clay mineral provinces in tidal mud flats at germany s north sea coast with illite k ar ages potentially modified by biodegradation abstract mineralogical studies chemical analyses and k ar dating were carried out on clay fractions from tidal mud flats along the lower saxony coast and its bays to identify material sources and sedimentary processes at this dynamic interface between air land and sea from the coast into the bays sediments are enriched in fine grained smectite relative to the coarser grained illite chlorite and kaolinite due to the weakening of the tidal current energy in the bays in addition the study area can be divided into two provinces on the basis of the illite k rb ratios and mg contents to the west schiermonnikoog dollart ley bay up to norderney island longshore currents carry suspensions from the belgian and dutch coasts to the east from langeoog island jade bay to the helgoland mud area suspensions from the elbe and weser rivers are mixed with submarine reworked glacial sediments whereas the portion of longshore current suspensions from the west decreases becoming negligible in the helgoland mud area off the elbe and weser estuaries the illite k ar data vary considerably and fail as source indicators due to differential settling and mixing of the clay material and probably to ar loss from illite by biodegradation during digestive processes only further offshore outside the zone of dynamic sediment dispersion do the k ar data fit provenance patterns

boron isotope variations in nature a synthesis the large relative mass difference between the two stable isotopes of boron 10b and 11b and the high geochemical reactivity of boron lead to significant isotope fractionation by natural processes published 11b values relative to the nbs srm 951 standard span a wide range of 90 the lowest 11b values around 30 are reported for non marine evaporite minerals and certain tourmalines the most 11b enriched reservoir known to date are brines from australian salt lakes and the dead sea of israel with 11b values up to 59 dissolved boron in present day seawater has a constant world wide 11b value of 39 5 in this paper available 11b data of a variety of natural fluid and solid samples from different geological environments are compiled and some of the most relevant aspects including possible tracer applications of boron isotope geochemistry are summarized

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

estuarine clay mineral distribution modern analogue for ancient sandstone reservoir quality prediction the spatial distribution of clay minerals in sandstones which may both enhance or degrade reservoir quality is poorly understood to address this clay mineral distribution patterns and host sediment properties grain size sorting clay fraction abundance and bioturbation intensity have for the first time been determined and mapped at an unprecedentedly high resolution in a modern estuarine setting ravenglass estuary uk results show that the estuary sediment is dominated by illite with subordinate chlorite and kaolinite although the rivers supply sediment with less illite and significantly more chlorite than found in the estuary fluvial supplied sediment has been locally diluted by sediment derived from glaciogenic drift deposits on the margins of the estuary detailed clay mineral maps and statistical analyses reveal that the estuary has a heterogeneous distribution of illite chlorite and kaolinite chlorite is relatively most abundant on the northern foreshore and backshore and is concentrated in coarse grained inner estuary dunes and tidal bars illite is relatively most abundant as well as most crystalline and most fe mg rich in fine grained inner estuary and central basin mud and mixed flats kaolinite has the highest abundance in fluvial sediment and is relatively homogenous in tidally influenced environments clay mineral distribution patterns in the ravenglass estuary have been strongly influenced by sediment supply residence time and subsequently modified by hydrodynamic processes there is no relationship between macro faunal bioturbation intensity and the abundance of chlorite illite or kaolinite based on this modern analogue study outer estuarine sediments are likely to be heavily quartz cemented in deeply buried burial temperatures exceeding 80 to 100 c sandstone reservoirs due to a paucity of clay grade material 0 5 to form complete grain coats in contrast chlorite enriched tidal bars and dunes in the inner estuary with their well developed detrital clay coats are likely to have quartz cement inhibiting authigenic clay coats in deeply buried sandstones

boron isotope geochemistry as a tracer for the evolution of brines and associated hot springs from the dead sea israel abstract a boron isotope study combined with analyses of elemental boron lithium and chlorine is used to suggest that brines from the dead sea and on shore hypersaline thermal springs hamme yesha hamme zohar and hamme mazor are the products of interaction of evaporated seawater with detrital sediments the high 11b values of the dead sea brines 55 7 to 57 4 versus nbs 951 and the hot springs 52 2 to 55 7 and low b li ratios 2 0 to 2 3 and 2 5 to 2 7 respectively relative to seawater indicate preferential removal of 10b from the brines and hence boron adsorption onto clay minerals the brackish en feshcha springs and the freshwater en dawid and nahal arugot springs yield lower b contents and 11b values 37 7 to 40 6 and 33 8 to 36 9 respectively the 11b values and b contents of diluted dead sea brines lie on calculated mixing lines between the composition of the brackish and freshwater springs with the composition of the dead sea the 11 b values of the hot springs however given their boron content are significantly lower than those of the mixing lines thus waters from the hot springs cannot be a mixing product of the dead sea brine with freshwater instead the dead sea brine has evolved from the brines of the hot springs through further isotopic fractionation and boron adsorption onto detrital sediments

