multiple indicator study of groundwater flow and chemistry and the impacts of river and paddy water on groundwater in the alluvial fan of the tedori river japan to investigate the source flow paths and chemistry of rich resources of high quality shallow groundwater in the alluvial fan between the tedori and sai rivers in central japan we analysed stable isotope ratios of h o and sr and concentrations of major dissolved ions and trace elements in groundwater river water and paddy water the sr 87 sr 86 ratios of the groundwater are related to near surface geology groundwater in sediment from the tedori river has high sr 87 sr 86 ratios 0 711 whereas that from the sai river in the north of the fan has low sr 87 sr 86 ratios 0 711 h 2 and o 18 values and sr 87 sr 86 ratios indicate that groundwater in the central and southern fans is recharged by the tedori river whereas recharge in the north is from the sai river mg2 ca2 sr2 hco3 and so42 concentrations and h 2 and o 18 values in the groundwater are high in the central fan and except for the northern area tend to increase with distance from the tedori river there are linear relationships between sr 87 sr 86 ratio and the reciprocal concentrations of sr2 mg2 and ca2 these geochemical characteristics suggest that as groundwater recharged from the tedori river flows towards the central fan it mixes with waters derived from precipitation and paddy water that have become enriched in these components during downward infiltration these results are consistent with our hydrological analysis and numerical simulation of groundwater flow thus verifying the validity of the model we used in our simulation of groundwater flow copyright c 2016 john wiley sons ltd

water geochemistry controlled by carbonate dissolution a study of the river waters draining karst dominated terrain guizhou province china concentrations of major ions and sr and sr isotopic compositions of two major river systems wujiang river and yuanjiang river in karst dominated regions and during winter were measured the rivers and their tributaries have high total dissolved solid concentrations with tz ranging from 2 1 to 6 3 meq l which are significantly higher than that of the global river average calcium and hco3 followed by mg2 and so42 dominate the chemical composition of major ions in the river waters both na k and cl si account for 5 10 of the cations and anions respectively the waters of the wujiang river have high sr2 concentrations and lower 87sr 86sr ratios 0 7077 0 7110 while those of the qingshuijiang river one of two major tributaries of the yuanjiang river system show higher sr isotopic ratios 0 7090 0 7145 and low sr concentrations the lithology and geography of the river basins largely control the chemical and isotopic compositions of these rivers analyses of the stoichiometry of the river waters show that the water chemistry is controlled by carbonate dissolution by both carbonic and sulfuric acid especially of the wujiang river and suggest an origin of sulfate mainly from atmospheric input because of coal combustion and or oxidation of sulfide minerals in the catchments we identify three main weathering sources limestone dolomite and silicates chemical and sr isotopic composition of wujiang river waters are characterized mainly by limestone weathering while those of the qingshuijiang river waters mainly by dolomite and silicate weathering chemical weathering rates of carbonate and silicate are estimated and the results indicate that the chemical weathering rates of carbonate in the catchments are remarkably high significantly higher than most large rivers it is considered that presence of sulfuric acid in the rock weathering overuse of land and deterioration of vegetation are most likely the key factors responsible for the high weathering rates of carbonate in the catchments

diapirism bulk homogeneous shortening and transcurrent shearing in the archaean dharwar craton the holenarsipur area southern india abstract qualitative strain data are spatially integrated in order to define archaean foliation trajectories and variations in strain intensity and ellipsoid type in the holenarsipur area dharwar craton southern india the study provides constraints on the bulk geometry the progressive deformation and the kinematic history of this region of archaean continental crust two major structural events have shaped the study area i a regional diapiric event contemporaneous with a magmatic event and ii a later sinistral transcurrent ductile shear event which has locally reoriented both foliations and stretching lineations the entire holenarsipur supracrustal belt underwent a common tectono metamorphic history that included two metamorphic events each event corresponds temporally to a distinct strain field the first a regional amphibolite facies event was contemporaneous with the main tectonic event and probably with the intrusion of halekote trondhjemites the second occurred under greenschist facies conditions and was restricted to a late transcurrent shear zone at the eastern boundary of the greenstone belt the strain pattern prior to transcurrent shearing cannot be explained by a thrusting event unless all trace of this event had been erased by the diapirism we interpret all structures older than the transcurrent shearing to be the direct result of vertical movements linked to body forces augmented by minor horizontal crustal shortening

