Distribution of Hydrogen and Oxygen Isotopes in Salt Lakes of the Qinghai—Xizang Plateau,China

The Qinghai-Xizang Plateau is an area where a large number of salt lakes are distributed. We have collected several hundred samples of natural waters over the Plateau since 1976 and carried out researches on their hydrogen and oxygen isotopes. The results indicate that the^δD and δ¹⁸O values of the salt lake waters over the Plateau range from −64.1 to +12.4‰ and from −11.19 to +8.62‰, respectively. From the different types of surfaces, ground and lake waters of various salinities it is inferred that the compositions of H and O isotopes in the initial water of Qinghai Lake are^δD=−55.0‰ and {ie336-1}; and those in the original water from the lakes in northern Xizang, are^δD=−116.0‰ and {ie336-2}. Brines in the salt lakes are derived from rain water through prolonged circulation. Oilfield water also makes some contribution to the salt lakes in the Qaidam Basin. Similar slopes of evaporation lines of water isotopes are noticed for the Qinghai Lake area and northern Xizang. This is attributed to the evolution of the isotopes in these water bodies in an environment of middle latitude and high elevation.     

Changes of δ<Superscript>18</Superscript>O and δD along the Dousitu River,Inner Mongolia,China, and their evidence of river water evaporation

On the basis of the hydrogeology of the Dousitu River drainage basin, the changes of water flow rate, δ¹⁸O and δD along the Dousitu River are discussed according to measured and analytical results. Changes of flow rate along the Dousitu River agree well with groundwater level contours and the recharge and discharge of groundwater to the river. When compared with other types of water in the area, it is obvious that the ¹⁸O and D of river waters have experienced evaporation. The changes of δ¹⁸O and δD along the Dousitu River are mainly caused by combined effects of groundwater recharge and river water evaporation. The recharge of groundwater makes δ¹⁸O and δD of the river water decrease. Evaporation makes δ¹⁸O and δD of the river water increase. The evaporation fractions of the river water are calculated using the kinetic fractionation theory. Results showed as much as 10–30% of water was evaporated in different segments of Dousitu River.     

Application of environmental groundwater tracers at the Sulphur Bank Mercury Mine, California, USA

Boron, chloride, sulfate, δD, δ¹⁸O, and ³H concentrations in surface water and groundwater samples from the Sulphur Bank Mercury Mine (SBMM), California, USA were used to examine geochemical processes and provide constraints on evaporation and groundwater flow. SBMM is an abandoned sulfur and mercury mine with an underlying hydrothermal system, adjacent to Clear Lake, California. Results for non-³H tracers (i.e., boron, chloride, sulfate, δD, and δ¹⁸O) identify contributions from six water types at SBMM. Processes including evaporation, mixing, hydrothermal water input and possible isotopic exchange with hydrothermal gases are also discerned. Tritium data indicate that hydrothermal waters and other deep groundwaters are likely pre-bomb (before ~1952) in age while most other waters were recharged after ~1990. A boron-based steady-state reservoir model of the Herman Impoundment pit lake indicates that 71–79% of its input is from meteoric water with the remainder from hydrothermal contributions. Results for groundwater samples from six shallow wells over a 6–month period for δD and δ¹⁸O suggests that water from Herman Impoundment is diluted another 3% to more than 40% by infiltrating meteoric water, as it leaves the site. Results for this investigation show that environmental tracers are an effective tool to understand the SBMM hydrogeologic regime.

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Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.

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Résumé Les concentrations en bore, chlorure, sulfate, δD, δ¹⁸O, et ³H d’échantillons d’eaux de surface et souterraine prélevés dans le banc de soufre de la mine de mercure (SBMM en anglais) en Californie, USA, ont été utilisées pour étudier les processus géochimiques et pour fournir des contraintes à l’évaporation et à l’écoulement des eaux souterraines. La SBMM est une mine de soufre et de mercure abandonnée, adjacente au lac Clear en Californie et sous laquelle se trouve un système hydrothermal.Les résultats des traceurs autres que le tritium (bore, chlorure, sulfate, δD, et δ¹⁸O) ont permis d’identifier des contributions de six types d’eaux à SBMM. Des processus tels que l’évaporation, le mélange, l’entrée d’eau hydrothermale et de possibles échanges isotopiques avec des gaz hydrothermaux ont également été identifiés. Les données de tritium montrent que les eaux hydrothermales et d’autres eaux profondes sont probablement d’age antérieure à la bombe (avant ~1952), alors que la plupart des autres eaux sont issues de la recharge après ~1990. Un modèle de réservoir représentant le lac situé dans la partie Herman Impoundment de l’ancienne mine, en régime permanent et basé sur le bore, montre que 71–79% de l’eau provient des précipitations, le reste provenant de contributions hydrothermales. Les résultats de δD et δ¹⁸O pour des échantillons d’eau souterraine de six puits peu profonds sur une période de 6 mois suggèrent que l’eau de Hermann Impoundment est encore diluée entre 3% jusqu’à plus de 40% lorsqu’elle quitte le site du fait de l’infiltration d’eau météorique. Les résultats de cette étude montrent que les traceurs environnementaux constituent un outil efficace pour comprendre le régime hydrogéologique de la SBMM.