surface distributions of salt marsh foraminifera from connecticut usa modern analogues for high resolution sea level studies abstract salt marsh foraminifera are routinely used as sea level indicators since their vertical distribution is closely linked with elevation relative to the tidal frame the precise nature of these relationships is variable in time and space and the accuracy of sea level reconstructions depends upon the selection of appropriate modern analogues that reliably reflect past fauna environment associations the marshes of connecticut usa are sites of ongoing research seeking to produce high resolution records of sea level change yet little published data regarding their modern foraminiferal distributions exist this paper presents new surface foraminiferal data from three connecticut salt marshes and evaluates their suitability as modern analogues for past sea level changes the results indicate that significant intra and inter site variability between these marshes and those of neighbouring states exists as a consequence of this the extrapolation of fauna environment relationships developed from marshes with different hydrographic physiographic vegetative or climatic characteristics may produce erroneous reconstructions even when adjusted for variations in tidal range these errors are potentially greatest if single indicator species are used since the relative abundance of individual taxa does not vary consistently with elevation even in high marsh environments from the same site whilst cluster analysis demonstrates that foraminiferal assemblages from connecticut are vertically zoned with respect to mean high water mhw the composition elevation and height range of these zones is variable between sites this spatial heterogeneity results in reconstructions of relatively low and variable precision that restricts their utility in high resolution sea level research new studies seeking to distil decimetre scale changes in relative sea level will need to employ quantitative methods capable of combining multi site information to develop fauna environment relationships that capture this spatial variability reconstructions will be most precise when employing local foraminiferal distributions but may require the collection of additional modern analogue samples from other regions when the extant foraminiferal population of a site differs in composition from its sub fossil counterpart

changes in clay mineral content of tidal flat sediments resulting from dike construction along the lower saxony coast of the north sea germany the clay mineral content of the 2 m fraction in tidal flat sediments in the former harle bay on the lower saxony coast has changed considerably since the thirteenth century up to the present time the proportion of smectite has decreased from 29 to 11 wt whereas the proportion of illite has increased by about 10 wt and those of chlorite and kaolinite by about 3 wt each the chemical composition of the major clay mineral illite has also changed al2o3 has decreased by about 2 wt k2o by about 1 5 wt and sio2 by about 3 wt it can be concluded that the changes in the clay mineral content are mainly influenced by dike construction and sea level rise modifying flow pattern submarine morphology sedimentation and tidal range these processes cause smectite to settle less rapidly because of its small grain size and low density resulting from interlayer water so that the sediment becomes impoverished in this mineral

stable isotope geochemistry of sediment hosted groundwater from a late paleozoic early mesozoic section in central europe abstract the boron isotopic composition in combination with oxygen hydrogen and sulfur isotopes and hydrochemical tracers is utilized to investigate the evolution of groundwaters from a late paleozoic permian to early mesozoic triassic section of the sedimentary cover in central europe n switzerland sw germany four distinct groundwater types have been identified a saline groundwater from permian rotliegend sediments 11b 13 7 to 33 0 18o 6 7 to 5 3 d 53 4 to 37 8 34s 16 4 to 17 1 b brackish to saline groundwater from lower triassic buntsandstein sediments 11b 6 4 to 22 3 18o 10 3 to 6 9 d 71 8 to 60 5 34s 18 2 to 18 4 c fresh to saline groundwater from middle triassic muschelkalk sediments 11b 10 2 to 7 7 18o 11 8 to 8 8 d 86 6 to 63 0 34s 15 8 to 21 4 and d saline groundwater from upper triassic keuper sediments 11b 26 3 18o 6 4 d 41 2 34s 16 1 as evidenced by b o h s stable isotope and hydrochemical e g na cl br cl ca so4 ca mg so4 k b and li b constraints interactions with sedimentary host rocks and inter aquifer mixing have contributed to the evolution of the investigated groundwaters

boron isotopic compositions of brine sediments and source water in da qaidam lake qinghai china abstract the isotopic compositions of boron in da qaidam lake quinghai have been determined by using the technique of thermal ionization mass spectrometry of cesium tetraborate the brines are enriched in 11b with an average 11b of 5 49 2 34 compared with those of lake sediments and boron minerals produced by the lake the apparent isotopic fractionation factors between brine and lake sediments as well as boron minerals are 0 988 0 001 and 0 986 0 001 respectively source water 11b values range from 11 72 to 16 69 depending on their origin

