on the hydrography of puyuhuapi channel chilean patagonia abstract this work describes the hydrographic conditions found in puyuhuapi channel northern chilean patagonia during recent years on a seasonal scale puyuhuapi channel was once a glacial valley but the retreating ice allowed the inflow of marine waters five surveys were conducted between 2008 and 2012 historical data from 1995 to 2007 were included a meteorological oceanographic buoy was also installed in the northern section of puyuhuapi channel and was operational beginning on april 12th 2011 puyuhuapi channel s surface characteristics highlight a fresher northern part and a more haline southern part except during winter when the pattern can reverse due to the intrusion of oceanic water via jacaf channel the channel exhibits a highly variable meridional and seasonal vertical stratification especially in its northern part where during spring and summer the water column is highly stratified but partially mixed during winter puyuhuapi channel is the only fjord channel with severe hypoxic conditions in all of chilean patagonia

fluid inclusions in the stripa granite and their possible influence on the groundwater chemistry fluid inclusions in quartz and calcite of the proterozoic stripa granite central sweden demonstrate that the rock and its fracture fillings have a complex evolutionary history the majority of inclusions indicate formation during a hydrothermal stage following emplacement of the stripa pluton total salinities of quartz inclusions range from 0 18 eq wt nacl for unfractured rock and from 0 10 eq wt for fractured rock vein calcites contain up to 25 eq wt nacl but the inclusion size is larger and the population density is lower homogenization temperatures are 100 150 c for unfractured rock and 100 250 for fractured rock pressure corrections assuming immediate post emplacement conditions of 2 kbar give temperatures about 160 c higher measurements of fluid inclusion population densities in quartz range from about 108 inclusions cm3 in grain quartz to 109 inclusions cm3 in vein quartz residual porosity from inclusion densities has been estimated to be at least 1 which is two orders of magnitude greater than the flow porosity breakage and leaching of fluid inclusions is proposed as an hypothesis for the origin of major solutes na ca cl in the groundwater evidence for the hypothesis is based on 1 mass balance only a small fraction of the inclusions need to leak to account for salt concentrations in the groundwater 2 chemical signatures brcl ratios of fluid inclusion leachates 0 0101 match those ratios for the deep groundwaters 0 0107 3 leakage mechanisms micro stresses from isostatic rebound or mining activities acting on irregular shaped inclusions could cause breakage and provide connection with the flow porosity and 4 experimental studies water forced through low permeability granites leach significant quantities of salt this hypothesis is consistent with the available data although alternate hypotheses cannot be excluded

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

rare earth element concentrations and nd isotopes in the southeast pacific ocean 1 three vertical profiles of rare earth element concentrations and nd isotopic compositions have been measured in the remote southeast pacific ocean the three stations represent contrasting environments the oligotrophic center of the gyre station gyr the transition zone east of the south tropical front station egy and the peru chile upwelling marked by a pronounced oxygen minimum station upx rare earth concentrations display nutrient like vertical profiles except at upx where surface waters are enriched at this station nd isotopic compositions are clearly more radiogenic than in the open ocean suggesting that boundary exchange process is releasing lithogenic rare earth element from the volcanic andes unexpected radiogenic values end reaching 3 7 are also observed at 2000 m at station gyr in the upper circumpolar deep water that commonly have end values around 6 exchange processes related to hydrothermal activity are suspected to produce this increase in end in the vicinity of the east pacific rise these results provide some guidance for higher resolution studies planned in this region by the international geotraces program

chemical multi isotopic li b sr u h o and thermal characterization of triassic formation waters from the paris basin this work reports chemical and isotope data and temperature estimates for seven water samples collected from triassic formations in the paris basin in france four samples were collected in the central part of the basin saline waters and three were collected at the edge of the basin near the recharge zone dilute waters the saline waters collected from the chaunoy and champotran boreholes have high salinities around 120 g l and very similar chemical and isotopic compositions the saline water sample from the la torche borehole has much higher salinity 168 g l and significantly different isotope characteristics the chemical geothermometers applied to these fluids from the centre of the basin give temperature values ranging between 80 and 100 c the fresh water samples collected at the edge of the basin have very different chemical and isotopic compositions these dilute water samples santenay and ch teauroux are shallow with colder temperatures of around 45 to 50 c the study of uranium activity ratios for these triassic formation waters allows us as a first approximation to estimate a mean apparent fluid circulation velocity of around 0 2 m yr which corresponds to a mean age slightly higher than 1 my for waters sampled in the chaunoy champotran and la torche fields in the centre of the basin the multi isotope characterization of triassic formation waters shows that our data are in agreement with literature values as concerns traditional isotope systematics delta18o deltad 87sr 86sr li and b isotope signatures in the centre of the paris basin are in a good agreement with a fluid signature derived mainly from water rock interactions involving clastic rocks with water essentially resulting from a seawater derived brine endmember diluted by meteoric waters the data reported in the present work for li and b isotopes could be used as a reference for future studies to characterize sandstone formation waters

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

characteristics and formation of eastern south pacific intermediate water 1 newly gathered hydrographic data from the eastern south pacific is combined with other high quality data mainly woce to reassess the properties and boundaries of the eastern south pacific intermediate water espiw to date the espiw has been only poorly described the espiw core is found off central and northern chile between the coast and 90 w and 20 38 s located at 50 400 m of depth its temperature varies between 11 13 c salinity ranges from 34 1 34 3 and its sigma t lies between 25 75 26 25 kgm 3 espiw spreads with the subtropical gyre circulation and can be traced to at least 150 w formed through the process of subduction southeastward of the wind driven gyre circulation the espiw communicates surface properties of the waters off central chile to tropical latitudes

the fault ruptures of the 1976 tangshan earthquake sequence inferred from coseismic crustal deformation the tangshan china earthquake with magnitude ms 7 8 occurred on 28 july 1976 two large aftershocks called the luanxian and ningho earthquakes followed within a few months the three major events and other small aftershocks make up the complete tangshan earthquake sequence trilateration measurements and precise levelings were made in the tangshan area before and after these shocks in this study the coseismic surface deformation of the tangshan area is modeled by the finite element method to infer the fault geometries and slip distributions of the sequence results show that most of the crustal deformation of the tangshan area was associated with right lateral slip on a nne striking mainshock fault rupture plane together with the ruptures of the two major aftershocks the fault associated with the mainshock rupture can be divided into southern and northern subfaults with different strikes dips and rakes and inhomogeneous slip distributions the rupture processes are reconstructed here by the complement of source time functions determined by teleseismic waveform modeling the luanxian earthquake was associated with pure normal faulting on a plane dipping 53 n while the ningho earthquake was associated with a left lateral strike slip faulting with a small normal component the focal mechanisms of the tangshan earthquake sequence are consistent with regional tectonics that is extensive right lateral strike slip fault movement in a nne direction and associated ne sw directed compression the rupture lengths are 48 km for the mainshock 18 km for the luanxian earthquake and 20 km for the ningho earthquake the averaged stress drops are 45 5 5 bar for the mainshock 34 3 2 bar for the luanxian earthquake and 15 1 9 bar for the ningho earthquake the high stress drop of the tangshan earthquake as compared with other intraplate earthquakes can be correlated to its long return period inferred from chinese historical earthquake catalogs

the use of 36cl and chloride bromide ratios in discerning salinity sources and fluid mixing patterns a case study at saratoga springs abstract the well known saratoga springs of new york state are low temperature 10 19 c mildly acidic highly carbonated mineral springs which discharge along the many normal faults in the saratoga mcgregor fault system of eastern north america fifteen saline and moderately saline fluids collected from the saratoga springs system and its surroundings were measured for 36 cl cl ratios chloride concentrations and cl br ratios to determine the sources of salinity fluid mixing patterns and history of these waters the springs have total chloride concentrations between 300 and 6500 mg l far in excess of local freshwater and cl br ratios typically in the range of 100 140 36 cl cl ratios for these waters range from 3 22 10 15 markedly below both the modern rainwater 36 cl cl ratio of above 1500 10 15 and the expected pre nuclear rainwater 36 cl cl ratio for the region of 400 10 15 indicating that cl and 36 cl in these springs are primarily derived from subsurface non meteoric sources 36 cl concentrations and cl br ratios can be effectively used to eliminate the possibility of magmatic ancient marine porefluid and evaporite contributions to the springs 36 cl production rates and secular equilibrium 36 cl cl ratios were derived for different subsurface lithologies in the region based on estimated subsurface neutron fluxes for different rock types a comparison of 36 cl cl ratios and cl br ratios in the saratoga springs with secular equilibrium 36 cl cl ratios and with cl br ratios in potential host formations indicates water rock interactions in the subsurface to be the main source of 36 cl to the springs especially from the ordovician carbonates which make up the aquifer and the underlying cambrian clastic rocks the more dilute springs appear to be a mix of saline springs and a meteoric component probably due to the addition of rainwater as the springs rose to the surface along the fault zone the use of chloride bromide ratios was found to be an effective way to support and clarify the information yielded by 36 cl cl ratios and chloride concentrations in the study of brine history

