Article

Strontium isotope systematics used to decipher the origin of groundwaters sampled from granitoids: The Vienne Case (France)

July 2001
Chemical Geology 177(3):287-308

July 2001
177(3):287-308

Authors:

French Geological Survey

Sr isotope data from surface, shallow and deep groundwaters from the granitoids of the Vienne District (France) are presented in this paper. In surface waters, the Sr contents in the rocks and groundwaters agree with previous data for groundwaters sampled from granitic and sedimentary rocks in France where a large range in 87Sr/86Sr ratios is observed. After correction for the Sr input from rain, the surface water samples plot within a mixing field that can be explained by three end-members, one anthropogenic (low 87Sr/86Sr and high Cl/Sr ratio) and two end-members characterised by low Cl/Sr ratios and a large range in 87Sr/86Sr ratios (from around 0.707–0.720).For deep groundwaters, the 87Sr/86Sr ratios and Sr contents are also determined by applying a correction to account for the influence of cleaning waters during drilling operations. The results are scattered amongst five different groups and the lack of a direct linear relationship between any of the samples implies that, as found for the shallow groundwaters, the results are due to mixing between more than two end-members.A model to determine the 87Sr/86Sr ratio (Irf) of groundwater after interaction with an actively weathering granite is developed. The results yield a low Irf value for waters associated with weathering of the tonalite (0.70463) and a higher one for waters associated with weathering of the monzogranite (0.70704). Given the much higher Irf values derived from the deep groundwater samples, these results indicate that the deep groundwaters analysed within the Vienne hydrosystem cannot be directly related to weathering of either tonalite or monzogranite. It is speculated that this high 87Sr/86Sr source originated from marine incursions during the Jurassic and have been diluted by mixing with former groundwaters produced by water–rock interaction (WRI) with the granites.

Investigation of meteoric water and parent fluid mixing in a two-phase geothermal reservoir system using strontium isotope analysis: A case study from Southern Bandung, West Java, Indonesia

Article

Jul 2021
GEOTHERMICS

Determinations of the recharge area and recharge mechanism in geothermal systems are essential for reservoir management and a sustainable resource use. To address this problem, studies aplenty have aimed to identify the recharge elevation using stable water isotopes, δ²H and δ¹⁸O. Nevertheless, the physical and chemical processes involved in the generation of a reservoir fluid from a deeply infiltrated recharge flow remain poorly understood. This study aims to clarify this process using strontium (Sr) concentrations and isotope composition from water and well rock samples by selecting a geothermal field with a two-phase reservoir system in Southern Bandung, West Java, Indonesia. The water samples are characterized by variable Sr isotopic compositions (⁸⁷Sr/⁸⁶Sr) (0.70450–0.70725) and low Sr concentrations (0.01–0.72 ppm). The ⁸⁷Sr/⁸⁶Sr of the well rocks is also variable (0.70400–0.70827) with particularly high Sr concentrations (9.1–53 ppm). Three types of domain that are the combinations of the reservoir fluid mixing with groundwater are identified. The first two types are shallow and deep groundwater composed of 90 % meteoric water and 10 % upflow fluids with Sr concentration 0.01 to 0.11 ppm and the ⁸⁷Sr/⁸⁶Sr from 0.7055 to 0.70725. The shallow groundwater may possibly carry a ⁸⁷Sr/⁸⁶Sr anomaly (higher than ⁸⁷Sr/⁸⁶Sr of plagioclase: 0.7065) from the anthropogenic activities through the pathways created by the intersection of the NW-SE and NE-SW inferred regional faults in the west part of the field, hosted by the Wayang Windu Formation. The deep groundwater type is also a mixture of 10 % parent fluid hosted by the deeper aquifer rocks Malabar Formation, with lower strontium isotopes ratio than the first aquifer (⁸⁷Sr/⁸⁶Sr 0.7045–0.7055). The third groundwater refers to the perched aquifer with mixture of 30 %–70 % parent fluid that has undergone condensation and mixing processes in Pangalengan Formation (⁸⁷Sr/⁸⁶Sr 0.70452–0.7052). This groundwater is thought to be the source of mostly hot springs in the study area.

Tracing biogeochemical processes and anthropogenic impacts in granitic catchments : temporal and spatial patterns and implications for material turnover and solute export

Thesis

Jan 2019

Christina Weyer

From a biogeochemical perspective, catchments can be regarded as reactors that transform the input of various substances via precipitation, deposition, or human activities as they pass through soils and aquifers towards receiving streams. Understanding and modeling the variability of solute concentration in catchment waters require the identification of prevailing processes, determining their respective contributions to the observed transformation of substances, their interplay with hydrological processes, and the determination of anthropogenic impacts. However, numerous biogeochemical processes often interact in a highly non-linear way and vary on temporal and spatial scales, resulting in temporally and spatially varying water chemistry in catchments. This is particularly true for riparian wetlands. Processes in this catchment area often superimpose the influence of the hill slope (and largest) area of the catchment on surface water quality. Accordingly, the first part of this thesis (Study 1 and 2), focuses on the temporal and spatial variability of biogeochemical processes at the catchment scale. Therefore, the first aim was to identify the prevailing biogeochemical processes which affect the quality of catchment waters in two forested granitic catchments. Based on these results, (i) the long-term behavior of these processes was determined (Study 1) and (ii) hot spots of these processes at the catchment scale along different flow paths were identified (Study 2). The second part (Study 3) focuses on the interplay between hydrological and biogeochemical processes in a riparian wetland, with the aim of systematically tracing back the temporal patterns of stream water chemistry to different biogeochemical processes and antecedent hydrological boundary conditions in the wetland. The third part (Study 4 and 5) focuses on weathering processes with the goal (i) of identifying the mineralogical sources of the groundwater’s buffer capacity against acid atmospheric deposition in a forested granitic catchment and (ii) determining the mineralogical sources of the high cation loads in surface water, induced by intensive agricultural activities in two agricultural granitic catchments. To reach these aims, multivariate statistical methods of dimensionality reduction (linear Principal Component Analysis, non-linear Isometric Feature Mapping), a low-pass filtering of time-series, a Cluster analysis, and major and trace element ratios and strontium isotopes were used. A small number of biogeochemical process bundles explained 94% and 89% of the variance of the data set in Study 1 and 2, respectively. In Study 1, redox and topsoil processes, road salt and sulfate contamination were identified as predominating processes influencing water chemistry in the respective catchments. Low-pass filtered time series of component scores revealed a different long-term behavior at different sampling sites in both catchments, which could be traced back to the fraction of wetland area in the respective subcatchments as well as by the varying thickness of the regolith. Study 2 revealed that the upper 1 m topsoil layer could be considered as a biogeochemical hot spot for redox processes, acid-induced podsolization, and weathering processes along different flow paths. Up to 97% of the biogeochemical transformation of the chemical composition of soil solution, groundwater and stream water in the Lehstenbach catchment was restricted to this soil layer representing less than 2% of the catchment’s regolith. Wetland stream water, mobilized in the topsoil layer being considered a biogeochemical hot spot, showed a highly dynamic temporal pattern of component scores. Study 3 revealed four different types of wetland stream water chemical status, depending on the interplay between discharge dynamics, biological activity, and the water table position in the wetland. The sequence of different stream water types roughly followed a seasonal pattern, albeit being heavily modified by the respective hydrological boundary conditions for different years. Extended periods of low groundwater level in the second half of the growing season drastically changed the chemical boundary conditions, becoming evident in a drastic reoxidation of reduced species like sulfides and corresponding effects. Weathering processes are one of the predominating biogeochemical process bundles influencing water chemistry in forested catchments. Study 4 showed that the mineralogical sources of the groundwater’s buffer capacity against acid atmospheric deposition were dominated by the release of base cations from apatite dissolution, preferential cation release from feldspars and biotite, and feldspars weathering. In Study 5, determining the mineralogical sources of the high cation loads in surface water induced by intensive agricultural activities revealed a dominant manure contribution in the topsoil, and enhanced mineral dissolution (plagioclase and biotite) by fertilizer application in subsoils, becoming the unique source of base cations in the saprolite. Stream water chemistry differed from that of soil water, suggesting that stream water chemistry was dominated by elements issued from enhanced mineral and rock weathering. Soil acidification induced by agriculture allows the mobilization of cations stored in soil layers, enhances the rock weathering and accelerates plagioclase dissolution, which can highly influence stream water quality. Numerous biogeochemical, hydrological, and anthropogenic processes were found to interact with each other, mostly with non-linear patterns, influencing catchment water chemistry. The integral approach used in this thesis would be a useful prerequisite to develop accurate and parsimonious models commonly used for water management purposes by distinguishing between short- term and long-term shifts, reducing the number of processes to the predominating ones ultimately to be included in the model, focusing on hot spots and including spatial patterns where necessary and appropriate.

Strontium isotope tracing of prehistoric human mobility in France

Thesis

Full-text available

Mar 2015

Malte Willmes

Human mobility in recent history is well documented and often related to drastic external changes, including war, famine, and the discovery and exploration of new geographic regions and resources. Reconstruction of mobility patterns in prehistory is thus a crucial part of understanding the forces that drove our ancestors, but it is complicated by the fact that the archaeological evidence becomes scarce as we go back in time. The application of stable isotopes in archaeological research has revolutionised palaeomobility studies by providing independent data, which can be used to evaluate models of migration, trade, and cultural change. This research project explores the use of strontium isotope ratios (87Sr/86Sr) to trace prehistoric human mobility patterns. Strontium isotope ratios vary across the landscape based on the age and composition of the underlying geology. Through diet humans incorporate strontium into their skeletal tissues such as bones and teeth. Teeth form during childhood and are resistant to weathering and geochemical alteration, often preserving the original isotope values. By comparing the strontium isotope ratios in teeth to the variations of strontium isotopes in the landscape it becomes possible to investigate mobility across geologically different areas between childhood and death. This study establishes the Isotopic Reconstruction of Human Migration (IRHUM) reference database and provides the first dataset of 87Sr/86Sr isotope ratios of plant and soil samples, covering all major geologic units of France. This provides a new powerful tool for the archaeological science community as it allows the mapping of the variations of bioavailable 87Sr/86Sr isotope across the landscape. Utilizing this dataset, a bioavailable 87Sr/86Sr isotope map for archaeological provenance studies in France is created. For the application of this method to human fossil teeth new analytical methods to detect diagenetic overprint were tested. These now allow for rapid scanning to investigate the suitability of samples, minimising the damage to fossil remains. Least destructive analytical techniques for strontium isotope analysis, such as micro drilling thermal ionisation mass spectrometry and in situ laser-ablation MC-ICPMS, were further developed and applied to a range of materials of known composition, including shark and dugong teeth, modern and archaeological fauna samples, and fossil and modern human teeth. Finally, strontium isotope tracing was applied to three key archaeological sites in France, including the Neanderthal sites of Moula-Guercy, and the Neolithic sites of Le Tumulus des Sables and La Grotte des Perrats. Strontium isotope tracing proved to be a valuable technique and in combination with additional strings of evidence from archaeological material and other isotopic tracers, such as oxygen, improved our understanding of prehistoric human mobility at these sites. By covering different geographic locations and different time periods this study tests geochemical fingerprinting and offers new insights into these renowned archaeological sites.

Strontium isotopes and rare earth elements in terrestrial hot-spring deposits: Characterization and geothermal implications

Article

May 2024
GEOL SOC AM BULL, GSA Bulletin

Identifying geothermal reservoir rock types is fundamental in geothermal exploration, but the absence of active surface geothermal manifestations (especially hot springs) in blind geothermal systems makes this identification difficult. Nevertheless, blind geothermal systems may develop early-formed hot-spring deposits. As (bio-)chemical precipitate, these deposits may retain geochemical signatures of spring waters and thus provide insights into reservoir rock types. To assess their geothermal implications, the 87Sr/86Sr and rare earth elements + yttrium (REE + Y) characteristics of hot-spring deposits in two geothermal systems were investigated and compared with those of their reservoir rocks. Results showed relatively uniform 87Sr/86Sr values in hot-spring deposits within each system, but occasional 87Sr/86Sr contamination induced by exogenous detritus input was also observed. The amount of detritus input relates to the potential for interaction with surrounding soils/rocks and is thus environmentally controlled. Hot-spring deposits with high Sr concentrations showed greater 87Sr/86Sr contamination resistance than those with low Sr concentrations, revealing the influence of Sr concentration in hot-spring deposits on detrital 87Sr/86Sr contamination. The detritus input also influenced the REE + Y signatures of the hot-spring deposits, underscoring the necessity of contamination assessment before geochemical interpretation. Excluding samples with significant 87Sr/86Sr and/or REE + Y contamination, the remaining samples closely mirrored their respective reservoir rocks in terms of 87Sr/86Sr, with partial overlap in REE + Y signatures. This suggests that the 87Sr/86Sr and REE + Y characteristics of hot-spring deposits provide valuable insights into reservoir rock types. However, variations in 87Sr/86Sr or REE + Y compositions between some hot-spring deposits and corresponding reservoir rocks indicate additional influencing factors beyond reservoir rock types. Therefore, a comprehensive understanding of reservoir rock types requires integrated geochemical characterization, probably including 87Sr/86Sr, REE + Y, and other parameters. These findings underscore the potential of geochemical characterization of hot-spring deposits for identifying geothermal reservoir rock types, and this geochemical approach can complement geological and geophysical data to improve exploration efficiency, especially in blind geothermal systems.

Sources of antimony contamination and its migration into water systems of Xikuangshan, China: Evidence from hydrogeochemical and stable isotope (H, O, S, and Sr) signatures

Article

Aug 2023

The Xikuangshan (XKS) mine was selected for a comprehensive Sb-related hydrogeochemical study because of its significant Sb contamination in water systems. Hydrochemical data, specifically multi-isotope (H, O, S, and Sr) data, were conducted to elucidate the primary sources and migration processes of Sb responsible for water system contamination. At the XKS Sb mine, water is near-neutral to alkaline and is characterized by high concentrations of SO42- and Sb. Sb occurs as Sb(OH)6- (the dominant species) in these oxidized waters. The hydrochemistry is mainly controlled by carbonate dissolution and silicate weathering. δ2HH2O and δ18OH2O values indicate that the infiltration recharge of mine water and mining activities regulate the migration of Sb in groundwater. δ34SSO4 and δ18OSO4 values indicate that dissolved SO42- and Sb primarily come from stibnite oxidation, bacterial SO42- reduction has either not occurred or is extremely weak, and the reductive dissolution of Fe (III) hydroxides does not significantly affect Sb migration in water. The 87Sr/86Sr ratios further indicate that the discharge of solid mine wastes leaching and smelting water is a crucial source of Sb contamination in groundwater. In addition, the relationship between δ34SSO4 and δ87Sr values suggests the complexity of the contamination source and migration of Sb in water. Finally, a robust conceptual hydrogeochemical model was developed using isotopic tools in combination with detailed hydrogeological and hydrochemistry characterization to describe the contamination source and migration of Sb in water systems at the XKS Sb mine.

Geological carbon cycle in a sandstone aquifer: Evidence from hydrochemistry and Sr isotopes

Article

Dec 2022
J HYDROL

Multi-isotope (δ2H, δ18O, δ13C-TDIC, δ18O-TDIC, 87Sr/86Sr) and hydrochemical study on fractured karstic and detritic shallow aquifers in the Pampean region, Argentina

Article

Oct 2020
ISOT ENVIRON HEALT S

Fluxes between fractured-karstified and detritic aquifers are commonly poorly understood in many environments. These two types of aquifers are in contact in the southeastern Pampean region in the Argentine Buenos Aires province, and the aim of this work is to analyze their relationship contributing to improve the hydrological model. A joint application of hydrochemical and multi-isotope (δ2H, δ18O, δ13C-TDIC, δ18O-TDIC, 87Sr/86Sr) tools was used. TDIC, δ2H, δ18O and δ13C-TDIC allowed differentiating two main end members. Water in the Pampeano aquifer (PA) which is transferred from the fractured-karstic aquifer (F-KA) is characterised by high TDIC around 500–700 mg/L, isotopically depleted in 18O (about −5.5 ‰) and high δ13C-TDIC (around −10.0 ‰). The other end member is direct recharge water infiltrated into the PA with TDIC ranging from 400 to 500 mg/L, slightly enriched in 18O (δ18O=−4.8 ‰), and δ13C-TDIC in the range of soil CO2 as a result of reactions with calcrete concretions (from −20.0 to −9.0 ‰). Dolomite dissolution is the main process controlling the chemistry of the low-mineralized (Mg–Ca-HCO3) waters, whereas high-mineralized (Na-HCO3) waters are strongly influenced by ion-exchange reactions with adsorbed Ca2+ and Mg2+ and by evaporation.

A Deep Alteration and Oxidation Profile in a Shallow Clay Aquitard: Example of the Tégulines Clay, East Paris Basin, France

Article

Full-text available

Jan 2018
GEOFLUIDS

The oxidation profile of a surficial clay aquitard was studied on a 35-meter borecore from the Albian Tégulines Clay near Brienne-le-Château (Paris Basin, France). Mineralogical, geochemical, and petrophysical data showed evidences of gradual oxidation taking place down to a depth of 20 m. Below 20 m, the clay material was nonplastic and nonfractured, and it inherited reduced redox conditions from bacterial sulfate reduction that occurred after sediment deposition. Above 20 m, the clay material was plastic. Up to a depth of 10-11 m, only rare yellowish aggregates of glauconite attested to limited oxidation, and pore water chemistry was unmodified. The 5-11 m depth interval was characterized by intensive pyrite oxidation, calcite dissolution, and formation of sulfate and iron hydroxide minerals. The upper 2-3 m was ochrous and entirely oxidized. These mineralogical changes were mirrored with pore water chemistry modifications such as an increase of alkalinity and sulfate concentration in the upper part of the profile. The presence of siderite at ∼11 m evinced the reactivity of Fe(II) in the structure of clay minerals with dioxygen from meteoric waters that infiltrated into the Tégulines Clay through vertical fractures.