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

strontium boron oxygen and hydrogen isotope geochemistry of brines from basal strata of the gulf coast sedimentary basin usa abstract significant spatial heterogeneities exist in the stable isotopic composition of saline formation waters from reservoirs of the smackover formation upper jurassic we focused on the southwest arkansas shelf a structurally simple portion of one of the interior basins of the northern gulf coast sedimentary basin here faulting and facies changes juxtapose dominantly oolitic carbonate strata against basal evaporites red beds and siliciclastics as well as metamorphosed basement rocks brines from this area have exceptionally high br and alkali element concentrations and have spatially heterogeneous hydrogen sulfide concentrations strontium boron oxygen and hydrogen isotope compositions exhibit coherent relations with other aspects of brine geochemistry sr isotope compositions range from those expected for carbonates and evaporites deposited from jurassic seawater 0 7071 to radiogenic ratios as high as 0 7107 generally most radiogenic sr isotope values are associated with h 2 s rich waters which also have elevated alkali element li b k rb concentrations these alkali element rich waters are associated with portions of the south arkansas fault system which reach basement boron isotope compositions are similarly heterogeneous ranging from values of 26 to 50 brines with highest b contents are most depleted in 11 b consistent with boron input from brines generated from high temperature siliciclastic diagenetic reactions normalizing b contents to br in the brines reveals a reasonable mixing trend between a dead sea type composition and texas gulf coast type shale sand reservoir waters oxygen and hydrogen isotope data exhibit regional variations which are controlled by meteoric water invasion along the northern limb of the southwest arkansas fault which has surface expression although oxygen isotope compositions are often near equilibrium with respect to reservoir carbonate it is more difficult to ascribe trends in d values to local water rock interaction the stable isotope trends can be explained either in terms of an evolved marine evaporite brine or a water evolved via water rock interaction and mixing with meteoric water in the vicinity of the southwest arkansas fault spatial heterogeneity in isotopic composition of formation waters from this relatively restricted study area suggests that assumptions of a homogeneous sr reservoir in dating regional mineralization events require careful assessment in ancient systems

chemical and boron isotope compositions of non marine brines from the qaidam basin qinghai china the general chemistry and boron isotope composition were investigated in fresh waters and hypersaline brines from the qaidam basin northern qinghai xizang tibet plateau china this basin is a large tectonically active system isolated from the ocean and composed of thick clastic and evaporite sediments the modern playas are subject to intense evaporation and are characterized by hypersaline brines as well as potash and borate evaporites the chemical composition of the dissolved solutes in the modern brines and waters reveals three main sources 1 inflow of hot springs enriched in sodium sulphate and boron evaporation of these waters leads to a high na cl ratio 1 a na cl so4 brine and an evaporite mineral assemblage of halite mirabilite borate lakes daqaidam and xiaoqaidam 2 inflow surface river waters which are modified by preferential dissolution of halite and potassium and magnesium salts characterized by a na mg cl solute type with low na cl 1 brcl licl and bcl ratios and 3 ca chloridic subsurface brines which are controlled by both salt dissolution and dolomitization processes evaporation and salt crystallization of mixtures of the latter two types leads to a marine like brine e g na mg cl type nacl ratio 1 and mineral assemblages similar to that predicted for progressive evaporation of seawater e g qarhan playa halite sylvite carnallite bischofite the 11 b values of the input waters to the qaidam basin range of 0 7 to 10 9 vs nbs 951 and brines from salt lakes 0 5 to 15 0 are similar to those of associated granitic rocks 11b 2 3 to 3 7 n 3 and hence indicate the non marine origin of these fluids the highest 11b values are associated with fluids with low bli ratios indicating selective removal of elemental boron and 10b by adsorption onto clay minerals the magnitude of 11b enrichment due to adsorption is 15 20 and thus non marine brines are well distinguished from marine derived brines 11b of 39 to 59 preserving the large isotopic difference 40 of their source waters it is proposed to use this distinctive isotopic signature for tracing the origin of ancient evaporite environments

sea level climate correlation during the past 1400 yr we present a new mean high water curve for hammock river marsh clinton connecticut obtained by improving the age model for an existing record of relative marsh elevation based on foraminiferal analysis of a 1 8 m long peat core unlike the earlier curve the new curve confirms trend changes in mean high water rise during the past 1400 yr as noted for salt marshes 15 km farther west suggesting a regional cause these trend changes and century scale mean high water variations in the clinton record correlate positively with large scale regional variations in sea surface and summer air temperature indicating a link between sea level and the climate ocean system on the basis of the clinton mean high water curve we conclude that real sea level oscillated centimeters to decimeters on a century time scale over the past 1400 yr was 25 25 cm higher ca a d 1050 medieval warm period than ca a d 1650 little ice age and rose at a mean rate of 1 mm yr 1 over the past 350 yr there was little or no rise during the cool 1800s