structural relations of charnockites of the archaean dharwar craton southern india abstract two varieties of charnockites are recognized in the dharwar craton of southern india the style and sequence of structures in one charnockite variety and related intermediate to basic granulites are similar to those in the supracrustal rocks of the dharwar supergroup and the adjacent peninsular gneiss this style has isoclinal folds with long limbs and sharp hinges with an axial planar fabric in some instances additional evidence of flattening is provided by pinch and swell and boudinage structures with basic granulites forming boudins in the more ductile charnockites enderbites in the limbs of isoclinal folds these folds are involved in near coaxial upright folding resulting in the bending of the axial planes of the isoclinal folds and the associated boudins all these structures are overprinted by non coaxial upright folds with axial planes striking nearly n s the map pattern of charnockites suggests that this sequence of structures is present not only on a mesoscopic scale but also on a macroscopic scale charnockites of this variety provide in some instances evidence of having been migmatized to give rise to hornblende biotite gneiss and biotite gneiss which form a part of the peninsular gneiss terrane the second variety comprises charnockite sensu stricto with an entirely different structural style this type occurs in the tensional domains of the hinge zones of the later buckle folds in the necks of foliation boudinage in shear zones and in release joints parallel to the axial planes of the later folds in the peninsular gneiss because the non coaxial later folds are associated with a strain pattern different from and later than that of the isoclinal folds of the first generation it follows that charnockites of the dharwar craton have evolved in at least two distinct phases separate both in time and in process

strontium isotope geochemistry of groundwater affected by human activities in nandong underground river system china abstract the nandong underground river system nurs is located in a typical karst area dominated by agriculture in se yunnan province china groundwater plays an important role in the social and economical development in the area the effects of human activities agriculture and sewage effluents on the sr isotope geochemistry were investigated in the nurs seventy two representative groundwater samples which were collected from different aquifers calcite and dolomite under varying land use types both in summer and winter showed significant spatial differences and slight seasonal variations in sr concentrations and 87sr 86sr ratios agricultural fertilizers and sewage effluents significantly modified the natural 87sr 86sr ratios signature of groundwater that was otherwise dominated by water rock interaction three major sources of sr could be distinguished by 87sr 86sr ratios and sr concentrations in karst groundwater two sources of sr are the triassic calcite and dolomite aquifers where waters have low sr concentrations 0 1 0 2 mg l and low 87sr 86sr ratios 0 7075 0 7080 and 0 7080 0 7100 respectively the third source is anthropogenic sr from agricultural fertilizers and sewage effluents with waters affected having radiogenic 87sr 86sr ratios 0 7080 0 8352 for agricultural fertilizers and 0 7080 0 7200 for sewage effluents respectively with higher sr concentrations 0 24 0 51 mg l due to the overlapping 87sr 86sr ratios it is difficult to distinguish the sources of sr in groundwater samples contaminated by agricultural fertilizers or sewage effluents based only on their 87sr 86sr ratios however 87sr 86sr ratios do provide key information for natural and anthropogenic sources in karst groundwater

a review of the inferred geodynamic evolution of the dharwar craton over the ca 3 5 2 5 ga period and possible implications for global tectonics the geological history and evolution of the dharwar craton from ca 3 5 2 5 ga is reviewed and briefly compared with a second craton kaapvaal to allow some speculation on the nature of global tec