Sources, migration and transformation of antimony contamination in the water environment of Xikuangshan, China: Evidence from geochemical and stable isotope (S, Sr) signatures

Article

Jun 2016

The Xikuangshan (XKS) mine in central China is the largest antimony (Sb) mine in the world. The mining activity has seriously contaminated the waters in the area. To determine the sources, migration and transformation of Sb contamination, 32 samples from groundwater (aquifer water), surface water and mine water were collected for water chemistry, trace element and SSO4 and Sr stable isotope analyses. The results showed that the groundwater and surface water were in an oxidized environment. The SSO4 and Sr isotope compositions in the water indicated that dissolved Sb and SO4(2) originated from sulfide mineral (Sb2S3) oxidation, whereas radiogenic Sr may have been sourced from silicified limestone and stibnite in the Shetianqiao aquifer. Furthermore, a positive correlation between δ(34)SSO4 and δ(87)Sr values revealed that the Sr, S and Sb in the waters had a common contamination source, i.e., silicified limestone and stibnite, whereas the Sr, S and Sb in rock and ore were sourced from Proterozoic basement clastics. The analysis also indicated that the isotope composition of dissolved SO4(2-) had been influenced by slight bacterial SO4 reduction in the Magunao aquifer. Mining or rock collapse may have caused Shetianqiao aquifer water to contaminate the Magunao aquifer water via mixing. This study has demonstrated that the stable isotopes of (34)SSO4 and (87)Sr, combined with hydrochemical methods, are effective in tracking the sources, migration and transformation of Sb contamination.

Hydrochemical evolution and source mechanisms governing the unusual lithium and boron enrichment in salt lakes of northern Tibet

Article

Full-text available

May 2024

The large-scale salt lakes widely distributed in the Tibetan Plateau provide unique and potential resources for lithium (Li) and boron (B). The concentration and characteristics of elements in these salt lakes resemble those found in geothermal water in northern Tibet, which highlights both as crucial sources of rare elements. This study presents comprehensive analyses of the hydrochemical composition and isotopes of B, strontium (Sr), hydrogen (H), and oxygen (O) in typical salt lakes, along with samples from surrounding springs and rivers in the Bangong-Nujiang suture zone of northern Tibet. The results reveal an extremely negative and anomalous distribution pattern of B isotopes in Zabuye Salt Lake that is closely associated with geothermal water. The enrichment of these elements in other salt lakes in the region is attributed to concentration of evaporation and sediment adsorption. Given the very high elevation of the recharge for geothermal water, the infiltration of salt lakes obviously cannot feed geothermal springs. On the contrary, we correlate the unusual enrichment of Li and B and other resources in salt lakes to geothermal spring discharge. The ultimate origin of these elements lies in magmatic sources, with later water-rock interaction leading to significant enrichment of incompatible elements such as Li, rubidium (Rb), cesium (Cs), and B in the geothermal system. The geothermal springs directly or indirectly fed the salt lakes, and with further evaporation, they became super-scale brine deposits.

Hard rock aquifer architecture and water circulation levels in the Strengbach critical zone observatory (France)

Article

Nov 2023

Characterizing the water-rock interactions and groundwater flow processes in the Paleozoic to Cenozoic strata aquifer systems with contrasting mineralogy at basin scale: Qingyi river, east China

Article

Aug 2023
J HYDROL

Sr Isotope, Major, and Trace Element Signatures in Karst Groundwaters

Article

Full-text available

Apr 2023

Natural and anthropogenic factors highly influence the concentration of major (Na, Mg, K, Ca) and trace (Sr, Ba, Mn, Li) elements, anions (HCO3−, NO3−, SO42−, Cl−), and Sr isotopic signatures. The current study identified the Sr isotopic signature in groundwaters from the Southern Carpathians and Apuseni Mountains karst areas of Romania and its relation to the water’s chemistry. The Sr concentration ranged between 16.5 and 658 µg/L, but in most groundwaters, it was below 200 µg/L. A considerable spatial variation and a low temporal variation, with a slightly lower Sr concentration in the winter than in spring, were observed. The strong positive correlation of the Sr with Ca, Mg, K, and Na indicated the common source of these elements. The main source of the Sr in groundwaters was the dissolution of carbonates, especially calcite, and dolomite to a lesser extent. The 87Sr/86Sr isotopic ratio ranged between 0.7038 and 0.7158. Generally, waters with a high Sr concentration and moderate 87Sr/86Sr ratios indicated carbonate dissolution, whereas samples with low Sr concentrations and high 87Sr/86Sr ratios suggested the dissolution of silicates.

Fate of Cesium and Strontium in Soil-to-Plant System (Overview)

Article

Full-text available

Jan 2022

Mamdouh F. Abdel-Sabour

Radioactive contaminated soils can present an immediate hazard to human health as well as a chronic hazard to the environment. Knowledge of soil-specific contaminant sorption-desorption characteristics is useful for the simulation and prediction of contaminant fate, transport and diffusion in soil-water-plant systems. The objectives of this overview paper were to explore the relative importance of soil type and some soil properties in the assessment of their environmental significance. And to explore the sorption of Cs and Sr on soils developed under dry climatic conditions. In general, the behaviour of radionuclides deposited on the soil surface is controlled by their retention time in the top soil. For example, the slow movement and low migration rate of radionuclides in the soil results in a long radionuclide residence time at the plant-rooting zone and, hence, increases the probability of radionuclide uptake by the plant. Cesium (137 Cs) and strontium (90 Sr) are of special concern for soil contamination during a long half-life. The sorption of Cs and Sr in soils may be affected by a number of factors, such as the quantity and quality of the clay fraction, pH, O.M, EC, SAR and ECC.

Lithium and Strontium isotopic systematics in the Nalenggele River catchment of Qaidam basin, China: quantifying contributions to lithium brines and deciphering lithium behavior in hydrological processes

Article

Oct 2022
J HYDROL

The salt lakes fed by the Nalenggele River in the Qaidam Basin, located on the northeastern Qinghai Tibetan Plateau (QTP), are major brine lithium reservoirs in China. The quantitative identifications of the Li sources and their dynamic behavior shed light on the formation mechanism of the brine Li deposits in closed-basin of arid regions. This study presents Li and Sr isotope ratios (δ⁷Li, ⁸⁷Sr/⁸⁶Sr) and other hydrogeochemical parameters for river waters, springs, spring river waters, shallow groundwaters, surface brines, and intercrystalline brines around the Nalenggele River Basin (NRB) and its adjacent small watersheds. The results indicate that the Nalenggele River water is a mixing product of hot springs and regional surface meltwater, and the source of dissolved Li in the NRB is mainly supplied by the hot springs. With multi-tracer models, it is confirmed that around 84.9% - 93.4% of dissolved Li is provided by the Li-rich hot spring waters, which account for only 3-5% of the total water input. Furthermore, the dissolved Li in the streams of different hydrological regions shows various isotopic fractionation behavior. In general, the lower average δ⁷Li values (average of +5.6‰) with more enriched Li with respect to Na in the waters of the piedmont Gobi region indicates a significant additional input of dissolved Li from bedrock and sediments. The second-stage alluvial fan of the NRB produces ⁷Li enrichments and Li-depleted waters (compared with Na), which can be explained by the adsorption of clay or Fe (Mn) oxide phases that fractionate Li isotopes. The highest average δ⁷Li values (+12.76‰) are observed when Li is not adsorbed by the scarce fine clastic sediments in the hypersaline environment of the salt lake region. It can be concluded that the continuous halite precipitation during the brine evolution not only causes the abnormal enrichment of Li in the brine (compared with Na) but also continuously sequesters the ⁶Li from the brines, resulting in a significant ⁷Li enrichment. Overall, these findings advance the understanding of the lithium sources of Li-rich brines and its enrichment and metallogenic process during water migration in hyper-arid regions and have crucial indicative significance for lithium cycling under a strong evaporation environment.

Fonctionnement hydrogéologique et processus de transfert dans le massif fissuré instable de Séchilienne (Alpes françaises) : apports du couplage de traceurs naturels et isotopiques

Thesis

Full-text available

May 2021

Pierre Nevers

Les risques gravitaires sont à l’origine de catastrophes importantes pouvant engendrer des dégâts matériels et humains, ils sont aussi l’un des mécanismes principaux de dénudation des chaines de montagne. Il est maintenant clairement établi qu’il existe un lien entre l’instabilité gravitaire et l’eau qu’elle reçoit. La compréhension du fonctionnement des aquifères de milieux instables est d’une importance fondamentale dans l’étude de ces structures complexes dont la déstabilisation implique des enjeux considérables. C’est dans cet esprit que cette thèse s’intéresse à la relation entre le milieu instable et les écoulements souterrains du versant de Séchilienne (Isère, France). Ce travail vise à caractériser dans un premier temps le fonctionnement hydrogéologique de l’aquifère du milieu instable au travers de l’analyse de deux exutoires au sein de l’instabilité. L’utilisation de données hydrogéologiques recueillies sur le long terme permet une analyse temporelle fournissant de bonnes informations sur le fonctionnement, le dynamisme et la recharge de l’aquifère à plusieurs échelles allant du cycle hydrologique à l’année. Les analyses corrélatoires se révèlent être un bon outil quant à la compréhension du fonctionnement hydrodynamique de l’aquifère. L’apport de la chimie des eaux, est essentielle à l’identification des signatures hydrochimiques caractérisant le versant. Elle permet par ailleurs d’obtenir des informations sur l’état d’altération du versant, la composition chimique des eaux dépendant des interactions eau-roche. L’analyse comparative des deux exutoires au sein de l’instabilité couplée à l’analyse d’un exutoire de la zone stable reflète l’hétérogénéité des milieux instables et fracturés. Ce travail s’axe dans une deuxième partie, sur le couplage entre traceurs isotopiques et chimie des éléments majeurs, afin de préciser l’amplitude des réactions d’altération chimique des phases minérales induites par les interactions eau-roches à l’intérieur du versant. L’utilisation d’un modèle de mélange permet d'attribuer les différents éléments majeurs à différentes sources et de quantifier l'implication des acides sulfurique et carbonique comme source de protons. Les résultats montrent que l'instabilité crée des conditions favorables et durables au sein de la rupture, par l'ouverture de nouvelles fractures apportant des surfaces fraîches et réactives permettant la production d'acide sulfurique par oxydation de la pyrite. Les résultats obtenus permettent d’autre part d’affiner le modèle hydrogéologique préexistant par la mise en évidence de la contribution de la dissolution du gypse au budget sulfate des eaux. L’originalité de ce travail réside également dans nos résultats qui montrent le comportement du glissement de terrain de Séchilienne qui, malgré son rôle dans l'accélération de l'altération chimique et physique des roches, agit à l’échelle des temps géologiques (c'est-à-dire à des échelles de temps plus longues que les précipitations de carbonate dans l'océan) comme une source de CO2 dans l'atmosphère.

Application of hydrochemical and multi-isotopic (⁸⁷Sr/⁸⁶Sr, δ¹³C-DIC, δ²H-H2O, δ¹⁸O-H2O) tools to determine contamination sources and processes in the Guadalhorce River Basin, southern Spain

Article

Mar 2022
SCI TOTAL ENVIRON

The integrated use of multi-isotopic (⁸⁷Sr/⁸⁶Sr, δ¹³C-DIC, δ²H-H2O, δ¹⁸O-H2O) and hydrochemical data was applied in the highly anthropized Guadalhorce river basin, southern Spain, to improve the knowledge about water contamination sources and processes and to achieve improved water resource management. The results obtained highlight the importance of the use of isotopes as tracers of pollutants. DIC, δ²H-H2O, δ¹⁸O-H2O and δ¹³C-DIC allowed differentiating two water recharge end members: direct rainwater, infiltrated into the upper and lower detritic aquifers of the sub-basins, and the Guadalhorce dam system, which act as a source in some groundwater and surface waters of the lower sub-basin. ⁸⁷Sr/⁸⁶Sr data supported the existing conclusions in relation to pollution sources in the study area. The Triassic basement (evaporites) of the carbonate and detritic aquifers of the basin generally controls the natural ⁸⁷Sr/⁸⁶Sr composition in waters of the upper sub-basin. Only one groundwater sample reflects the influence of a human organic source (sewage) in its composition. On the other hand, mixing of human inorganic (fertilizers and detergents) strontium sources is required to explain the ⁸⁷Sr/⁸⁶Sr contents of the lower sub-basin waters. Discriminating the use of domestic detergents as another anthropogenic source of strontium and sulphate in waters is a novel finding in this research. The conclusions reached can be extrapolated to other anthropized basins.

Landslides as geological hotspots of CO2 emission: clues from the instrumented Séchilienne landslide, western European Alps

Article

Full-text available

Jun 2021

This study makes use of a highly instrumented active landslide observatory (9 years of data) in the French Alps, the Séchilienne slope. Here, we use a combination of major element chemistry and isotopes ratios (87Sr / 86Sr, δ34S) measured in different water types of the stable and unstable part of the Séchilienne instability to assess the contribution of the different lithologies of the slope and the chemical weathering mechanisms. Chemical and isotopic ratios are used to characterize weathering processes and the origin of waters and their flow paths through the massif. A mixing model allows us to allocate the different major elements to different sources, to identify secondary carbonate formation as a major process affecting solutes in the subsurface waters of the instability, and to quantify the involvement of sulfuric and carbonic acids as a source of protons. We show that the instability creates favorable and sustained conditions for the production of sulfuric acid by pyrite oxidation, by opening new fractures and supplying fresh reactive surfaces. We clearly identify the contribution of the dissolution of each mineral phase to the chemistry of the waters, with a clear role of remote gypsum dissolution to the sulfate budget in the sampled waters. We are also able to refine the preexisting hydrogeological views on the local water circulation and water flow paths in the instability by showing the hydrological connectivity of the different zones. Overall, our results show that the Séchilienne landslide, despite its role in accelerating rock chemical and physical weathering, acts as a geological source of CO2 to the atmosphere. If generalizable to other large instabilities in mountain ranges, this study illustrates the complex coupling between physical and chemical erosion and their impact on the carbon cycle and global climate. The study also highlights the importance of distinguishing between sulfite oxidation and gypsum dissolution as a source of sulfate ions to rivers, particularly in mountain ranges.

New understandings of the sea spray effect and its impact on bioavailable radiogenic strontium isotope ratios in coastal environments

Article

Full-text available

Oct 2020
JASR

Archaeological chemists compare the radiogenic strontium isotope ratios of humans to those of the environment in order to assess paleomobility in contexts across the world, spanning from periods before modern humans to current forensic applications. These methods rely on the variability of bioavailable strontium isotope ratios that is typically attributed to the age and composition of the geology, among other environmental factors. One such factor, the Sea Spray Effect, refers to the homogenizing impact of marine strontium on the radiogenic strontium isotope ratios found in terrestrial settings that are incorporated into the human diet by eating coastal foods. This paper explores the impact of sea spray and ocean-derived strontium on bioavailable strontium isotope ratios through the analysis of plant samples that were systematically collected along three 200 m-long transects and a hilltop control location. The uninhabited island of Inishark, Co. Galway, Ireland provides a close to pristine setting that allows these findings to be generalized to coastal contexts worldwide. Mixing models are used to interpret the impact of sea spray in comparison to that of the underlying geology and soils. The results highlight the patterned and variable manner in which ocean-derived strontium is taken up by terrestrial plants at varying distances from the coast. We suggest that the morphology of the droplet cloud formed by sea spray as it travels to shore may result in a dead zone, causing less sea spray to land directly next to the sea cliffs. The spatial and isotope data indicate that ocean-derived strontium does not have as great of an impact directly adjacent to the shoreline as it does on the isotope ratios found between 50 and 200 m from the coast. The archaeological implications of this finding include the need for more intensive baseline sampling and increased uncertainty when discussing conclusions about paleomobility in coastal settings.

O, H, and Sr isotope evidence for origin and mixing processes of the Gudui geothermal system, Himalayas, China

Article

Full-text available

Oct 2019

The Gudui geothermal field records the highest temperature at equivalent borehole depths among the mainland hydrothermal systems in mainland China. Located about 150 km southeast of Lhasa City, the capital of Tibet, the Gudui geothermal field belongs to the Sangri–Cuona rift belt, also known as the Sangri–Cuona geothermal belt, and is representative of the non-volcanic geothermal systems in the Himalayas. In this study, oxygen-18 and deuterium isotope compositions as well as ⁸⁷Sr/⁸⁶Sr ratios of water samples collected from the Gudui geothermal field were characterized to understand the origin and mixing processes of the geothermal fluids at Gudui. Hydrogen and oxygen isotope plots show both, deep and shallow reservoirs in the Gudui geothermal field. Deep geothermal fluids are the mixing product of magmatic and infiltrating snow-melt water. Calculations show that the magma fluid component of the deep geothermal fluids account for about 21.10%–24.04%; magma fluids may also be a contributing source of lithium. The linear relationship of the ⁸⁷Sr/⁸⁶Sr isotopic ratio versus the 1/Sr plot indicates that shallow geothermal fluids form from the mixing of deep geothermal fluids with cold groundwater. Using a binary mixing model with deep geothermal fluid and cold groundwater as two end-members, the mixing ratios of the latter in most surface hot springs samples were calculated to be between 5% and 10%. Combined with basic geological characteristics, hydrogen and oxygen isotope characteristics, strontium concentration, ⁸⁷Sr/⁸⁶Sr ratios, and the binary mixing model, we infer the 6th-Class Reservoirs Evolution Conceptual Model (6-CRECM) for the Gudui geothermal system. This model represents an idealized summary of the characteristics of the Gudui geothermal field based on our comprehensive understanding of the origin and mixing processes of the geothermal fluid in Gudui. This study may aid in identifying the geothermal and geochemical origin of the Gudui high-temperature hydrothermal systems in remote Tibet of China, whose potential for geothermal development and utilization is enormous and untapped.