heterogeneities and interconnections in groundwaters coupled b li and stable isotope variations in a large aquifer system eocene sand aquifer southwestern france abstract the study of stable isotope of the water molecule and elemental data for groundwater in the large eocene sand aquifer system of sw france showed that the 18 o values of groundwater fall in the range 5 6 to 10 6 vs smow with 2 h values varying between and 34 3 to 72 3 vs smow there is no relationship between 18 o and 2 h values and the salinity but the stable isotopes data plot on or near the global meteoric water line taken as a whole the enriched samples clearly correlate with present day recharge while the most depleted samples reflect an old recharge groundwaters in the present study display large ranges of both boron concentrations 7 to 2550 g l 1 and boron isotopic compositions the lowest 11 b value being close to 18 0 and the highest one near 36 2 the scatter of b concentrations and 11 b values reflects the different rock types contributing to the supply of dissolved boron carbonates evaporites and silicates as well as an input from rainwater and fractionation during water rock interaction with clay minerals lithium concentrations in groundwater also span a wide range 0 6 to 253 g l 1 as do the lithium isotopic signatures that range between 6 5 and 28 6 we can evidence there that the b isotopic compositions are controlled by water rock interactions while li and 7 li variations are also controlled by water rock interaction processes dissolution and formation of alteration minerals that can occur at different temperatures within the groundwater system

coprecipitation and isotopic fractionation of boron in modern biogenic carbonates abstract the abundances and isotopic composition of boron in modern biogenic calcareous skeletons from the gulf of elat israel the great barrier reef australia and in deep sea sediments have been examined by negative thermal ionization mass spectrometry the selected species foraminifera pteropoda corals gastropoda and pelecypoda yield large variations in boron concentration that range from 1 ppm in gastropod shells to 80 ppm in corals the boron content of the biogenic skeletons is independent of mineralogical composition and is probably related to biological vital effects the 11 b values of the carbonates range from 14 2 to 32 2 relative to nbs srm 951 and overlap with the 11 b values of modern deep sea carbonate sediments 11 b 8 9 to 26 2 the variations of 11 b may be controlled by isotopic exchange of boron species in which 10 b is preferentially partitioned into the tetrahedral species and coprecipitation of different proportions of trigonal and tetrahedral species in the calcium carbonates carbonates with low 11 b values 15 may indicate preferential incorporation of tetrahedral species whereas the higher 11 b values 30 may indicate 1 1 uptake of both boron species assuming equilibrium with seawater 2 2 preferential incorporation of b oh 4 from in situ high ph internal fluids of organisms that are isolated from seawater the b content and 11 b values of deep sea sediments foraminifera tests and corals are used to estimate the global oceanic sink of elemental boron by calcium carbonate deposition as a result of enrichment of b in corals a substantially higher biogenic sink of 6 4 0 9 10 10 g yr is calculated for carbonates this is only slightly lower than the sink for desorbable b in marine sediments 10 10 10 g yr and approximately half that of altered oceanic crust 14 10 10 g yr thus carbonates are an important sink for b in the oceans being 20 of the total sinks the preferential incorporation of 10 b into calcium carbonate results in oceanic 11 b enrichment estimated as 1 2 0 3 10 12 per mil g yr the boron isotope composition of authigenic well preserved carbonate skeletons may provide a useful tool to record secular boron isotope variations in seawater at various times in the geological record the potential use of boron isotope geochemistry in skeletons as a tracer for palaeoenvironments is demonstrated in ostracoda and foraminifera from the gulf of carpentaria australia the 11 b values of glacial age buried skeletons 4 0 and 4 9 respectively are lower than that of their modern equivalents 17 6 and 13 3 respectively this may reflect a terrestrial boron isotope signature of the water in the gulf during the late quaternary when it was isolated from the ocean

boron isotope geochemistry of thermal springs from the northern rift valley israel a boron isotope study was carried out on groundwaters from the northern rift valley israel the relatively high salinity 18 000 mgcl l 1 boron content 3 9 mg l 1 and 11 b value 44 and the low b cl ratios of the saline tiberias hot spring suggest dilution of deepseated trapped cacl2 brines with a 11b 44 which is consistent with previous interpretations based on na cl 0 58 and 18o 3 values the 11b values of the springs in hammat gader decrease gradually from 11b of 41 9 to 20 9 with increasing salinity 70 to 497 mgcl l 1 temperature 25 50 c and boron content 0 1 0 3 mg l 1 the 11b values suggest that boron is derived from leaching of calcium carbonate or desorption of clay minerals of a 11b 14 and mixing with meteoric water of a high 11b value the relatively low 11b values of two low salinity springs 1240 and 2700 mgcl l 1 along the sea of galilee 11b 31 6 and 31 8 and the lake itself 24 suggest that a significant fraction of boron in these waters is also derived from rock leaching the influence of boron that is leached from the rocks is limited and can be recognized mainly in boron depleted groundwater the variations of 11b na cl and 18o parameters in the hammat gader springs demonstrate the sensitivity of each element to different sources whereas oxygen isotope compositions reflect the meteoric source the major ions e g na cl and br cl ratios record the influence of the deep seated brines and boron isotopes in diluted groundwater are sensitive to water rock interaction