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

hydrothermal water rock interaction and the redistribution of li b and cl in the taupo volcanic zone new zealand abstract lithium b and cl occur as trace elements in the dominant protoliths rhyolite andesite and greywacke underlying high temperature hydrothermal systems in the taupo volcanic zone tvz the fluid mobility of li decreases substantially at 200 c 20 c with the pervasive deposition of quartz chlorite regardless of protolith and altering fluid compositions boron and cl are more fluid mobile than li at all temperatures with mobility affected by the rock type composition of circulating aqueous solutions and to a limited extent by incorporation of the trace elements in hydrothermal minerals uptake of b by clays decreases its mobility at 320 c occur compared to volcanic rocks the mobility of b and cl in greywackes is very low and thus the b cl signature of greywacke in hydrothermal aqueous solutions of the tvz is overwhelmed by the effects of rhyolite and andesite dissolution temperature dependent transitions from mg fe clays and phyllosilicates to k bearing illitic clays tend to decrease the mg li ratios in aqueous solutions at 200 c

fluid transfers at a basement cover interface part ii large scale introduction of chlorine into the basement by mesozoic basinal brines significant fracture and porosity sealing characterizes the sedimentary cover basement interface in the northwestern margin of the aquitaine basin france dolomite and calcite and sometimes fluorite barite and quartz constitute most of the fracture fillings they contain primary inclusions of brines having chlorinities in the range of 3 3 to 5 5 mol cl kg solution with total homogenization temperatures in between 65 and 130 c for quartz and slightly lower for dolomite barite fluorite and calcite crush leach analyses indicate that brines are characterized by na k ratios of 5 to 40 na li ratios of 20 to 530 and cl br ratios of 200 to 1000 which are rather typical of deep basinal brines the fluid 18o signature is estimated to be 6 6 1 8 smow for a crystallization temperature of 100 20 c between 80 and 120 c and the d value is 30 10 smow the fluid source for the fracture filling mineral is interpreted as a deep sedimentary brine expelled during a period of maximum subsidence in the aquitaine basin which migrated along the sediment cover basement interface which is characterized by high permeabilities below the toarcian shales the sealing is likely to be linked to the mixing of the brines with dilute ascending hot waters these dilute waters infiltrated from emerged zones convected and heated at depth reaching temperatures of 100 c up to 150 c on the basis of cation geothermometry extensional activity of probable cretaceous age related to the gascogne gulf rifting could be considered as the most likely cause of a significant fluid migration event at the basement cover interface all along the margins of the french massif central these processes are large scale as shown by the similarities of mineral sequences fluid types and general features of most of the f ba pb zn deposits located at the basement sedimentary cover interface the mass transfer of cl linked to this stage is significant and accounts for the early introduction of large amounts of chlorine in the granitoid microporosity this probably explains the significant chlorine concentrations of the present day fluids recovered in the granitoid aquifer

double diffusive layering and mixing in patagonian fjords abstract double diffusive layering was quantified for the first time in the chilean patagonian fjords region 41 5 56 s approximately 600 temperature and salinity profiles collected during 1995 2012 were used to study water masses quantify diffusive layering and compute the vertical diffusivity of heat development of diffusive layering or simply layering was favored by relatively fresh cold waters overlying salty warm waters fresh waters are frequently derived from glacial melting that influences the fjord either directly or through rivers salty waters are associated with modified subantarctic msaaw and subantarctic water saaw double diffusive convection occurred as layering in 40 of the year round data and as salt fingering in 5 m 2 s 1 diffusive layering events presented a meridional gradient with less layering within the 41 47 s northern region relative to the southern region between 47 and 56 s layering occupied on average 27 and 56 of the water column in the northern and southern regions respectively thermohaline staircases were detected with microprofile measurements in martinez and baker channels 48 s showing homogeneous layers 2 4 m thick below the pycnocline 10 40 m also in this area increased vertical mixing coincided with the increased layering events high values of thorpe scale l t 7 m dissipation rate of tke e 10 5 10 3 w kg 1 and diapycnal eddy diffusivity k 10 6 10 3 m 2 s 1 were associated with diffusive layering implications of these results are that diffusive layering should be taken into account together with other mixing processes such as shear instabilities and wind driven flows in biological and geochemical studies

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

geochemistry and14c dating of groundwaters from jurassic aquifers of north aquitaine basin france twenty seven samples from a confined lower middle jurassic aquifer and an unconfined oxfordian aquifer of the north aquitaine basin france have been analysed for their major elements br 18o 2h 13c and14c contents hydrochemistry indicates 1 a dissolution of carbonate and anhydrite near the recharge zone and 2 a dilution of a saline water derived from a seawater halite mixing in the deeper part of the aquifer the mixing is also visible in a 18o vs cl diagram in which two different groups appear recent waters and old waters indicating a mixing process between fresh and saline groundwaters the composition of the saline water is likely to be 34 100 11 200 ppm in cl 70 20 ppm in br and more than 3 5 07 vs smow in18o 13c contents indicate 1 a c exchange with caco3 matrix for groundwaters near the recharge zone and 2 a participation of organic matter in the deep part of the aquifer residence times for waters near the area of the aquifer outcrop correspond to holocene and late pleistocene periods the depletion in stable isotopes of 10 to 15 000 y b p waters show a late glacial period infiltration to the aquifer after a distance of about 10 km in the aquifer the14c activities are 0 pmc showing the presence of old groundwaters

deep fluid circulation in fault zones massive fluid circulation in retrogressive ductile shear zones is a well established but poorly understood phenomenon in some cases surface derived fluids which must initially have been at hydrostatic pressures can be shown to have entered shear zones in which fluids would normally be expected to be at lithostatic pressure in these circumstances thermal convection is an unlikely driving force for fluid movement underthrusting of a surficial fluid reservoir beneath shear zones is a viable mechanism in some cases but not for metasomatic shear zones in the pyrenees where insufficient underthrusting has occurred seismic pumping provides an alternative mechanism to explain the paradox of fluid access into ductile shear zones a kinematic analysis of a hypothetical fault zone shows that stress and dilatancy cycles will be out of phase above and below the frictional quasiplastic transition if this effect is sufficiently large hydraulic gradients may force fluid downward across the transition immediately after earthquake rupture through highly permeable microcrack networks between earthquake cycles plastic creep in mylonites will overprint microcrack networks increase fluid pressure and promote slow upward movement of fluid at low permeability for smaller shear zones such as those in the pyrenees seismic pumping could occur down a shallow decollement with subsequent upward fluid flow through shear zones in the hanging wall of the decollement

chromophoric and fluorescent dissolved organic matter in and above the oxygen minimum zone off peru key points two amino acid like and three humic like fdom components were found in and above the oxygen minimum zone off the coast of peru the distribution of cdom and amino acid like fdom covaried with chl a suggesting phytoplankton as their major source presence of dom microbial reworking and dom release by anoxic sediment was illustrated by the distribution of humic like fdom as a result of nutrient upwelling the peruvian coastal system is one of the most productive regions in the ocean sluggish ventilation of intermediate waters characteristic for the eastern tropical south pacific etsp and microbial degradation of a high organic matter load promotes deoxygenation at depth dissolved organic matter dom plays a key role in microbial respiration and carbon cycling but little is known on dom distribution and cycling in the etsp dom optical properties give important insights on dom sources structure and biogeochemical reactivity here we present data and a conceptual view on distribution and cycling of chromophoric cdom and fluorescent fdom dom in and above the oxygen minimum zone omz off peru five fluorescent components were identified during parafac analysis highest intensities of cdom and of the amino acid like fluorescent component c3 occurred above the omz and coincided with maximum chl a concentrations suggesting phytoplankton productivity as major source high intensities of a marine humic like fluorescent component c1 observed in subsurface waters indicated in situ microbial reworking of dom fdom release from inner shelf sediment was determined by seawater analysis and continuous glider sensor measurement and included a humic like component c2 with a signature typical for terrestrially derived humic acids upwelling supplied humic like substances to the euphotic zone photo reactions were likely involved in the production of a humic like fluorescent component c5 our data show that variable biological and physical processes need to be considered for understanding dom cycling in a highly dynamic coastal upwelling system like the etsp off peru

palaeorecharge conditions of the deep aquifers of the northern aquitaine region france summary the study was carried out in the northern part of the aquitaine basin extending in southwest france the basin has been intensively exploited for various purposes for many years although the geological context is well known there are still some gaps in the knowledge about the hydrogeochemical regime groundwater average residence time and the palaeohydrological conditions prevailing during the recharge period which would help to secure sustainable exploitation of the resources environmental isotopes 18 o 2 h 3 h 13 c together with radiocarbon were used to evaluate hydrochemical evolution residence time and palaeorecharge conditions for jurassic cretaceous and eocene aquifers radiocarbon activity in the aquifers varies widely between 0 and 94 pmc after radiocarbon corrections the ages indicate both modern and old waters sometimes exceeding the limit for 14 c dating the fontes and garnier model is best adapted to the specificity of the carbonate system the content in stable isotopes of water is varying between 7 7 and 4 9 for 18 o and 52 3 to 29 6 for 2 h the wide ranges of stable isotopic values imply variable climatic conditions a group of isotopically depleted samples was detected indicating colder climatic conditions during the recharge radiocarbon ages calculation together with isotopic signature point out that the depletion in stable isotopic values fits the period between 20 and 15 ka b p and therefore indicate the last glacial maximum lgm according to the correction model the transition from pleistocene to holocene would occur between 15 and 12 ka b p palaeohydrological data from the northern aquitaine basin does not confirm a significant hiatus in the recharge history the recharge conditions in south europe seem to have occurred under discontinuous permafrost conditions as documented by many palaeoclimatological archives this is in favour of an uninterrupted recharge of the confined aquifers of northern aquitaine basin such information should be considered by modellers in their attempts to simulate the hydrogeological functioning of large confined aquifers on the very long time range