Water Quality Assessment of a Meromictic Lake Based on Physicochemical Parameters and Strontium Isotopes ( 87 Sr/ 86 Sr) Analysis: A Case Study of Lubí nskie Lake (Western Poland)

Article

Full-text available

Oct 2019

In 2017, hydrochemical surveys of meromictic Lubí nskie Lake (W Poland) and its water inflows were carried out. The lake experienced complete mixing in 2008 due to a series of orkan winds, and since 2015, intensifying worsening of water quality in the lake has been observed. Our aim was to determine the degree of transformation of Lubí nskie Lake based on water chemistry and to identify the source of pollution of the lake using strontium isotopes (87 Sr/ 86 Sr) as a new chemical tracking tool. The physicochemical analysis confirmed the meromictic character of the lake. The comparison with previous studies (2003 and 2008) showed significant year-to-year differentiation, indicating intensifying eutrophication of the lake's water, both in the epilimnion and the hypolimnion. Nine spring niches, directly supplying the lake, provide water with very high phosphorus and nitrogen concentrations (up to 10 kg of nitrogen and 0.9 kg of phosphorus daily). The strontium isotopes (87 Sr/ 86 Sr) analysis indicated that the lake's water was supplied mostly by the springs, and recharge from deep aquifers is of secondary importance. Moreover, strontium isotope data and the relationship between Sr and Cl content support the finding that the high load of nutrients is of anthropogenic origin and reaches the lake through springs.

Assessment of Chaves Low-Temperature CO 2 -Rich Geothermal System (N-Portugal) Using an Interdisciplinary Geosciences Approach

Article

Full-text available

Feb 2019
GEOFLUIDS

This paper reviews the results of a multi- and interdisciplinary approach, including geological, geomorphological, tectonic, geochemical, isotopic, and geophysical studies, on the assessment of a Chaves low-temperature (77°C) CO 2 -rich geothermal system, occurring in the northern part of the Portuguese mainland. This low-temperature geothermal system is ascribed to an important NNE-trending fault, and the geomorphology is dominated by the “Chaves Depression,” a graben whose axis is oriented NNE-SSW. The study region is situated in the tectonic unit of the Middle Galicia/Trás-os-Montes subzone of the Central Iberian Zone of the Hesperic Massif comprising mainly Variscan granites and Paleozoic metasediments. Chaves low-temperature CO 2 -rich geothermal waters belong to the Na-HCO 3 -CO 2 -rich-type waters, with pH≈7 . Total dissolved solids range between 1600 and 1850 mg/L. Free CO 2 is of about 500 mg/L. The results of SiO 2 and K ² /Mg geothermometers give estimations of reservoir temperature around 120°C. δ¹⁸ O and δ² H values of Chaves low-temperature CO 2 -rich geothermal waters indicate a meteoric origin for these waters. No significant ¹⁸ O-shift was observed, consistent with the results from the chemical geothermometry. δ¹³ C CO2 values vary between −7.2 and −5.1‰ vs. V-PDB, and CO 2 / ³ He ratios range from 1×10 ⁸ to 1×10 ⁹ , indicating a deep (upper mantle) source for the CO 2 . ³ He/ ⁴ He ratios are of about 0.9 (R/Ra). The Chaves low-temperature CO 2 -rich geothermal waters present similar ⁸⁷ Sr/ ⁸⁶ Sr ratios (between 0.728035 and 0.716713) to those of the plagioclases from granitic rocks (between 0.72087 and 0.71261) suggesting that water mineralization is strongly ascribed to Na-plagioclase hydrolysis. Geophysical methods (e.g., resistivity and AMT soundings) detected conductive zones concentrated in the central part of the Chaves graben as a result of temperature combined with the salinity of the Chaves low-temperature CO 2 -rich geothermal waters in fractured and permeable rock formations. This paper demonstrates the added value of an integrated and multi- and interdisciplinary approach for a given geothermal site characterization, which could be useful for other case studies linking the assessment of low-temperature CO 2 -rich geothermal waters and cold CO 2 -rich mineral waters emerging in a same region.

A strontium (87Sr/86Sr) isotopic study on the chemical evolution and migration of groundwaters in a low-rank coal seam gas reservoir (Surat Basin, Australia)

Article

Feb 2019
APPL GEOCHEM

Strontium isotopes, water chemistry and whole rock chemistry have been used to investigate the evolution of water from its surface meteoric composition into methane-rich groundwater. Previous studies established that co-produced Surat Basin coal seam gas waters from the Walloon Subgroup (Queensland, Australia) are meteoric in origin and are distinct across the main production regions but the dominant hydrochemical processes have yet to be determined. In this study, strontium isotope ratios (⁸⁷Sr/⁸⁶Sr) were measured on production waters from 36 coal seam gas wells, 14 sequentially leached host rock samples and 6 whole rock samples to improve understanding of the water-rock reactions that control spatial variability in solute and isotope chemistry. Strontium isotope ratios of Walloon Subgroup production waters across all production areas are uniformly low in value, ranging from 0.70338 to 0.70456. The majority of values are significantly lower than shallow Walloon formation waters in the recharge zone and extend the lower range of ⁸⁷Sr/⁸⁶Sr ratios recorded for Surat Basin groundwaters. These very low ⁸⁷Sr/⁸⁶Sr ratios (0.70338) are reached early along the flow paths, within 10 km of the shallow recharge area waters, before then undergoing a gradual increase with flow distance. Mineralogical and geochemical analyses of whole rock samples representing each of the main lithologies across the Walloon Subgroup has identified that the low ⁸⁷Sr/⁸⁶Sr ratios are not derived from any one interval but rather the combination of the same few minerals that are present in every unit. The rapid accumulation of relatively non-radiogenic strontium early in the flow path across all three gas producing regions has been attributed to a combination of fluid-rock interactions occurring within the Walloon Subgroup itself. Initial surface ⁸⁷Sr/⁸⁶Sr ratio values are quickly dominated through a combination of processes whereby recharge waters with low Sr concentrations are absorbed onto montmorillonite clays via cation exchange and this combined with weathering of plagioclase causes a re-equilibration of the groundwater to lower ⁸⁷Sr/⁸⁶Sr ratios. Strontium ratios then start to slowly increase again with flow distance through silicate weathering of K-feldspars and muscovites, which are present at low levels across the basin. Local geological features such as the Hutton-Wallumbilla fault and the Kogan and Undulla anticlines appear to influence flow paths and consequently water and gas composition.

STRONTIUM CONTENT IN SANDY SOILS IN AGRICULTURE FIELDS (CASE STUDY: MOUNDOU, CHAD)

Article

Full-text available

Sep 2018

During evaluation of physical and chemical properties of sandy soils and theirfertility in Southern part of Republic of Chad it has been revealed that some soilshave very high content of strontium. Its content varies from 10 to 270 mg/kg ofsoil depending on type of soil, depth of soil layers, clay and organic content.Strontium content negatively correlates with total content of calcium andphosphorus in layers of soil. Low CEC (CEC - Cation-exchange capacity) of soilmay be a reason of possible translocation of strontium from higher to lower layersof soils. Strontium content in soils do not relates with level of radioactivity of soilmeasured. The highest content of strontium has been found in soils developed onsome eolian and colluvio-alluvium deposits. Some researchers hypothesize thatsome endemic and chronic diseases such as Kashin-Beck disease, `Dysostosisenchondralis endemic`, endemic hoiter, osteoarthritis might be caused by highcontent of strontium in water and plant foods contaminated with it. Absence ofconsensus on etiological factors of these diseases confirms that it is worthconsidering necessity of further studies of different affects of high content ofstrontium in water and foods on human health directly or indirectly throughcausing misbalance in mineral nutrition.

Hydrogeochemical and isotopic characterization (87Sr/86Sr) of Barreiras and Upper Pirabas aquifers systems in Castanhal and Santa Maria do Pará municipalities, Pará State

Chapter

Full-text available

Sep 2017

Isotopic composition of strontium and hydrogeochemical studies have been conducted in water samples from Barreiras and Upper Pirabas aquifers systems in subareas of Castanhal and Santa Maria do Pará to characterize their waters, as well as detection of possible mixing processes between them. Barreiras aquifer has waters predominantly Cl–-Na+, resulting from the strong contribution of meteoric water and anthropogenic action and high vulnerability. The waters of the Upper Pirabas Aquifer System are mostly HCO3–-Ca2+, due the strong inflence of carbonate dissolution and less vulnerability to human action. Isotopic results showed that the Barreiras Aquifer samples are more radiogenic (0.712716 to 0.723881) that the sample of the Upper Pirabas Aquifer System (0.706080 to 0.709063), occurring a light homogenization process of isotopic ratios of these aquifer systems in the rainy season. Statistical studies have shown good correlations between the system aquifers (≥ 0.7). The multivariate statistical analysis (PCA), with the 87Sr/86Sr diagram vs. 1/Sr showed a mix trend between these aquifers and rainwater during the wet season. The hydrogeochemical modeling (Schoeller diagram) indicated that the degree of mixing of waters of the Aquifer Pirabas Superior in Barreiras is around 10% during the rainy season.

Coupled S and Sr isotope evidences for elevated arsenic concentrations in groundwater from the world's largest antimony mine, Central China

Article

Dec 2017
J HYDROL

The Xikuangshan(XKS) mine, the world's largest antimony mine, was chosen for a detailed arsenic hydrogeochemical study because of the elevated arsenic in bedrock aquifers used by local residents. Hydrochemical data, δ³⁴S values of dissolved SO4²⁻ and ⁸⁷Sr/⁸⁶Sr ratios have been analyzed to identify the predominant geochemical processes that control the arsenic mobilization within the aquifers. Groundwater samples can be divided into three major types: low arsenic groundwater (0–50 µg/L), high arsenic groundwater (50–1000 µg/L) and anomalous high arsenic groundwater (>1000 µg/L). Arsenic occurs under oxidizing conditions at the XKS Sb mine as the HAsO4²⁻ anion. The Ca/Na ratio correlates significantly with HCO3⁻/Na and Sr/Na ratios, indicating that carbonate dissolution and silicate weathering are the dominant processes controlling groundwater hydrochemistry. The δ³⁴S values of the groundwater indicate that dissolved SO4²⁻ in groundwater is mainly sourced from the oxidation of sulfide minerals, and elevated As concentrations in groundwater are influenced by the mixing of mine water and surface water. Furthermore, the δ³⁴S values are not correlated with dissolved As concentrations and Fe concentrations, suggesting that the reduction dissolution of Fe(III) hydroxides is not the dominant process controlling As mobilization. The ⁸⁷Sr/⁸⁶Sr ratios imply that elevated As concentrations in groundwater are primarily derived from the interaction with the stibnite and silicified limestone. More specifically, the excess-Na ion, the feature of Ca/Na ratio, and the spatial association of elevated As concentrations in groundwater collectively suggest that high and anomalous high arsenic groundwater are associated with smelting slags and, in particular, the arsenic alkali residue. In general, the hydrochemistry analysis, especially the S and Sr isotope evidences elucidate that elevated As concentrations and As mobilization are influenced by several geochemical processes, including: (1) bedrock weathering; (2) oxidation of arsenopyrite and the dominant sulfides in the ores; (3) mixing of mine drainage and surface water; (4) leaching of the arsenic alkali residue; and (5) sorption-desorption from Fe/Mn oxides/hydroxides.

Geosciences in the assessment of thermal and mineral groundwater systems in N-Portugal: a review

Article

Full-text available

Dec 2019

In the North of Portugal, thermal and mineral groundwater resources (e.g., Chaves CO2-rich thermal—76 °C—waters) are being used in the local Spas, and are considered one of the main sources of local/regional development/income. A multidisciplinary approach, including geological, tectonic, geochemical and isotopic (²H, ¹⁸O, ¹³C, ⁸⁷Sr, ³H, ¹⁴C and ³He/⁴He) methodologies, was used to assess local/regional conceptual circulation models. In the case of the Chaves CO2-rich thermal waters, this approach provided important data to answer the most commonly asked questions so as to enable the elaboration of a robust hydrogeological conceptual model, namely (1) Chaves thermal waters belong to the HCO3/Na/CO2-rich type (with pH ≈7), in that the result of meteoric waters–granitic rocks–gas (CO2) interaction; (2) Padrela Mountain (NE-Chaves), ascribed to high-fractured rocks, is the main recharge area; the stable isotopic composition of the groundwater samples indicate a mean recharge altitude higher than 1150 m a.s.l.; (3) the mean Sr isotopic ratio of the thermomineral waters (⁸⁷Sr/⁸⁶Srmean = 0.722419) is similar to that of the Sr isotopic ratios of the plagioclases of the granitic rocks (e.g. ⁸⁷Sr/⁸⁶Sr = 0.72087; ⁸⁷Sr/⁸⁶Sr = 0.71261), indicating that hydrolysis of plagioclase is the main water–rock interaction process, favoured by the presence of deep-seated (mantle-derived) CO2 (δ¹³C values in the range of −6 to −1‰ vs. PDB, and the CO2/³He values from 5.1 × 10⁸ to 7.5 × 10⁹, are typical of MORB fluids); (4) the income of carbon-14 free to Chaves CO2-rich thermal waters system does not permit reliable ¹⁴C groundwater dating; (5) the geothermometric results (e.g. K²/Mg and silica geothermometers) indicate equilibrium temperatures around 120 °C, and a maximum depth of about 3.5 km reached by the Chaves CO2-rich thermal waters system was estimated. The discharge zones are mainly related to the intersection of the main local/regional fault lineaments (and conjugate structures), responsible for promoting the mineral and thermal groundwater ascent.

A hydrogeochemistry and multi-isotope (Sr, O, H, and C) study of groundwater salinity origin and hydrogeochemcial processes in the shallow confined aquifer of northern Yangtze River downstream coastal plain, China

Article

Sep 2017
APPL GEOCHEM

Economically developed coastal areas have a high water demand, and their groundwater resources can be threatened by salinization. Many methods and tracers have been used to discriminate the source of salinization because a single method does not yield reliable results. In this paper, the shallow confined coastal plain aquifer, north of the downstream Yangtze River in China, is used as a case study to investigate the origin of the salinity and the relevant geochemical processes for this aquifer. Multiple environmental tracers of major ions, minor ions (Br⁻, I⁻), and isotopes (¹⁸O, ²H, ¹³C, ⁸⁷Sr, ³H, ¹⁴C) were used so as to provide reliable conclusions. The TDS distribution of the aquifer has an increasing trend, from below 500 mg/L in the inland areas to more than 20,000 mg/L around the southeast coastline. The water chemical type evolves from HCO3-Ca to Cl-Na as the TDS increases. The results suggest that the groundwater salinity is influenced by seawater intrusion. The seawater proportions in the groundwater samples range from 0.07% to 94.41% and show the same spatial distribution pattern as TDS. The ³H and ¹⁴C values show that the highest salinity was mainly caused by a seawater transgression around 6000a B.P. The aquifer is also affected by other hydrogeochemical processes: base exchange has enriched Ca²⁺ and depleted K⁺ and Na⁺, sulfate reduction has reduced the concentration of SO4²⁻ and enriched HCO3⁻, and iodine-rich organic matter decomposition has enriched the concentration of I⁻. The iodine enrichment also suggests paleo-seawater intrusion. In addition, the precipitation of carbonate minerals has decreased the concentration of Ca²⁺, Mg²⁺, and HCO3⁻, albeit to a limited extent.

A multi-isotope approach (O, H, C, S, B and Sr) to understand the source of water and solutes in some the thermal springs from West Coast geothermal area, India

Article

Full-text available

Jun 2017

The West Coast belt, consisting of nearly 60 thermal springs, is one of the most diversified geothermal fields in India. The present work describes the multi-isotopic (O, H, C, S, B and Sr) characterization of thermal waters carried out in the Tural-Rajwadi geothermal field, situated in southern sector of the west coast geothermal area. The aim of this study is to delineate the origin of thermal water as well as to ascertain the sources of carbon, sulphur, boron and strontium dissolved in those thermal springs. The stable isotopes (δ2H and δ18O) and tritium data indicate that these thermal springs are not recently recharged rain water rather, it contains very old component of water. Oxygen-18 shift is observed due to rock-water interaction over a long period of time. Carbon isotopic composition of DIC points out to the silicate weathering with soil CO2 coming from C3 type of plants whereas δ34S of dissolved sulphate confirms the marine origin of sulphate. This marine signature is basically derived from paleo-seawater possibly entrapped within the flows. Boron isotopic data reveals that both the seawater and rock dissolution are the sources of boron in the thermal waters whereas high 87Sr/86Sr ratios (0.7220–0.7512) of the thermal waters conclusively establishes that archean granitic basement is the predominant rock source of strontium, not the Deccan flood basalts. In addition, like strontium, concentrations of lithium, rubidium and caesium are also governed by the rock-water interaction. Thus, the combined use of this multi-isotope technique coupled with trace element concentrations proves to be an effective tool to establish the sources of solutes in the thermal water.