interaction between different water bodies in a small catchment in the paris basin brevilles france tracing of multiple sr sources through sr isotopes coupled with mg sr and ca sr ratios abstract intensive monitoring of the cuise sands aquifer in a small agricultural catchment 3 km2 where agricultural practices are well documented over nearly 5 a showed significant disparities for major element concentrations sr concentrations isotopic compositions and 3h values depending on the groundwater sampling locations lower 87sr 86sr values 0 7079 0 7085 associated with low no 3 concentrations low mg sr molar ratios 0 7085 and higher mg sr molar ratios 250 suggest a contribution of sr from anthropogenic sources strontium isotopes coupled with mg sr and ca sr ratios of groundwater in this catchment successfully demonstrated the capacity to trace fertilizer contributions which significantly modify the natural sr isotopic signature of groundwater the specific geochemical signature of groundwater revealed by sr isotopes in addition to major and trace element concentrations in particular mg sr and ca sr molar ratios demonstrated the partial isolation of groundwater bodies in this catchment compartmentalisation of the aquifer is compatible with fault distribution as defined by geological and geophysical investigations thus the sr isotopic tool coupled with mg sr and ca sr ratios has been applied with success to trace water pathways and recharge and to provide scenarios for the hydrological functioning of the system

strontium isotopes as tracers of groundwater induced floods the somme case study france major ions trace elements and o h and sr isotopes have been determined for surface water and groundwater in the somme catchment northern france the present study using a coupled hydrological and geochemical stable and sr isotopes approach focuses on the interactions between ground and surface water stable water isotopes 18o 2h show that all waters have a purely local origin from precipitation without significant evaporation or water rock interaction as all points plot close to the general meteoric water line water chemistry in the different catchments shows large variations in major element contents plotting na vs cl contents and mg2 no3 k so42 sr2 concentrations reveals a slight variations in groundwater composition b agricultural input into surface waters and c some similarities between ground and surface waters suggesting the former to be responsible for the chemical signature of the dissolved river load strontium isotope ratios measured in groundwater range from 0 70769 to 0 70808 clearly higher than that of chalk matrix water 0 707337 variations of sr isotope signatures in groundwater from the chalk aquifer are significant and help identifying different groundwater bodies the different signatures in groundwater are better explained by matrix heterogeneity which can present lateral facies variations than by a strong anthropogenic influence the sr isotope compositional range in surface waters is very wide varying from 0 70775 to 0 70816 and defining a trend towards a more radiogenic sr isotope signature with high sr contents and high mg sr ratios the relationship between 87sr 86sr and the mg sr ratios allows different end members to be defined the rivers are influenced by anthropogenic disturbance even during flood periods and river water has geochemical characteristics very similar to those of groundwater indicating a strong influence from groundwater feeding the rivers

the combined use of 87sr 86sr and carbon and water isotopes to study the hydrochemical interaction between groundwater and lakewater in mantled karst abstract the hydrochemical interaction between groundwater and lakewater influences the composition of water that percolates downward from the surficial aquifer system through the underlying intermediate confining unit and recharges the upper floridan aquifer along highlands in florida the 87sr 86sr ratio along with the stable isotopes d 18o and 13c were used as tracers to study the interaction between groundwater lakewater and aquifer minerals near lake barco a seepage lake in the mantled karst terrane of northern florida upgradient from the lake the 87sr 86sr ratio of groundwater decreases with depth mean values of 0 71004 0 70890 and 0 70852 for water from the surficial aquifer system intermediate confining unit and upper floridan aquifer respectively resulting from the interaction of dilute oxygenated recharge water with aquifer minerals that are less radiogenic with depth the concentrations of sr2 generally increase with depth and higher concentrations of sr2 in water from the upper floridan aquifer 20 35 g l relative to water from the surficial aquifer system and the intermediate confining unit result from the dissolution of sr bearing calcite and dolomite in the eocene limestone dissolution of calcite 13c 1 6permil is also indicated by an enriched 13cdic 8 8 to 11 4 in water from the upper floridan aquifer relative to the overlying hydrogeologic units 13cdic groundwater downgradient from lake barco was enriched in18o and d relative to groundwater upgradient from the lake indicating mixing of lakewater leakage and groundwater downgradient from the lake the 87sr 86sr ratio of groundwater and aquifer material become less radiogenic and the sr2 concentrations generally increase with depth however sr2 concentrations are substantially less than in upgradient groundwaters at similar depths the lower sr2 concentrations result from the influence of anoxic lakewater leakage on the mobility of sr2 from clays based on results from mass balance modeling it is probable that cation exchange plays the dominant role in controlling the 87sr 86sr ratio of groundwater both upgradient and downgradient from lake barco even though groundwater from the three distinct hydrogeologic units displays considerable variability in sr concentration and isotopic composition the dominant processes associated with the mixing of lakewater leakage with groundwater as well as the effects of mineral water interaction can be ascertained by integrating the use of stable and radiogenic isotopic measurements of groundwater lakewater and aquifer minerals