hydrochemical assessment of the rochefort marsh role of surface and groundwater in the hydrological functioning of the wetland abstract the interaction between a wetland the rochefort agricultural marsh and its underlying aquifers was studied using both geochemical and isotopic approaches water from the various components of the hydrosystem water from ditches shallow bri groundwater silty clay deposits deep bri groundwater and groundwater in the kimmeridgian aquifer confined and unconfined was sampled and analysed for major and trace elements sr br stable water isotopes 18 o and 2 h and sr isotopes the salinity of groundwater in the marsh cl up to 15 5 g l can be attributed to seawater trapped in the clay sediments during the flandrian 12 000 6400 bp the groundwater has since undergone more or less major chemical evolution due to water rock interactions and mixing with fresh water rainwater ditch water and kimmeridgian groundwater from the edge of the marsh the chemical characteristics of the groundwater in the confined kimmeridgian underlying the bri formation exclude the possibility of a salt wedge the combined use of 18 o 2 h cl br and sr contents and 87 sr 86 sr ratios enabled exchanges between surface water in marsh canals and ditches and groundwater in the shallow bri aquifer 7 m and in the confined kimmeridgian 18 m aquifers to be defined and quantified during the summer the ditches recharge the shallow bri aquifer by sub irrigation gravity flow by up to 26 the presence of a very compact layer of clay 1 2 m deep prevents the rapid recharge of the deep bri aquifer by rainfall and direct hydraulic connections between the ditches and the deep bri aquifer on the scale of the marsh the confined kimmeridgian groundwater recharges the bri aquifer by upward flow maximum contribution estimated to be 76 13 this flow being relatively limited and preferentially on the edge of the marsh the deep bri groundwater contributes very locally to recharging the confined kimmeridgian aquifer maximum contribution estimated to be 61 36 this study demonstrates the interest in combining hydrological and geochemical tools in order to identify and quantify the hydraulic interconnections between a wetland and its groundwater components a prior understanding of how wetlands function is crucial for the sustainable management of such ecosystems

salt marsh foraminifera from the great marshes massachusetts environmental controls abstract by using sites in the great marshes at barnstable massachusetts usa this study examines the effects of a set of environmental parameters on the foraminiferal distribution the studied parameters are elevation above mean high water salinity of the porewater various sediment characteristics vegetation and food source relations between the environmental parameters and foraminiferal properties frequencies densities and diversities are quantified with correlation coefficients for the first time siphotrochammina lobata and balticammina pseudomacrescens are documented in the new england region the following species show a significant correlation with one or more of the studied parameters and are designated as key species haplophragmoides manilaensis jadammina macrescens balticammina pseudomacrescens miliammina fusca and tiphotrocha comprimata based on cluster analysis and the presence absence or dominance of the key species characteristic associations are distinguished the distribution of three associations is indicative of specific marsh environments the marsh fringe the middle marsh and the marsh edge these three marsh units are separated by their own salinity regime flooding and sediment characteristics the marsh fringe is typified by the h manilaensis association and experiences freshwater input seepage surface runoff and rainwater and only slight marine influence resulting in low salinity values 2 5 20 the width of the marsh fringe is variable dependent on the amount of seepage which in turn is controlled by the permeability of the basement and the peat the j macrescens association characterizes the middle marsh where salinities are controlled by infiltration of sea and rainwater and by evaporation salinity values are higher than 20 while temporarily salinity can reach extreme high values during periods without flooding and high evaporation rates e g 44 the fully marine m fusca association occupies the daily flooded marsh edge where the salinities have the same values as cape cod bay water ca 28 unlike many other salt marshes the distribution of foraminiferal assemblages in the great marshes does not show a vertical zonation with respect to mean high water this shows that a worldwide applicable model for paleoenvironmental studies in salt marshes based on foraminifera is not feasible each salt marsh has its own characteristics regional factors such as climate play an important role in the salinity regime while the local upland characteristics determine if seepage takes place thus each marsh has its own foraminiferal fingerprint showing the opportunistic behaviour of the salt marsh agglutinants a surface study is an indispensable first step in assessing the value of foraminifera as paleo ecological indicators

