Clarkes of concentrations of trace elements in the Riphean fine-grained terrigenous rocks of the Uchur-Maya region and the Yenisei Range

The clarkes of concentrations (K_c) of a wide range of trace elements (Li, Be, B, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Sr, Y, Zr, Nb, Mo, Ag, Cd, In, Sb, Cs, Ba, REE, Hf, Ta, Hg, Tl, Pb, Bi, Th, and U) were analyzed for fine-gained terrigenous rocks (mudstones, metapelites) from the reference Riphean sections of the Uchur-Maya region and the Yenisei Range. It was established that the shales and mudstones of the Uchur and Aimchan groups in the Riphean hypostratotype section are characterized by moderate (2.5 < K_c < 5) and intense (K_c > 5) geochemical specialization for Li, B, and Zn. At the same time, the similar rocks of the Lakhanda and Ui groups do not exhibit any distinct geochemical specialization, although they are notably enriched in HREE. The metapelites from the basal formations of the Riphean sedimentary successions in the Yenisei Range are distinctly specialized for B and slightly for Li, Rb, Be, Nb, Ta, Th, Ge, and Cd. In addition, moderate specialization for Cu is characteristic of the metapelites from the Korda and Lopatino formations; for Bi, Sb, Hg, and V, for their analogs from the Potoskui Formation; and, for Hg and Cs, for the similar rocks from the Lopatino Formation. The metapelites of the Lower Riphean Korda Formation from the central zone of the Yenisei Range have elevated contents of significantly more elements (Li, Be, Sc, V, Cr, Co, Ni, Zn, As, Rb, Y, Zr, Nb, Sb, Ag, In, Hf, Hg, and others) than their counterparts from its eastern near-platform part. The mudstones of the ore-bearing (Pb, Zn) Gorevo Formation are characterized by elevated concentrations of several ore elements such as Pb, Cd, As, Sb, and Bi. The elevated K_c values of the rare lithophile and of several ore elements in the metapelites of the Yenisei Range are determined by the high geochemical differentiation of the Early Precambrian blocks constituting the western margin of the Siberian Craton, which were eroded in the Riphean, and the syn-sedimentary riftogenic and intraplate magmatism. On the contrary, the fine-grained and terrigenous rocks from the basal part of the Riphean section in the Uchur-Maya region are compositionally closer to the immature Late Archean substrates or their Early Proterozoic analogs.     

西藏羊八井热田的碱金属元素研究

本文研究了西藏羊八井高温地热田及毗邻90km²范围内土壤中碱金属元素的地球化学特征,结果表明,碱金属元素锂、铷和铯可以作为一组新的地球化学指标用于热田勘查,圈定热田范围,其作用与已提出的汞、砷、锑和铋地球化学指标相类似。文章对碱金属元素在地热系统中的分布及地球化学行为、异常形成原因进行了初步的讨论。相关分析表明,这些地球化学指标有密切的相关关系,反映了具有共同成因。利用热水中的钠、钾元素作为地热温标对羊八井热田地下热水的温度进行了估算。     

Mercury, arsenic, antimony, bismuth and boron as geochemical indicators for geothermal areas

From 1982 to 1983, 131 soil samples were collected within an area of 60 km² in known geothermal field and their vicinities in Tengchong, Yunnan Province. Distinct anomalies of Hg, As, Sb and Bi were found on the known geothermal fields. The contour of the multiplicative anomaly of Hg × As × Sb encircled the two known geothermal fields, Reshuitang and Rehai, within its extent, disclosing the interrelation between these two fields, and enlarging their future prospects. The B anomaly is related to structural features. Significant correlations among Hg, As and Sb are shown by correlation analysis. It was concluded that a geochemical survey with a density of two samples per km² could be carried out effectively to delineate promising targets of geothermal resources.     

Chemistry of rainwaters in the south Pacific area of Russia

On the south-eastern edge of Russia, the chemical composition of rainwater is controlled by sea salts, terrestrial material, as well as volcanic (Kuril islands volcanic area) and anthropogenic emissions, mostly in the southern part of the area. The predominant major ions of the Primorye, Sakhalin and the Kuril Islands rainwaters were respectively HCO₃⁻–SO₄²⁻, Ca–Na, and of Cl–Na. Concentration of trace elements changes within 1–2 orders of magnitude but some difference in the distribution of the elements between continental and island rainwater is found. The concentration of the chemical elements in the particulate fraction varies from < 10% to 90% of the total concentration (dissolved + particulate) with the following distribution: Tl, Na, Ca, Sr, Zn, Cd (< 10%)–Be, Th, Bi, Rb, U, K, Sc (10–20%)–Cu, Mn, Mg, Mo, Se, Ba, Ni, As, Ag, Cs, Co, Y, Ga, V (20–50%)–Sb, Pb, Ge, Cr, Fe, Al (50–90%).The concentration of elements of the particulate fraction of the rainwater usually is significantly different from concentrations in the crust, including both higher and lower concentrations. The terrestrial contribution to dissolved elements was evaluated and follows the decreasing order: Fe > K, Mg, Ca > Ba, Sr > Na (65–1%). Close order was found for total (dissolved and solid) concentrations. Sea salt contribution to dissolved element concentration in the rainwater decrease in the following order: Cl, Mg > K, SO₄ > Ca > HCO₃⁻, Ba, Fe (78–0.1%). Calculation of anthropogenic and volcanic inputs for two ions (Cl⁻ and SO₄²⁻) shows that anthropogenic inputs for the Vladivostok and Yuzno-Sakhalinsk cities can be evaluated as 15–20% of Cl⁻ and up to 80–90% of SO₄²⁻. Volcanic components in the Kuril Islands, where anthropogenic inputs are absent, can reach up to 76% of SO₄²⁻ and 36% of Cl⁻.     