Respective roles of the weathering profile and the tectonic fractures in the structure and functioning of crystalline thermo-mineral carbo-gaseous aquifers

Article

Full-text available

Feb 2017
J HYDROL

Crystalline thermo-mineral and carbo-gaseous (CTMCG) hydrosystems are well known for their economic importance in fields such as thermal, spa activities and natural mineral water (NMW) bottling. Such systems are usually associated with strong structural complexity, which is rarely characterised in detail or robustly. This research focuses on a CTMCG hydrosystem associated with a peri-alpine graben. A multidisciplinary approach with a very large set of data and methods - geological modelling with geophysics and geological data from outcrops and several boreholes, hydrodynamic data, hydrochemistry, hydrogeological and geochemical modelling - reveals very novel results and allows a robust conceptual model to be constructed. The aquifer at the origin of the carbogaseous natural mineral water is the 100-125 m-thick fractured stratiform layer of the weathering profile of the crystalline rock (granite). It forms a rather large and thick inertial aquifer that can be numerically modelled, in a similar fashion to a porous medium. The majority of tectonic faults length act as impervious boundaries that divide this aquifer into around ten elongated compartments that were precisely delineated. These tectonic faults are permeable only along two small areas that were also precisely located. These permeable zones feed some aquifer compartments with deep, highly mineralised carbo-gaseous water, which mixes with “fresher” water and forms the exploited NMW. These results can be generalised and in particular show a strong opposition between low-inertia CTMCG hydrosystems without a subsurface reservoir, as the weathering profile was eroded, and high-inertia hydrosystems such as the one studied.

Chemical and strontium isotope characterization of rainwater in karst virgin forest, Southwest China

Data

Full-text available

Dec 2016

Acid rain and alkalization in southwestern China： chemical and strontium isotope evidence in rainwater from Guiyang

Data

Full-text available

Dec 2011

Using radon to understand parafluvial flows and the changing locations of groundwater inflows in the Avon River, southeast Australia

Article

Full-text available

Sep 2016

Understanding the location and magnitude of groundwater inflows to rivers is important for the protection of riverine ecosystems and the management of connected groundwater and surface water systems. This study utilizes 222Rn activities and Cl concentrations in the Avon River, southeast Australia, to determine the distribution of groundwater inflows and to understand the importance of parafluvial flow on the 222Rn budget. The distribution of 222Rn activities and Cl concentrations implies that the Avon River contains alternating gaining and losing reaches. The location of groundwater inflows changed as a result of major floods in 2011–2013 that caused significant movement of the floodplain sediments. The floodplain of the Avon River comprises unconsolidated coarse-grained sediments with numerous point bars and sediment banks through which significant parafluvial flow is likely. The 222Rn activities in the Avon River, which are locally up to 3690 Bq m−3, result from a combination of groundwater inflows and the input of water from the parafluvial zone that has high 222Rn activities due to 222Rn emanation from the alluvial sediments. If the high 222Rn activities were ascribed solely to groundwater inflows, the calculated net groundwater inflows would exceed the measured increase in streamflow along the river by up to 490 % at low streamflows. Uncertainties in the 222Rn activities of groundwater, the gas transfer coefficient, and the degree of hyporheic exchange cannot explain a discrepancy of this magnitude. The proposed model of parafluvial flow envisages that water enters the alluvial sediments in reaches where the river is losing and subsequently re-enters the river in the gaining reaches with flow paths of tens to hundreds of metres. Parafluvial flow is likely to be important in rivers with coarse-grained alluvial sediments on their floodplains and failure to quantify the input of 222Rn from parafluvial flow will result in overestimating groundwater inflows to rivers.

Groundwater contamination studies by environmental isotopes: A review

Article

Jan 2016

Water demand for urban, industrial, and agricultural purposes is a major concern in developed and third world countries. A careful evaluation for an appropriate and sustainable use of water resources is a priority. Geochemical processes can lead to measurable variations of the aquatic environment, which can be studied through the analysis of the dissolved solutes. Even if this review is not meant to be exhaustive, it is intended to give a view on the importance of environmental isotopes in the context of groundwater quality assessments. This is done by briefly recalling some basic notions for each described system, followed by relevant applications and reports about some significant case studies. This review includes well-established isotopic systematics, such as those of O and H in water, C in dissolved inorganic carbon (DIC), S and O in sulfates, and N and O in nitrates and those of boron and Sr, which in the last lustrums have found large application in the field of water geochemistry. This chapter ends with some examples related to nontraditional isotopes, i.e., Fe, Cr, and Cu, in order to highlight the potential of the environmental isotopes to trace sources, fate, and behavior of different solutes and metals in surface water and groundwater.

Isotope and REE Characterization of Groundwater Aquifers within the Aquifer Storage and Recovery Programme in Sukhothai (N.-Thailand)

Article

Full-text available

Jan 2016

Using environmental isotopes and dissolved methane concentrations to constrain hydrochemical processes and inter-aquifer mixing in the Galilee and Eromanga Basins, Great Artesian Basin, Australia

Article

Aug 2016
J HYDROL

Assessing magmatic contributions to rift-related geothermal systems in collisional orogens: Insights from the Sangri-Cona rift, southern Tibetan Plateau

Article

May 2024

87Sr/86Sr Tracer for the Formation and Evolution of Deep Underground Brines in Sedimentary Basins

Conference Paper

Oct 2023

The basic research on the source and evolution of deep underground brines is helpful to deepen understanding for the formation of natural hydrosphere, and also of great significance to evaluate the diagenetic history assessment of basins (such as mineralization, crustal circulation, fluid flow and migration) and reservoir yield management. In recent years, the combination of traditional element geochemistry and isotope techniques, especially the 87Sr/86Sr isotope, has made the research on the source, formation and evolution of deep underground brines in basins gradually becoming an international hot topic. In this paper, the research progress of application and development of 87Sr/86Sr tracer for the source and formation of deep underground brines was summarized and commented. And the numerical ranges of different stable isotopes in deep underground brines and other natural reservoirs are summarized. Until now, the studies indicated that the 87Sr/86Sr values in deep underground brines mainly ranged from 0.70810 to 0.72413. This paper is helpful to deepen the understanding of strontium isotope and provide a reference for research on the formation and evolution of deep underground brines in in sedimentary basins.

Origin of Li brine-type deposits in the Cretaceous gypsum-bearing formation of the Jitai Basin, South China: Constraints from geochemistry and H, O, Li, B, and Sr isotopes

Article

Feb 2022
APPL GEOCHEM

Li brine-type deposits have recently been discovered in the Upper Cretaceous gypsum-bearing formation of the Jitai Basin, South China. The source and enrichment mechanism of Li in brines, however, are still unclear. To define the origin of lithium and evaluate the water-rock interaction process, this work presents chemical and multi-isotope data for Li-rich brines from the Jitai Basin. Seven brine samples collected from Meigang boreholes contain high salinities of 190–339 g/L, lithium concentrations of 60.6–106.0 mg/L, and low magnesium/lithium ratios of ∼11. The good correlation between δD and δ¹⁸O values suggests that the primary brine has been diluted by meteoric water, while contributions from halite dissolution or secondary brines having dissolved solid halite are also indicated by the high Na/Cl (0.58–0.63) and Cl/Br (average of ∼26987) mass ratios, the Na deficit and Ca excess, and the fact that high-salinity brines have lower δD, δ¹⁸O and δ³⁴SSO4 values. Among the chemical geothermometers commonly used in the literature, only the SiO2-chalcedony, Na/K/Ca and K/Mg thermometric relationships give concordant temperature values of 120 ± 15 °C for the deep reservoir of these brines, suggesting that the latter are not in full chemical equilibrium with the reservoir rocks (excess of sodium due to halite dissolution), but this temperature can be considered as representative of their deep reservoir. Moreover, most of the chemical geothermometers yield close temperature values of 115 ± 15 °C for the deep reservoir of three neighboring dilute thermal waters. The homogeneous ⁸⁷Sr/⁸⁶Sr ratios (0.713865–0.713915) and δ¹¹B (+1.8‰–+3.4‰) and δ⁷Li (+13.1‰–+14.2‰) values show a close affinity to the continental crust, possibly implying a fluid signature involving the interactions between clastic host rocks and brines. X-ray diffraction and scanning electron microscopy analyses and Li contents of reservoir rocks reveal the presence of dominant lithian muscovites of clastic origin, probably originating from weathering of Li-enriched igneous rocks, which contribute to most of the lithium input in the hydrologic system of the basin. Thus, it is proposed that lithium enrichment in brines from the Upper Cretaceous gypsum-bearing clastic aquifers of the Jitai Basin was generated by water-rock interactions involving lithian muscovites.

Multi-isotopic (O, H, C, S, Sr, B, Li) characterization of waters in a low-enthalpy geothermal system in Havza (Samsun), Turkey

Article

Dec 2021
GEOTHERMICS

In this study, multi-isotopic (O, H, C, S, Sr, B, Li) compositions were used to perform geochemical characterization, determine the source and reservoir rocks, and explain the water-rock interaction mechanisms for geothermal fluids in the low-enthalpy Havza (Samsun) geothermal field (HGF) in Turkey. The geothermal water of Na-HCO3 water type has a wellhead temperature of 53°C, pH of nearly 7.7 and an EC value of 1140 µS/cm. The geothermal springs of Ca-HCO3 water type have an EC value of nearly 667 µS/cm and a temperature of nearly 26°C. The reservoir temperatures of the HGF geothermal system were calculated as 60–90°C and 108–160°C by silica and SO4-H2O oxygen isotope geothermometers, respectively. Stable isotope compositions (δ²H and δ¹⁸O) show that the geothermal well water is mixed with deeply circulated waters fed from higher elevations (∼ 830–1260 m), while the geothermal spring water is mixed with shallow cold water. The positive δ¹³C value (+3.01‰) indicates that the dissolved inorganic carbon (DIC) in the geothermal well water has no contribution from the atmospheric CO2 but originates in the metamorphic CO2 and marine limestones. However, the DIC in the geothermal springs is derived from C3 plants and silicate weathering. The values of ³⁴SCDT show that the sulfate in the geothermal waters is due to the dissolution of sulfate minerals. The values of δ¹¹B (-1.12 to +9.37 ‰) in the geothermal well and spring waters reflect both leaching of surrounding rocks and mantle-derived B. The reservoir rock may be Late Cretaceous-Permian limestones and Jurassic sandstones considering ⁸⁷Sr/⁸⁶Sr ratios (0.707108–0.707688) and δ⁷Li values (-7.44 to +6.18 ‰), whereas it might be Jurassic sandstones based on δ¹¹B values. The strontium isotope composition of the geothermal spring water indicates the mixing of deep geothermal waters and cold groundwaters.

Strontium isotopic and hydrochemical characteristics of shallow groundwater and lake water in the Badain Jaran Desert, North China

Article

Aug 2021

Shallow groundwater and lake water are the dominant water resources in the Badain Jaran Desert. There are still controversial hypotheses related to the origin of groundwater in this desert. Few studies have been conducted to explore the Sr provenance of these waters and assess the water–rock interactions using a Sr isotope approach until now. In this text, the Sr isotope data of waters in the hinterland of the Badain Jaran Desert and neighbouring areas are reported. The waters in the Badain Jaran Desert have few links to its surrounding rivers, but could be influenced by the precipitation in the Yabulai Mountains. The ⁸⁷Sr/⁸⁶Sr ratio changes constantly, while the Sr²⁺ concentration of shallow groundwater gradually decreases from Yabulai to the desert hinterland to Gurinai-Guaizihu. Combined with hydrochemical data and hydrodynamic conditions, these results show that the dissolved Sr of waters in the desert hinterland is controlled by the Yabulai precipitation and catchment weathering. They further show that the desert shallow groundwater Sr originates mainly from the Yabulai precipitation (> 94 %), while whole-rock weathering contributes little (< 6 %), as calculated using isotope mass balance equations. Relative Sr contributions to lakes from shallow groundwater and catchment weathering are calculated to be 92.5 and 7.5 %, respectively.

Origin of the enrichment of B and alkali metal elements in the geothermal water in the Tibetan Plateau: Evidence from B and Sr isotopes

Article

Jun 2021
CHEM ERDE-GEOCHEM

Geothermal fields distributed in the southern Tibet Plateau rifts such as Yangbajing - Dangxiong basin, and the Yaluzangbu suture are characterized by intensive hydrothermal activity and high enrichment of trace elements (e.g., Li, Rb, Cs, B and Br) in geothermal springs. However, the origin of these elements and their enrichment mechanisms in those geothermal waters remain unclear. This study presents data for the enriched elements, incompatible elements, and B and Sr isotopes, in the geothermal water in the Tibetan Plateau and compares them with some typical geothermal fields worldwide, in an attempt to provide new insights into the origin and mechanism of the enrichment of these trace elements. The results indicate that all geothermal water samples from the Tibetan Plateau show more negative δ¹¹B values than those from local precipitation and rivers. Considering the wide existence of a high-conductivity zone in the middle or even upper-crust interpreted to correspond to re-melt magmatic fluids in the Tibet, the main sources of the typical chemical composition of geothermal waters in the Tibetan Plateau can be classified into two main types: residual magmatic fluids derived from crustal partial remelting and deep circulated groundwater modified by water–rock interactions. In particular, the possible source of magmatic fluids may play a more significant role for special geochemical compositions of geothermal water in the Tibet. Such resources are beneficial for the development and utilization of the geothermal water itself and also serve as a stable source for feeding the salt lake resources.

Evolution of groundwater chemistry in coastal aquifers of the Jiangsu, east China: Insights from a multi-isotope (δ2H, δ18O, 87Sr/86Sr, and δ11B) approach

Article

Nov 2020
J CONTAM HYDROL

Groundwater salinization is currently a very serious and challenging issue in many parts of the world. With an increasing demographic pressure and remarkable changes of water and land uses over the last decades, the multilayer coastal aquifer system of Jiangsu province, east China, was affected by increasing salinization. In this study, we investigate the groundwater salinization process and the salinity sources of the aquifer system in Nantong area (southern part of the Jiangsu coastal plain) using a multi-isotope (δ²H, δ¹⁸O, ⁸⁷Sr/⁸⁶Sr, and δ¹¹B) approach. The results show that the TDS (total dissolved solids) values in most deep groundwater samples are generally lower than those of the shallow groundwater samples. The TDS of both shallow and deep groundwater increase from western Nantong (inland) to the eastern coastal region of the Yellow Sea. The chemical types transform from Ca-Mg-HCO3 or Mg-Ca-HCO3 to NaCl. The stable hydrogen and oxygen isotopes signatures of the groundwater samples indicate that local precipitation likely acts as the main recharge source of both the shallow and deep confined groundwater systems. The deep groundwater shows more depleted isotopes, suggesting recharging by the precipitation under a cold climate before the Holocene period. The shallow groundwater features heavier water isotopes, indicating recharging source from recent precipitation under a warm climate. The variations in δ¹¹B and ⁸⁷Sr/⁸⁶Sr of groundwater samples can be explained by the changes of solute sources. In the inland region (western Nantong), shallow groundwater with higher TDS is mainly caused by evaporation-induced concentration, whereas in coastal areas, seawater intrusion exerts a major influence on the chemical composition of the shallow groundwater. Our results show that that seawater intrusion mainly occurs in eastern and southeastern Nantong area. We also find that hydraulic connection between shallow and deep groundwater is strengthened by continuous overexploitation, and deep groundwater is mixed with shallow groundwater at some points. The mixing between upper saline water and deep freshwater, together with water-rock interactions, likely explain the observed low salinity in deep groundwater in coastal areas. Overall, with growing observations of salty seawater intrusion in the estuary region of the Yangtze River, future efforts are needed to prevent further seawater intrusion as sea level rises and groundwater table declines. In this context, our findings provide key information for groundwater management in other coastal aquifers, east China.

Behaviour of Li isotopes during regolith formation on granite (Massif Central, France): Controls on the dissolved load in water, saprolite, soil and sediment

Article

Jun 2019
CHEM GEOL

Lithium (Li) contents and isotopes were studied in all environments of a small river catchment draining granite in the Margeride mountains of the French Massif Central. This covered surface waters, primary and accessory minerals of the granites, the whole rock, and soil and sediment samples developed in the catchment, completed with regional data for mineral waters and rainwater. The integrated investigation aimed at evaluating the potential of Li isotopes as effective tracers of water/rock interaction processes within a granitic environment. The δ⁷Li values and Li concentrations were measured on sediment- and soil samples, following standard acid-dissolution procedures and chemical purification of Li using the cationic exchange resin protocol in a clean lab. Lithium-isotope compositions were measured with a Neptune MC-ICP-MS and Li concentrations by ICP-MS. The samples represented different stages of granite weathering, including fresh granite, weathered-rock, surface saprolite, and sediments in riverbanks and fields bordering the streams. The extent of Li mobility during granite weathering was first evaluated through determining the percentage change relative to Ti, with a range from −31 to −66% in the collected samples. The weathered-rock was depleted by −47% for Li with negative δ⁷Li values ranging from −1.9 to −3.4‰. Soil to riverbank sediment samples were characterized by less negative δ⁷Li values, indicating that Li is enriched in soil with fractionation of Li isotopes and changes of the mineral abundance in the samples. To complement this first view, we i) Modelled the theoretical Li isotope signature of water interacting with granite, using a weathering model based on dissolution; ii) Applied an atmospheric-input correction to surface waters; iii) Applied a Raleigh equation for modelling the Li isotope fractionation when compared with corrected surface water and mineral water; and iv) Compared Li isotopes with Sr-isotope data in a larger weathering framework.