a sea level rise curve from guilford connecticut usa abstract high resolution stratigraphic studies based on sediment chemistry lithology macroflora and benthic foraminiferal assemblages in three peat cores from coastal salt marshes at guilford connecticut show that coastal marshes are ephemeral environments marsh wide environmental variations were common and century long episodes of relative submergence alternated with emergence despite about 2 m of relative sea level rise rslr in connecticut over the last 1500 years the marshes have expanded both landwards and seawards and marsh accretion has been outpaced only marginally by rslr we used radiocarbon dating and the level of anthropogenic markers metal pollution as dated with 210 pb in the cores for age control for most of the last 1000 years the rate of rslr was between 1 3 and 1 8 mm yr but over the last 300 400 years it increased to 2 9 3 3 mm yr and has been faster than the accretion rate especially in the middle marsh the net submergence rate or submergence index ratio of the rate of rslr and marsh accretion rate averaged about 1 15 over the last 1000 years and increased to about 1 5 over the last 200 years the rate of rslr was very sluggish during the early part of the little ice age but we found a slightly higher rate during the little climate optimum this excursion is close to the noise level however the most significant observation is that rslr increased strongly around a d 1650 the onset of this acceleration falls in the middle to end of the little ice age and thus preceded the period of modern global warming that started late last century and that has been tentatively correlated with anthropogenic emissions of greenhouse gases

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

the boron isotope geochemistry of smectites from sodium magnesium and calcium bentonite deposits abstract the mineralogical chemical and isotopic analyses of smectites with variable interlayer cation occupancies from bentonite deposits in various depositional environments reveal new insights into the boron sources and the fluids involved in bentonitization in marine and non marine environments smectites from bentonites have non exchangeable structural boron concentrations of 0 2 to 196 g g b smectites from sodium bentonites have higher boron concentrations 30 g g than those from magnesium or calcium bentonites most smectites have a small interstratified illitic component that has a major influence on boron concentrations requiring the use of modified fluid mineral boron partitioning coefficients which indicate that bentonites formed from fluids of highly variable boron concentrations of 100 mg l b and a chlorine content of 76 4 mg l to 59 076 mg l the sodium bentonites formed from boron rich saline fluids or brines whereas the fluids involved in calcium and magnesium bentonite formation have a more variable boron composition and salinity the 11b values of the structural boron in tetrahedral sites of smectites range from 30 1 to 12 2 the smectites from terrestrial depositional settings have 11b values of 30 1 to about 0 whereas smectites from marine depositional settings have negative as well as positive 11b values the boron isotope values indicate that all examined bentonites from terrestrial depositional settings as well as many bentonites from marine depositional settings formed from basinal fluids or brines the boron isotope geochemistry of smectites is demonstrated to be a tool for elucidating the fluids involved in the formation of clay mineral deposits it also has great potential for tracing fluids in other settings involving authigenic clay minerals such as sedimentary basins and surficial crystalline rocks as well as man made applications such as in disposal sites for highly active nuclear waste

boron isotope systematics of marine sediments abstract boron contents and boron isotopic compositions were determined for modern and ancient permian to miocene marine sediments including pelagic clay calcareous ooze siliceous ooze and neritic clay sediments 11b values of modern marine sediments range from 6 6 to 4 8 isotopic variation is controlled by the simple mixing of four major constituents detritus of continental origin marine smectite biogenic carbonates and biogenic silica detritus of continental origin with an average 11b value of 13 to 8 is the low 11b end member constituent of marine sediments and its boron is largely controlled by the concentration of illite which originates from wind or fluvial transport marine smectite biogenic carbonate and biogenic silica on the other hand represent the high 11b end members with 11b values of 2 3 to 9 2 8 0 to 26 2 and 2 1 to 4 5 respectively these high 11b values are the result of the equilibrium uptake of boron from seawater spatial variations in boron isotopes in the pacific sediments are essentially due to the distribution of the above four constituents although ancient argillaceous sediments shale and slate have boron contents that are identical with those of modern equivalents boron contents of limestone and chert are distinctly lower than those of modern calcareous and siliceous oozes ancient marine sediments have systematically lower 11b values 17 0 to 5 6 than those of the modern sediments the lower 11b values can be caused by diagenesis which induces 1 preferential removal of high 11b boron in calcium carbonate and silica during recrystallization and 2 boron isotopic exchange in the course of the smectite illite transition the observed boron isotopic compositions of ancient argillaceous sediments are distinctly different from those of fresh and altered morb therefore boron isotope systematics will be useful in identifying components from the descending oceanic slab involved in the formation of island arc magma and in investigating mantle crust recycling through subduction processes