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

residence time indicators in groundwater the east midlands triassic sandstone aquifer the east midlands triassic sherwood sandstone aquifer which has been the subject of detailed radiometric age studies is used to investigate both inert and reactive constituents of groundwater as indicators of residence time detailed resampling of the aquifer in 1992 has provided a considerable body of new inorganic geochemistry data though without radiocarbon several inert indicators are defined including the isotopic ratios 18o 2h 36cl noble gas ratios as well as the halogen elements cl br f i and their element ratios these form a group of essentially unreactive tracers primarily reflecting changing rainfall inputs and palaeoclimatic conditions except at outcrop where human impacts are also seen clearly the concentrations of cl mainly from atmospheric sources remain below 25 mg l 1 cl over a distance of some 30 km from outcrop reactive indicators the result of time dependent water rock interactions include 13c mg ca sr ca na cl and show diagnostic trends along the flow lines however the concentrations of certain trace elements li rb cs mn and mo which are not limited by solubility constraints show linear trends along the present day flow gradient this water rock interaction is taking place in groundwaters with low total mineralisation and it can be demonstrated that reactions involving these elements and isotopes are occurring entirely within the aquifer since high salinity groundwaters are found below the sherwood sandstone there is good correlation between some of the elements and 14c activities in the 1977 data set and this has been used to derive a concentration age relationship for the 1992 set of data a chemical timescale for the aquifer is then established using a li and b a combination of five trace elements the age of the fresh groundwater is thus shown to be up to 100 ka bp indicating the likelihood of semi continuous recharge during the devensian glacial period preceding the glacial maximum when no recharge occurred 10 20 ka bp this approach may be of value in extending groundwater dating beyond the radiocarbon timescale as well as interpreting sites where no radiocarbon data are available the scatter from the mean age line indicates those groundwaters which are derived from either rapid or slower than average flow zones within the aquifer as well as age stratification this stratification is borne out by a depth profile of groundwater from a new borehole near to outcrop which is shown by a combination of chemical and isotopic tracers to contain holocene overlying late pleistocene water

distribution of siphonophores chaetognaths euphausiids and oceanographic conditions in the fjords and channels of southern chile abstract interior waters of the fjords and channels of southern chile 41 5 s 56 s receive inputs of subantarctic water equatorial subsuperficial water and western pacific subsurface water from the adjacent pacific ocean by means of numerous connecting channels that lead inward from the ocean margin these waters become mixed in the interior zone with freshwater from precipitation river flow and meltwater from cordilleran glaciers a two layered positive estuarine circulation becomes established with a superficial layer having a net movement towards the adjacent ocean and a deep layer with net movement towards the fjords the biomass of the interior waters is composed principally of planktonic crustaceans copepods and euphausiids chaetognaths and gelatinous carnivores in a southerly direction decreases are observed in biomass in relative abundance and in species diversity of siphonophores chaetognaths and euphausiids only a few species have been able to adapt successfully to the extreme oceanographic conditions typical of the region reflected in dominant monospecific populations such as muggiaea atlantica sagitta tasmanica and euphausia vallentini the zooplankton fauna of interior waters characterized by its low degree of specific richness is made up of a mixture of species typical of subantarctic water sagitta tasmanica s decipiens euphausia lucens nematoscelis megalops thysanoessa gregaria antarctic water pyrosthephos vanhoeffeni dimophyes arctica sagitta marri s gazellae eukrohnia hamata e bathyantarctica euphausia vallentini temperate and warm epipelagic waters eudoxoides spiralis lensia conoidea chelophyes appendiculata muggiaea atlantica sphaeronectes gracilis s fragilis abylopsis tetragona sagitta enflata and mesopelagic water physophora hydrostatica stylocheiron maximum vogtia pentacantha v serrata

the formation of a subsurface anticyclonic eddy in the peru chile undercurrent and its impact on the near coastal salinity oxygen and nutrient distributions the formation of a subsurface anticyclonic eddy in the peru chile undercurrent pcuc in january and february 2013 is investigated using a multi platform four dimensional observational approach research vessel multiple glider and mooring based measurements were conducted in the peruvian upwelling regime near 12 30 s the dataset consists of 10000 glider profiles and repeated vessel based hydrography and velocity transects it allows a detailed description of the eddy formation and its impact on the near coastal salinity oxygen and nutrient distributions in early january a strong pcuc with maximum poleward velocities of 0 25 m s at 100 to 200 m depth was observed starting on january 20 a subsurface anticyclonic eddy developed in the pcuc downstream of a topographic bend suggesting flow separation as the eddy formation mechanism the eddy core waters exhibited oxygen concentrations 1 mol kg an elevated nitrogen deficit of 17 mol l and potential vorticity close to zero which seemed to originate from the bottom boundary layer of the continental slope the eddy induced across shelf velocities resulted in an elevated exchange of water masses between the upper continental slope and the open ocean small scale salinity and oxygen structures were formed by along isopycnal stirring and indications of eddy driven oxygen ventilation of the upper oxygen minimum zone were observed it is concluded that mesoscale stirring of solutes and the offshore transport of eddy core properties could provide an important coastal open ocean exchange mechanism with potentially large implications for nutrient budgets and biogeochemical cycling in the oxygen minimum zone off peru

strontium isotopic variations in jurassic and cretaceous seawater a high resolution seawater strontium isotope curve has been generated through the analysis of well dated and well preserved belemnites and oysters from the middle and upper jurassic and the lower cretaceous of great britain analysis of fe and mn concentrations in these fossils has yielded criteria for eliminating samples that are diagenetically altered the strontium isotope curve remains relatively flat through the aalenian and early bajocian rapidly descends through the late bajocian and bathonian and reaches a minimum in the callovian and oxfordian it then begins a rapid increase in the kimmeridgian and portlandian that continues through much of the early cretaceous the curve levels off in the barremian suddenly dips downwards in the aptian and recovers gradually through the albian the strontium isotopic variations are sufficiently large and the data are presented with sufficient stratigraphic detail to allow precise correlation to the classic ammonite zones and lithologic sections of great britain using the techniques of strontium isotope stratigraphy model results indicate that much of the variation in seawater 87sr86sr between 120 and 40 ma can be explained by changing the intensity of mid ocean ridge hydrothermal fluxes proportionally to estimated mid ocean ridge crustal generation rates it is also possible that the variations during the rest of the mesozoic and the permian are primarily reflections of changing hydrothermal inputs the model results have several important implications first they provide an example in which the variations in the strontium isotope curve are not necessarily driven by changes in fluvial inputs second they suggest that from at least the aptian through the eocene variations in continental weathering were minimal this heightens the importance of the rapid rise in seawater 87sr86sr beginning 40 ma as a significant transition to an extended period of increasing fluvial 87sr fluxes continuing to the present finally the results suggest that several documented short term excursions towards lower 87sr86sr in the latest triassic pliensbachian toarcian callovian oxfordian aptian albian and cenomanian turonian are interpretable as pulses of seafloor hydrothermal activity if so the strontium isotope record offers a means of constraining the timing duration and magnitude of known or proposed hydrothermal events in the geological record

hydrography of the eastern south pacific ocean results from the sonne 102 cruise may june 1995 abstract full depth conductivity temperature depth hydrographic measurements were taken in may june 1995 along 28 15 35 15 and 43 15 s from the chilean coast to 86 88 w from the r v sonne sections of potential temperature salinity neutral density and oxygen are presented to illustrate the water column structure in this sparsely sampled region a more comprehensive database on all available hydrographic data from the region was compiled these data and available meteorological data are used to help in the interpretation of the sonne results a number of important features found in the sections are discussed including a shallow salinity minimum apparently ventilated from south of 37 s salt fingering as a possible mechanism to transport high salinity subtropical water into the shallow salinity minimum equatorial subsurface water subantarctic mode water and antarctic intermediate water geostrophic calculations of alongshore flow show the poleward peru chile undercurrent at each of the three sections with a poleward descending core and peak velocities of 10 cm s 1 as in earlier works a deep pacific outflow is found near the chilean coast part of a clockwise deep circulation in the chile basin

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

water masses in the humboldt current system properties distribution and the nitrate deficit as a chemical water mass tracer for equatorial subsurface water off chile abstract three sections are used to analyze the physical and chemical characteristics of the water masses in the eastern south pacific and their distributions oceanographic data were taken from the scorpio may june 1967 piquero may june 1969 and krill june 1974 cruises vertical sections of temperature salinity dissolved oxygen nitrate nitrite phosphate and silicate were used to analyze the water column structure five water masses were identified in the zone through t s diagrams subantarctic water subtropical water equatorial subsurface water antarctic intermediate water and pacific deep water their proportions in the sea water mixture are calculated using the mixing triangle method vertical sections were used to describe the geographical distributions of the water mass cores in the upper 1500 m several characteristic oceanographic features in the study area were analyzed the shallow salinity minimum displacement towards the equator the equatorial subsurface salinity maximum associated with a dissolved oxygen minimum zone and a high nutrient content displacement towards the south and the equatorward intermediate antarctic salinity minimum associated with a dissolved oxygen maximum the nitrate deficit generated in the denitrification area off peru and northern chile is proposed as a conservative chemical tracer for the equatorial subsurface waters off the coast of chile south of 25 s

elevated trace metal content of prokaryotic communities associated with marine oxygen deficient zones little is known about the trace metal content of marine prokaryotes in part due to their co occurrence with more abundant particulate phases in the upper ocean such as phytoplankton and biogenic detritus lithogenic minerals and authigenic mn and fe oxyhydroxides we attempt to isolate these biomass signals in particulate data from the us geotraces eastern pacific zonal transect cruise gp16 in the eastern tropical south pacific etsp which exhibited consistent maxima in p and other bioactive trace metals and minima in particulate mn in the oxygen deficient zones odzs of 13 stations nitrite maxima and nitrate deficits indicated the presence of denitrifying prokaryotic biomass within etsp odzs and deep secondary fluorescence maxima at the upper odz boundaries of 10 stations also suggested the presence of low light autotrophic communities odzs were observed as far west as 99 w more than 2300 km from the south american coast where eolian lithogenic and lateral resuspended sedimentary inputs were negligible presenting a unique opportunity to examine prokaryotic metal stoichiometries odz particulate p maxima can rival gyre mixed layer biomass concentrations are highly sensitive to oxygen and are in excess of amounts scavengable by local fe oxyhydroxides and acid volatile sulfides even after correction for lithogenic and ferruginous scavenged metals odz p maxima are often enriched in cd co cu ni v and zn exhibiting particulate trace metal ratios to p that exceed mixed layer biomass ratios by factors of 2 9 odz prokaryotic communities may be largely hidden tm rich pools involved in the marine cycles of these bioactive trace metals

