain their initial thickness in plan view the f 1 hingelines are refolded in a lobate cuspate to box style whose axial traces form conjugate pairs the models are dynamically scaled to represent folds with km scale wavelengths the evolution of surface structures map patterns at different depths and equal area projections synthesized from structure contour maps were used for analysis comparable to regional analysis common to field studies gravitational body forces effectively damp the vertical amplitudes of both the first and second generation folds thereby enhancing the formation of type 2 interference

reassessing the stable δ88 86sr and radiogenic 87sr 86sr strontium isotopic composition of marine inputs the stable strontium isotope system 88 86sr has recently been suggested to be a suitable proxy for determining variations in the strength of the marine carbonate system the principal output flux of oceanic sr however in order to be able to interpret carbonate driven variations in 88 86srseawater a robust understanding of 88 86srinput is required surprisingly only a limited amount of 88 86sr data currently exists for rivers and hydrothermal fluids thus this study assesses the variability of 88 86sr and 87sr 86sr in global rivers hydrothermal fluids and porewaters as well as minor marine sr sources such as continental dust rainwater and glacial ice our analyses broadly confirm the findings of krabbenhoft et al 2010 and reveal flux weighted 88 86srriverine and 87sr 86srriverine compositions of 0 32 and 0 71299 respectively the hydrothermal fluids analysed in this study are consistent with an end member 88 86srhydrothermal composition that is the same as the oceanic crust at 0 24 although three samples that display 88 86sr compositions offset from the seawater hydrothermal mixing trend suggest that the precipitation of alteration phases such as anhydrite may drive 88 86srhydrothermal to higher values porewater fluids obtained from sediment cores in the atlantic and pacific oceans have 88 86sr compositions within error of seawater 0 39 implying that the diagenetic flux of sr may not significantly affect the 88 86sr composition of seawater continental loess samples have 88 86sr compositions that are consistently lighter than or equal to terrestrial silicates with their tendency to lower values thought to reflect the preferential removal of heavier sr isotopes into solution during weathering finally rainwater and glacial ice samples have 88 86sr compositions that are also isotopically lighter than their associated water sources a factor that may be attributed to interaction with isotopically light loess and additional sr contributions from the bedrock together the principal marine inputs define flux weighted oceanic 88 86srinput and 87sr 86srinput compositions of 0 32 and 0 71161 these values are consistent with an elevated supply of riverine sr to the oceans due to increased post glacial weathering but require the enhanced weathering of exposed carbonate shelves during glacial periods or significant changes in the rate of carbonate burial to match observed changes in the 87sr 86sr ratio of seawater our results confirm that providing a diagenetically robust proxy can be found the 88 86sr and 87sr 86sr isotope systems should provide a useful proxy for investigating changes in the marine carbonate system through time