possible relationship between nonvolcanic tremor and the 1998 2001 slow slip event south central alaska 1 we document the occurrence of nonvolcanic tremor nvt in south central alaska for 3 months of each year between 1999 and 2001 to provide a first order attempt to understand the relationship between nvt and a large slow slip event that occurred over a 2 to 3 year period between 1998 and 2001 the majority of the nvt signals observed after the onset of the slow slip event are bursts lasting between 10 and 15 min with frequencies ranging from 1 to 6 hz by the summer of 2001 the quantity of nvt has decreased dramatically from the previous summers and episodes rarely last up to 10 min the decrease in nvt activity in the summer of 2001 is coincident with the end of the slow slip event there is a clear spatial correlation between the observed nvt and the slow slip event with most of the nvt events located on the downdip edge of the region of highest slip depth estimates range widely over the region with approximately half concentrated near the interpreted north america yakutat pacific plate interface and the remainder located above the plate interface however owing to inadequate station coverage and poor knowledge of the local structure determining accurate depths is difficult and thus the relationship between the nvt and the plate interface is problematic this is the first study giving evidence that the relationship between slow slip events and nvt seen in cascadia and southwest japan may also exist in alaska

high resolution stratigraphy with strontium isotopes the isotopic ratio of strontium 87 to strontium 86 shows no detectable variation in present day ocean water but changes slowly over millions of years the strontium contained in carbonate shells of marine organisms records the ratio of strontium 87 to strontium 86 of the oceans at the time that the shells form sedimentary rocks composed of accumulated fossil carbonate shells can be dated and correlated with the use of high precision measurements of the ratio of strontium 87 to strontium 86 with a resolution that is similar to that of other techniques used in age correlation this method may prove valuable for many geological paleontological paleooceanographic and geochemical problems

tracing the sources of strontium in karst groundwater in chongqing china a combined hydrogeochemical approach and strontium isotope groundwater quality in karst regions is largely controlled by natural processes and anthropogenic activities over the past 10 years dissolved sr and its radiogenic isotope 87sr 86sr were widely used to trace the sources of solutes in groundwater however there is little research about hydrogeochemistry and sr isotopic compositions of the karst groundwater in chongqing karst area in this paper thirty five representative karst groundwater samples were collected from different aquifers limestone and dolomite and various land use types hydrochemical types of karst groundwater in chongqing were mainly of the ca hco3 type or ca mg hco3 type the dissolved sr concentrations of the studied groundwater ranged from 0 57 to 15 06 mmol l and the 87sr 86sr varied from 0 70751 to 0 71627 the groundwater samples from different aquifers and land use types showed distinctive dissolved sr concentrations and 87sr 86sr the very positive relationship between ca sr and mg sr in dolomite and limestone aquifers suggests that ca mg and sr element come mainly from the release of carbonate rock under the groundwater rock co2 gas interaction according to the 87sr 86sr ratio the sr element in karst groundwater in chongqing was controlled by the weathering of limestone dolomite and silicate rock allogenic water in a non karst area the relationship 87sr 86sr versus sr2 k na shows that the anthropogenic inputs also obviously contribute to the sr contents the research results show that the karst groundwater in chongqing is facing serious crisis of water quality and needs to be protected further