geochemistry of bolivian salars lipez southern altiplano origin of solutes and brine evolution abstract the southern bolivian altiplano is a volcanic area which contains numerous undrained basins occupied by playas and saline lakes locally named salars solutes carried by springs and rivers into the salars originate mostly from the alteration of the volcanic rocks and the re solution of ancient buried evaporites both weathering and hydrothermal alteration lead to na hco 3 inflow waters of similar composition high contents of lithium and boron are not specifically related to hydrothermal activity evaporite leaching leads to na cl inflow waters of higher salinity atmospheric precipitation contributes only a small amount of ca and so 4 and very little na or cl the calculated evaporative evolution of the inflow waters shows that about half of them should become highly alkaline brines and the other half should end as near neutral brines however alkaline soda lakes are rare in this region most lake brines are of the na cl and na cl so 4 types to understand this anomaly one characteristic sequence of evaporating waters was studied in detail precipitation of calcite and mg smectites accounts only partially for the reduction of alkalinity a further loss of alkalinity is probably related to the oxidation of wind blown native sulfur in peripheral ponds wind blown sulfur is also deposited around the lakes on the drainage basins in the rainy season ephemeral streams carry along sulfur particles in permanent pools of the preconcentration areas a hydrologic control of brine chemistry is suspected inflow waters that should become alkaline appear to evolve to neutral brines if they remain in contact with atmospheric dust and peripheral colluvium for a long time on the contrary inflow waters to soda lakes are generally close to the shore and have only minimal contact with atmospheric dust and peripheral sediments presently all lakes are at relatively low levels and inflow waters often drain an important area of the drainage basin before reaching the topographic low in the past lakes were at higher levels and less interaction occurred between inflow waters atmospheric dust and peripheral sediments as a result the chemistry of some lakes may have changed during the quaternary

nitrogen biogeochemical cycling in the northwestern indian ocean abstract the vertical distribution and fine scale structure of nitrate no 3 nitrite no 2 nitrous oxide n 2 o phosphate po 4 oxygen o 2 and chlorophyll chl were determined in the north western indian ocean nwio along a meridional section 67 e from the equator to the gulf of oman using an autoanalyser for micromolar levels of nutrients and chemiluminescence and gas chromatographic methods for nanomolar levels of no 3 and no 2 and n 2 o respectively three biogeochimically contrasting regimes were investigated 1 the highly oligotrophic nutrient depleted subtropical gyre 2 the nonsoonal upwelling of nutrient rich intermediate waters of the southeastern arabian coast and 3 the denitrifying o 2 depleted zone odz ca 150 1200 m depth in the arabian sea concentrations of no 3 and no 2 were severely depleted in surface oligotrophic waters from the equator average 43 and 3 6 nm respectively to the subtropical gyre 12 15 n average 13 3 and 2 0 nm respectively with similar levels in the more stratified gulf of oman upwelling waters off southern arabia had three orders of magnitude higher no 3 levels and throughout the nwio the calculated no 3 fuelled primary production appeared to be regulated by no 3 concentration existing redfield o 2 no 3 regeneration ratios 9 1 previously derived for the deep indian ocean were confirmed 9 35 within the oxic upper layers of the nwio the no potential temperature relationship broecker 1974 earth and planetary science letters 23 100 107 needed for the derivation of expected no 3 and no 3 deficits within the denitrifying odz were refined using an isopycnal binary mixing model along the 26 6 density layer to take into account the inflowing contribution of no 3 depleted persian gulf water vertically integrated no 3 deficits increased northwards from 0 8 mol no 3 n m 2 at sta 2 04 n up to 6 49 mol no 3 n m 2 at sta 9 at the mouth of the gulf of oman then decreased to 4 10 moles no 3 n m 2 toward sta 11 near the straits of hormuz when averaged for the denitrification area of the arabian sea this corresponds to a deficit of 118 tg no 3 n adopting a recent freon 11 based estimate of water residence time of 10 years olson et al 1993 deep sea research ii 40 673 685 for the o 2 depleted layer we calculate an annual net denitrification flux of 11 9 tg n to the atmosphere or approximately 10 of the global water column denitrification rates supersaturated n 2 o concentrations were found in both surface oxic and upwelling waters up to 246 and peaked at the base of the odz up to 1264 in the northern arabian sea both nitrification in oxic waters and denitrification in hypoxic layers can be invoked as sources of n 2 o the inventory of excess n 2 o amounted to 2 55 1 3 tg n 2 o n corresponding to annual production of 0 26 0 13 tg from denitrification this is comparable to earlier law and owens 1990 nature 346 826 828 estimates of the ventilation flux of n 2 o 0 22 0 39 tg yr 1 from the upwelling region of the arabian sea the decadal response times for circulation deoxygenation denitrification and ventilation of the odz derived n 2 o and co 2 greenhouse gases and their monsoonal coupling implies the arabian sea is a sensitive oceanic recorder of global climate change

granite hydrothermal interaction a simultaneous estimation of the mineral dissolution rate based on the isotopic doping technique we propose an experimental evaluation of the simultaneous dissolution rate of k feldspar biotite and plagioclase during the interaction between a granite and a fluid artificially enriched in the less abundant strontium and potassium isotopes experiments were carried out at 453 k and 10 bars for a time of 6 months putting powered granite in contact with fluids spiked in 39k and 84sr and saturated with respect to kaolinite low temperature albite prehnite calcite adularia and quartz the evolution of the rb 39k sol vs 41k 39k sol and 87sr 86sr sol vs 84sr 86sr sol ratios allows us to identify a single rock end member from the first month of interaction this indicates that the dissolving mineral assemblage remains constant during the remaining 5 months of interaction associating the mass conservation law to the isotopic mixing equations for both sr and k we evaluate that the mass of dissolved plagioclase is 3 4 times higher the mass of dissolved biotite and 10 20 times higher the mass of dissolved sanidine the rate of potassium dissolution is estimated assuming that the 41k 39k sol ratio is continuously in equilibrium with the ratio in neogenic phases coupling the proportion of dissolved minerals to the overall rate of potassium dissolution and normalising to the mineral surface area we finally estimate that in our experimental conditions plagioclase and biotite dissolve with a rate of respectively 3 1 10 12 and 6 2 10 13 mol m 2 s 1 while the k feldspar dissolution rate is 4 2 10 13 mol m 2 s 1

the tangshan aftershock sequence aftershocks of the tangshan china earthquake sequence occurred on strike slip normal and thrust faults in an intensely faulted region the generally northeast trending aftershock zone outlines an area 150 km long and 30 km wide except for a northwest southeast trend of aftershocks which is about 60 km wide the main shock fault plane inferred from the locations of the aftershocks varies in strike from n30 e at the southern end to n50 e at the northeastern end with the change in strike occurring near the epicenter of the main shock fault plane solutions of the aftershocks indicate that strike slip faulting occurred along the tangshan fault and thrust faulting occurred on smaller transverse faults south and west of the tangshan fault although faulting during the main shock included right lateral strike slip and thrust movement perturbations to the prevailing stress field due to slip during the main shock and the configuration of existing faults encouraged normal faulting in the northeast part of the zone the largest aftershock occurred about 45 km northeast of the main shock and was associated with normal faulting at shallow depths two other large aftershocks both associated with large strike slip components occurred southwest of the main shock fault plane solutions and p wave and s wave forms of these two aftershocks indicate primarily left lateral motion along a northwest striking fault plane the aftershocks range in depth from near the surface to about 20 km fault plane solutions of 61 of the aftershocks indicate that the overall deformation consists of north south extension accommodated by both normal and strike slip faults such that some east west crustal shortening and possibly some crustal thinning took place

behaviour of boron and strontium isotopes in groundwater aquifer interactions in the cornia plain tuscany italy abstract the cornia plain alluvial aquifer in tuscany is exploited intensely to meet the demand for domestic irrigation and industrial water supplies the b concentration of groundwater however is often above the european limit of 1 mg l 1 with the result that exploitation of these water resources requires careful management boron and sr isotopes have been used as part of a study on the origin and distribution of b dissolved in groundwater and indirectly as a contribution to the development of appropriate water management strategies the geochemistry of the cornia plain groundwater changes from a hco3 facies in the inland areas to a cl facies along the coastal belt where seawater intrusion takes place the b concentration of groundwater increases towards the coastal areas while the 11b 10b ratio decreases this indicates that there is an increasing interaction between dissolved b and the sediments forming the aquifer matrix whose b content is in the order of 100 mg kg 1 adsorption desorption exchanges take place between water and the sediment fine fraction rich in clay minerals with a net release of b from the matrix into the groundwater and a consequent 11b shift from positive to negative values the aquifer matrix sediments therefore seem to be the major source of b dissolved in the groundwater the groundwater matrix interactions triggered by the ionic strength increase caused by seawater intrusion can also be detected in the ca na ion exchanges dissolved sr follows a trend similar to that of ca while the 87sr 86sr ratio is equal to that of the exchangeable sr of the aquifer matrix and therefore does not change significantly these results have helped to define a new strategy for groundwater exploitation with the final objective of reducing b concentration in the water extracted from the aquifer