porphyry tungsten molybdenum orebodies polymetallic veins and replacement bodies and tin bearing greisen zones in the fire tower zone mount pleasant new brunswick the fire tower zone at mount pleasant contains geologically complex deposits that are associated with two distinct phases of granite an older fine grained granite associated with tungsten molybdenum orebodies and a younger granite porphyry to which tin and polymetallic zones appear to be related based on potassium argon and rubidium strontium isotope analyses both phases of granite and their associated deposits were emplaced at approximately 340 to 330 m y ago geochemically both phases are silica rich aluminous potassic and fluorine rich porphyry tungsten molybdenum orebodies occur mainly in fire tower breccia and to a lesser extent in quartz feldspar porphyry country rock and the fine grained granite which underlies the breccia the orebodies consist of mineralized fractures quartz veinlets and disseminations in breccia matrix wolframite and molybdenite the principal ore minerals occur together with abundant fluorite and arsenopyrite and minor amounts of bismuth and bismuthinite associated greisen type alteration consists of quartz topaz sericite fluorite which grades outward through an assemblage of quartz biotite chlorite topaz into propylitic alteration mainly chlorite sericite crosscutting relationships between mineralized fractures and veinlets indicate that mineralization occurred in multiple stages the earlier stages being more tungsten rich and the later stages more molybdenum rich tin bearing polymetallic veins and replacement bodies in many places spatially related to granite porphyry are superimposed on the porphyry tungsten molybdenum orebodies and surrounding rocks they consist mainly of chlorite abundant fluorite and complex assemblages of disseminated to massive sulfide and oxide minerals some cassiterite rich relatively sulfide poor zones occur also within greisen altered granite porphyry the relationship of these zones to the polymetallic veins and replacement bodies is not clear cassiterite rich greisen occurs typically at deeper levels and may represent either the roots of the higher level polymetallic zones or an entirely separate stage of mineralization the contrast in the styles of mineralization between porphyry tungsten molybdenum ore bodies on the one hand and tin and polymetallic zones on the other is striking formation of the porphyry deposits appears to be related to the development of high fluid pressures associated with crystallization of the underlying fine grained granite magma and subsequent fracturing and breccia formation the tin and polymetallic zones indicate not only a significant change in the composition of the ore forming fluids but also formation at fluid pressures that were either too low or too localized to cause extensive fracturing and brecciation

implicit modeling of folds and overprinting deformation abstract three dimensional structural modeling is gaining importance for a broad range of quantitative geoscientific applications however existing approaches are still limited by the type of structural data they are able to use and by their lack of structural meaning most techniques heavily rely on spatial data for modeling folded layers but are unable to completely use cleavage and lineation information for constraining the shape of modeled folds this lack of structural control is generally compensated by expert knowledge introduced in the form of additional interpretive data such as cross sections and maps with this approach folds are explicitly designed by the user instead of being derived from data this makes the resulting structures subjective and deterministic this paper introduces a numerical framework for modeling folds and associated foliations from typical field data in this framework a parametric description of fold geometry is incorporated into the interpolation algorithm this way the folded geometry is implicitly derived from observed data while being controlled through structural parameters such as fold wavelength amplitude and tightness a fold coordinate system is used to support the numerical description of fold geometry and to modify the behavior of classical structural interpolators this fold frame is constructed from fold related structural elements such as axial foliations intersection lineations and vergence poly deformed terranes are progressively modeled by successively modeling each folding event going backward through time the proposed framework introduces a new modeling paradigm which enables the building of three dimensional geological models of complex poly deformed terranes it follows a process based on the structural geologist approach and is able to produce geomodels that honor both structural data and geological knowledge

strontium isotopes trace biological activity in the critical zone along a climate and vegetation gradient abstract weathering and ecosystem nutrition are intimately linked through the supply of fresh mineral nutrients from regolith and bedrock the geogenic nutrient pathway however the prominence of this link is dependent on the efficiency of nutrient recycling from plant litter the organic nutrient cycle isotope ratios of strontium sr an element that behaves similarly to ca in ecosystems confer two types of information radiogenic sr isotopes inform as to the sources of sr and the degree of weathering while stable sr isotopes constrain partitioning between compartments of the critical zone bedrock water secondary solids and plants to date however neither the reactions nor the mass balance between compartments that fractionate sr isotopes nor the fractionation factors involved are well understood here we present geochemical budgets of sr using radiogenic and stable sr isotopes and ca sr ratios at four sites along a substantial climate and primary production gradient in the coastal mountains of chile we found that sr release through weathering is isotopically congruent and released sr is not strongly isotopically fractionated either during secondary mineral formation or transfer into the exchangeable pool despite this the 88sr 86sr ratio of bio available sr which should reflect the ratio of dissolved sr is higher than that of rock and regolith we propose that this offset is caused by plants while 88sr 86sr in plant organs at the four study sites systematically increased from roots towards their leaves whole plant sr isotope compositions indicate preferential uptake of light sr into plants with a fractionation of up to 0 3 relative to the bio available pool despite this strong biological fractionation 88sr 86sr ratios in bio available sr do not covary with biomass production across our study sites because with greater plant growth sr is recycled more times after release by weathering an isotope neutral process rather the loss of sr from the ecosystem in solid organic material sets the isotope ratio of dissolved or bio available sr organic solids thus appear to constitute a significant export path of elements released during weathering with the removal of solid plant debris reducing the recycling factor of sr and possibly that of other mineral nutrients too