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Resumen Se han utilizado datos de concentraciones de boro, cloruros, sulfatos, δD, δ¹⁸O, y ³H en muestras de aguas superficiales y subterráneas procedentes de la Mina de Mercurio Sulphur Bank (SBMM), California, USA, para estudiar los procesos geoquímicos y caracterizar la evaporación y el flujo del agua subterránea. SBMM es una mina abandonada de azufre y mercurio con un sistema hidrotermal subyacente, cercano al Lago Clear, California.Los resultados de los trazadores que no son ³H (por ejemplo, boro, cloruros, sulfatos δD, y δ¹⁸O) identifican las contribuciones de seis tipos de agua en la SBMM. Se han identificado diversos procesos, como evaporación, mezcla, entrada de agua hidrotermal y la posibilidad de intercambios isotópicos con gases hidrotermales. Los datos de tritio indican que las aguas hidrotermales y otras aguas subterráneas profundas son probablemente pre-bombas (previas a ~1952) en edad mientras que la mayoría de las otras aguas se han recargado después de ~1990. Un modelo estacionario basado en el boro de la fosa del lago Herman Impoundment indica que el 71–79% de su entrada procede de agua meteórica con restos de contribución hidrotermal. Los resultados para las muestras de aguas subterráneas procedentes de seis pozos superficiales en un periodo de 6 meses para δD y δ¹⁸O sugieren que el agua procedente de Herman Impoundment se diluye en otro 3% hasta más del 40% debido a la infiltración de agua meteórica., que sale del sitio. Los resultados de esta investigación muestran que los trazadores ambientales son una herramienta efectiva para entender el régimen hidrogeológico de la SBMM.

     

Isotopes of deuterium and oxygen-18 in thermal groundwater in China

Compositions of deuterium and ¹⁸O isotopes of 90 representative samples indicate that thermal groundwater in most parts of China is meteoric in origin. Latitude, altitude, and continent effects have significant bearing on the values of δD and δ¹⁸O of the hot water samples. Oxygen-18 shift is not significant in most of the thermal groundwater, especially the hot water of low-to-moderate temperature. Slight oxygen-18 shift is only found in some hot springs of high temperature in Tibet and western Yunnan and in thermal groundwater of low-to-moderate temperature in the deep-seated carbonate aquifers in the northern North China Plain (including the Tianjin area). Near-surface boiling may causes the shift of the former and the latter may be attributed to exchange of oxygen-18 between water and carbonates in the geothermal systems of taphrogenic basin-type. Hot springs in Tibet and western Sichuan have very low contents of δD and δ¹⁸O, possibly due to recharge of precipitation and snow-melting water of extremely depleted δD and δ¹⁸O values at high latitudes of several thousands of meters.     

Characteristics of isotope in precipitation,river water and lake water in the Manasarovar basin of Qinghai–Tibet Plateau

The stable hydrogen and oxygen of lake, river, rain and snow waters were investigated to understand the water cycle characteristics of the drainage basin of Manasarovar Lake in Tibet. Both δD and δ ¹⁸O of river water are larger than those of lake water and the effect of altitude on both δD and δ ¹⁸O is not very significant. This phenomenon was suggested to occur because Manasarovar basin is located in Qinghai–Tibet Plateau which has low latitude, high altitude, abundant glaciers, thin air and intensive solar radiation, resulting in higher evaporation in lake water.     