Section: Isotopic Evidence Bibliography

Research

Full-text available

Apr 2019

Michael Hochrein

This represents one of several sections of "A Bibliography Related to Crime Scene Interpretation with Emphases in Geotaphonomic and Forensic Archaeological Field Techniques, Nineteenth Edition" (The complete bibliography is also included at ResearchGate.net.). This is the most recent edition of a bibliography containing resources for multiple areas of crime scene, and particularly outdoor crime scene, investigations. It replaces the prior edition and contains approximately 10,000 additional citations. As an ongoing project, additional references, as encountered, will be added to future editions. Popular and scientific references to the use of stable isotopes in identifying skeletal remains; or, more accurately, identifying geographical ranges in which the decedent may have lived, are the focus of this section. It also includes topics such as Carbon 14 dating and bomb pulse data. Stable isotope analyses may provide investigators clues to the spatial history of unidentified victims. Our bones and teeth, throughout our lives become reservoirs for those chemical elements to which we are exposed. The longer those exposures to the varied concentrations of different elements in different areas of the world, the more likely the victim can be determined as having resided in a particular area. By knowing the areas inhabited by a victim, the more likely investigators will be able to track down his, or her, identity. Unlike radioactive isotopes, stable isotopes never disintegrate. Schwarz, (2007), provides a good example of the forensic value of stable isotopes: "Most of the O atoms in our body come from the water we drink, and is usually isotopically like the precipitation where we live. Therefore, we can often learn where a person lived from the isotopic composition of their teeth and bones. Fortunately, we now have maps showing the distribution of 18O/16O ratios in precipitation falling over North America and Europe which we can use to help trace the place of origin of a murder victim. Even burned remains can be analyzed this way." (Schwarz, 2007:28) Like DNA, stable isotope analyses will continue to be developed and be refined. And like DNA analyses, it may someday be a staple in the forensic scientist's toolbox. Because stable isotope analysis is so dependent on the proper collection of known environmental samples, the researcher is also referred to the section Geoarchaeology and Soil Science. Our culture obviously impacts and reflects where we live and what we consume. For those reasons, the researcher may find useful citations in the section entitled Criminal and Cultural Behavior. That said, crime scene investigators should also remember that other animal species and plant life associated with crime scenes, also reflect stable isotope signatures which may aid in reconstructing crime scene events. (2076 citations)

The Campo de Calatrava Volcanic Field (central Spain): Fluid geochemistry in a CO2-rich area

Article

Mar 2019
APPL GEOCHEM

The Campo de Calatrava Volcanic Field (CCVF) located in central-southern Spain (along with Selva-Emporda in Catalonia, NE Spain) is regarded as one of the most important CO2 emitting zones in Peninsular Spain. Here, we report and evaluate new molecular and isotopic geochemistry of thermal waters and CO2-rich gas discharges from the CCVF. Locally, these CO2-rich fluid emissions represent the remnants of the past volcanic activity that affected this area from the late Miocene through the Quaternary, with the most recent events occurring in the Holocene. The locations of discharging fluids and previous volcanic centers appear to be aligned along well-defined NW-SE and NNW-SSE lineaments, with subordinate trends in the ENE-WSW direction. The chemical and isotopic composition of the thermal waters suggests a meteoric origin, dominated by three distinct geochemical facies: 1) HCO3-Mg(Ca) type waters, associated with a relatively shallow aquifer and related to the interaction of meteoric waters with CO2-rich gases, alkaline volcanic products, and sedimentary formations, 2) SO4(Cl)-Ca(Mg) type waters, which stems from the two rivers (Guadiana and Jabalón) that drain Triassic evaporitic rocks before entering the study area, and 3) HCO3-Na type waters, hosted in deep geopressurized CO2-rich reservoirs within the Ordovician basement rocks. The ⁸⁷Sr/⁸⁶Sr isotopic compositions (ranging between 0.70415 and 0.71623) and δ³⁴S-SO4 values (+10.7 to +18.3‰ vs. CDT) of CO2-rich fluids are consistent with interactions between water and either the Paleozoic basement, Triassic evaporites, Quaternary volcanic rocks, or a combination thereof. Dissolution of a CO2-rich gas phase into the aquifer produces low pH values (down to 5.4) and enhances water-rock interactions causing relatively high salinity (Total Ionic Salinity: up to ∼185 meq/L). Carbon dioxide is by far the most abundant gas constituent (up to 992 mmol/mol) and is dominated by mantle-derived sources as indicated by the combination of relatively high helium isotopic ratios (up to 2.7 R/Ra), high isotopic ratios of carbon in CO2 (ranging between −6.8 and −3.2‰ V-PDB), and the carbon isotopic signature of TDIC (from −6.8 to +2.2‰ vs. VPDB). In the last two decades, numerous (CO2-rich) gas blowouts have occurred in the area during well drillings, suggesting the presence of a geopressurized gas reservoir at relatively shallow depth.

Characterizing multiple water-rock interactions in the critical zone through Sr-isotope tracing of surface and groundwater

Article

Apr 2018
APPL GEOCHEM

Here, we report on Sr isotopes, from shallow and deep groundwater from catchments located on granite and schist around the world. This extensive approach of Sr isotope tracing, initiated in France on areas impacted by intensive agricultural activities, was enlarged to Africa (granite-gneiss and schists 2200-700 Ma of the Congo Basin; Archean granitoid/gneisses and sedimentary greenstone 3700-2500 Ma of the Orange River); India and Nepal (Archean granites 2500 Ma and Palaeoproterozoic granodiorite and schists 3100-1600 Ma for India; Himalaya metamorphic, silicate metasediments and gneisses 630 to 490 Ma); North America (3500–2500 Ma silicate rocks in the Mackenzie basin; 1000 to 70 Ma silicate rocks in the Fraser Basin in Canada and 1760 to 1430 Ma anorthosite and granite in the Laramie aquifer in Wyoming); South America in French Guiana (Archean gneiss 3400 to 2700 Ma and granite-gneiss rocks 2300 to 1900 Ma); Australia (65 Ma arenaceous and argillaceous rocks; and considering both surface and groundwater). In this extensive approach, the Sr and Mg contents are well correlated and both are partly related to agricultural and weathering inputs. The relationship between Sr-isotope and Mg/Sr ratios allows definition of the relative impact on surface and groundwater of processes occurring in the Critical Zone, mainly rain, agricultural practices and water-rock interactions.

Groundwater mixing and mineralization processes in a mountain–oasis–desert basin, northwest China: hydrogeochemistry and environmental tracer indicators

Article

Sep 2017

Hydrogeochemistry and environmental tracers (2H, 18O, 87Sr/86Sr) in precipitation, river and reservoir water, and groundwater have been used to determine groundwater recharge sources, and to identify mixing characteristics and mineralization processes in the Manas River Basin (MRB), which is a typical mountain–oasis–desert ecosystem in arid northwest China. The oasis component is artificial (irrigation). Groundwater with enriched stable isotope content originates from local precipitation and surface-water leakage in the piedmont alluvial–oasis plain. Groundwater with more depleted isotopes in the north oasis plain and desert is recharged by lateral flow from the adjacent mountains, for which recharge is associated with high altitude and/or paleo-water infiltrating during a period of much colder climate. Little evaporation and isotope exchange between groundwater and rock and soil minerals occurred in the mountain, piedmont and oasis plain. Groundwater δ2H and δ18O values show more homogeneous values along the groundwater flow direction and with well depths, indicating inter-aquifer mixing processes. A regional contrast of groundwater allows the 87Sr/86Sr ratios and δ18O values to be useful in a combination with Cl, Na, Mg, Ca and Sr concentrations to distinguish the groundwater mixing characteristics. Two main processes are identified: groundwater lateral-flow mixing and river leakage in the piedmont alluvial–oasis plain, and vertical mixing in the north oasis plain and the desert. The 87Sr/86Sr ratios and selected ion ratios reveal that carbonate dissolution and mixing with silicate from the southern mountain area are primarily controlling the strontium isotope hydrogeochemistry.

Hydrostratigraphic and hydrochemical characterisation of aquifers, aquitards and coal seams in the Galilee and Eromanga basins, Central Queensland, Australia

Thesis

Full-text available

Jan 2015

Claudio E. Moya

Inter-aquifer mixing studies are usually made carrying out hydrochemical and isotopic techniques only. In this thesis these techniques have been integrated with three-dimensional geological modelling proving to be a better approach for inter—aquifer mixing assessment in regional areas, and also highlighting the influence of faulting in the understanding of groundwater and gas migration, which could not be possible using the two fist techniques alone. The results are of particular interest for coal seam gas basins and can even be used as exploration tools as areas of higher permeability and gas migration were identified.

Origin and classification of geothermal water from Guanzhong Basin, NW China: Geochemical and isotopic approach

Article

Jun 2016

Combined with tectonic evolution, a multi-isotopic method (δD, δ18O, 87Sr/86Sr and 14C) and hydrochemistry data have been used to study the origin and classification of geothermal water in the Guanzhong Basin. The study shows that geothermal water of Xianli terrace primarily came from northwest direction when accepting recharge. A small amount supply source of geothermal water in Xi’an City is from Qinling Mountain and the principal supply source comes from the west direction, but geothermal water of Chang’an District mainly accepts supply from Qinling Mountain. Based on geothermal environment is open or not, the degree of water-rock interaction, and the origin of geothermal water, geothermal water of the study area can be divided into four types: A, geothermal water of Gushi depression, perfect closed thermal environment and significant water-rock interaction, belonged to residual sedimentary water origin; B, geothermal water of Xianyang City, good closed environment and relatively significant water-rock interaction, belonged to residual sedimentary water origin mixed with fossil leaching water; C, geothermal water of Xi’an City, half closed environment and some water-rock interaction, belonged to fossil leaching water origin; D, geothermal water of Chang’an District, open environment and mixed with modern precipitation, belonged to fossil leaching water origin.

Chemical Weathering in the Loch Vale Watershed, Rocky Mountain National Park, Colorado

Article

Full-text available

Dec 1990

Mineralogic, hydrologic, and geochemical data were used to determine the source of solutes to surface waters draining the Loch Vale Watershed (LVWS), an alpine-subalpine drainage located in the Front Range of Colorado. The flux of dissolved solids from LVWS is primarily controlled by interactions between snowmelt and materials derived from the local bedrock; the biomass has only a minor effect on solute budgets except for ammonium. LVWS is underlain by Precambrian granite and gneiss, the major minerals include quartz, microcline, plagioclase, biotite, and sillimanite. Small amounts of calcite were found along hydrothermally altered zones in the bedrock. Mass balance calculations indicate that the weathering of calcite contributes nearly 40% of the cations derived within the basin. The importance of calcite weathering in LVWS is a result of its chemical reactivity and the high rate of physical erosion in this alpine environment. The average cationic denudation rate in the drainage (390 eq/ha/yr) is similar to long-term rates in forested Adirondack watersheds (500-600 eq/ha/yr), but much lower than the average for the North American Continent (3800 eq/ha/yr). Surface waters in LVWS are susceptible to acidification should acid deposition from the atmosphere increase.

Seawater Sr isotope variation over the past 300 kyr and influence of global climate cycles

Article

Full-text available

Apr 1992

THE past 300,000 years have been characterized by glacial/inter-glacial fluctuations accompanied by glacio-eustatic changes in sea level and changes in continental erosion arising from varying low-latitude rainfall and river drainage. Here we use measurements of strontium isotopes in foraminifera and corals to place limits on variations in the Sr isotope composition of sea water in response to these changing inputs. We find small variations of about 20 p.p.m. in the 87Sr/86Sr ratio, which for the foraminiferal record seem to follow a cycle close to the 100-kyr periodicity seen for a number of other climate-related phenomena. These are superimposed on a general increase in87Sr/86Sr through the Cenozoic to the present. On short timescales these changes are likely to be controlled by variations in the global riverine Sr flux, and thus by weathering rates, rather than in the hydrothermal Sr flux at mid-ocean ridges. We show that transient variations over a 50-kyr timescale can be explained on the basis of the present-day global drainage system in conjunction with the perturbations expected to accompany climate changes over the past 300 kyr.

Dissolved load of the Loire River: Chemical and isotopic characterization

Article

Full-text available

Oct 2000
CHEM GEOL

The Loire River, with one of the largest watersheds in France, has been monitored just outside the city of Orleans since 1994. Physico-chemical parameters and major and trace elements were measured between 2-day and 1-week intervals according to the river flow. The sampling site represents 34% of the total Loire watershed with 76% silicate rocks and 24% carbonate rocks.Elements are transported mainly in the dissolved phase with the ratio of total dissolved salts (TDS) to suspended matter (SM) ranging between 1.6 and 17.4. Chemical weathering of rocks and soils are thus the dominant mechanisms in the Loire waters composition. The highest TDS/SM ratios are due to dissolved anthropogenic inputs. The database shows no link between NO3− content and river flow. The Na+, K+, Mg2+, SO42−, and Cl− concentrations are seen to decrease with increasing discharge, in agreement with a mixing process involving at least two components: the first component (during low flow) is concentrated and may be related with input from the groundwater and sewage station water, the second component (during high flow) is more dilute and is in agreement with bedrock weathering and rainwater inputs. A geochemical behaviour pattern is also observed for HCO3− and Ca2+ species, their concentrations increase with increasing discharge up to 300 m3/s, after which, they decrease with increasing discharge. The Sr isotopic composition of the dissolved load is controlled by at least five components — a series of natural components represented by (a) waters draining the silicate and carbonate bedrock, (b) groundwater, and (c) rainwaters, and two kinds of anthropogenic components.The aim of this study is to describe the mixing model in order to estimate the contribution of each component. Finally, specific export rates in the upper Loire watershed were evaluated close to 12 t year−1 km−2 for the silicate rate and 47 t year−1 km−2 for the carbonate rate.

Natural and Anthropogenic Budgets of a Small Watershed in the Massif Central (France): Chemical and Strontium Isotopic Characterization of Water and Sediments

Article

Full-text available

Jan 1996

A small watershed (160 km2) located in the Massif Central (France) has been chemically, isotopically and hydrologically studied through its dissolved load, bed sediments and soils. This watershed is underlain by basaltic bedrock and associated soils in which the vegetation is dominated mainly by meadows.Dissolved concentrations of major ions (Cl, SO4, NO3, HCO3, Ca, Na, Mg, K, Al and Si), trace elements (Rb and Sr) and strontium isotopes have been determined for two different hydrologic periods on the main stream of the Allanche river and its tributaries.The major objectives of this study were to characterize the chemical and isotopic signatures of each reservoir occurring in the watershed. Changes in chemical and isotopic signatures are interpreted in terms of fluctuations of the different components inputs: rainwater, weathering products, anthropogenic addition.Water quality may be influenced by natural inputs (rainwater, weathering processes) and anthropogenic additions (fertilizers, road salts, etc.). Precipitation serves as a major vehicle for dissolved chemical species in addition to the hydrosystem and, in order to constrain rain inputs, a systematic study of rainwaters is carried out over a one year period using an automatic collector. Corrections of rainwater addition using chloride as an atmospheric input reference were computed for selected elements and the Sr/Sr ratio. After such corrections, the geochemical budget of the watershed was determined and the role of anthropogenic additions evaluated through the relationship between strontium isotopes and major and trace element ratios. Thus, 10% of Ca and Na originate in rainwater input, 40 to 80% in fertilizer additions and 15 to 50% in rock weatheringThe cationic denudation rates for this watershed are around 0.3 g s–1 km2 during low water discharge and 0.6 g s–1 km2 in high water stage. This led to a chemical denudation rate of 5.3 mm/1000 years.For solid matter, the normalization of chemical species relative to parent rocks shows the depletion or enrichment in soils and sediments. The use of K and Ca as mobile reference illustrates the weathering state of soils and sediments relative to parent rocks. This weathering state for bed sediments range from 15 to 45% for the K normalization and from 2 to 50% for the Ca normalization. For the soils, the weathering state ranges from 15 to 57% for the K normalization and from 17 to 90% for the Ca normalization.

Geochemical studies in the drainage basin of the Rio Vouga (Portugal). I. General hydrogeochemistry from its origin to the Ria de Aveira

Article

Jan 1984

A comparison of water and rock chemistry, using discriminant function analysis of the data obtained on the water chemistry, showed that distinction between granitic and metasedimentary waters is possible. However, partial weathering of rock-forming minerals as well as contributions of marine aerosols and of fertilizers to the water chemistry obfuscate straighforward relationships. A brief survey of water chemistry in the Ria de Aveiro revealed that the elements Al, Fe, and Mn behave conservatively during estuarine mixing, which is probably caused by conservative mixing of colloidal matter in this lagoon.-from Authors

Géochimie isotopique (Nd, Sr) et géochimie des éléments traces des basaltes alcalins du Massif Central français: Contraintes pétrogénétiques et arguments en faveur du métasomatisme mantellique

Article

Jan 1982

Catherine Chauvel

Strontium isotopic data and geochemical calculations as indicators for the origin of saline waters in crystalline rocks.

Article

Jan 1987

Groundwaters collected at deep levels in the granitic body of Stripa in central Sweden, are of a saline type. Our results clearly discard a marine origin for the primary waters, but they do not definitely address the alternative possibility which is a leaching of fluid inclusions.-from Authors

Composition des ruisseaux non pollu??s de France

Article

Jan 1986

Michel Meybeck

A strontium isotope study of groundwater-rock interaction in the Carnmenellis granite

Article

Jan 1986

Subsuperficial changes in chemical composition of the thermomineral waters of Vichy basin. Geothermal implications.

Article

Jan 1976

The chemical analyses of the mineral waters issuing in the basin of Vichy St Yorre provide the means to decipher different subsuperficial modifications superposed on the fluid originating at great depths: (1) Increasing amounts of dissolved Ca, Sr, Mg and sometimes K, by gradual attack of shallow host rocks. (2) Precipitation of silica and associated aluminium. (3) Mixing with fresh surface waters. The comprehensive study of these alterations allows to shed light on the initial composition of deep water. From the silica content, the Na/K ratio and the calcite saturation, a temperature of 135°C is inferred for this water.