insights into combined radiogenic and stable strontium isotopes as tracers for weathering processes in subglacial environments this study reports stable and radiogenic strontium isotope behaviour in the dissolved load and suspended sediments from the subglacial outflow of the lemon creek glacier juneau ice field alaska over a single melt season in situ measurements discharge total alkalinity ph and conductivity are combined with elemental concentrations x ray diffraction xrd analysis and radiogenic strontium isotope measurements to interpret the variations observed in stable strontium isotopic ratios the stable sr isotope composition 88sr 86sr ratio expressed as 88 86sr of the dissolved load averages 0 31 0 05 and is heavier than both the suspended sediment 0 18 0 03 as well as local bedrocks 0 20 to 0 26 we attribute the enrichment of heavier isotopes in the dissolved load to the uptake of lighter sr isotopes by secondary weathering minerals driving the dissolved load to heavier values x ray diffraction xrd analysis confirms the presence of clays in the suspended sediments and thermodynamic modelling suggests the presence of iron oxy hydroxide phases although it is not possible to completely rule out the effect of dissolution of primary minerals in controlling sr isotopic compositions of the dissolved load our data indicate that the extent of secondary mineral formation likely plays a significant role the preferential weathering of minerals such as biotite consistent with the mineralogical assemblages found in the suspended sediments as well as the potential presence of radiogenic calcites from metacarbonates derived from the yukon tanana terrain may be driving the small seasonal shifts in 87sr 86sr of the dissolved load to more radiogenic compositions from 87sr 86sr dl 0 71048 to 0 710647 using the combination of stable and radiogenic strontium isotopes to investigate weathering processes shows that radiogenic sr isotopes provide information regarding weathering of primary phases while the stable sr isotope data appear to record information regarding the extent of secondary mineral formation where secondary minerals incorporate the light isotopes driving the dissolved load to heavy values

strontium isotope fractionation of planktic foraminifera and inorganic calcite we have investigated the strontium isotope fractionation 88 86srcarb aq between inorganic calcite and aqueous sr2 ions by precipitation experiments at a constant temperature of 25 c and precipitation rates r ranging from 102 3 to 104 2 mol m2 h strontium isotope ratios were measured using the 87sr 84sr double spike technique it was found that strontium isotope fractionation in these calcites is strongly dependent on the precipitation rate view the mathml source the measured 88 86sr values are significantly correlated with previously measured 44 40ca and sr ca values of the same calcite samples 88 86srcarb aq 0 18 44 40cacarb aq 0 01 view the mathml source the slope of 88sr 86sr versus 44ca 40ca fractionation is 0 18 0 04 and compatible with a kinetic fractionation during dehydration of the strontium and calcium ions but not with isotope fractionation in a diffusive boundary layer using published equilibrium 44 40cacarb aq and view the mathml source values we estimate the equilibrium isotope fractionation of strontium to be very close to zero 88 86sreq carb aq 0 01 0 06 this estimate is confirmed by strontium isotope values of natural inorganic calcites that precipitated very slowly in basalts of the ocean crust the results from the inorganic calcites are used to explain strontium isotope fractionation of planktic foraminifera specimens of two warm water species globigerinoides ruber and globigerinoides sacculifer were picked from the holocene section of a caribbean sediment core we found no significant difference in 88 86sr between the two species in addition g ruber specimens from marine isotope stage 2 in the same core show 88 86sr values identical to the holocene specimens the strontium isotopes of both foraminifera species are strongly fractionated 88 86srcarb aq 0 248 0 005 when compared to published data of other major marine calcifiers applying the results from the inorganic precipitation experiments we find that the strong foraminiferal strontium isotope fractionation can be explained by calcification in a largely open system at high precipitation rates comparable in magnitude to rates known from scleractinian reef corals this interpretation is in good agreement with the kinetic calcification model for planktic foraminifera by kisakurek et al 2011 which was based on calcium isotopes and elemental sr ca ratios