Gold mineralization in the Mazowe area, Harare-Bindura-Shamva greenstone belt, Zimbabwe: II. Genetic relationships deduced from mineralogical, fluid inclusion and stable isotope studies, and the Sm-Nd isotopic composition of scheelites

In the Mazowe area some 40 km NW of Harare in Zimbabwe, gold mineralization is hosted in a variety of lithologies of the Archean Harare-Bindura-Shamva greenstone belt, in structures related to the late Archean regional D2/3 event. Conspicuous mineralzogical differences exist between the mines; the mainly granodiorite-hosted workings at Mazowe mine are on pyrite-rich reefs, mines of the Bernheim group have metabasalt host rocks and are characterized by arsenopyrite-rich ores, and Stori's Golden Shaft and Alice mine, both in metabasalts, work sulfide-poor quartz veins. In contrast to the mineralogical diversity, near-identical fluid inventories were found at the different mines. Both H₂O-CO₂-CH₄ fluids of low salinity, and highly saline fluids are present and are regarded to indicate fluid mixing during the formation of the deposits. Notably, these fluid compositions in the Mazowe gold field markedly contrast to ore fluids “typical” of Archean mesothermal gold deposits on other cratons. Stable isotope compositions of quartz from the various deposits (δ¹⁸O=10.8 to 13.2‰ SMOW), calcite (δ¹⁸O=9.5 to 11.9‰ SMOW and δ¹³C=−3.2 to −8.0‰ PDB), inclusion water (δD=−28 to −40‰ SMOW) and sulfides (δ³⁴S=1.3 to 3.2‰ CDT) are uniform within the range typical for Archean lode gold deposits worldwide. The fluid and stable isotope compositions support the statement that the mineralization in the Mazowe gold field formed from relatively reduced fluids with a “metamorphic” signature during a single event of gold mineralization. Microthermometric data further indicate that the deposits formed in the PT range of 1.65–2.3 kbar and 250–380 °C. Ages obtained by using the Sm/Nd and Rb/Sr isotope systems on scheelites are 2604 ± 84 Ma for the mineralization at Stori's Golden Shaft mine, and 2.40 ± 0.20 Ga for Mazowe mine. The Archean age at Stori's is regarded as close to the true age of gold mineralization in the area, whereas the Proterozoic age at Mazowe mine probably reflects later resetting. Received: 30 September 1998 / Accepted: 17 August 1999     

Study of shallow groundwater quality evolution under saline intrusion with environmental isotopes and geochemistry

Evolution of the shallow groundwater quality under saline intrusion in porous aquifer system has been studied with environmental isotopes and geochemistry in the Laizhou Bay area, China. Two campaigns of water sampling from various sources were carried out in spring and winter for environmental isotopic and chemical analyses. The origin of groundwater salinity from intrusion of both modern seawater and deep brine water was identified by analysing the correlations between ¹⁸O, D, T, Cl⁻, SO₄²⁻ and electrical conductivity. The results indicate that the brine is originated from evaporating and concentrating of intruded seawater and its δD and δ¹⁸O are different from modern seawater but similar to those of mixture of seawater with fresh groundwater. It is hard to distinguish the salinity origin in this area by the δD–δ¹⁸O relationship alone. The relations between δ¹⁸O and conductivity, Cl⁻ and SO₄²⁻ have been used to identify the salinity origin due to the distinct difference in salinity between the brine and seawater, conjunctively with use of T. A threshold of T = 12 TU was adopted to identify the origin of saline groundwater.     

Imprint of meteoric water on the stable isotope compositions of igneous and secondary minerals,Kap Edvard Holm Complex,East Greenland