composition and origin of clay minerals in holocene sediments from the south eastern north sea the distribution of clay minerals varies systematically in sediments from holocene core material taken along a profile from the east frisian coast to the doggerbank the proportion of illite increases with distance from the coast at the expense of kaolinite whereas slight variations are seen in smectite and chlorite abundances the chemical composition changes and the k rb ratio and k ar isotopic age of illite increase seawards this trend results from progressive mixing processes of riverine detritus with pleistocene fluvioglacial material reworked during the holocene transgression however the clay fluvial flux only became dominant during the decreasing rate of sea level rise in the late holocene especially near the shore for example modern sediments in tidal flats contain 75 of river borne holocene supplied clay detritus whereas this amount is only 10 in modern marine sediments at the doggerbank

geochemical and isotopic evidences for a severe anthropogenic boron contamination a case study from castelluccio arezzo central italy abstract in 2009 a deterioration of garden plants watered with domestic wells was related to high boron concentrations up to 57 mg l measured in the shallow aquifer from the industrial area of castelluccio tuscany italy where several factories are or were using boron compounds for their industrial processes since 2012 a geochemical and isotopic survey of stream ground and waste waters and sediment samples was performed in addition monthly geochemical surveys were carried out from january to september 2013 during which concentrations of boron up to 139 mg l were measured the geochemical dataset also included raw borax and sodium boron hydride and anthropogenic materials b rich slags and muds stored in one of the local factories the latter being to the best of our knowledge analyzed for the first time in this work for bulk and leachate boron concentration and isotopic ratios the results highlighted that the high concentrations of boron found in the local shallow aquifer had unequivocally an anthropogenic source it was suggested that prolonged interaction between industrial presently stored at ground level or buried by products and waste and meteoric waters was likely the main process responsible of the groundwater contamination as supported by the analysis of the major solutes the dispersion of the contaminant could not clearly be observed downward the shallow hydrogeological circuit consequently the presence of other sources of boron in the industrial area of castelluccio cannot be excluded this would also explain the reason why no univocal results were obtained by the 11 b 10 b isotopic ratios measured in water sediment and bulk and leachate anthropogenic samples to minimize the boron contamination a hydraulic barrier should be constructed where the highest concentrations of boron were measured

geochemical and boron oxygen and hydrogen isotopic constraints on the origin of salinity in groundwaters from the crystalline basement of the alpine foreland abstract the b isotopic composition in combination with o and h isotopes and hydrochemical tracers is utilized to constrain the evolution of basement hosted groundwaters via water rock interactions and fluid infiltration from external sedimentary reservoirs two distinct groundwater types have been identified in the central european crystalline basement n switzerland sw germany 1 fresh groundwaters characterized by low values of 11b 3 5 to 0 6 18o 12 0 to 10 0 and d 86 8 to 71 9 and 2 brackish groundwaters with distinctly heavier b o and h isotopic compositions 11b 6 4 to 17 6 18o 9 4 to 5 6 d 67 6 to 60 8 fresh groundwaters show a systematic decrease in 11b related to an increase in b concentrations and degree of total mineralization along the pathway of groundwater migration which can only be interpreted in terms of leaching of crystalline host rocks a 11b value of 3 3 is inferred for the crustal b source mainly hercynian granites involved in the leaching process in agreement with the known 11b range of granitic rocks the evolution of brackish groundwaters derived from crystalline basement reservoirs with little water circulation is more complex as indicated by b o h stable isotope and hydrochemical e g b cl na cl and br cl constraints brackish groundwaters from the study area are influenced by admixture of sediment derived fluids which infiltrated from late paleozoic permo carboniferous and early mesozoic lower triassic sedimentary strata the data presented show that b isotopes are sensitive to mixing processes of fluids derived from different crustal reservoirs and hence may be utilized as a tracer for constraining the internal autochthonous vs external allochthonous origin of salinity in basement hosted groundwaters