the δ44ca temperature calibration on fossil and cultured globigerinoides sacculifer new tool for reconstruction of past sea surface temperatures we report direct 44ca temperature calibration on cultured and fossil calcite foraminifera showing that ca isotopes are potentially a new proxy for past sea surface temperatures sst samples have been analyzed using a 43ca 48ca double spike and thermal ionization mass spectrometry tims in order to avoid species dependent isotope fractionation we focused our investigations on a single foraminifera species globigerinoides sacculifer which is known to inhabit shallow euphotic waters in tropical and subtropical oceans ca isotope measurements were performed on cultured g sacculifer that grew in seawater kept at temperatures of 19 5 26 5 and 29 5 c a 44ca change of 0 24 0 02 per 1 c is defined by the weighted linear regression through reproduced 44ca data of the three temperatures 95 confidence level application of this new method to fossil g sacculifer of an equatorial east atlantic sediment core geob1112 5 46 7 s 10 45 0 w 3125 m indicates that the 44ca difference between marine isotope stage 1 mis 1 and mis 2 is 0 71 0 24 according to the current 44ca temperature calibration this value corresponds to a temperature difference between mis 1 and mis 2 of 3 0 1 0 c

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

calibration of stable oxygen isotope signatures in galapagos corals a 2 year 1993 1994 study was conducted in the galapagos islands ecuador to determine the relationship between 18o in skeletal carbonate and sea surface temperature sst in three species of reef building corals pavona clavus pavona gigantea and porites lobata coral samples were grown at 3 10 and 3 m depth at bartolome island champion iisland and urvina bay isabela island respectively hourly measurements of sst and sea surface salinity sss were taken at each site immediately adjacent to colonies which were stained biannually to establish the chronology of growth in addition surface waters were sampled periodically bimonthly to monthly at each site to determine variation in 18o seawater results indicate the mean annual ssts were similar between sites varying from 22 9 c at champion to 23 8 c at urvina bay comparisons of monthly sst averages between instrumental and remote sensing satellite 1 1 grid data show a high correspondence r2 ranging from 0 84 to 0 94 indicating that remote sensing data are useful for interpreting the 18o record in corals when instrumental data are lacking here 18ocoral analyses of eight specimens show that coralline aragonite is a reliable indicator of sst in galapagos in general higher resolution coral sampling year resolved more of the monthly variation in sst up to 97 at a sampling resolution of 1 4 samples per millimeter of linear skeletal growth comparisions of the 18ocoral signal among and between species at the same site showed consistent seasonal patterns of variation closely tracking sst in addition comparisons between sites were highly concordant with some differences reflecting local variation in sst seasonal patterns however were essentially the same over the entire region thus we conclude that the 18ocoral signal from coral skeletons in galapagos can be used to interpret regional changes in sst variation

the influence of initial fold geometry on type 1 and type 2 interference patterns an experimental approach abstract experiments on superposed folding were performed in a plane strain pure shear rig using paraffin wax as an analogue for rocks a series of pre formed cylindrical folds were refolded with the compression direction acting parallel to the initial fold hinge direction the intermediate axis perpendicular to the first fold axial plane and the extension direction parallel to the first fold axial plane and perpendicular to its axis type 1 interference geometry roundness tightness and amplitude were varied to investigate the influence of first fold geometry on the interference patterns experimental folding of an initially planar layer oriented parallel to the first fold envelope provides a reference geometry for comparison the results suggest that hinge roundness has less influence on the interference pattern than other factors close initial folds refold into type 2 interference patterns which become even more pronounced as the tightness increases open folds produce type 1 interference patterns folds with the same interlimb angle and the same roundness produce different interference patterns depending on relative amplitude folds with relatively large amplitude are refolded into type 2 patterns whereas folds with small amplitude give clear dome and basin structures in a second set of experiments the compression direction also acted parallel to the first fold hinge but the orientations of the intermediate and extension axes were interchanged the interference patterns obtained are very similar to those in type 1 interference geometry suggesting that the major factor in determining whether type 1 or type 2 interference patterns develop is the initial fold geometry and not the kinematics of the second deformation