 Hydrogen and oxygen isotope analyses have been made of hydrous minerals in gabbros and basaltic xenoliths from the Eocene Kap Edvard Holm intrusive complex of East Greenland. The analyzed samples are of three types: (1) primary igneous hornblendes and phlogopites that crystallized from partial melts of hydrothermally altered basaltic xenoliths, (2) primary igneous hornblendes that formed during late–magmatic recrystallization of layered gabbroic cumulates, and (3) secondary actinolite, epidote and chlorite that formed during subsolidus alteration of both xenoliths and gabbros. Secondary actinolite has a δ¹⁸O value of −5.8‰ and a δD value of −158‰. These low values reflect subsolidus alteration by low–δ¹⁸O, low–δD hydrothermal fluids of meteoric origin. The δD value is lower than the −146 to −112‰ values previously reported for amphiboles from other early Tertiary meteoric–hydrothermal systems in East Greenland and Scotland, indicating that the meteoric waters at Kap Edvard Holm were isotopically lighter than typical early Tertiary meteoric waters in the North Atlantic region. This probably reflects local climatic variations caused by formation of a major topographic dome at about the time of plutonism and hydrothermal activity. The calculated isotopic composition of the meteoric water is δD=−110 ± 10‰, δ¹⁸O ≈−15‰. Igneous hornblendes and phlogopites from pegmatitic pods in hornfelsed basaltic xenoliths have δ¹⁸O values between −6.0 and −3.8‰ and δD values between −155 and −140‰. These are both much lower than typical values of fresh basalts. The oxygen isotope fractionations between pegmatitic hornblendes and surrounding hornfelsic minerals are close to equilibrium fractionations for magmatic temperatures, indicating that the pegmatites crystallized from low–δ¹⁸O partial melts of xenoliths that had been hydrothermally altered and depleted in ¹⁸O prior to stoping. The pegmatitic minerals may have crystallized with low primary δD values inherited from the altered country rocks, but these values were probably overprinted extensively by subsolidus isotopic exchange with low–δD meteoric–hydrothermal fluids. This exchange was facilitated by rapid self–diffusion of hydrogen through the crystal structures. Primary igneous hornblendes from the plutonic rocks have δ¹⁸O values between +2.0 and +3.2‰ and δD values between −166 and −146‰. The ¹⁸O fractionations between hornblendes and coexisting augites are close to equilibrium fractionations for magmatic temperatures, indicating that the hornblendes crystallized directly from the magma and subsequently underwent little or no oxygen exchange. The hornblendes may have crystallized with low primary δD values, due to contamination of the magma with altered xenolithic material, but the final δD values were probably controlled largely by subsolidus isotopic exchange. This inference is based partly on the observation that coexisting plagioclase has been extensively depleted in ¹⁸O via a mineral–fluid exchange reaction that is much slower than the hydrogen exchange reaction in hornblende. It is concluded that all hydrous minerals in the study area, whether igneous or secondary, have δD values that reflect extensive subsolidus isotopic equilibration with meteoric–hydrothermal fluids. Received: 22 March 1994 / Accepted: 26 January 1995     

A geochemical survey of spring water from the main Ethiopian rift valley, southern Ethiopia: implications for well-head protection

The report discusses the stable isotope values and major solute compositions of 16 springs and river-water samples along a topographic gradient in the main rift valley of southern Ethiopia. Most of the springs used for drinking water supplies discharge from local flow systems at scales of only tens of meters. The δ¹⁸O and δD values of waters unaffected by shallow evaporation form a local meteoric water line of δD=8.1δ¹⁸O+19.0, almost identical to that for the eastern Mediterranean area. The δ¹⁸O values show an altitude effect of –0.5‰ per 100-m elevation rise. Total dissolved nitrogen concentrations locally exceed 6 mg/L (as N), and phosphate concentrations were elevated above background levels in some springs, exceeding 0.2 mg/L PO₄, probably due to agricultural practices upgradient of the springs. Modest well-head protection should be considered to protect public health from the effects of pollution by agricultural waste, given the very local scale of the flow systems providing spring water to Ethiopian villages. Electronic Publication     

Spatio-temporal variation of stable isotopes in precipitation in the Heihe River Basin,Northwestern China

An intensive investigation of the spatial and temporal variations of δD and δ ¹⁸O in precipitation was conducted during 2002–2004 in six sites in the Heihe River Basin, Northwestern China. The δD and δ ¹⁸O values for 301 precipitation samples ranged from +59 to −254 and +6.5 to −33.4‰, respectively. The relationship between δD and δ ¹⁸O defines a well-constrained line given by dD = 7.82d¹⁸\textO + 7.63 \delta D = 7.82\delta {}^{18}{\text{O}} + 7.63 , which is nearly identical to the meteoric water line in the Northern China. This wide range indicates that stable isotopes in precipitation were primarily controlled by different condensation mechanisms as a function of air temperature and varying sources of moisture. The results of backward trajectory of each precipitation day at Xishui show that the moisture of the precipitation in cold season (October–March) mainly originated from the west while the moisture source was more complicated in warm season (April–September). The simulation of seasonal δ ¹⁸O variation shows that the stable isotope composition of precipitation tended to a clear sine-wave seasonal variation. The spatial variation of δ ¹⁸O shows that the weighted average δ ¹⁸O values decreases with the increasing altitude of sampling sites. The great difference of air temperature which led to the differences of condensation mechanisms and local recycled continental moisture may have influence upon the isotopic composition of rain events in different sites.     