strontium isotope geochemistry of groundwaters and streams affected by agriculture locust grove md the effects of agriculture on the isotope geochemistry of sr were investigated in two small watersheds in the atlantic coastal plain of maryland stratified shallow oxic groundwaters in both watersheds contained a retrievable record of increasing recharge rates of chemicals including no3 cl mg ca and sr that were correlated with increasing fertilizer use between about 1940 and 1990 the component of sr associated with recent agricultural recharge was relatively radiogenic 87sr 86sr 0 715 and it was overwhelming with respect to sr acquired naturally by water rock interactions in the oxidized non calcareous portion of the saturated zone agricultural groundwaters that penetrated relatively unoxidized calcareous glauconitic sediments at depth acquired an additional component of sr from dissolution of early tertiary marine caco3 87sr 86sr 0 708 while undergoing o2 reduction and denitrification ground water discharge contained mixtures of waters of various ages and redox states two streams draining the area are considered to have higher 87sr 86sr ratios and no3 concentrations than they would in the absence of agriculture however the streams have consistently different 87sr 86sr ratios and no3 concentrations because the average depth to calcareous reducing denitrifying sediments in the local groundwater flow system was different in the two watersheds the results of this study indicate that agriculture can alter significantly the isotope geochemistry of sr in aquifers and streams and that the effects could vary depending on the types sources and amounts of fertilizers added the history of fertilizer use and groundwater residence times

the use of strontium and lead isotopes to identify sources of water beneath the fresh kills landfill staten island new york usa abstract a study was undertaken to explore whether the isotopic compositions of pb and sr are useful to distinguish mixtures of uncontaminated groundwater seawater and landfill leachate at the fresh kills landfill staten island new york ratios of 87sr 86sr ranged from 0 7088 to 0 7137 and could be used to distinguish sr that was derived from seawater from that in uncontaminated groundwater lead isotopic abundances did not vary systematically among the different water sources plots of 87sr 86sr versus dissolved organic c b and nh4 defined perpendicular trends documenting where leachate or sea water mixed with uncontaminated groundwater and demonstrating that leachate has not contaminated groundwater in aquifers beneath the landfill

strontium isotope geochemistry of groundwater in the central part of the dakota great plains aquifer usa abstract the dakota aquifer of the central and eastern great plains of the united states is an important source of water for municipal supplies irrigation and industrial use although the regional flow system can be characterized generally as east to northeasterly from the rocky mountains towards the missouri river locally the flow systems are hydrologically complex this study uses sr isotopic data from groundwater and leached aquifer samples to document the complex subsystems within the dakota aquifer in nebraska and kansas the interaction of groundwater with the geologic material through which it flows has created spatial patterns in the isotopic measurements that are related to long term water rock interaction during which varying degrees of isotopic equilibrium between water and rock has been achieved and the alteration of nacl fluids by water rock interaction specifically sr isotopic data distinguish brines from kansas and western nebraska from those in eastern nebraska the former are interpreted to reflect interaction with permian rocks whereas the latter record interaction with pennsylvanian rocks the sr isotopic composition of groundwater from other parts of nebraska and kansas are a function of the dynamic interaction between groundwater and unlithified sediments e g glacial till and loess followed by interaction with oxidized and unoxidized sediments within the dakota formation this study illustrates the power of combining sr chemistry with more conventional geochemical data to obtain a more complete understanding of groundwater flow systems within regional aquifer systems where extensive monitoring networks do not exist

structural evolution of the peninsular gneiss an early precambrian migmatitic complex from south india the peninsular gneiss which is considered by a number of workers to be the basement on which the supracrustal rocks of the dharwar group were deposited is a composite gneiss formed by migmatization of pre existing metasedimentary and meta igneous rocks these gneisses show the same style and sequence of superposed deformation as those in the enclaves of metamorphic rocks and in the linear dharwar schist belts outside the main migmatization is broadly coeval with the isoclinal first folding which is followed by near coaxial refolding and non coaxial upright folding small inclusions of migmatized amphibolite and granodioritic to dioritic gneiss with a fabric athwart to and overprinted by the earliest deformation affecting the dharwar group of rocks in a large part of the gneissic terrane point to at least one deformation a metamorphic event and one episode of migmatization antedating the isoclinal first folds in the rocks of the dharwar group the peninsular gneiss in its present state therefore represents an extensively remobilized basement