systematic use of trace element distribution patterns in log log diagrams for plutonic suites trace element modelling has been widely used for petrogenetic interpretation of basaltic systems this paper indicates how to select trace element pairs having very different bulk distribution coefficients d which when plotted on simple log log diagrams permit the identification of the main magmatic process magma mixing partial melting fractional crystallization involved in the genesis of plutonic rocks fractional crystallization gives a straight line on such a diagram with a strong decrease of the compatible element whereas the concentrations of the element with d 1 increase slowly a similar evolution of the solids in equilibrium is observed and when data of at least one of the cumulates are directly available it is possible to calculate the d and f parameters of the sequence of fractional crystallization an example of this procedure is shown for a french hercynian plutonic suite the basic suite of variscan corsica

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

dissolved load of the loire river chemical and isotopic characterization the loire river with one of the largest watersheds in france has been monitored just outside the city of orleans since 1994 physico chemical parameters and major and trace elements were measured between 2 day and 1 week intervals according to the river flow the sampling site represents 34 of the total loire watershed with 76 silicate rocks and 24 carbonate rocks elements are transported mainly in the dissolved phase with the ratio of total dissolved salts tds to suspended matter sm ranging between 1 6 and 17 4 chemical weathering of rocks and soils are thus the dominant mechanisms in the loire waters composition the highest tds sm ratios are due to dissolved anthropogenic inputs the database shows no link between no3 content and river flow the na k mg2 so42 and cl concentrations are seen to decrease with increasing discharge in agreement with a mixing process involving at least two components the first component during low flow is concentrated and may be related with input from the groundwater and sewage station water the second component during high flow is more dilute and is in agreement with bedrock weathering and rainwater inputs a geochemical behaviour pattern is also observed for hco3 and ca2 species their concentrations increase with increasing discharge up to 300 m3 s after which they decrease with increasing discharge the sr isotopic composition of the dissolved load is controlled by at least five components a series of natural components represented by a waters draining the silicate and carbonate bedrock b groundwater and c rainwaters and two kinds of anthropogenic components the aim of this study is to describe the mixing model in order to estimate the contribution of each component finally specific export rates in the upper loire watershed were evaluated close to 12 t year 1 km 2 for the silicate rate and 47 t year 1 km 2 for the carbonate rate

mg isotopic composition of carbonate insight from speleothem formation simultaneous high precision measurement of 24 mg 25 mg and 26 mg isotopic compositions were made by multiple collector inductively coupled mass spectrometry mc icp ms relative to the international standard srm980 data are presented on low mg calcite speleothems and their associated host rocks and waters from four caves one in the french alps and three in israel covering various climate conditions in addition data are presented on three dolostones and three limestones from the himalaya the overall variation is 4 13x and 2 14x in n 26 mg and n 25 mg respectively this is 35 times the uncertainty of the measurements and clearly demonstrates that the terrestrial isotopic composition of mg is not unique each speleothem shows a characteristic range of n 26 mg values that are attributed to the isotopic composition of the local water differences between the isotopic composition of mg in the water dripping from stalactites and that of the modern speleothem are interpreted as being due to mg isotopic fractionation during carbonate precipitation in the temperature range of 4 18 c the low mg calcite is enriched in light isotopes by 1 35x amu and the dependence on temperature has been found to be less than 0 02x amu c despite various geological settings the n 26 mg of the studied dolostones is 2 0 1 2x higher than the n 26 mg of the limestones all together these results suggest a strong mineralogical control and a weak temperature effect on the mg isotopic composition of carbonate a 2002 elsevier science b v all rights reserved