Recharge source and hydrogeochemical evolution of shallow groundwater in a complex alluvial fan system,southwest of North China Plain

Many cities around the world are developed at alluvial fans. With economic and industrial development and increase in population, quality and quantity of groundwater are often damaged by over-exploitation in these areas. In order to realistically assess these groundwater resources and their sustainability, it is vital to understand the recharge sources and hydrogeochemical evolution of groundwater in alluvial fans. In March 2006, groundwater and surface water were sampled for major element analysis and stable isotope (oxygen-18 and deuterium) compositions in Xinxiang, which is located at a complex alluvial fan system composed of a mountainous area, Taihang Mt. alluvial fan and Yellow River alluvial fan. In the Taihang mountainous area, the groundwater was recharged by precipitation and was characterized by Ca–HCO₃ type water with depleted δ¹⁸O and δD (mean value of −8.8‰ δ¹⁸O). Along the flow path from the mountainous area to Taihang Mt. alluvial fan, the groundwater became geochemically complex (Ca–Na–Mg–HCO₃–Cl–SO₄ type), and heavier δ¹⁸O and δD were observed (around −8‰ δ¹⁸O). Before the surface water with mean δ¹⁸O of −8.7‰ recharged to groundwater, it underwent isotopic enrichment in Taihang Mt. alluvial fan. Chemical mixture and ion exchange are expected to be responsible for the chemical evolution of groundwater in Yellow River alluvial fan. Transferred water from the Yellow River is the main source of the groundwater in the Yellow River alluvial fan in the south of the study area, and stable isotopic compositions of the groundwater (mean value of −8.8‰ δ¹⁸O) were similar to those of transferred water (−8.9‰), increasing from the southern boundary of the study area to the distal end of the fan. The groundwater underwent chemical evolution from Ca–HCO₃, Na–HCO₃, to Na–SO₄. A conceptual model, integrating stiff diagrams, is used to describe the spatial variation of recharge sources, chemical evolution, and groundwater flow paths in the complex alluvial fan aquifer system.     

Drainage and nutrient attenuation in a riparian interception-wetland: southern Minnesota,USA

Riparian wetlands have multiple source waters that require understanding to effectively manage water quantity and quality. Source waters were determined in an interception-wetland located a relatively flat clayey till terrain in southern Minnesota. Data loggers were used to measure precipitation, water stage from monitoring wells and a tile-drain outlet. Over 70 oxygen (δ¹⁸O), hydrogen (δD) and geochemical water samples were collected from seven locations over different seasons (9 events) from 1996 to 1999. Results indicate the dominant source water input to the wetland was drained shallow groundwater beneath intensively managed cropland (P = 0.000). Evapotranspiration was the dominant export pathway. Nitrate–nitrogen (NO₃-N) concentrations significantly decreased (P = 0.000) in the cattail-willow portion of the wetland. Total phosphorous (TP) concentrations were relatively high in the grass portion of the wetland (673 ± 549 μg L⁻¹), and relatively low in the cattail-willow portion of the wetland (139 ± 85 μg L⁻¹) because source waters were low in TP. Overall, the interception-wetland design limited out-of-bank flooding, yet allowed sufficient gradient between the cropland and the wetland outlet to minimize potential crop damage and provide hydraulic storage for nutrient attenuation.     

Salinization properties of a shallow groundwater in a coastal reclaimed area,Yeonggwang, Korea

The need for more agricultural or residential land has encouraged reclamation at the coastal areas of Korea since 1200 ad (approximately). The groundwaters of these reclaimed areas could be expected to reveal hydrogeochemical properties different from those of areas directly affected by seawater intrusion. The purpose of this study, therefore, was to examine the salinization of shallow groundwater in a coastal reclaimed area and to identify the effect of land reclamation on groundwater quality. Major cations and anions, iodide, total organic carbon, δD, δ ¹⁸O and δ ¹³C were measured to assist the hydrogeochemical analysis. Chloride, δD and δ ¹⁸O data clearly show that the Na–Cl type water results from mixing of groundwater with seawater. In particular, the δD and δ ¹⁸O of Ca+Mg–Cl+NO₃ type groundwaters are close to the meteoric water line, but Na–Cl type waters enriched in chloride are ¹⁸O-enriched with respect to the meteoric water line. Meanwhile, carbon isotopic data and I/Cl ratios strongly suggest that there are various sources of salinity. The δ ¹³C values of Na–Cl type groundwaters are generally similar to those of Ca+Mg–Cl+NO₃ type waters, which are depleted in ¹³C with respect to seawater. I/Cl ratios of Na–Cl type groundwater are 10–100 times higher than that of seawater. Because the reclamation has incorporated a large amount of organic matter, it provides optimum conditions for the occurrence of redox processes in the groundwater system. Therefore, the salinization of groundwater in the study area seems to be controlled not only by saltwater intrusion but also by other effects, such as those caused by residual salts and organic matter in the reclaimed sediments.     