The Global Water Cycle

Article

Jun 1987
Estuaries

Rb-Sr isotope systematics of a granitic soil chronosequence: The importance of biotite weathering

Article

Aug 1997
GEOCHIM COSMOCHIM AC

The RbSr isotope systematics of bedrock, soil digests, and the cation exchange fraction of soils from a granitic glacial soil chronosequence in the Wind River Mountains, Wyoming, USA, were investigated. Six soil profiles ranging in age from 0.4 to ∼300 kyr were studied and revealed that the ratio of exchangeable strontium in the B-horizons decreased from 0.7947 to 0.7114 with increasing soil age. Soil digests of the same samples showed much smaller variation in from 0.7272 to 0.7103 and also generally decreased with increasing soil age. Elevation of the ratios of Sr released by weathering over the soil digest and bedrock values results from the rapid weathering of biotite to form hydrobiotite and vermiculite in the younger soils. Biotite is estimated to weather at aaproximately eight times the rate of plagioclase (per gram of mineral) in the youngest soil profile and decreases to a rate of only ∼20% of that of plagioclase in the oldest soil. ratios of the soil cation exchange fraction are estimated to be depleted by factors of up to 11 over the ratios released by weathering, due to ion exchange partitioning. This study demonstrates that the ratio released by weathering of crystalline rocks can deviate significantly from bedrock values, and that in soils less than ∼20 kyr in age which contain biotite in the soil parent material, weathering-derived values can be elevated so dramatically that this factor must be considered in estimations of weathering rates based on strontium isotopes.

Isotopic ratios and release rates of strontium measured from weathering feldspars - Reaction stoichiometry and the effect of cations

Article

May 1998
GEOCHIM COSMOCHIM AC

Based upon dissolution of feldspars under controlled laboratory conditions, we conclude that Sr release, at pH 3, is neither consistently stoichiometric nor constant for the feldspars measured. Bytownite, microcline, and albite all initially release Sr at rates which are 5 (bytownite) to 160 (microcline) times faster than steady-state release rates. The Sr/Si ratios in the early effluents are significantly elevated compared to the bulk mineral values. The 87Sr/86Sr measured in effluent early in dissolution is higher than the bulk mineral 87Sr/86Sr for bytownite, but lower than bulk mineral ratios for microcline and albite. 87Sr/86Sr ratios for the feldspar powders also changed markedly during dissolution of the three phases. In part, nonstoichiometric release of Sr can be explained by the presence of secondary phases (exsolution lamellae or minute quantities of accessory phases) or by surface leaching. Although we infer that these feldspars eventually release Sr with isotopic composition roughly equal to that of the bulk mineral at steady-state, the feldspars dissolve at extremely different rates (bytownite releases Sr at a steady-state rate ∼102 to 103 times faster than albite and microcline, at pH 3). Therefore, a mixture of these feldspars, or of other minerals exhibiting vast differences in dissolution rate, will release 87Sr/86Sr ratios distinctly different from the bulk whole rock. In addition, initial Sr release rates of the minerals (bytownite > microcline > albite) differ from steady-state release rates (bytownite > albite > microcline), complicating analysis of weathering solutions. Log (rate constants) for bytownite, albite, and microcline decrease from −13.5 to −16.4 to −17.2 (mol Sr cm−2 s−1). Interpretation of catchment scale riverine 87Sr/86Sr ratios on the basis of whole-rock Sr isotopes is, therefore, problematic at best, and would require normalization of bulk isotopic ratios by relative rates of dissolution of Sr-contributing phases.

Granite-hydrothermal interaction: A simultaneous estimation of the mineral dissolution rate based on the isotopic doping technique

Article

Apr 1998
EARTH PLANET SC LETT

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.

87Sr/86Sr values in groundwaters of the East Bull Lake pluton, Superior Province, Ontario, Canada

Article

Feb 1987
APPL GEOCHEM

The East Bull Lake pluton is a 2.48 Ga-old, layered mafic intrusion located on the southern margin of the Superior Province, Precambrian Shield in Ontario, Canada. The groundwaters have been studied as part of a detailed geological mapping and geochemical study of the pluton for the Canadian Nuclear Fuel Waste Management Program.All groundwater samples are dilute—the most concentrated NaCl type water contains 3.1 g/l total dissolved solids. Present day87Sr/86Sr values of the rock samples varies from 0.705 to 0.714 and the groundwaters from 0.711 to 0.720. The CaHCO3 recharge waters show the greatest range in values, in contrast to the deeper NaHCO3 and deep NaCl waters where a narrow range of 0.712–0.713 is found. Fracture-filling laumontite, calcite and gypsum have the same isotopic signature as the deep water.The CaHCO3 water is the youngest component of the groundwater system and its spread in isotopic values reflects local conditions at the surface. The NaCl water is considered to be the oldest component and its Sr isotopic ratio value indicates equilibration with silicate fracture mineral phases. The isotopic data suggest that laumontite, calcite, and gypsum fracture phases have either crystallized from this water or are currently controlling its isotopic composition by dissolution. No age can be assigned to the deep waters, except that the NaCl component may date from the Early Paleozoic, based on geological arguments or, more likely, be 104–106 years old based on kinetic studies of rock-water interaction and other isotopic data.If seawater was one component of the NaCl water history, there is no record of this in the87Sr/86Sr ratios.

Chemical Kinetics of Water-Rock Interaction

Article

Jun 1984

Antonio Lasaga

The recent literature on the kinetics of water-rock interactions is reviewed. The data are then extended to provide a quantitative framework for the description of weathering and alteration. The available experimental data on dissolution of silicates verifies quantitatively the usual mineral stability series in sedimentary petrology. The rate of hydration of carbonic acid is shown to be a possible limiting factor in water-rock interactions. The framework is developed to enable use of laboratory dissolution experimental results and thermodynamics to arrive at a rate law applicable up to equilibrium and therefore applicable to natural systems. The kinetic justification for the significance of a water-rock ratio is discussed. With a proper treatment of fluid flow, the equations are applied to the weathering profile leading to the development of bauxites from nepheline syenites.

Saline ground waters and brines in the Canadian Shield: Geochemical and isotopic evidence for a residual evaporite brine component

Article

Mar 1994
GEOCHIM COSMOCHIM AC

Saline Ca-Na/Cl type groundwaters and brines sampled in deep mines over an extensive area of the Canadian Precambrian Shield have elevated Br / Cl ratios which may indicate that the chlorinity of these waters was derived from the infiltration of residual evaporitic brines, remnants of the great marine incursions of the Paleozoic era. Boron concentrations in these waters are generally low (i.e., < ~2 mg/ L) relative to seawater or Alberta Basin Devonian formation waters. However, the 11 B / 10 B ratios of these waters are significantly greater than the average value for continental crustal rocks with the highest values (~4.19) approaching that of present-day seawater (4.20). Moreover, the boron isotopic ratios generally trend to higher values with increasing chlorinity which supports the conclusion from the Br-Cl relationship that most of the chloride in shield brines is of marine origin, rather than a product of water/rock interactions. If this is correct, crystalline rocks must then be sufficiently permeable on a regional scale to have allowed the brine to infiltrate to depths of several kilometers where it now resides.

The Evolution of Saline and Thermal Groundwaters in the Carnmenellis Granite

Article

Sep 1984

W. M. Edmunds

The Carnmenellis granite and its aureole contain the only recorded thermal groundwaters (up to 52 °C) in British granites. They occur as springs in tin mines at depths between 200 and 700 m and most are saline (maximum mineralization 19 310 mg 1 ⁻¹ ). Mining activity has disturbed the groundwater circulation pattern developed over a geological time-scale and levels of bomb-produced tritium (> 4 TU) indicate that a significant component (up to 65 %) of the most saline waters are of recent origin. All components of all the mine waters are of meteoric origin. Radiogenic ⁴ He contents, ⁴⁰ Ar/ ³⁶ Ar ratios, and uranium series geochemistry suggest that the thermal component has a likely residence time of at least 5 × 10 ⁴ years and probably of order 10 ⁶ years. The thermal waters have molar Na ⁺ /Cl ⁻ ratios considerably less than 1 but they are enriched relative to sea water in all major cations except Mg. The groundwater is also particularly enriched in Li with contents ranging up to 125 mg 1 ⁻¹ . The groundwater salinity, which may reach a maximum of 30 000 mg 1 ⁻¹ , is shown to result from weathering reactions of biotite (probably through a chloritization step) and plagioclase feldspar, to kaolinite. On volumetric considerations, fluid inclusions cannot contribute significantly to the groundwater salinity, and stable isotope ratios rule out any contribution from sea water. Groundwater silica contents and molar Na ⁺ /K ⁺ ratios suggest that the likely equilibration temperature is 54°C, which would imply a depth of circulation of about 1.2 km.

Variation of seawater 87Sr/86Sr throughout Phanerozoic time

Article

Jan 1982
GEOLOGY

Precise measurements of 786 marine carbonate, evaporite, and phosphate samples of known age provide a curve of seawater 87Sr/86Sr versus geologic time through the Phanerozoic. Many episodes of increasing and decreasing values of 87Sr/86Sr of seawater have occurred through the Phanerozoic. The Late Cambrian Early Ordovician seawater ratios are approximately equal to the modern ratio of 0.70907. The lowest ratios, ˜0.7068, occurred during the Jurassic and Late Permian. The configuration of the curve appears to be strongly influenced by the history of both plate interactions and seafloor spreading throughout the Phanerozoic. The curve provides a basis for dating many marine carbonate, evaporite, and phosphate samples. Furthermore, diagenetic modifications of original marine 87Sr/86Sr values are often interpretable. Analysis of 87Sr/86Sr data, therefore, may provide useful information on regional diagenetic patterns and processes. All of the Cenozoic samples and some of the Cretaceous samples are from Deep Sea Drilling Project (DSDP) cores. With the exception of the DSDP samples, the curve was constructed only from samples containing at least 200 ppm Sr and not more than 10% dilute acid insoluble material. All measurements are made by comparison with standard SrCO3 (NBS SRM 987) for which a 87Sr/86Sr of 0.71014 is assumed. Precision is estimated to be ± 0.00005 at the 95% confidence level. Measured ratios of 42 modern marine samples average 0.70907, with a standard deviation of 0.00004. *Present addresses: (Denison) Suite 616, One Energy Square. 4925 Greenville Avenue, Dallas, Texas 75206; (Nelson) 2516 West Five Mile Parkway, Dallas, Texas 75233

Tracage des apports anthropiques sur un petit bassin versant: Utilisation des rapports isotopiques du strontium

Article

Jun 1997

Philippe Négrel

La composition chimique des rivières est influencée par la lithologie des bassins drainés et les influences anthropiques même mineures (villages, cultures, salage des routes, pollution atmosphérique, etc.). Cette étude a été menée le long d'un cours d'eau d'orientation ouest-est, depuis les têtes de bassin des différents affluents jusqu'à l'exutoire et concerne les flux d'éléments chimiques. Les contrastes isotopiques ⁸⁷Sr/⁸⁶Sr entre les sources potentielles en présence (roche-atmosphère-polluant) doivent permettre leur identification.

Calcite veins of the Stripa granite (Sweden) as records of the origin of the groundwaters and their interactions with the granitic body

Article

Aug 1989
GEOCHIM COSMOCHIM AC

A Sr isotopic study combined with stable isotope determinations ( 18 O and 13 C ), petrographic observations and speciation calculations suggests that the Stripa granite (Sweden) contains at least three different types of calcite veins. One type with 18 O = -18 to -24%. (PDB) and 87 Sr / 86 Sr = 0.7814 to 1.0696 probably formed at temperatures above 200°C, together with chlorite and epidote, during one or two metamorphic events which are recorded in the Rb-Sr systematics of some minerals of the granite at 1.4 and 0.8 Ga. Another type with 18 O = -12 to -18%. (PDB) and 87 Sr / 86 Sr = 0.7406 to 0.7536 and mainly associated with chlorite, is most likely in equilibrium with the presentday groundwaters, which probably have reacted with the fracture minerals of the granitic body for a long time without any supply of external fluids. The third type of calcite with 18 O = -12 to -18%. (PDB), 13 C = -5 to -45%. (PDB) and 87 Sr / 86 Sr = 0.7266 to 0.7406, could have formed from reactions involving methane oxidation or sulphate reduction in the presence of bacteria.

87Sr/86Sr composition of seawater during the Phanerozoic

Article

Sep 1974
GEOCHIM COSMOCHIM AC

87 Sr/ 86 Sr measurements of 108 sedimentary carbonate rocks have been used to trace variations in the strontium isotopic composition of seawater during the Phanerozoic. The lowest 87 Sr/ 86 Sr observed for any suite of carbonates is taken as the best approximation to the value in well-mixed contemporary seawater. Our data support the existence of low 87 Sr/ 86 Sr in the Cretaceous and Late Jurassic but they do not support further structure beyond a general trend through the Phanerozoic, which may correlate with the continental denudation rate.

The sources and transport of Sr and Nd isotopes in the Baltic Sea

Article

Nov 1992
EARTH PLANET SC LETT

We have determined the concentration and isotopic composition of Sr and Nd in waters from the Baltic Sea. The Baltic Sea is an intracontinental, stratified, brackish water, estuarine-like system, and the rivers emptying into it drain a suite of terranes ranging from Proterozoic-Archean in the north to Phanerozoic in the south. The sampled brackish waters range in salinity from seawater (SW) at 35.289‰ to a minimum of 2.460‰ at the surface in the innermost part of the Gulf of Bothnia. The Sr concentrations show generally conservative behavior, indicating a simple two-component mixing. However, small deviations (3–70 ‰) from a perfect mixing line reveal that the imprints from rivers with different Sr concentrations are preserved in the blending. Strontium concentrations from a depth profile across the redoxcline in the Baltic proper indicate that vertical particle transport alters the Sr concentration in the water. Our estimated concentration of Sr in the average freshwater input to the Baltic is ∼ 0.03 ppm, which is only about 0.4% of the SW concentration. The Sr isotopic data range from ε^(Sr)(SW) = 0 in seawater to ε_(Sr)^(BW)(SW) = 7.8 in the least saline Baltic water (BW) sample in the Gulf of Bothnia. The isotopic composition of Sr versus 1/Sr in the Baltic Sea follows an almost perfect mixing line, which shows that seawater Sr is mixed with much more radiogenic components. Calculated end-member values of ε_(Sr)^*(SW) for each sample show that the riverine input into the Gulf of Bothnia has ε_(Sr)^*(SW) = 120–200 and 10–50 ε units in the Baltic proper. These values are in general agreement with direct measurements of river waters in each region. However, the calculated values in the Gulf of Bothnia are lower than the measured river water input in this region, which indicates the presence of less radiogenic Sr, presumably originating from the river waters draining the southern part of the basin which are partially transported northward and mixed with Sr from the Gulf of Bothnia rivers. The Nd concentration in the Baltic Sea is not conservative, varying between 5 and 45 ppt, with the highest concentrations in the bottom waters due to vertical particulate transport. A plot of ε_(Nd)(O) in Baltic water yields a good correlation with the calculated freshwater end member ε_(Sr)^*(SW). The data show that it is possible to unravel the different freshwater sources into the Baltic and to identify the zones of particulate removal of both non-conservative species such as the REE and of quasi-conservative species such as Sr. The use of isotopic tracers in this estuarine environment may provide a much better insight into mixing and element transport. It should also be possible to trace lateral movements of freshwater inputs.

A strontium isotopic study of mineral and surface waters from the C??zallier (Massif Central, France): Implications for mixing processes in areas of disseminated emergences of mineral waters

Article

Feb 1997
CHEM GEOL

Surface and mineral waters from a geothermal area (Cézallier) in the centre of the Massif Central, France, were analysed for Sr isotopes, Sr and major elements in order to use Sr isotopes to investigate the discharge of a mineralised water area, especially in the case of disseminate mineralised water emergences.The 87Sr86Sr ratios of mineralised waters ranged from 0.715541 to 0.716773. The variation in 87Sr86Sr values was small for the 5 mineral springs sampled over two periods (5 × 10−6–14 × 10−6). Regarding the reproductivity of the 87Sr86Sr ratio measurements, no differences can be seen and the 87Sr86Sr ratio of mineral waters can be considered to be constant with time. The 87Sr86Sr ratios of surface waters collected along the Zagat River ranged from 0.705303 to 0.715091. The lowest values were always observed in the headwaters. The difference in the 87Sr86Sr ratios between the two sampling periods was ∼ 22 × 10−4 and can be related to the hydrological situation (low or high flow). The 87Sr86Sr ratios of surface waters collected in the drain ranged from 0.715072 to 0.716585. The difference in the 87Sr86Sr ratios between the two sampling periods is ∼ 11 × 10−4 for the drain headwaters and ∼ 13 × 10−5 at the outlet of this area. Likewise, these variations can also be related to the hydrological situation.Plots of 87Sr86Sr vs. 1Sr ratios show two distinct binary mixing trends and the existence of at least four end-members. A mixing parameter f giving the proportions of the two components can be estimated for assumed 87Sr86Sr ratio and Sr content values of the pure end-members.An estimate of the mineral water discharge can be calculated using the results of the mixing model and the measured flow. In the drain area, the mixing model gives an estimate ∼ 0.5–1 l s−1, or 10–13% of mineral water in the total flow. A similar calculation was done for the river where the mineral water flow was ∼ 0.96 l s−1 (3.5 m3 h−1 100 m downstream from the bridge in April 1994, and 6 m3 h−1 20 m downstream from the bridge in September 1994.