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

origin of groundwater salinity current seawater vs saline deep water in a coastal karst aquifer based on sr and cl isotopes case study of the la clape massif southern france origin of groundwater salinity current seawater vs saline deep water in a coastal karst aquifer based on sr and cl isotopes case study of the la clape massif southern france a b s t r a c t in this study a typical coastal karst aquifer developed in lower cretaceous limestones on the western med iterranean seashore la clape massif southern france was investigated a combination of geochemical and isotopic approaches was used to investigate the origin of salinity in the aquifer water samples were collected between 2009 and 2011 three groundwater groups a b and c were identified based on the hydrogeological setting and on the cl a concentrations average and maximum cl a concentrations in the recharge waters were calculated cl ref and cl ref max to be 0 51 and 2 85 mmol l respectively group a includes spring waters with cl a concentrations that are within the same order of magnitude as the cl ref concentration group b includes groundwater with cl a concentrations that range between the cl ref and cl ref max concentrations group c includes brackish groundwater with cl a concentrations that are significantly greater than the cl ref max concentration overall the chemistry of the la clape groundwater evolves from dominantly ca hco 3 to nacl type on binary diagrams of the major ions vs cl most of the la clape waters plot along mixing lines the mixing end members include spring waters and a saline component current seawater or fossil saline water based on the br cl molar ratio the hypothesis of halite dissolution from triassic evaporites is rejected to explain the origin of salinity in the brackish groundwater groundwaters display 87 sr 86 sr ratios intermediate between those of the limestone aquifer matrix and current mediterranean seawater on a sr mixing diagram most of the la clape waters plot on a mixing line the end members include the la clape spring waters and saline waters which are similar to the deep geo thermal waters that were identified at the nearby balaruc site the 36 cl cl ratios of a few groundwater samples from group c are in agreement with the mixing hypothesis of local recharge water with deep saline water at secular equilibrium within a carbonate matrix finally phreeqc modelling was run based on cal cite dissolution in an open system prior to mixing with the balaruc type saline waters modelled data are consistent with the observed data that were obtained from the group c groundwater based on several trac ers i e concentrations and isotopic compositions of cl and sr calculated ratios of deep saline water in the mixture are coherent and range from 3 to 16 and 0 to 3 for groundwater of groups c and b respectively with regard to the la clape karst aquifer the extension of a lithospheric fault in the study area may favour the rise of deep saline water such rises occur at the nearby geothermal balaruc site along another lithospheric fault at the regional scale several coastal karst aquifers are located along the gulf of lion and occur in mezosoic limestones of similar ages the 87 sr 86 sr ratios of these aquifers tend toward values of 0 708557 which suggests a general mixing process of shallow karst waters with deep saline fossil waters the occurrence of these fossil saline waters may be related to the introduction of seawater during and after the flandrian transgression when the highly karstified massifs invaded by seawater formed islands and peninsulas along the mediterranean coast

trace element mobility and lithium isotope exchange during hydrothermal alteration of seafloor weathered basalt an experimental study at 350 c 500 bars abstract the relative mobility of trace incompatible elements and exchange of lithium isotopes during alteration of basalt previously altered by exposure to seawater at low temperatures seafloor weathered were experimentally determined at 350 c 500 bars these data are important as a means to test models calling for hydrothermal alteration of weathered basalt as a source of alkali elements for hot spring vent fluids at mid ocean ridges weathered basalt used for the experiment was characterized by high cs rb b k and li concentrations high cs rb and low k rb and ba rb ratios respectively relative to fresh basalt the basalt is enriched in 7li consistent with a history involving li uptake during seafloor weathering the experiment involved a na ca k cl fluid and flexible cell hydrothermal equipment which permitted periodic sampling of the fluid phase at experimental conditions the extraction efficiency of all trace incompatible elements was significant and ranged from 40 to 80 cesium rubidium lithium and boron were particularly mobile whereas ba sr and to a lesser degree k were taken up by alteration minerals early stage release of li was dominated by 7li most probably as a consequence of the dissolution of low temperature alteration phases in the weathered basalt that were rendered unstable at the elevated temperatures of the experiment subsequently however an increase in 6li in solution was observed owing to a combination of mineral dissolution from li bearing components in fresh basalt and isotopic equilibration effects owing to the mobility of li during hydrothermal alteration of weathered basalt it is unlikely that dissolution of weathered basalt components in subseafloor reaction zones 350 400 c could occur without noticeably affecting the lithium isotope composition of vent fluids as inferred previously from field studies thus the relatively high cs rb ratios of some vent fluids which were thought to be the result of hydrothermal alteration of weathered basalt may be caused by other effects such as partitioning of rb relative to cs into hydrothermal minerals at temperatures in excess of 400 c cs rb ratios in vent fluids from a wide range of pacific and atlantic ridge localities however reveal relatively large variations in space and time which suggest that a single process is unlikely to account for all of the data the relative mobility of trace alkali elements in weathered basalt not only constrains models of alkali element enrichment in hot spring vent fluids at mid ocean ridges but also provides data bearing on potential sources of alkali elements for arc magmas in subduction zones

modification of no po and no po during flow across the bering and chukchi shelves implications for use as arctic water mass tracers the no and po tracers 9 no3 o2 and 135 po4 o2 respectively and their derivative no po have found increasing use in arctic water mass analyses for identifying the specific basin or shelf areas from which surface waters originate based upon assumed differences in pacific and atlantic derived content and basin to basin differences within the arctic following shipboard sampling in june september 1993 and may june 1994 both north and south of bering strait we have found evidence that pacific derived waters flowing north to bering strait do not necessarily have any unique no po or no po identity that would permit unequivocal use as a water mass tracer in particular no po ratios in the bering sea continental shelf 150 m waters varied from 0 7 to 1 1 which encompasses ratios previously reported for arctic continental shelf and atlantic origin waters in the arctic ocean the highest no po ratios 1 in the bering sea were observed to the southwest of st lawrence island close to where high nutrient waters are first upwelled onto the shelf and seasonally early in the biological production cycle by contrast later in the summer north of bering strait at the depth of the arctic ocean nutrient maximum the highest concentrations of silica 60 m were associated with low no po ratios 0 7 apparent increases in the proportions of sea ice melt in these waters inferred from 18o and salinity regressions were associated with lower no po ratios this pattern the potential for sea air exchange and a significant relationship between decreases in nitrate phosphate ratios and both no po ratios and silica concentrations indicate that biological and physical processes north and south of bering strait affect the fidelity of these nutrient based tracers these results indicate the need for consideration of shelf based processes before no po ratios and other nutrient based tracers can be successfully applied as arctic circulation tracers

changes in the advection of antarctic intermediate water to the northern chilean coast during the last 970 kyr 1 the antarctic intermediate water aaiw is a key player in global scale oceanic overturning processes and an important conduit for heat fresh water and carbon transport the aaiw past variability is poorly understood mainly due to the lack of sedimentary archives at intermediate water depths we present records of benthic stable isotopes from sediments retrieved with the seafloor drill rig marum mebo at 956 m water depth off northern chile geob15016 27 29 48 s 71 07 58 w that extend back to 970 ka the sediments at this site are presently deposited at the boundary between aaiw and pacific deep water pdw for previous peak interglacials our results reveal similar benthic 13c values at site geob15016 and of a newly generated stack of benthic 13c from various deep pacific cores representing the average pdw this suggests unlike today the absence of aaiw at the site and the presence of nearly pure pdw in contrast more positive 13c values at site geob15016 compared to the stack imply a considerable aaiw contribution during cold phases of interglacials and especially during glacials besides we used three short sediment cores to reconstruct benthic 13c values from the aaiw core during the last glacial and found a 13c signature similar to today s assuming that this was the case also for the past 970 kyr we demonstrate that sea level changes and latitudinal migrations of the aaiw formation site can only account for about 50 of the full range of past 13c increases at site geob15016 during cold periods other processes that could explain the remaining of the positive 13c anomalies are increases in glacial aaiw production and or deeper convection of the aaiw with respect to preceding interglacials

seasonal climatology of hydrographic conditions in the upwelling region off northern chile over 30 years of hydrographic data from the northern chile 18os 24os upwelling region are used to calculate the surface and subsurface seasonal climatology extending 400 km offshore the data are interpolated to a grid with sufficient spatial resolution to preserve cross shelf gradients and then presented as means within four seasons austral winter july september spring october december summer january march and fall april june climatological monthly wind forcing surface temperature and sea level from three coastal stations indicate equatorward upwelling favorable winds throughout the year weakest in the north seasonal maximum alongshore wind stress is in late spring and summer december march major water masses of the region are identified in climatological t s plots and their sources and implied circulation discussed surface fields and vertical transects of temperature and salinity confirm that upwelling occurs year round strongest in summer and weakest in winter bringing relatively fresh water to the surface nearshore surface geostrophic flow nearshore is equatorward throughout the year during summer an anticyclonic circulation feature in the north which extends to at least 200 rn depth is evident in geopotential anomaly and in both temperature and geopotential variance fields subsurface fields indicate generally poleward flow throughout the year strongest in an undercurrent near the coast this undercurrent is strongest in summer and most persistent and organized in the south south of 21os a subsurface oxygen minimum centered at 250 m is strongest at lower latitudes low salinity subsurface water intrudes into the study area near 100 m predominantly in offshore regions strongest during summer and fall and in the southernmost portion of the region the climatological fields are compared to features off baja within the somewhat analogous california current and to measurements from higher latitudes within the chile peru current system