Stable isotope variations in a coral (Favia speciosa) from the Gulf of Kutch during 1948–1989 A.D.: Environmental implications

The stable isotopic analyses (δ¹⁸O and δ¹³C) of a coralFavia speciosa spanning forty two years (1948–89 A.D.), collected from the Pirotan island (22.6°N, 70°E) in the Gulf of Kutch have been carried out to assess its potential for retrieving past environmental changes in this region. It is seen that the summer (minima) δ¹⁸O variations in the coral CaCO₃ are negatively correlated with seasonal (summer) monsoon rainfall in the adjoining region of Kutch and Saurashtra and a qualitative reconstruction of historical rainfall variations in this region can be obtained by analyzing the δ¹⁸O in this species of coral. The observed mean seasonal range of δ¹⁸O variations is 0.34 ±0.17‰ (n = 42), whereas the expected range calculated (from available SST and measured δ¹⁸O of sea water) is ∼ 1.1 ±0.15‰ The difference is due to the coarse resolution of sampling, which can be corrected. The seasonal range in δ¹³C is ∼ l‰ and is explained by changes in: a) the light intensity related to the cloudiness during monsoons and b) phytoplankton productivity.     

10Be meltwater signal in Orca basin sediments,Gulf of Mexico

An increase in the cosmogenic beryllium-10 content of the Orca basin sediments due to the flooding of the Gulf of Mexico (GM) by meltwaters during the late Wisconsin interglacial is reported. A strong negative correlation (γ =-0.99) betweenδ ¹⁸ O (in the range o f-1.5‰ to +0.5‰) and¹⁰Be/Al ratio is seen. During intense flooding reflected by a decrease in δ¹⁸O by ∼ 2‰, this correlation may not hold as some of the sediments with low¹⁰Be/Al ratio and deposited on the shelf and slope regions of the GM during the earlier glacial period would also be washed into the basin. The deposited sediment would then be a mixture with a¹⁰Be/Al ratio lower than expected from the correlation     

Stable isotope characteristics and origin of ore-forming fluids in copper-gold-polymetallic deposits within strike-slip pull-apart basin of Weishan-Yongping continental collision orogenic belt, Yunnan Province, China

More than 140 middle-small sized deposits or minerals are present in the Weishan-Yongping ore concentration area which is located in the southern part of a typical Lanping strike-slip and pull-apart basin. It has plenty of mineral resources derived from the collision between the Indian and Asian plates. The ore-forming fluid system in the Weishan-Yongping ore concentration area can be divided into two subsystems, namely, the Zijinshan subsystem and Gonglang arc subsystem. The ore-forming fluids of Cu, Co deposits in the Gonglang arc fluid subsystem have δD values between −83.8‰ and −69‰, δ¹⁸O values between 4.17‰ and 10.45‰, and δ¹³C values between −13.6‰ and 3.7‰, suggesting that the ore-forming fluids of Cu, Co deposits were derived mainly from magmatic water and partly from formation water. The ore-forming fluids of Au, Pb, Zn, Fe deposits in the Zijinshan subsystem have δD values between −117.4‰ and −76‰, δ¹⁸O values between 5.32‰ and 9.56‰, and Δ¹³C values between −10.07‰ and −1.5‰. The ore-forming fluids of Sb deposits have δD values between −95‰ and −78‰, δ¹⁸O values between 4.5‰ and 32.3‰, and Δ¹³C values between −26.4‰ and −1.9‰. Hence, the ore-forming fluids of the Zijinshan subsystem must have been derived mainly from formation water and partly from magmatic water. Affected by the collision between the Indian and Asian plates, ore-forming fluids in Weishan-Yongping basin migrated considerably from southwest to northeast. At first, the Gonglang arc subsystem with high temperature and high salinity was formed. With the development of the ore-forming fluids, the Zijinshan subsystem with lower temperature and lower salinity was subsequently formed. Translated from Mineral Deposits, 2006, 25(1): 60–70 [译自: 矿床地质]     