Evidence for slowly changing 87Sr86Sr in runoff from freshwater limestones of southern France

Article

Aug 1987
CHEM GEOL

ratios have been determined in modern rivers and freshwater limestones dating from 65 Ma to the present over an area extending from the Pyrénées to the Massif Central (southern France). About 40 Ma ago, the Alpine mountain range of the Pyrénées was strongly uplifted by the Alpine orogenic activity and its pre-Hercynian basement dominated by schists, gneisses and granites was rapidly exposed from beneath its blanket of Mesozoic marine limestones. Meanwhile, the ratio of the rivers has remained remarkably constant in both space (with the exception of the very few northernmost samples) and time: in this area, extreme variations through the orogenic period are small with lying between 0.7073 and 0.7084 at 55–65 Ma and 0.7077–0.7096 for the last 30 Ma. River Sr is controlled by a nearly binary mixing of silicate () and () end-members with negligible influence of evaporites.It is inferred that the silicate/sediment contribution ratio of the world-average rivers to seawater Sr changes at a very slow rate. Even taking major basaltic events into account does not alter this conclusion as their contribution to the river Sr is very subordinated to other components. It is inferred that the seawater secular main trend over the Phanerozoic is controlled by hydrothermal alteration of oceanic basalts and slow variation of the limestone/silicate contribution ratio to the riverine Sr. Oceanic events [changes in organic productivity and carbonate compensation depth (CCD)] may produce intense, short-term variations but recovery of steady-state seawater is delayed by 40–80 Ma through diagenetic Sr remobilization in carbonate sediments.

Contamination of deep formation waters by drilling fluids: Correction of the chemical and isotopic composition and evaluation of errors

Article

Jul 2001
APPL GEOCHEM

Contamination of deep formation waters by drilling fluids is a problem that concerns most types of drilling operations (petroleum wells, geothermal boreholes) and is crucial in the course of feasibility and safety studies of potential radioactive-waste repositories. Residual contamination of formation-water samples has an important impact on the accuracy of the characterisation of the natural hydrogeochemical background of the study sites. Based on a literature review and on experience acquired on the sites of the French Agency for Nuclear Waste Disposal (ANDRA), this article proposes a general method for the correction of residual contamination, including estimates of the associated errors. The quantification of the contamination is based on tracing techniques and on a geochemical survey during the pumping test preceding sampling. The correction and estimation of errors require repeated measurements of the tracer(s) and the chemical and isotopic species during pumping. The method is applied to a pumping test in a research well in deep granite of the Vienne district (France) where multi-tracing of drilling fluids has been used.

Synopsis of strontium isotope variations in groundwater at Äspö, southern Sweden

Article

Sep 1999
APPL GEOCHEM

Strontium isotope ratios are used to identify end-member ground-water compositions at Äspö in southeastern Sweden where the Hard Rock Laboratory (HRL) has been constructed to evaluate the suitability of crystalline rock for the geologic disposal of nuclear waste. The Hard Rock Laboratory is a decline (tunnel) constructed in 1.8 Ga-old granitic rock that forms islands in an archipelago along the Swedish coast. Ground-water samples were obtained for isotopic analyses from boreholes drilled from the surface and from side boreholes drilled within the HRL. Infiltration at Äspö occurs primarily through fractures zones in the granitic bedrock beneath thin soils throughout the area. Because of extremely low Sr concentrations, rain and snow are not important contributors to the Sr isotope budget of the ground-water system. At shallow levels, water percolating downward along fractures and fracture zones acquires a δ87Sr between +9.5 and +10.0‰ and maintains this value downward while Sr concentrations increase by two orders of magnitude. Ground-water samples from both boreholes and from in the HRL show the effects of mixing with saline waters containing as much as 59 mg/L Sr and δ87Sr values as large as +13.9‰. Baltic Sea water is a potential component of the groundwater system with δ87Sr values only slightly larger than modern marine values (+0.3‰) but with much lower concentrations (1.5 mg/L) than ocean water (8 mg/L). However, because of large Sr concentration differences between the saline groundwater (59 mg/L) and Baltic Sea water (1.5 mg/L), δ87Sr values are not particularly sensitive indicators of sea-water intrusion even though their δ87Sr values differ substantially.

Geochemical Mass Balances and Weathering Rates in Forested Waters of the Southern Blue Ridge

Article

Dec 1985

M. A Velbel

Mass-balance equations expressing mineral weathering reactions have been derived on the basis of empirical determinations of mineral compositions and combination of compositional data with petrographic (micromorphological) data. Calculations of the rates of weathering for each of the three major rock-forming silicate minerals - as well as the rate of mineral nutrient uptake - in deeply weathered profiles of several small watersheds in the Nantahala Mountains, North Carolina, are presented. Published data on the elemental composition of forest biomass, elemental fluxes via rain and streams, and stoichiometries of mineralogical transformations serve as parameters for construction and constraint of the geochemical mass-balance calculations of the individual watersheds. They are quantitatively consistent with laboratory studies of mineral weathering and geomorphological studies of regional denudation rates. Possible sources of discrepancies are noted, and may be resolved by refinement of laboratory kinetic data and field surface area determinations. -M.S.

Atmospheric inputs and river transport of dissolved substances

Article

Jan 1983

Michel Meybeck

Several different types of behaviour can be observed for elements between atmospheric input and river transport including very limited chemical or biological reactivity (CI-, in most cases), change of speciation (C, N, P), recycling to atmosphere (C, N, S, K), increase of dissolved contents through weathering (Si, Ca, Mg, Na), and build-up in soil or vegetation (C, N, P, Ca, Mg, K). Internal cycling within the soil and biosphere reservoirs is generally one or two orders of magnitude higher than wet and dry fallout rates or stream outputs. The influence of atmospheric input on river chemistry is exemplified by French streams, where it depends on the erodibility of basin rocks and on atmospheric inputs regulated by the distance to the Atlantic coast , wind-blown dust , vegetat ion aerosol release, and anthropic inputs. For any major element (Xj), the atmospheric contribution to stream transport can be estimated on the basis of the stream CI content, the rainfall/runoff ratio in the basin, and the regional X^/Cl- ratio in rainfall. For nutrients, the

Variation in the strontium isotopic composition of seawater (8 Ma to present): Implications for chemical weathering rates and dissolved fluxes to the oceans

Article

Oct 1990
Chem Geol Isot Geosci

Measurements of 87Sr/86Sr on samples of planktonic foraminifers were used to reconstruct changes in the Sr isotopic composition of seawater for the past 8 Ma. The late Neogene was marked by a general, but not regular, increase in 87S/ 86Sr with two breaks in slope at 5.5 and 2.5 Ma. These times mark the beginning of two periods of steep increase in 87Sr/86Sr values, relative to preceding periods characterized by essentially constant values. During the last 2.5 Ma, 87Sr/86Sr values increased at an average rate of 54° 10−6 Ma−1. This steep increase suggests that the modem ocean is not in Sr isotopic equilibrium relative to its major input fluxes. A non-equilibrium model for the modern Sr budget suggests that the residence time of Sr is ∼ 2.5 Ma, which is significantly less than previously accepted estimates of 4–5 Ma.

Sr isotopic evidence for discrete saline components in stratified ground waters from crystalline bedrock, Outokumpu, Finland

Article

Jan 1988
GEOLOGY

We present a continuous Sr-isotope depth profile of waters, sampled in situ in the deepest borehole in Finland (˜1.1 km). The waters, all with a meteoric oxygen- and hydrogen-isotope signature, are compositionally stratified; a recent fresh-water zone (0.05 mg/L Sr, 87Sr/86Sr >0.730) ˜400 m thick is underlain by two saline-water zones, the upper with ˜25 mg/L Sr and 87Sr/86Sr = ˜0.724, the lower with 45 mg/L Sr and 87Sr/86Sr = ˜0.723. The Sr-isotope data show that the stratification is not due merely to upward dilution of saline water by fresh surface waters; two discrete saline waters are present. The two saline-water components are homogeneous in composition, apparently unaffected by local variations in rock composition either within the borehole or between neighboring boreholes. The implication is that the saline waters did not develop in isolated pockets but, rather, in large, well-mixed bodies. Most likely salinization mechanisms involve breakdown of low-Rb/Sr minerals (e.g., plagioclase feldspar) and/or leaching of fluid inclusions.

87Rb-87Sr studies of waters in a geothermal area: The Cantal, France

Article

Feb 1978
EARTH PLANET SC LETT

We have determined K, Rb and Sr concentrations and 87Sr/86Sr ratios in fresh surface waters, a rain water sample and five geothermal waters from the Cantal volcanic area in the Massif Central, France. A comparison with appropriate rock types of the region showed no apparent chemical and isotopic fractionation occurring in the fresh water-surface rock system. The thermo-mineral water results suggest that all springs discharge dissolved Sr from the following contributors: Hercynian granito-metamorphic basement, lacustrian sediments underlying the volcano, Miocene-Pliocene volcanic rocks of basaltic to rhyolitic composition.

Principles of isotope geology. Second edition

Article

Faure

This is a text in isotope geology/geoscience that integrates material taught in various courses into a unified picture of the earth sciences. It presents an exposition of the principles used in the interpretation of isotopic data and shows how such interpretations apply to the solution of geological problems. References up to 1985 are included with chapters in this edition. New chapters on Sm-Nd, Lu-Hf Re-Os, and K-Ca decay schemes and cosmogenic radionuclides have been added. Data summaries and references have been expanded.

The 87Sr/86Sr values of Canadian Shield brines and fracture minerals with applications to groundwater mixing, fracture history, and geochronology

Article

Jan 1990
GEOCHIM COSMOCHIM AC

Analyses of saline waters, fracture minerals, and host rocks from seven localities on the Canadian Shield demonstrate the utility of the ratio in the study of groundwater systems in crystalline rocks. The ratios range from 0.704 to 0.753 and have obtained their signatures by mineral/rock interactions, primarily involving the feldspars. We have identified brines from isolated pockets in the same mines where extensive flow regimes exist. There is mixing of different brines as well as mixing with meteoric waters.The isotopic results on calcites from fractures and shear zones show more than one generation of mineral growth in a given fracture. The ratios of the calcites vary from values identical to the present-day brine in the fracture zone to ratios with Archean signatures. This implies that activity may occur in fault zones over a very long time.The brines are very rich in Sr (up to 2400 mg/1), very low in Rb, and have relatively radiogenic ratios. They are ubiquitous in Shield rocks and, if they were present throughout geological time, they may be one reason why ages of felsic plutons are commonly younger than associated ages.

Strontium as a tracer of weathering processes in a silicate catchment polluted by acid atmospheric inputs, Strengbach, France

Article

Oct 2000
CHEM GEOL

This paper determines the weathering and atmospheric contributions of Ca in surface water from a small spruce forested silicate catchment (N–E France) receiving acid atmospheric inputs. The bedrock is a granite with K-feldspar and albite as dominant phases. The calcium content in plagioclase is low and the Ca/Na ratio in surface water is high, reflecting other sources of calcium from those expected from the weathering of major mineral phases. The biotite content is low. Only traces of apatite were detected while no calcite was found in spite of a major hydrothermal event having affected the granite. The strontium isotopic ratio 87Sr/86Sr and Sr content was used as a tracer of weathering and was determined in minerals and bulk bedrock, open field precipitation, throughfall, soil solution, spring and stream water. The Sr isotopic ratio of the reacting weathering end-member was predicted by simulating the alteration of the granite minerals by incorporating strontium into the water–rock interaction kinetic code KINDIS. In the early stages of water–rock interaction, K-feldspar and biotite strongly influence the isotopic composition of the weathering solution whereas, the Na-rich plagioclase appears to be the main long-term reactive weathering end-member. Approximately 50% of dissolved Sr in streamwater are atmospherically derived. The 87Sr/86Sr ratios of exchangeable Sr in the fine fraction at 1-m depth from a soil profile indicate that the amount of exchangeable Sr seems essentially controlled by atmospheric inputs. The exception is the deep saprolite where weathering processes could supply the Sr (and Ca). Na-Plagioclase weathering obviously control the chemistry and the isotopic composition of surface waters. The weathering of trace mineral plays a secondary role, the exception is for apatite when plagioclase is absent. Our hydrochemical, mineralogical and isotopic investigations show that a major part of the strong Ca losses detected in catchment hydrochemical budgets that result from the neutralization of acid precipitation has an atmospheric origin. Consequently, in the long term, in such areas, the availability of such an exchangeable base cation might be strongly limited and surface waters consequently acidified.

Origin of deep saline groundwaters in the Vienne granitic rocks (France): constraints inferred from boron and strontium isotopes

Article

Jan 2002
GEOFLUIDS

As part of a preliminary geological characterization programme to assess the feasibility of an underground laboratory in granitic rock, a series of 17 deep boreholes (maximum depth, 900 m) was drilled by ANDRA in the Vienne district, France. A salinity gradient was demonstrated in the granitic waters with concentrations varying from approximately 1 g L−1 at 150 m depth at the top of the basement (beneath the sedimentary cover) to 10 g L−1 in the deeper part (from 400 to 600 m depth). Sr and B isotope ratios were measured in order to better understand the origin of the salinity and to evaluate the degree of water–rock interaction in the system. The results obtained were compared to those of mineral spring waters emerging from the granitic basement in the Massif Central. Evidence in support of a significant marine contribution include: (i) the Cl–Br investigations agree with a marine origin for the saline groundwaters without evolution from seawater; (ii) the 87Sr/86Sr ratio of the Vienne deep groundwaters (0.7078–0.7084) is in agreement with a palaeo-seawater isotopic signature; (iii) measured δ11B values for the deepest brine samples are enriched in 11B (up to 36.1‰) relative to the granitic springs. The combined use of δ11B, Cl, B, Br, Sr contents and 87Sr/86Sr ratios makes it possible to define and quantify a mixing model between marine and crustal end-members in order to explain the origin of the deep saline groundwaters in the Vienne granitic rocks.

Strontium isotope composition of marine carbonates of Middle Triassic to Early Jurassic age, Lombardic Alps, Italy*

Article

Jun 2006
SEDIMENTOLOGY

The ⁸⁷ Sr/ ⁸⁶ Sr ratios and strontium concentrations for thirty‐three samples of marine carbonate rocks of Middle Triassic to Early Jurassic age have been determined. The samples were collected from four measured sections in the areas of Val Camonica in northern Italy. The strontium concentrations vary from 40 to 7000 ppm. Most of the samples are calcitic limestones containing less than 10% of non‐carbonate residues. Dolomitic samples and those containing appreciable non‐carbonate residues have significantly diminished strontium concentrations. ⁸⁷ Sr/ ⁸⁶ Sr ratios of the carbonate phases of these rocks appear to be unaffected by dolomitization and by the presence of non‐carbonate minerals. The average ⁸⁷ Sr/ ⁸⁶ Sr ratios of the formations vary systematically in a stratigraphic sense. The ratio increased from Early Anisian to Early‐Middle Ladinian, declined during Late Ladinian and Carnian, rose again during the Norian and then declined throughout the Late Norian (Rhaetian), Hettangian, Sinemurian and Pliens‐bachian ages. The average ⁸⁷ Sr/ ⁸⁶ Sr ratios, relative to 0.7080 for the Eimer and Amend standard, are: Anisian: 0.70805 ± 00019; Early Ladinian: 0.7085 ± 0.00038; Late Ladinian: 0.70791 ± 0.00013; Carnian: 0.70776 ± 0.00015; Norian and Rhaetian: 0.70791 ± 0.00014; Hettangian: 0.70762 ± 0.00021; Sinemurian: 0.7070 ± 0.00038; Pliensbachian: 0.7070 ± 0.00015. These variations reflect changes in the isotopic composition of Sr entering the oceans in early Mesozoic time due to varying rates of weathering and erosion of young volcanic rocks (low ⁸⁷ Sr/ ⁸⁶ Sr) and old granitic rocks (high ⁸⁷ Sr/ ⁸⁶ Sr). The data presented in this report contribute to a growing body of information regarding the changes that have occurred in the ⁸⁷ Sr/ ⁸⁶ Sr ratio of the oceans in Phanerozoic time.

Granite-fluid interaction at near-equilibrium conditions: Experimental and theoretical constraints from Sr contents and isotopic ratios* 1

Article

Apr 1995
CHEM GEOL

Fluid-granite interaction at near-equilibrium conditions was investigated by doping an experimental system with 84Sr. Reactions were performed at 453 K, saturated vapour pressure, and fluid/rock ratio of 20. The initial composition of the experimental fluid corresponded to the theoretical saturation with respect to kaolinite, quartz, laumontite, low-temperature albite, calcite and adularia. Sr was used to trace parent-mineral dissolution, neogenic phase precipitation, and to identify the reactions at Sr2+ steady state.The interaction is described, initially, by the isotopic mixing of the solution ratio and the granite ratio. However, in the rock end-member every main mineral has a different ratio. The evolution of ratio in solution as a function of showed that in the early stage of the interaction (where the dissolution of the rock is the dominant reaction) 87Sr-enriched phases, such as biotite, strongly influence the isotopic budget. After some time, the ratio of the fluid approaches the Sr isotopic ratio of the bulk rock, suggesting that fluid-granite isotopic equilibration is attained. When the dissolution of the granite is stopped and once the Sr2+ concentration reached steady state, variations of the ratio with time can be interpreted by an isochemical dissolution-precipitation of neogenic phases.