strontium 86 labeling experiments show spatially heterogeneous skeletal formation in the scleractinian coral porites porites this paper presents the results of an effort to label calcium carbonates formed by marine organisms with stable isotopes to obtain information about the biomineralization processes the growing skeleton of the scleractinian coral porites porites was labeled three times with enhanced abundances of sr 86 the distribution of sr 86 in the skeleton was imaged with the nanosims ion microprobe with a spatial resolution of similar to 200 nm and combined with images of the skeletal ultra structure importantly the distribution of the sr 86 label in the p porites skeleton was found to be strongly heterogeneous this constrains the physical dimensions of the hypothetical extracellular calcifying fluid ecf reservoir at the surface of the growing skeleton which is implicit in most geochemical models for coral biomineralization these new experimental capabilities allow for a much more detailed view of the growth dynamics for a wide range of marine organisms that biomineralize carbonate structures citation houlbreque f a meibom j p cuif j stolarski y marrocchi c ferrier pages i domart coulon and r b dunbar 2009 strontium 86 labeling experiments show spatially heterogeneous skeletal formation in the scleractinian coral porites porites geophys res lett 36 l04604 doi 10 1029 2008gl036782

evidence for mass dependent isotopic fractionation of strontium in a glaciated granitic watershed abstract the stable isotope composition of strontium expressed as 88 86sr may provide important constraints on the global exogenic strontium cycle here we present 88 86sr values and 87sr 86sr ratios for granitoid rocks a 150 yr soil chronosequence formed from these rocks surface waters and plants in a small glaciated watershed in the central swiss alps incipient chemical weathering in this young system whether of inorganic or biological origin has no resolvable effect on the 87sr 86sr ratios and 88 86sr values of bulk soils which remain indistinguishable from bedrock in terms of sr isotopic composition although due in part to the chemical heterogeneity of the forefield the lack of a resolvable difference between soil and bedrock isotopic composition indicates that these soils have thus far witnessed minimal net loss of sr a low degree of chemical weathering is also implied by bulk soil chemistry the isotopic composition of sr in streamwater is more radiogenic than median soil reflecting the preferential weathering of biotite in the catchment streamwater 88 86sr values however are indistinguishable from bulk soil 88 86sr values implying that no resolvable fractionation of sr isotopes takes place during release to the weathering flux in the damma forefield analyses of plant tissue reveal that plants rhododendron and vaccinium preferentially assimilate the lighter isotopes of sr such that their 88 86sr values are significantly lower than those of the soils in which they grow additionally 88 86sr values of foliar and floral tissues are lower than those of roots contrary to observations for ca for which sr is often used as an analogue in weathering studies we suggest that processes that discriminate against sr in favour of ca due to the different nutritional requirement of plants for these two elements are responsible for the observed contrast

seasonal changes in the radiogenic and stable strontium isotopic composition of xijiang river water implications for chemical weathering seasonal changes in strontium sr isotopic systematics in large rivers can effectively track temporal variations in regional chemical weathering and help to better constrain the sr isotopic budget of global oceans however such records are scarce here we present a year long time series of both radiogenic and stable sr isotope measurements 87sr 86sr and 88sr from river water at guiping in the middle reaches of the xijiang river south china temporal changes in chemical weathering in the drainage basin were investigated by recording seasonal changes in the composition of both sr isotopes and major ions in the river water river water 87sr 86sr values range from 0 708487 to 0 710336 with most values being 0 7092 are generally accompanied by high rb sr ratios and low ph and 13c of dissolved inorganic carbo dic and occur during periods of large river flux this indicates that the contribution to the chemistry of river water from the weathering of silicate rocks is enhanced during rainy seasons seasonal variation in river water 88sr is large from 0 147 to 0 661 with higher 88sr values generally corresponding to higher 87sr 86sr values again low 88sr values 0 3 suggest a dominant contribution from the weathering of carbonate rocks whereas the high 88sr values may represent a contribution from intensive weathering of silicate rocks using the time series data we estimated the flux weighted averages of sr concentration 87sr 86sr and 88sr for the xijiang river to be 1 00 mol l 0 70960 and 0 38 respectively the sr concentration and 87sr 86sr results are close to previous estimates while the 88sr value is amongst the highest recorded for the large rivers of the world and is close to that of seawater our results indicate that large rivers draining through tropical sub tropical regions could play an important role in regulating the stable sr isotopic budget of global oceans