Reconstruction of Antarctic climate change using ice core proxy records from the coastal Dronning Maud Land,East Antarctica

Antarctic ice core records have provided unprecedented information on past climatic changes and forcing factors on decadal to millennial timescales. The glaciochemical and stable isotope records of a shallow ice core from the coastal Dronning Maud Land (East Antarctica) were used here to reconstruct the coastal Antarctic environmental variability during the past ∼470 years. Sea salt ion data indicate a significant additional contribution of chloride ions compared to sea water values, possibly through atmospheric scavenging. The nitrate (NO₃ ⁻) profile exhibit significant temporal shifts than that of the sulphate (SO₄ ²⁻), with a major shift around 1750 AD. The changes in NO₃ ⁻ record are synchronous with the proxy record of solar activity (¹⁰Be profile from a South Pole ice core), suggesting enhanced NO₃ ⁻ values during periods of reduced solar activity like the Dalton Minimum (∼1790–1830 AD) and Maunder Minimum (∼1640–1710 AD). The δ¹⁸O records reveal that the more negative δ¹⁸O values were coeval with several events of increased NO₃ ⁻ concentrations, suggesting enhanced preservation of NO₃ ⁻ during periods of reduced air temperatures. The δ¹⁸O and δD records of the core also suggest significant short-term and long-tem variability with more negative values indicating relatively lower air temperatures prior to 1715 AD. The δ¹⁸O records also revealed a significant warming of 2.7°C for the past 470 years, with a warming of ∼0.6°C per century.     

Stable isotope systematics of surface water bodies in the Himalayan and Trans-Himalayan (Kashmir) region

Stable hydrogen (δD) and oxygen (δ¹⁸O) isotope ratios of the headwaters of the Indus and its tributaries, surface ice in glaciers, saline and fresh water lakes and thermal springs in the Himalayan and Trans-Himalayan (Kashmir) region are reported. The δ5D-δ¹⁸ relationship for the river samples shows a slope of 9.12 +-0.29 which agrees well with the estimate of 8.99 ±0.33 based on a simple Rayleigh fractionation model. The unique signature of a higher deuterium excess (d) of the ‘Western Disturbance’ is preserved in these samples. An altitude effect of -0.9 per mil/km is observed in the δ¹⁸O of Indus waters. At a lower altitude (Beas) the altitude effect is almost double, indicating that the altitude effect decreases with elevation in this region.     

Ore fluid geochemistry of the Jinlongshan Carlintype gold ore belt in Shaanxi Province, China

THEJINLONGSHANGOLDOREBELTINZHEN’ANCOUN TY,SOUTHERNSHAANXIPROVINCE,ISLOCATEDINTHEWEST ERNQINLINGGOLDPROVINCE(NO.16INFIG.1;CHEN YANJINGETAL.,2004).ITWASDISCOVEREDINTHEDEVO NIANSTRATAINTHELATE1980S).ITSGEOLOGICALSETTING ANDMETALLOGENICEVOLUTIONARESIMILARTOT…     

Fresh Water Inflow and Oyster Productivity in Apalachicola Bay,FL (USA)

Apalachicola Bay lies at the mouth of the Apalachicola River, where seasonally variable freshwater inflows and shifting winds have long been thought to contribute to the support of an unusually productive and commercially important oyster fishery. Links between the river and productivity have been shown to lie in salinity-induced reductions in oyster predators and oyster disease as well as organic supplements from an extensive floodplain. Several studies have also indicated that nitrogen (N) and phosphorous (P) carried by the river are important in fertilization of bay primary production. While there is concern that upstream water withdrawals may impact the fishery, the importance of riverine N to oyster diets remains unclear. We measured N and carbon (C) stable isotopes (δ¹⁵N, δ¹³C) in macroalgae, surface-water nitrate, and surface sediments, which showed a gradient from enriched riverine δ¹⁵N values to more depleted values in the Gulf of Mexico. In contrast, δ¹³C of particulate matter is depleted in the river and enriched offshore. Oyster stable isotope values throughout Apalachicola Bay are more complex, but are dominated by freshwater inputs and reflect the variability and hydrodynamics of the riverine inflows.