strontium 87 strontium 86 as a tracer of mineral weathering reactions and calcium sources in an alpine subalpine watershed loch vale colorado sr isotopic ratios of atmospheric deposition surface and subsurface water and geologic materials were measured in an alpine subalpine watershed to characterize weathering reactions and identify sources of dissolved ca in stream water previous studies have noted an excess of ca in stream water above that expected from stoichiometric weathering of the dominant bedrock minerals mixing calculations based on 87 sr 86 sr indicate that on an annual basis 26 67 of ca export in streams is atmospherically derived 23 61 is from weathering of plagioclase and the remainder is from weathering of calcite present in trace amounts in the bedrock a potential source of error when applying sr isotopes in catchment studies is determination of the 87 sr 86 sr of sr released by mineral weathering which is complicated by the wide range of mineral isotopic compositions particularly in older rocks and the variable rates at which the minerals weather in this study base flow stream chemistry was used to represent the 87 sr 86 sr of sr derived from mineral weathering because it effectively integrates the potentially variable isotopic composition of sr released by weathering in the alpine environment

kimberlite lamproite ultramafic lamprophyre and carbonatite relationships on the dharwar craton india an example from the khaderpet pipe a diamondiferous ultramafic with associated carbonatite intrusion abstract are kimberlites lamproites ultramafic lamprophyres and carbonatites genetically associated or not there are strong opinions for and against any relationship the 20 ha khaderpet pipe discovered by rio tinto exploration is an unusual diamondiferous carbonatite kimberlite clan rock kcr association in the anumpalle cluster of the wajrakarur kimberlite field in the dharwar craton of peninsular indian the khaderpet pipe has a discrete sovite phase intrusive into kcr breccia not noticed elsewhere in the wajrakarur kimberlite field petrographically the kcr is a clast supported lithic breccia and crystal lithic tuff with occasional pelletal lapilli clasts show a weak horizontal imbrication the overall appearance of the tuffs and breccias is suggestive of terminal blocked vent accumulations that formed by under pressure with spallation of country rock causing an abundance of granitoid debris the sovite phase has up to 95 calcite occasionally showing flow textured polycrystalline laths set in a minor saponite matrix there are mineralogical gradations from an olivine rich ultramafic to a calcite dominant rock resembling pure carbonatite rare ree mineral phases in the carbonatite include allanite and other ree rich unidentified mineral phases xenocrystic high pressure phases in both ultramafic and carbonatite include mantle derived diamonds lherzolitic eclogitic and subcalcic pyrope ti poor andradite chrome diopside picrochromite and picroilmenite extensive metasomatism in the form of reddening of country rock feldspars by hematite introduction of green chlorite and saponitic alteration of breccia clasts and the ultramafic phase is common the chemistry of the khaderpet ultramafic component suggests that the kcr is transitional between kimberlite and ultramafic lamprophyres like certain other pipes in the wajrakarur kimberlite field with strong enrichment in lree cao and co2 however low mgo 13 and high cao 10 values are more typical of ultramafic lamprophyres such as alnoite or aillikite the significant carbonate content and the presence of accessory ti andradite would lead to the kcr being classified as an ultramafic lamprophyre under the iugs classification the khaderpet carbonatite component shows extreme enrichment in ree approaching that of world average carbonatite given the chemical and petrological characteristics of a carbonatite along with the associated and widespread aureole of metasomatism this phase is considered to be a late stage fractionation product of the khaderpet diamond bearing ultramafic magma