Groundwater 87Sr/86Sr values in the Eye-Dashwa Lakes pluton, Canada: Evidence for plagioclase-water reaction

Article

Jan 1991
Chem Geol Isot Geosci

The Eye-Dashwa Lakes pluton is a Sr-rich felsic intrusive of the sanukitoid suite located in NW Ontario in the Superior Province of the Canadian Shield. The 87Sr/86Sr values of the CaNaCl-type saline, deeper groundwaters fall in the narrow range of 0.7057–0.7070, similar to the 87Sr/86Sr value in plagioclase but not to that in K-feldspar, biotite, or the whole rock. This suggests that the water isotopic composition is the result of plagioclase-water interaction. The fracture minerals gypsum and calcite have similar 87Sr/86Sr ratios, indicating that they have crystallized from waters similar to the present deep groundwaters. The shallow, CaHCO3-type, dilute groundwaters show a wider spread in the Sr ratio of 0.7065–0.7278, reflecting their derivation from minerals in the overlying soil.The results for the saline groundwaters are consistent with thermodynamic and kinetic models that demonstrate the relatively rapid dissolution of plagioclase with respect to other rock-forming silicates, and should have application to most brines located in silicate host rocks.

Rare earth elements, neodymium and strontium isotopic systematics in mineral waters: Evidence from the Massif Central, France

Article

Oct 2000
APPL GEOCHEM

Rare Earth Elements (REEs), and Sr and Nd isotope distributions, have been studied in mineralized waters from the Massif Central (France). The CO2-rich springs are characterized by a neutral pH (6–7) associated with total dissolved solids (TDS) from 1 to 7 g l⁻¹. The waters result from the mixing of very mineralized water pools, thought to have equilibrated at a temperature of around 200°C with superficial waters. These two mineral water pools evidenced by Sr isotopes and dissolved REEs could reflect 2 different stages of water–rock interaction and an equilibrium with different mineral assemblages.

Chloride Loading in the South Fork of the Shenandoah River, Virginia, U.S.A

Article

Sep 1989

W. Cullen Sherwood

Loading trends and sources of CI– in the South Fork of the Shenandoah River, Virginia were analyzed for the period 1929–1982. CI– has increased from approximately 2 mg/L (2,776 tons/yr) to over 10 mg/L (14,256 tons/yr). Natural CI– is estimated to be 1.01 mg/L (1,388 tons/yr) with precipitation providing 0.99 mg/L and rocks 0.02 mg/L. From 1929 to 1949 CI– concentrations were relatively constant and independent of discharge, conforming to the Type II curve of Davis and Zobrist (1978), indicative of natural or relatively uncontaminated streams. Since 1952 CI– concentrations increased exponentially as river discharge decreases conforming to the Type I curve of Davis and Zobrist for polluted streams. Since 1965 anthropogenic CI– loading at 12,868 tons/yr has remained relatively constant. Four major sources contribute 92.2 percent (11,871 tons/yr) of the anthropogenic CI–: (1) deicing salts—4,149 tons/yr, (2) domestic sewage—3,015 tons/yr, (3) livestock and poultry wastes—2,458 tons/yr, and (4) commercial fertilizers—2,249 tons/yr.

Geochemical Study of a Granitic Area – The Margeride Mountains, France: Chemical Element Behavior and 87Sr/86Sr Constraints

Article

Sep 1999

Philippe Négrel

A small watershed (89 km2) underlain by granite or granite-gneiss in the Margeride mountains, southern Massif Central (France), has been studied using the chemical and isotopic composition of its dissolved load, bed sediments and soils. Dissolved concentrations of major ions (Cl, SO4, NO3, HCO3, Ca, Na, Mg, K, Al and Si), trace elements (Rb and Sr) and strontium isotopes have been determined for three different hydrologic periods in the main stream of the Desges river and its tributaries. The aim was to characterize the chemical and isotopic signatures of each reservoir in the watershed; signature changes are interpreted as fluctuations in the different influencing components: rainwater, weathering products and anthropogenic addition. In the study area, as in other watersheds in granite environments, the only source for input of chemical species into the dissolved load at high altitude is chemical weathering and atmospheric deposition, whereas at lower altitude, human influence plays a non-negligible role. As precipitation is a major vehicle for the addition of dissolved chemical species into the hydrosystem, a systematic rainwater study using an automatic collector was carried out over one year in order to better constrain rain elemental input. Corrections for rainwater addition, using chloride as an atmospheric-input reference, were computed for selected elements and for 87Sr/86Sr ratios. After these correction, the geochemical budget of the watershed was determined and the role of anthropogenic addition was evaluated based on strontium isotope relationships. For particulate matter, we used the normalization of chemical species relative to parent rocks and the element ratios which reflect the depletion or enrichment in soils and sediments. Both the immobile- and mobile-element approaches have been tested, using Ti/Zr and La/Ce ratios for the former and Ca/Sr, K/Rb, and K/Fe ratios for the latter.

Chemical weathering of a soil chronosequence on granitoid alluvium: II. Mineralogic and isotopic constraints on the behavior of strontium

Article

Jan 1997
GEOCHIM COSMOCHIM AC

The use of strontium isotopes to evaluate mineral weathering and identify sources of base cations in catchment waters requires an understanding of the behavior of Sr in the soil environment as a function of time. Our approach is to model the temporal evolution of 87Sr/86Sr of the cation exchange pool in a soil chronosequence developed on alluvium derived from central Sierra Nevada granitoids during the past 3 Ma. With increasing soil age, 87Sr/86Sr of ammonium-acetate extractable Sr initially decreases from values typical of K-feldspar to those of plagioclase and hornblende and then remains constant, even though plagioclase and hornblende are absent from the soils after approximately 1 Ma of weathering. The temporal variation of 87Sr/86Sr of exchangeable Sr is modeled by progressively equilibrating Sr derived from mineral weathering and atmospheric deposition with Sr on exchange sites as waters infiltrate a soil column. Observed decreases in quartz-normalized modal abundances of plagioclase, hornblende, and K-feldspar with time, and the distinct87Sr/86Sr values of these minerals can be used to calculate Sr flux from weathering reactions. Hydrobiotites in the soils have nearly constant modal abundances, chemistry, and 87Sr/86Sr over the chronosequence and provide negligible Sr input to weathering solutions. The model requires time and soil horizon-dependent changes in the amount of exchangeable Sr and the efficiency of Sr exchange, as well as a biologic cycling term. The model predicts that exchangeable Sr initially has 87Sr/86Sr identical to that of K-feldspar, and thus could be dominated by Sr leached from K-feldspar following deposition of the alluvium. The maximum value of 87Sr/86Sr observed in dilute stream waters associated with granitoids of the Yosemite region is likewise similar to that of the K-feldspars, suggesting that K-feldspar and not biotite may be the dominant source of radiogenic Sr in the streams. This study reveals that, when attempting to use Strontium isotopes to identify sources of base cations in catchment waters and biomass, both preferential leaching of Sr from minerals during incipient soil development and changing Sr exchange efficiency must be considered along with chemical contributions due to mineral dissolution.

Nd-Sr isotopic and trace element geochemistry of river sediments and soils in a fertilized catchment, New South Wales, Australia

Article

Jan 1999
GEOCHIM COSMOCHIM AC

Neodymium and strontium isotopes and a suite of trace elements have been used to distinguish between the various sources of particulate loads and soils in a major catchment of the Murray-Darling drainage system, the largest river in Australia. One of the goals was to estimate additions of Sr and rare earth elements of anthropogenic (fertilizer) origin to the natural catchment sources to the soils and streams. Among possible sediment sources, Tertiary basalts and Paleozoic metagraywackes have the lowest ⁸⁷Sr/⁸⁶Sr and highest ϵNd, whereas Paleozoic metapelitic rocks have negative ϵNd and the highest ⁸⁷Sr/⁸⁶Sr. Phosphate fertilizers have strongly negative ϵNd and ⁸⁷Sr/⁸⁶Sr similar to Tertiary seawater. Soils formed on basalt and metagraywacke have compositions that are shifted toward higher ⁸⁷Sr/⁸⁶Sr and lower ϵNd than their parent rocks. REE patterns and elemental ratios such as Nd/P are also distinctive between fertilizer and natural catchment sources.

Controls over the Sr isotopic composition of river water

Article

May 1992
GEOCHIM COSMOCHIM AC

Strontium concentrations and isotope ratios have been measured in river and ground waters from the Ganges, Orinoco, and Amazon river basins. When compared with major element concentrations, the data set has allowed a detailed examination of the controls over the strontium isotope systematics of riverine input to the oceans in the following environments: 1.(1) “typical” drainage basins containing limestones, evaporites, shales, and alumino-silicate metamorphic and igneous rocks;2.(2) shield terrains containing no chemical or biogenic sediments; and3.(3) the floodplains that constitute the largest areas of many large rivers. The strontium concentration and isotope composition of river waters are largely defined by mixing of strontium derived from limestones and evaporites with strontium derived from silicate rocks. The strontium isotope composition of the limestone endmember generally lies within the Phanerozoic seawater range, which buffers the ratios of major rivers. A major exception is provided by the rivers draining the Himalayas, where widescale regional metamorphism appears to have led to an enrichment in limestones of radiogenic strontium derived from coexisting silicate rocks. The strontium isotope systematics of rivers draining shield areas are controlled by the intense, transportlimited, nature of the weathering reactions, and thereby limits variations in the strontium flux from these terrains. Floodplains are only a minor source of dissolved strontium to river waters, and precipitation of soil salts in some floodplains can reduce the riverine flux of dissolved strontium to the oceans. The most effective mechanisms for altering the isotope ratio and flux of riverine strontium to the oceans are increased glaciation and large-scale regional metamorphism of the type produced during continental collision. Both mechanisms provide a means for increasing the ratio of the global riverine flux.

The isotopic and chemical composition of CO2-rich thermal waters in the Mont-Dore region (Massif-Central, France)

Article

Jul 1997
APPL GEOCHEM

Chemical and isotope compositions of fluid samples, collected between 1974 and 1986 from 52 springs or shallow boreholes located in the Mont-Dore region (Massif Central, France), were examined. Some springs and wells were sampled several times during this period. The fluids emerge from Quaternary volcanic rocks or Paleozoic granite at temperatures between 4 and 62°C, and the origin of the H2O is meteoric. The waters can be classified into three groups: bicarbonate fluids, mixed bicarbonate-chloride fluids (with a mineralization up to 8 g/l), and acid-sulfate fluids. Only two fluids contain sufficient Cl⁻ to be considered as ‘mature’ waters. Previous work has demonstrated that they all contain partly mantle-derived CO2 gas, and that the CO2-rich gas phase and bicarbonate-chloride waters are separated at substantial depth.

Strontium isotopic constraints on the origin of ore-forming fluids of the Viburnum Trend, southeast Missouri

Article

May 1991
GEOCHIM COSMOCHIM AC

We have measured and Rb and Sr concentrations in several minerals, primarily sulfides, spanning the paragenesis of hydrothermal mineralization in the Viburnum Trend in southeast Missouri. Separate measurements were made for fluid inclusions opened by crushing or thermal decrepitation and for the solids. For comparison, measurements were also made on samples of probable local aquifers, the Bonneterre Formation and the Lamotte Sandstone. For some of the samples, concentrations of K, Ca, Cl, Na, and Mg are also reported.In several cases are different (higher) in the solids than in the fluid inclusions. We have investigated the possibility that either type of sample gives spurious results, e.g., that the fluid inclusions are secondary or contaminated by host dolomite, or that Sr in the solids reflects a detrital rather than an authigenic source. Consideration of mass balance, overall solute chemistry, and examination of non-sulfide dissolution residue, however, suggests that both types of sample reflect primary fluid Sr composition. We thus adopt the working hypothesis that Sr isotopic composition in fluids at the time of hydrothermal mineralization was highly variable.The observed results for the Viburnum Trend do not conform well to expected trends for Mississippi Valley-type (MVT) mineralization based primarily on analyses of gangue carbonates, barite, and fluorite. Fluid inclusion Sr in some of the Viburnum Trend samples is more radiogenic than in the host dolomite but only moderately so; in other samples, notably main-stage octahedral galena, fluid inclusion Sr composition is within the range observed for the host dolomite. In contrast, Sr in some of the sulfides is very radiogenic, much more so than previously reported for MVT minerals, and is very radiogenic early in the paragenesis (pyrite, chalcopyrite, sphalerite), less radiogenic during main-stage ore deposition, and again more radiogenic in later paragenetic stages.

Isotopic and Trace-Element Constraints on the Origin and Evolution of Saline Groundwaters From Central Missouri

Article

Feb 1989
GEOCHIM COSMOCHIM AC

Na-Ca-Cl groundwaters with salinities of 1 to 30% discharge from natural springs and artesian wells in Mississippian carbonates and Ordovician sandstones and carbonates in central Missouri. Carbonate saturation and quartz supersaturation are maintained throughout the salinity range. Major and trace element and isotopic variations in the waters are used to place constraints on models for rock-water interaction and regional hydrology. The groundwaters have δD values that range from −108 to −45‰ and δ^(18)O values that range from −14.7 to −6.5‰ (SMOW). These data lie approximately along the meteoric water line, ranging from values similar to local recharge in Missouri, to significantly lower values that are similar to δ^(18)O and δD for meteoric recharge in high altitude and high latitude regions of North America. The more saline samples have the lowest ^(18)O and D contents, a trend that is opposite to that observed in most other studies of saline waters. The H-O isotopic correlation and the range in salinity and several major and trace element concentrations in central Missouri groundwaters are readily explained by a saline-dilute water mixing model. 87Sr/86Sr ratios for the groundwaters range from 0.7155 to 0.7161. These values are significantly higher than previously published values for: 1) estimates of ^(87)Sr/^(86)Sr in Phanerozoic seawater (0.7068–0.7092); and 2) carbonates of the Mississippian Burlington-Keokuk Fm. (0.7075–0.7105), through which some of the waters migrate as they pass to the surface. ϵNd(0) values in the groundwaters range from −10.9 to −8.1, and ^(147)Sm/^(144)Nd ratios range from 0.108 to 0.128. These values are similar to or lower than previously published analyses of carbonates and other authigenic phases from the Burlington-Keokuk Fm. (mean ϵNd(0) = −7.8 ± 0.8 (1σ); mean ^(147)Sm/^(144)Nd = 0.141). The H, O, Sr and Nd isotopic data and the results of model calculations preclude: 1) models involving the modification of ancient seawater for the origin of the saline waters, and 2) extensive interaction between the groundwaters and their host carbonates. The waters apparently acquired their δ^(18)O and δD values as meteoric recharge and their 87Sr/86Sr and rare earth element signatures from extraformational crustal sources (high ^(87)Sr/^(86)Sr; low ϵNd(0); low 147Sm/144Nd) and largely preserved these isotopic signatures during subsequent migration through the carbonates. Chemical exchange via rock-water interaction is required for isotopic exchange to occur. Therefore, the present state of chemical equilibrium between the groundwaters and carbonate aquifer minerals may serve to limit rock-water interaction, and hence preserve the extraformational isotopic signatures in the waters. The integration of geochemical, isotopic and hydrologic data on a local and regional scale suggests a history for the central Missouri groundwaters involving: 1) meteoric recharge in the Front Range of Colorado; 2) dissolution of Permian halite in the subsurface of Kansas; 3) interaction with predominantly silicate mineral assemblages in Paleozoic strata (and possibly Precambrian basement), with aquisition of crustal Sr and REE signatures; 4) dilution and migration to shallow aquifer levels in central Missouri; and 5) mixing with local meteoric recharge through Mississippian carbonates with no significant change of the isotopic signatures acquired in stage (3).

Chemistry of rainwater in the Massif Central (France): A strontium isotope and major Element Study

Article

Nov 1998
APPL GEOCHEM

Atmospheric aerosols (sea salt, crustal dust, and biogenic aerosols) are the primary source of dissolved species in rainwater as well as one of the sources of dissolved species in river water. Chemical weathering studies require quantification of this atmospheric input. The crustal component of atmospheric input can have various origins, both distant and local. The proportions of the various inputs (marine, distant or local) are determined in this study.Strontium isotope ratios and Ca, Na, K, Mg, Al, Cl, SO4, NO3 and Sr concentrations were measured in rainwater samples collected in the Massif Central (France) over a period of one year. Each sample, collected automatically, represents a monthly series of rain events. Chemical composition of the rainwater samples varied considerably and the 87Sr/86Sr ratios ranged between 0.709198 and 0.713143.Using Na as an indicator of marine origin, and Al for the crustal input in rain samples, the proportion of marine and crustal elements was estimated from elemental ratios. A marine origin of 4 to 100% of Cl, of 0.6 to 20% of the SO4, of <1 to 10% of Ca, <1 to 40% of K, 4 to 100% of Mg and 1 to 44% of Sr was determined.Strontium isotopes were used to characterize the crustal sources. The 87Sr/86Sr ratios of the crustal sources varied considerably from 0.7092 to 0.71625 and indicate the occurrence of multiple sources for the crustal component in the analysed rainwaters.

Saline groundwaters in the hercynian granites (Chardon Mine, France): Geochemical evidence for the salinity origin

Article

Jan 1999
APPL GEOCHEM

In this study, the chemical evolution of high Cl− Chardon mine groundwaters is modelled as a mixing between an oxidising recharge and an old marine component on which the water–rock interaction is superimposed. Chemical and isotopic similarities with saline Carnmenellis mine groundwaters are emphasised and a general comparison with other brines is discussed.The cation content of deep granitic groundwaters is indicative of the water–rock interaction. In the case of Chardon and Carnmenellis groundwaters, the high Na/Cl ratio can still be related to the contribution of a brine of sedimentary origin to the water salinity. The differences in the hydrochemistry related to their geological context only appears at the trace metals level. On the contrary, brines in plutonic rocks which exhibit a low Na/Cl ratio represent groundwaters having a residence time in the host rock, long enough to equilibrate with secondary aluminosilicates. In that case, the brine origin is difficult to assess if only based on the water cation content.

Strontium isotope systematics used to decipher the origin of groundwaters sampled from granitoids: The Vienne Case (France)

Abstract

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