calcium isotope δ 44 40 ca fractionation along hydrothermal pathways logatchev field mid atlantic ridge 14 45 n we investigate the logatchev hydrothermal field at the mid atlantic ridge 14 degrees 45 n to constrain the calcium isotope hydrothermal flux into the ocean during the transformation of seawater to a hydrothermal solution the ca concentration of pristine seawater ca sw increases from about 10 mm to about 32 mm in the hydrothermal fluid endmember ca hydend and thereby adopts a delta ca 44 40 hydend of 0 95 0 07 parts per thousand relative to seawater sw and a sr 87 sr 86 isotope ratio of 0 7034 4 we demonstrate that delta ca 44 40 hydend is higher than that of the bedrock at the logatchev field from mass balance calculations we deduce a delta ca 44 40 of 1 17 0 04 parts per thousand sw for the host rocks in the reaction zone and 1 45 0 057 parts per thousand sw for the isotopic composition of the entire hydrothermal cell of the logatchev field the values are isotopically lighter than the currently assumed delta ca 44 40 for bulk earth of 0 92 0 187 parts per thousand sw skulan j depaolo d j and owens t l 1997 biological control of calcium isotopic abundances in the global calcium cycle geochim cosmochim acta 61 12 2505 2510 and challenge previous assumptions of no ca isotope fractionation between hydrothermal fluid and the oceanic crust zhu p and macdougall j d 1998 calcium isotopes in the marine environment and the oceanic calcium cycle geochim cosmochim acta 62 10 1691 1698 schmitt a d chabeaux f and stille p 2003 the calcium riverine and hydrothermal isotopic fluxes and the oceanic calcium mass balance earth planet sci lett 6731 1 16 here we propose that ca isotope fractionation along the fluid flow pathway of the logatchev field occurs during the precipitation of anhydrite two anhydrite samples from the logatchev hydrothermal field show an average fractionation of about delta 44 4c ca 0 57 parts per thousand relative to their assumed parental solutions ca isotope ratios in aragonites from carbonate veins from odp drill cores indicate aragonite precipitation directly from seawater at low temperatures with an average delta ca 44 40 of 1 54 0 08 parts per thousand sw the relatively large fractionation between the aragonite precipitates and seawater in combination with their frequent abundance in weathered mafic and ultramafic rocks suggest a reconsideration of the marine ca isotope budget in particular with regard to ocean crust alteration c 2008 elsevier ltd all rights reserved

progress in the study and modelling of similar fold interferences abstract similar fold interferences are examined in two different ways 1 1 we show the importance of taking into account the original position of the stratification with respect to the orientations of two interfering fold phases basin and dome cases correspond to particular orientations of the interfering phases with respect to each other in all other cases coaxiality may be achieved for particular positions of the original stratification 2 2 we have achieved a computer aided modelling which allows the visualization by means of sections and block diagrams of any two or three similar fold interferences the program allows us to define the stratification orientations of the various phases and their profiles sinusoidal or drawn by hand and orientations and dimensions of the selected section or block diagram faults may also be represented this modelling method is a powerful research tool that we hope to apply in future to detailed studies of fold interferences to achieve quantitative field models of multiply folded and faulted terranes