boron isotope geochemistry of australian salt lakes boron isotope geochemistry has been investigated in brines groundwaters and sediments from the modern australian salt lakes of victoria south australia and western australia by applying negative thermal ionization mass spectrometry techniques the geochemical history of the brines has been reconstructed by using 11b bcl and nacl ratios the victorian volcanic crater lakes of southeastern australia have water salinities of up to 60 g l molar nacl ratios 0 87 similar to the marine ratio molar bcl ratios of 2 9 10 4 to 4 9 10 4 and 11b values of 54 to 59 relative to nbs 951 the depletion of total b and the high positive 11b values relative to seawater bclratio 7 9 10 4 11b 39 are attributed to a marine cyclic salt origin together with adsorption processes in closed systems with low water sediment wr ratios in contrast salt lakes from south australia and western australia which are large shallow playas associated with halite gypsum and detrital clay minerals have interstitial and surface brines characterized by salinities of 80 to 280 g l molar nacl ratios of 0 85 to 1 molar bcl ratios of 4 10 6 to 4 10 4 and 11 values of 25 to 48 the 11 values of these brines are different from those of groundwaters from the great artesian basin 11 15 9 to 2 2 with high molar bcl ratios of 1 10 3 to 3 8 10 2 country rocks 11b 8 7 to 6 8 and modern detrital sediments present in these salt lakes 11b 3 2 to 12 3 the 11b values of these salt lakes overlap with those of surface and brackish waters 11b 28 to 35 and with the b isotopic composition of seawater 11b 39 both low molar nacl ratios 39 of some brines indicate interaction of the brines with detrital sediments within the salt lake systems 11 values 39 suggest mixing of brines of marine origin from which b was partly removed by adsorption with waters of terrestrial origin with low 11 values nacl ratios are used as indicators of the origin of the salts as well as of halite dissolution precipitation the 11 values and bcl ratios are sensitive to a marine or non marine origin adsorption of boron onto clays and the effective water sediment ratio at low wr ratios the preferential removal of 10b from the solution affects the bulk solution whereas at high wr ratios the 11 value of a solution is not affected by adsorption although the 11 value of borate minerals may be a discriminant of marine or non marine origin boron isotopes are less distinctive in evaporative environments where boron is not an abundant component and where water sediment interaction occurs

groundwater origins and mixing pattern in the multilayer aquifer system of the gafsa south mining district a chemical and isotopic approach major ion geochemistry and environmental isotopes were used to identify the origins and the mineralisation processes of groundwater flowing within the three aquifer levels of the multilayer system of the gafsa south mining district southwestern tunisia it has been demonstrated that groundwaters are characterised by a ca mg so4 water type geochemical pattern is mainly controlled by the dissolution of halite gypsum and or anhydrite as well as by the incongruent dissolution of dolomite 18o and 2h values are much lower than the isotopic signature of regional precipitation and fall close to the meteoric water lines indicating that groundwaters have not been significantly affected by evaporation or mineral water reactions the distribution of stable and radiogenic isotopes 18o 2h 13c and 14c within the aquifer levels suggests that the deep confined aquifer receives a significant modern recharge at higher altitudes while the shallow unconfined aquifer has been mainly recharged under cooler paleoclimatic condition likely during late pleistocene and early holocene humid periods however waters from the intermediate confined unconfined aquifer have composite isotopic signatures highlighting that they are derived from a mixture of the two first end members

understanding groundwater systems and their functioning through the study of stable water isotopes in a hard rock aquifer maheshwaram watershed india summary groundwater degradation through abstraction contamination etc shows a world wide increase and has been of growing concern for the past decades in this light the stable isotopes of the water molecule 18 o and 2 h from a hard rock aquifer in the maheshwaram watershed andhra pradesh india were studied this small watershed 53 km 2 underlain by granite is endorheic and representative of agricultural land use in india with more than 700 bore wells in use in such a watershed the effect of overpumping can be severe and the environmental effects of water abstraction and contamination are of vital importance a detailed and dynamic understanding of groundwater sources and flow paths in this watershed thus is a major issue for both researchers and water managers especially with regards to water quality as well as the delimitation of resources and long term sustainability to this end the input from monsoon precipitation was monitored over two cycles as well as measuring spatial and temporal variations in 18 o and 2 h in the groundwater and in precipitation individual recharge from the two monsoon periods was identified leading to identification of periods during which evaporation affects groundwater quality through a higher concentration of salts and stable isotopes in the return flow such evaporation is further affected by land use rice paddies having the strongest evapotranspiration

using foraminiferal transfer functions to produce high resolution sea level records from salt marsh deposits maine usa quantitative analyses of foraminiferal distributions along the coast of maine are used to provide transfer functions for reconstruction of sea level changes from fossil foraminiferal assemblages the indicative meaning of fossil assemblages is most accurately predicted by a training set that incorporates live and dead foraminifera and that uses flooding duration not height as the predictor variable sea level records are produced for two sites in maine usa a middle marsh site in scarboro and a high marsh site in machiasport these records offer temporal resolution of five to seven years and span the past century they are compared with instrumental data from a nearby tidal station to assess their accuracy strong correlations are found between the geologic records and the observational data in particular between the foraminiferal record from machiasport and the tide gauge record from eastport r2 0 83 p 0 005 thus a foraminifera based transfer function approach offers great potential for reso