sources of sulfur in the nandong underground river system southwest china a chemical and isotopic reconnaissance abstract sulfur isotopic compositions 34s and major ions were measured in groundwater and surface waters in order to elucidate the source s of elevated so 4 2 content in some of these waters in the nandong underground river system nurs located in an agricultural and urbanization dominated area in sw china the major chemical composition of analyzed groundwater and surface water from nurs was characterized by ca hco3 or ca mg hco3 type in forested and grass land areas and ca cl no3 so4 or ca mg cl no3 so4 type in urban and agricultural areas respectively the anomalously high so 4 2 concentrations in waters collected from urban and agricultural areas indicated a likely anthropogenic origin for so 4 2 the groundwater collected from forested and grass land areas was characterized by relatively low 34 s so 4 2 from 1 7 to 4 3 and low so 4 2 concentrations of less than 10 mg l 1 consistent with an origin for so 4 2 in these waters from a mixture of rainfall derived so 4 2 and so 4 2 from oxidation of bedrock sulfide high so 4 2 groundwater and surface water 20 mg l 1 collected from urban areas was characterized by elevated 34 s so 4 2 from 8 3 to 12 1 compared to lower 34 s so 4 2 in samples from cultivated land areas 3 7 to 6 4 indicating that the so 4 2 in these two groups of waters resulted from different anthropogenic sources the s isotopic composition of so 4 2 in urban areas is consistent with addition of so 4 2 from detergent sewage whilst in cultivated land areas isotope composition indicates that additional so 4 2 could be derived from fertilizers and or increased oxidation of sulfide

structural pattern in the dharwar craton high grade and low grade supracrustal belts sargur and dharwar set in a matrix of gneisses dotted with granitic plutons of different ages make up the dharwar craton the overall structural pattern is one of subparallel linear belts and stringers whose regional trend changes from nw se in the northern part to n s in the south both the high grade and low grade belts show three principal episodes of folding however the correlation between the deformation episodes in the sargur and the dharwar rocks is controversial and the structural relations between them are not unequivocally established parallelism of the first phase structures in the sargur and the dharwar rocks can be interpreted either as synchronous development or rotation of the earlier sargur structures into parallelism with the younger dharwar structures during later deformation the extension of the supracrustal belts is parallel to the f 2 axial traces of the second deformation granite diapirism and basement uplift further modified

sources of sr and implications for weathering of limestone under tallgrass prairie northeastern kansas abstract grasslands of north central kansas are underlain by carbonate aquifers and shale aquitards chemical weathering rates in carbonates are poorly known and because large areas are underlain by these rocks solute fluxes are important to estimating global weathering rates grasslands exist where the amount of precipitation is extremely variable both within and between years so studies in grasslands must account for changes in weathering that accompany changes in precipitation this study 1 identifies phases that dominate chemical fluxes at konza prairie biological station kpbs and long term ecological research site and 2 addresses the impact of variable precipitation on mineral weathering the study site is a remnant tallgrass prairie in the central usa representing baseline weathering in a mid temperate climate grassland groundwater chemistry and hydrology in the 1 2 km 2 watershed used for this study suggest close connections between groundwater and surface water water levels fluctuate seasonally high water levels coincide with periods of precipitation plus low evapotranspiration rather than during precipitation peaks during the growing season precipitation is concentrated before recharging aquifers suggesting an as yet unquantified residence time in the thin soils groundwater and surface water are oversaturated with respect to calcite within limitations of available data water is more dilute in more permeable aquifers and water from one aquifer morrill is indistinguishable from surface water cations other than ca co vary with each other especially sr and mg potassium and si co vary in all aquifers and surface water and increases in concentrations of these elements are the best indicators of silicate weathering at this study site silicate weathering indices correlate inversely to aquifer hydraulic conductivity 87 sr 86 sr in water ranges from 0 70838 to 0 70901 and it decreases with increasing sr concentration and with increasing silicate weathering index carbonate extracted from aquifer materials shales soil and tufa has sr ranging from about 240 soil to 880 ppm paleozoic limestone 87 sr 86 sr ranges from 0 70834 0 00006 limestone to 0 70904 0 00019 soil in all cases 87 sr 86 sr of aquifer limestone is lower than 87 sr 86 sr of groundwater indicating a phase in addition to aquifer carbonate is contributing solutes to water aquifer recharge controls weathering during periods of reduced recharge increased residence time increases the total amount of all phases dissolved mixing analysis using 87 sr 86 sr shows that two end members are sufficient to explain sources of dissolved sr it is proposed that the less radiogenic end member is a solution derived from dissolving aquifer material longer residence time increases its contribution the more radiogenic end member solution probably results from reaction with soil carbonate or eolian dust this solution dominates solute flux in all but the least permeable aquifer and demonstrates the importance that land surface and soil zone reactions have on groundwater chemistry in a carbonate terrain