using cl br ratios and other indicators to assess potential impacts on groundwater quality from septic systems a review and examples from principal aquifers in the united states summary a detailed review was made of chemical indicators used to identify impacts from septic tanks on groundwater quality potential impacts from septic tank leachate on groundwater quality were assessed using the mass ratio of chloride bromide cl br concentrations of selected chemical constituents and ancillary information land use census data well depth soil characteristics for wells in principal aquifers of the united states chemical data were evaluated from 1848 domestic wells in 19 aquifers 121 public supply wells in 6 aquifers and associated monitoring wells in four aquifers and their overlying hydrogeologic units based on previously reported cl br ratios statistical comparisons between targeted wells where cl br ratios range from 400 to 1100 and cl concentrations range from 20 to 100 mg l and non targeted wells indicated that shallow targeted monitoring and domestic wells 0 5 mg l shallow groundwater from target domestic wells relative to non target wells 1 5 mg l corresponded to significantly higher potassium boron chloride dissolved organic carbon and sulfate concentrations which may also indicate the influence of septic tank effluent impacts on groundwater quality from septic systems were most evident for the eastern glacial deposits aquifer and the northern high plains aquifer that were associated with the number of housing units using septic tanks high permeability of overlying sediments mostly oxic conditions and shallow wells overall little or no influence from septic systems were found for water samples from the deeper public supply wells the cl br ratio is a useful first level screening tool for assessing possible septic tank influence in water from shallow wells

chlorine transport processes through a 2000 m aquifer aquitard system abstract in the paris basin in france the callovo oxfordian cox is currently studied over a 250 km2 surface area by the french national radioactive waste management agency in order to assess the feasibility of long term underground nuclear waste repository the cox is a 140 m thick clay rich layer which is part of the 2000 m aquitard aquifer system constituting the sedimentary cover in such sedimentary context the transport processes of potential contaminants can be represented by both vertical diffusion and horizontal advection through the most permeable layers chloride is used as a natural conservative tracer and is monitored in term of concentrations and isotopic composition 37cl for both pore and groundwater during this study the samples were collected from three boreholes located in the center of the studied zone one of them est433 going down to 2000 m depth the main solute transport process is shown to be vertical diffusion from the massive keuper halite level to the rest of the sedimentary pile this global diffusive system can be occasionally disturbed by horizontal circulation of groundwater occurring in the oxfordian and dogger limestone formations therefore these circulations cut the global diffusive system in a succession of independent diffusive systems in this study the data set was implemented in a simplified 2d solute transport model and scenarii reproducing known history in term of paleo circulations inside the system were applied and allowed to obtained a good fit of the data model results showed that paleo circulations occurring between 145 ma and 110 ma still have an impact on current distribution of chloride in the system especially for 37cl the model highlights the need of the presence of a circulation spatially limited at the base of the liassic formation to fit the data the best fit obtained indicated current residence time of 500 ka in the dogger and oxfordian with respective onset of the circulations at 20 ma and 5 ma

warming and circulation change in the eastern south pacific ocean deep ocean temperature salinity and dissolved oxygen observations in the eastern south pacific ocean collected during the late austral fall in 1995 are compared with observations made there 28 years earlier during the same season and similar el nino southern oscillation phase warming observed above 800 m at 43 s reflects the production of warmer subantarctic mode water in recent decades warming observed above 1600 m at 28 s is due to downward isotherm displacement and southward movement of water masses by 100 200 km as revealed by joint analysis of temperature and oxygen data such changes would be expected for a weaker subtropical gyre in the south pacific an observed oxygen decrease between about 1800 m and 2900 m at 28 s may indicate enhanced southward boundary current flow at mid depths off chile

fluid mixing and recycling during pyrenean thrusting evidence from fluid inclusion halogen ratios abstract syntectonic fluids have been sampled through fluid inclusion microthermometry and crush leach analyses cations and halogens from a 50 km n s transect through the central southern pyrenees the fluid inclusions are contained in syntectonic quartz veins in triassic redbeds cretaceous carbonates and hercynian basement rocks with some calcite and dolomite data from limestones and evaporites in more external parts of the belt the main datasets come from 1 alpine shear zones cutting the neouvielle granodiorite in the hercynian axial zone at the north end of the transect 2 an imbricate zone beneath the alpine gavarnie thrust at the pic de port vieux 3 several localities in the footwall and hangingwall of the gavarnie thrust on the southern margin of the axial zone the inclusion fluids generally decrease in salinity from 27 35 at the northern end of the transect to 7 22 on the southern margin of the axial zone the majority of the inclusions have cl br ratios lower than seawater and are interpreted as relict fluids after seawater evaporation and halite precipitation in the upper trias this interpretation is supported by cl br na systematics which are consistent with a change from halite to halite sylvite precipitation with progressive evaporation fluids in the basement shear zones are interpreted to have essentially the same evaporitic origin as those still contained in sedimentary formations although it is possible that final concentration of brines in the neouvielle massif involved retrograde hydration reactions with removal of water by precipitation of hydrous minerals the fluids are also very similar in salinity and halogen chemistry to those found in veins associated with mesozoic pb zn f deposits which predate the thrusting the lower salinities seen at the southern margin of the axial zone are interpreted to reflect mixing of the brines with a higher level fluid connate or meteoric water circulating within the mesozoic carbonates of the higher thrust sheets at one locality where triassic evaporites are still present high cl br ratios at relatively low salinities are present in inclusions within the underlying triassic redbeds but low cl br ratios at higher salinities are seen lower in the sequence this is consistent with dissolution of halite by a dilute fluid but with limited penetration downwards we suggest that the fluid history of the pyrenees evolved through a series of stages 1 upper triassic evaporite formation with sinking of brines into underlying redbeds and fractured basement rocks 2 circulation of brines with formation of pb zn deposits along faults at some time between the triassic and the upper cretaceous 3 renewed extension with erosion of triassic rocks in many areas and further drawing down of triassic brines into the basement 4 deposition of u cretaceous and palaeocene carbonates containing connate waters of marine origin 5 formation of the pyrenean thrust belt with overpressuring and expulsion of the brines along shear zones and faults 6 creation of topography with a high level circulation system in the mesozoic thrust sheets driven largely by topography at the southern margin of the axial zone there was limited mixing of the deeper overpressured brines with these more dilute hydrostatically pressured fluids an important point is that because of their density hypersaline brines are difficult to expel from the upper crust and may be involved in a succession of alteration and mineralisation events in the same general area over hundreds of millions of years

characterizations of geothermal springs along the moxi deep fault in the western sichuan plateau china abstract abundant geothermal springs occur along the moxi fault located in western sichuan province the eastern edge of the qinghai tibet plateau highlighted by geothermal water outflow with an unusually high temperature of 218 c at 21 5 mpa from a 2010 m borehole in laoyulin kangding earthquake activity occurs relatively more frequently in the region and is considered to be related to the strong hydrothermal activity geothermal waters hosted by a deep fault may provide evidence regarding the deep underground their aqueous chemistry and isotopic information can indicate the mechanism of thermal springs cyclical variations of geothermal water outflows are thought to work under the effect of solid earth tides and can contribute to understanding conditions and processes in underground geo environments this paper studies the origin and variations of the geothermal spring group controlled by the moxi fault and discusses conditions in the deep ground flow variation monitoring of a series of parameters was performed to study the geothermal responses to solid tides geothermal reservoir temperatures are evaluated with na k mg data the abundant sulfite content dissolved oxygen do and oxidation reduction potential orp data are discussed to study the oxidation reduction states strontium isotopes are used to trace the water source the results demonstrate that geothermal water could flow quickly through the moxi fault the depth of the geothermal reservoir influences the thermal reservoir temperature where supercritical hot water is mixed with circulating groundwater and can reach 380 c to the southward along the fault the circulation of geothermal waters becomes shallower and the waters may have reacted with metamorphic rock to some extent our results provide a conceptual deep heat source model for geothermal flow and the reservoir characteristics of the moxi fault and indicate that the faulting may well connect the deep heat source to shallower depths the approach of hot spring variation research also has potential benefits for earthquake monitoring and prediction

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

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

a more precise chronology of earthquakes produced by the san andreas fault in southern california improved methods of radiocarbon analysis have enabled us to date more precisely the earthquake ruptures of the san andreas fault that are recorded in the sediments at pallett creek previous dates of these events had 95 confidence errors of 50 100 calendar years new error limits are less than 23 calendar years for all but two of the dated events this greater precision is due to larger sample size longer counting time lower background noise levels more precise conversion of radiocarbon ages to calendric dates and better stratigraphic constraints and statistical techniques the new date ranges with one exception fall within the broader ranges estimated previously but our estimate of the average interval between the latest 10 episodes of faulting is now about 132 years variability about the mean interval is much greater than was suspected previously five of the nine intervals are shorter than a century three of the remaining four intervals are about two to three centuries long despite the wide range of these intervals a pattern in the occurrence of large earthquakes at pallett creek is apparent in the new data the past 10 earthquakes occur in four clusters each of which consists of two or three events earthquakes within the clusters are separated by periods of several decades but the clusters are separated by dormant periods of two to three centuries this pattern may reflect important mechanical aspects of the fault s behavior if this pattern continues into the future the current period of dormancy will probably be greater than two centuries this would mean that the section of the fault represented by the pallett creek site is currently in the middle of one of its longer periods of repose between clusters and sections of the fault farther to the southeast are much more likely to produce the next great earthquake in california the greater precision of dates now available for large earthquakes recorded at the pallett creek site enables speculative correlation of events between paleoseismic sites along the southern half of the san andreas fault a history of great earthquakes with overlapping rupture zones along the mojave section of the fault remains one of the more attractive possibilities

a pacific hydrographic section at 88 w water property distribution full depth conductivity temperature depth ctd hydrographic measurements with high horizontal and vertical resolution were made in february april 1993 along a line lying at a nominal longitude of 88 w and extending from southern chile 54 s to guatemala 14 n it crossed five major deep basins southeast pacific chile peru panama and guatemala basins east of the east pacific rise vertical sections of potential temperature salinity potential density oxygen silica phosphate nitrate and nitrite are presented to illustrate the structure of the entire water column some features of interest found in the sections are described and an attempt is made to interpret them in terms of the isopycnal property distributions associated with the large scale ocean circulation these features include various near surface waters observed in the tropical and subtropical regions and the fronts that mark the boundaries of these waters the possible importance of salt fingering to the downward salt transfer from the high salinity subtropical water a shallow thermostad pycnostad developed at 16 18 5 c in the subtropical water low salinity surface water in the subantarctic zone west of southern chile large domains of extremely low oxygen in the subpycnocline layer on both sides of the equator and a secondary nitrite maximum associated with a nitrate minimum in these low oxygen domains high salinity low oxygen high nutrient subpycnocline water that is carried poleward along the eastern boundary by the peru chile undercurrent the subantarctic mode and antarctic intermediate waters middepth isopycnal property extrema observed at the crest of the sala y gomez ridge influences of the north pacific and the north atlantic upon deep waters along the section and the characteristics and sources of the bottom waters in the five deep basins along the section

geochemistry of evaporite bearing series a tentative guide for the identification of metaevaporites literature on metasedimentary rocks indicates that former evaporites have been assumed where brines are present as fluid inclusions or minerals such as scapolite tourmaline and lazurite which are considered as evidence of equilibria with brines very few works take into account the chemical composition of rocks because chemical data on evaporite bearing sedimentary series are scarce

the tangshan earthquake sequence and its implications for the evolution of the north china basin the 1976 tangshan earthquake sequence that occurred on the northern margin of the north china sedimentary basin is one of the strongest and most destructive intracontinental earthquake sequences ever recorded by worldwide long period seismograph networks we have studied the source process of the six largest events of this earthquake sequence by formally inverting long period p and sh wave seismograms from the world wide standardized seismographic network our analysis shows that the main shock was caused by motion on at least three fault segments each with a different orientation the initial and dominant faulting occurred on two segments of a north northeast trending right lateral strike slip fault system the last stage of faulting had a significant component of thrusting and occurred on an east northeast trending subsidiary fault at the southern end of the main fault the largest aftershock occurred at the northeastern end of the main fault and had a nearly pure normal faulting mechanism with east west striking nodal planes this event occurred in a pull apart region where the north northeast trending main strike slip fault system steps to the right this region subsided by more than 1 m during the earthquake sequence to the north of this step the main fault is delineated by numerous aftershocks whose mechanisms are by and large consistent with right lateral slip on this segment the large event in 1945 m 6 3 probably occurred on this part of the fault a region of substantial subsidence up to 1 5 m associated with the earthquake sequence was also observed in the south where the main fault system takes another step to the right two of the large aftershocks occurred nearby and had strike slip mechanisms the overall faulting process of the tangshan sequence is well characterized by right lateral slip on a set of right stepping faults the mechanisms and the points of nucleation of the strongest shocks and the extent of the ruptures appear to be closely tied to preexisting fault geometries a compilation of the mechanisms of large earthquake sequences in the north china basin strongly suggests that the present deformation of the entire basin is dominated by motions on right lateral strike slip systems trending north northeast the basin seems to have formed and evolved as a large transtensional structure at an en echelon step of a large scale strike slip system the deformation within the basin is both strike slip and extensional and appears to occur on smaller scales in an approximately selfsimilar fashion as evidenced by the deformation during the tangshan sequence this interpretation provides an explanation for the variable rate of subsidence in both space and time and the scatter in measured heat flow values as well as the overall shape of the north china basin it also provides an explanation for occasional thrust faulting earthquakes that occur apparently as a result of geometrical complexities of the strike slip faults transpression these observations are otherwise difficult to fit into a simple model of regional crustal extension and thermal subsidence

observed property changes in eastern south pacific antarctic intermediate water 1 we compared potential temperature and salinity of antarctic intermediate water along 32 30 s from the coast of chile to the central south pacific ocean between 2003 and 1992 based on two vertically and horizontally high resolution repeat sections each being 6795 km long the temperature of antarctic intermediate water considering the entire body of the water mass along the section increased by 0 048 c and salinity by 0 002 the increase in salinity could be explained by a slight shift in the evaporation precipitation balance of the south pacific ocean

boron isotope and geochemical evidence for the origin of urania and bannock brines at the eastern mediterranean effect of water rock interactions the origin of hypersaline brines from urania and bannock deep anoxic basins in the eastern mediterranean sea has been investigated by integrating geochemical data and boron isotopic ratios bottom brines from urania basin have chloride contents up to 4200 mmole kg h2o and a marine na cl ratio 0 87 all the other ionic ratios are different from the marine ratios and show a relative enrichment in ca k br and b and depletion in mg and so4 as normalized to the chloride ion the 11b values of the urania brines 11b 29 8 2 9 n 7 are lower than that of mediterranean seawater 39 the concentrations of cl and na which make up 95 of the total dissolved ions in molal units suggest that the urania brines were derived from eightfold evaporated seawater the relative enrichment of ca and depletion of mg and so4 reflect dolomitization gypsum precipitation and sulfate reduction processes which modified the original evaporated seawater while the brines were entrapped as interstitial waters in the sedimentary section of the mediterranean the relative enrichments of br b and k and the low 11b value of the urania brines suggest high temperatures interactions of the evaporated sea water with sediments mass balance calculations suggest that desorption of exchangeable b from the sediments 11b 20 modified the marine b isotopic composition of the original eightfold evaporated seawater potassium was also leached from clay minerals whereas br was contributed from degradation of organic matter in the sediments this is consistent with a thermal anomaly up to 45 c recorded at depth in the region of urania basin in contrast bottom brines and shallow interstitial fluids from bannock basin with low temperatures 15 c show marine 11b 11b 39 6 2 8 n 5 38 5 2 2 n 5 respectively and b cl ratios 7 10 4 the b isotope data confirm that the bannock brines were derived from twelvefold evaporated seawater we argue that the brines from both basins are relics of fossil evaporated seawater that was entrapped in late miocene sediments and accumulated in the deep basins of the mediterranean seafloor

late quaternary variability of sedimentary nitrogen isotopes in the eastern south pacific ocean 1 we present high resolution bulk sedimentary 15n data from the southern edge of the present day oxygen minimum zone of the eastern south pacific the record is interpreted as representing changes in water column nitrogen removal during the last 70 000 years we found significant fluctuations in the isotopic signal that suggest major reorganizations of the oxygen minimum zone at millennial timescales these fluctuations were not related to other millennial scale changes like the northern hemisphere s dansgaard oeschger climate swings or local changes in primary productivity so appear to be dictated by the southern hemisphere s climate rhythm this is preliminarily corroborated by an overall agreement between our 15n data and the sedimentary proxy of ice sheet dynamics in patagonia which is in turn correlated with surface water properties at the midlatitude subduction region of the eastern south pacific intermediate waters finally potential implications on late quaternary changes in atmospheric co2 concentrations are discussed

air sea co2 fluxes along the coast of chile from co2 outgassing in central northern upwelling waters to co2 uptake in southern patagonian fjords 1 carbon system parameters measured during several expeditions along the coast of chile 23 s 56 s have been used to show the main spatial and temporal trends of air sea co2 fluxes in the coastal waters of the eastern south pacific chilean coastal waters are characterized by strong pco2 gradients between the atmosphere and the surface water with high spatial and temporal variability on average the direction of the carbon flux changes from co2 outgassing at the coastal upwelling region to co2 sequestering at the nonupwelling fjord region in chilean patagonia estimations of surface water pco2 along the patagonian fjord region showed that while minimum pco2 levels strong co2 undersaturation occurs during the spring and summer period maximum levels including co2 supersaturation occur during the austral winter co2 uptake in the patagonia fjord region during spring summer is within the order of 5 mol c m 2 yr 1 indicating a significant regional sink of atmospheric co2 during that season we suggest that the co2 sink at patagonia most probably exceeds the co2 source exerted by the coastal upwelling system off central northern chile

stable chlorine isotopes in phanerozoic evaporites abstract modern seawater has a uniform 37cl value 0 0 with an exception in the upper current of the bosphorus 0 4 marine halite ranging in age from cambrian to miocene has 37cl values of 0 0 0 9 with most of the data in the range 0 0 0 5 mean 37cl values differ measurably between basins with no evident relationship to basin size or to age smaller evaporite bodies have the largest 37cl ranges potash facies halite has mean 37cl values lower than those of halite facies salt in the east siberia and zechstein basins the bulk 37cl of bedded halite preserving sedimentary textures cannot be shifted measurably after deposition under plausible natural conditions during the phanerozoic a detectable change in the 37cl values of the oceans is unlikely as a result of cl fluxes to and from the mantle and evaporites in halite the values of 37cl that cannot be explained by fractionation occurring on crystallization are best explained by the addition of non marine cl with 37cl 0 0 to evaporite brine

the faulting process of tangshan earthquake inverted simultaneously from the teleseismic waveforms and geodesic deformation data abstract it is well known that for natural earthquakes the faulting processes are highly complicated to study such processes all of the different types of data that can be acquired should be incorporated into the investigations in accordance with this consideration the faulting process of the tangshan earthquake m s 7 8 on 27 july 1976 is investigated first the geometrical attitude of the fault is determined by analysing the geological structure intensity distribution locations of the aftershocks and geodesic data collectively then the faulting process is simultaneously inverted from 14 wwssn long period teleseismic waveforms and 70 horizontal geodesic static deformation data the results show that the tangshan earthquake is one of the strongest intraplate earthquakes with a complex faulting process the dimension of the main fracture is approximately 100 km by 15 km with a change in direction at the central part of the fault the southern segment strikes at about ne30 becoming 50 60 for the northern segment the total seismic moment inverted is 2 0 10 20 nm and the dislocation was relatively concentrated near the central part of the fault where the slip elapsed for a longer time these results suggest that near the city of tangshan there might be a strong unbroken block and the fault changes its trend there hence the fault system was locked before the earthquake when the regional stress increased and exceeded the strength limit the fracture initiated from this location and extended bilaterally