dissolution rates and vadose zone drainage from strontium isotope measurements of groundwater in the pasco basin wa unconfined aquifer abstract strontium isotope ratios 87sr 86sr measured in groundwater samples from 273 wells in the pasco basin unconfined aquifer below the us department of energy hanford site show large and systematic variations that provide constraints on groundwater recharge weathering rates for saturated zone dissolution of the aquifer host rocks communication between unconfined and deeper confined aquifers and vadose zone groundwater interaction the impact of millions of cubic meters of wastewater discharged to the vadose zone 103 105 times higher than ambient drainage shows up strikingly on maps of groundwater 87sr 86sr extensive access through the many groundwater monitoring wells at the site allows for an unprecedented opportunity to evaluate the strontium geochemistry of a major aquifer hosted primarily in unconsolidated sediments and relate it to both long term properties and recent disturbances groundwater 87sr 86sr increases systematically from 0 707 to 0 712 from west to east across the hanford site in the general direction of groundwater flow as a result of addition of sr from the weathering of aquifer sediments and from diffuse drainage through the pasco basin vadose zone the lower 87sr 86sr groundwater reflects recharge waters that have acquired sr from columbia river basalts based on a steady state model of sr reactive transport and drainage there is an average natural drainage flux of 0 1 4 mm yr near the western margin of the hanford site and ambient drainage may be up to 30 mm yr in the center of the site assuming an average bulk rock weathering rate of 10 7 5 g g yr the weathering rates cannot be higher than those assumed by more than a factor of 2 3 in order to match sr isotope data

geochemical and isotopic characteristics of shallow groundwater within the lake qinghai catchment ne tibetan plateau abstract major ions isotopic ratios of strontium 87 sr 86 sr hydrogen d and oxygen 18 o of groundwater samples were analyzed to decipher spatial variation controlling factors solute sources and the recharge source of shallow groundwaters within the lake qinghai catchment shallow groundwaters in this area are slightly alkaline with 97 being fresh water of good quality though there are high concentrations of nitrate and sulfide in buha and lakeside groundwaters most of the shallow groundwaters are of the ca 2 hco 3 type whereas part of groundwaters surrounding the lake ls belongs to the na cl type as lake water qhl groundwater geochemistry is controlled by regional lithological association ion exchange and mineral precipitation the dissolved sr concentrations and 87 sr 86 sr ratios vary from 1 0 to 15 6 mol l and from 0 709859 to 0 715779 respectively the first quantitative calculation in groundwater using a forward model shows that 40 of dissolved sr is from carbonate weathering 33 from evaporite dissolution 17 from silicate weathering and the remainder from atmospheric input for the whole catchment carbonate weathering dominates groundwater geochemistry in shaliu sl hargai hg and buha bh samples while evaporite dissolution dominates ls and daotang dt samples d and 18 o data show that rain water is the major recharge source of both river water and shallow groundwater within the lake qinghai catchment qinghai lake water is characterized by buha type water but its sr geochemistry is different from the shallow groundwater due to carbonate precipitation although shallow groundwater contributes 5 of the dissolved sr to the qhl groundwater must be taken into account when the chemistry and budget of lake water are characterized