the geochemistry of brines and minerals from the asse salt mine germany the chemistry and stable isotopes 18o d of highly concentrated chloride brines and minerals from the asse salt mine in the north of the federal republic of germany were studied chemical data indicate the occurrence of three types of brines a mg cl type of carnallitite origin with li 100 mg kg and c almost pure mgcl2 type brines with li 100 mg kg the first group may be subdivided into brines with li 4 0 mg kg and brines with li between 18 and 30 mg kg lithium is shown to be an efficient complementary tool in tracing the origin of the brines the complex evolution of carnallitite type brines is discussed in detail isotopic data of brines that were sampled directly from seepages presumably unaltered indicate that these brines are not a mixture with relatively fresh ground water from the overburden sediments the stable isotope composition 18o and d of hydration water in carnallite kieserite and polyhalite sampled from the asse mine were also studied it is shown that water extracted from the so called primary carnallite is isotopically different from water extracted from secondary carnallite the isotopic fractionation factors for 18o and d between carnallite hydration water and mother solution were studied in the laboratory assuming that crystallization water of the so called primary carnallite samples is not altered the isotopic composition of the mother solution is evaluated

paleo water rock interaction determined through isotopic tracing sr o c u in fracture fill minerals evidence from the vienne granitoids france abstract based on the concepts a that the stable c and o isotopes combined with the sr isotope ratios of fracture fills should reflect the source groundwater from which the solid phases precipitated and b that u series disequilibria usd enable the calculation of residence time for the u by using fe oxides as the best candidate an isotopic toolbox was applied to fracture fill from the crystalline basement of the vienne district the fracture fills are formed mainly of carbonates clays and fe oxides the isotope data indicate two main generations of carbonate that originated from hydrothermal circulation and equilibrium with present day groundwaters but the sr isotope ratios highlight another component with a higher 87 sr 86 sr ratio reflecting the complexity of the water rock interactions for the usd the fe hydroxides located at 207 m depth yield an age of 102 5 ka st germain i interglacial stage whereas those located at 277 m and 300 m yield respective ages of 173 15 ka and 181 10 ka these corresponding to the transition between the penultimate glacial period isotopic stage 6 and the end of the preceding interglacial stage isotopic sub stage 7a investigating water rock interaction 87 sr 86 sr 18 o 13 c usd in the fracture fill minerals from the crystalline basement has shown that such an approach is relevant to developing an understanding of how the groundwater system has changed over time

storm response of the karstic carbonate aquifer of southcentral kentucky abstract temperature and specific conductance were continuously measured in the downstream drainage of the turnhole spring subbasin in the southcentral kentucky karst precipitation was monitored with a rain gage network in the catchment area so that the storm response of specific conductance and temperature could be examined the aquifer feeding the turnhole spring is highly karstic with much of the discharge through integrated open conduits some of which carry water from surface sinking stream catchments both temperature and specific conductance fluctuate rapidly in response to storm events the conductivity curves and to a lesser extent the temperature curves show a sharp dip that lags some hours behind the storm pulse at the onset of the dip is a complicated sequence of fine structures that is interpreted to be the inputs from conduit tributaries to the master trunk drainage system the recovery curves have an exponential form that can be fitted to produce a characteristic response time for the conduit system

geochemical and hydrological processes controlling groundwater salinity of a large inland wetland of northwest australia abstract understanding mechanisms of hydrochemical evolution of groundwater under saline and brine wetlands in arid and semiarid regions is necessary to assess how groundwater extraction or injection in large scale basins may affect the natural interface between saline fresh aquifers in those systems we investigated the evolution of groundwater of the fortescue marsh a large inland wetland of northwest australia that is mainly supplied by floodwater from the upper fortescue river catchment the marsh is located in the pilbara region one of the world s major iron ore provinces where mining activities often occur below water tables here we quantified the stable isotope and chemical composition of groundwater surface water and rainfall in and around the marsh to better understand how saline marshes and playa lakes function geochemically hydrologically and ecologically the deep groundwater 50 m depth of the fortescue marsh is highly saline 100 g l 1 whilst shallow groundwater 0 20 m depth and surface water are mainly fresh or brackish currently the marsh is mainly recharged by occasional floodwater consequently salt in the marsh is concentrated by evaporation of rainfall we expected that the hydrochemical composition of surface and groundwater would therefore reflect the chemical composition of rainwater we analysed 206 water samples for stable isotope composition 2 h 18 o and water chemistry including ph dissolved oxygen electrical conductivity ec and total dissolved solids tds as well as na ca mg k si fe hco 3 so 4 cl sr and br we then developed geochemical models and a salt inventory to estimate the geological time of salt accumulation and to decouple geochemical characteristics of salt from modern groundwater we found that groundwater associated with the marsh can be divided into two distinct groups that are characterised by their stable isotope compositions i fresh and brackish groundwater tds 1 18 o 8 0 0 9 and ii saline and brine groundwater tds 10 g l 1 18 o varies from 2 5 to 7 2 fresh groundwater was evaporated by

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

water rock interaction processes in the triassic sandstone and the granitic basement of the rhine graben geochemical investigation of a geothermal reservoir saline fluids have been collected in the rhine graben over the last two decades both from the triassic sandstone aquifer and the granitic basement down to a depth of 3500m their salinities and location are compared in order to distinguish the respective influences of temperature and host rock mineralogy in the water rock interaction processes the comparison shows that sulphates in the sedimentary formations were dissolved by the fluids which also led to br enrichment mica dissolution has strongly increased the rb and cs contents which then provide an indication of the degree of water rock interaction the sr isotopic ratios are used to compare the fluids with the granite minerals two relationships are revealed for the fluids in the sandstone and the granite one related to widespread mica dissolution which could have affected both the buntsandstein and the granite and the other to subsequent plagioclase dissolution which is observed only in the granite computations showed that 12 5g of mica and 1 658 of plagioclase per liter of fluid have been dissolved the nature of these two relationships suggests two different evolutions for the fluids and the individualization of the two reservoirs during the graben s history the cation concentrations are mainly controlled by temperature and are independent of the type of host rock equilibrium with the rock mainly caused ca and k concentration variations which has induced clear ca k and ca 18o k 18o correlations geothermometric computations indicate that with increasing depth the cations the silica and the 18o so4 geothermometers evolve towards a value close to 230 c this demonstrates the existence of a hot reservoir in the granite of the graben at a depth estimated at 4 5 5 km

seawater intrusion and associated processes in a small coastal complex aquifer castell de ferro spain an attempt to identify the hydrogeochemical processes that accompany current or past intrusion of seawater in the castell de ferro coastal aquifer se spain was made using ionic deltas ionic ratios and saturation indices alluvial and coastal quaternary sediments and triassic marbles constitute this complex aquifer cation exchange dolomitization and calcite dissolution were identified as operating in the aquifer the cation exchange processes in the detrital materials are different from those in the marbles in addition it was determined that while the processes of marine intrusion associated with periods of low groundwater levels still persist in the detrital aquifer in the carbonate sector the flushing process characteristic of wetter conditions has begun

the surface rupture zone and paleoseismic evidence on the seismogenic fault of the 1976 ms 7 8 tangshan earthquake china abstract the ms 7 8 tangshan earthquake of 1976 was the largest earthquake that occurred in the northern north china plain over the last 300 years most of the earthquake scarps had been disturbed or had disappeared except for some seismic ruins and relics that were protected or had remained aerial photos taken after the earthquake also indicate the locations of some of these scarps in this study we reinvestigated the surface rupture zone of this earthquake and conducted composite borehole profiling and trenching across the new found surface rupture to obtain the paleo earthquake events of the seismogenic fault the following major conclusions regarding the ms 7 8 tangshan earthquake have been reached 1 the length of the rupture zone of the tangshan earthquake was 47 km in addition to the east and west sides of the main surface rupture there was a prominent secondary fissure zone 2 the tangshan fault experienced nine paleoearthquake events since 115 ka the timing of the four faulting events prior to the 1976 earthquake was 7 76 8 13 ka around 16 2 ka around 24 3 ka and 32 41 ka considering the earthquake of 1976 the recurrence interval of the five strong earthquake events is about 8 1 ka 3 the magnitudes of these paleoearthquakes e2 to e5 which happened before the tangshan earthquake were about ms 7 6 7 7 ms 7 5 7 9 ms 7 7 7 8 and ms 7 5 respectively research on the 1976 tangshan earthquake is important for improving earthquake predictions in the north china plain

using the cl br ratio as a tracer to identify the origin of salinity in aquifers in spain and portugal summary a study on the applicability of the cl br molar ratio for identifying the origin of groundwater salinity is presented according to the experience gained in spain and portugal cl br ratios in atmospheric bulk deposition have helped to distinguish groundwater in which cl derives only from atmospheric sources from groundwater in which cl is contributed by endogenous lithological or anthropogenic sources considering the seawater cl br ratio of 655 4 cl br ratios may be increased up to 1500 in groundwater by the addition of wastewater loaded with nacl or leaching of solid waste and decreased to 300 by the use of br based pesticides or leaching farm animal or septic waste leaching and dissolution of natural and industrial nacl and of gypsum rich formations containing some nacl may yield cl br ratios between one thousand and several thousand although leaching of potassium halides near salt mines produces cl br ratios below the seawater ratio when cl content in groundwater is not affected by extreme evaporation up to halite saturation at 6 2 mol l 1 of nacl and if there are no other cl sources recharge by rainfall can be estimated by relating cl in atmospheric bulk deposition to derived groundwater the cl br ratio appears to be a good tracer for discriminating non atmospheric cl contributions to groundwater provided chemical analyses are accurate since its variability is not wide data have been collected from different areas of spain and portugal and are explained and illustrated by two cases described in detail the donana aquifer in southwest spain and the canary islands both showing the mixing paths