Application of geochemical methods in the search for geothermal fields

From 1983 to 1985, an orientation study was carried out in about 20 geothermal fields in China. Semi-detailed and detailed surveys were conducted in an area of 90 km² in Yangbajing, Tibet. Hg, As, Sb and Bi were used as indicators to extend the promising area of known geothermal fields to 16 km². In the northern part of the extended promising area, three drill holes were sunk and high-temperature thermal water of 160°C was obtained. In the southern part, outside the geochemical anomaly, two holes were drilled but no thermal water was found. The inner zone of the Hg anomaly coincides closely with the distribution of drill holes that met thermal water with temperatures higher than 140°C. The distribution of Bi values may indicate that the thermal water in the southern part is at shallower depth. A semi-regional survey in an area of 200 km² in Tengchong, Yunnan Province delineated several new prospects, which will possibly extend the resources of the Rehai geothermal field. An element zoning pattern similar to that of hydrothermal mineral deposits was discovered in the Rehai geothermal field. A semi-regional survey conducted in Xiaotangshan near Beijing indicated that the possible extent of the Xiaotangshan geothermal field may reach 30 km². Drilling confirmed that the outer zone of the Hg anomaly is in accordance with the distribution of 40°C thermal water, and the intermediate and inner zones of the Hg anomaly are associated with higher temperature thermal water. Research during the three years 1983–1985 demonstrated that exploration geochemistry is an effective tool for finding geothermal fields.     

Determination of major and trace elements in European bottled mineral water — Analytical methods

A total of 1785 European bottled water samples were analyzed using standard laboratory methods. The bottled water samples were purchased in 2008 at supermarkets throughout 40 European countries. The samples were analyzed for 71 chemical parameters (As, Al, As, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Hg, Ho, I, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sc, Se, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn, Zr, Br⁻, HCO₃⁻, Cl⁻, F⁻, NH₄⁺, NO₂⁻, NO₃⁻, PO₄³⁻, SO₄²⁻, SiO₂, pH, and EC) by quadrupole inductively coupled emission spectroscopy (ICP-QMS, trace elements), inductively coupled plasma atomic emission spectroscopy (ICP-AES, major elements), ion chromatography (IC, anions), atomic fluorescence spectrometry (AFS, Hg), titration (alkalinity), photometric methods (NH₄⁺), potentiometric methods (pH), and conductometric methods (specific electrical conductivity, EC). A very strict quality control procedure was followed by analysing blanks, international reference materials, an internal project standard, and duplicate analyses, as well as by analysing 23 elements by both ICP-QMS and ICP-AES. Analysis of marketed bottled water from springs, wells or boreholes, apart from the evaluation of its quality with respect to inorganic elements, it may provide a cheap alternative to obtain a first impression about groundwater chemistry at the European scale.     

Geochemical mapping in northern Honshu,Japan

Geochemical mapping of northern Honshu in the Northeast Japan Arc was carried out using stream sediments at a sampling density of one sample per 130 km². More than 50 elements were determined in 395 stream sediment samples (<0.18 mm fraction). In geochemical maps, areas with especially low concentrations of large ion lithophile elements (LILE), Be and Li widely overlap with the distribution of Quaternary volcanic rocks along the volcanic front. The areas rich in mafic elements are associated with mafic rocks in many cases. On a regional scale, Ni, Cr and Cu contents are higher in the eastern Paleozoic–Mesozoic basement zone, Pb and Tl tend to be higher on the western zones, and Zn and Cd are high in the western back-arc zone. The areas especially rich in Cu, Zn, Cd, Pb, Bi and Tl coincide with the distribution of large mineral deposits. High concentrations related to Kuroko, hydrothermal-vein, and skarn-type deposits are recognized. High values of As and Sb are related to active geothermal areas near volcanoes and ore deposits. Chemical variations of K, Ce, Th and Sn in the stream sediments are concordant with chemical variations in major rocks. The median and mean concentrations for the stream sediments in northern Honshu, showing arc signatures, are lower in Rb, Cs, Th, Li, K, Be, Ta, LREE, Ni, Hg and Sn, and higher in Sc, Ca and Cd relative to the whole area of Japan, largely because of the contribution of Cenozoic island-arc volcanic rocks that are generally poor in incompatible elements. The averaged chemical compositions of the stream sediments for the geologic zones show systematic variations of many elements. The contrasting variations of LREE and Th contents, which are lower in the zones of Cenozoic rocks relative to the zones of pre-Neogene basements, reflect the regional variations in the main rocks, and also reflect the change of geological settings of the studied area from the continental margin to an island arc during the Cenozoic.     

Geochemical Atlas of the Slovak Republic at a scale of 1:1,000,000

The Geochemical Atlas of Slovak Republic (49,036 km²) at a scale of 1 : 1,000,000 was compiled during 1991–1995 together with maps of associated geochemical and ecological features at a scale of 1 :200,000. Investigations were aimed at the evaluation of concentrations and distributions of Al, As, Ba, Be, Ca, Ce, Co, Cd, Cs, Cr, Cu, Fe, Ga, Hg, K, La, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, Sb, Se, Sn, Sr, Th, U, V, W, Y, Zn, Zr in groundwater (16,359 samples), stream sediments (24,422 samples), rocks (3839 samples), soils (9892 samples from 4946 profiles; A and C horizons of each profile were sampled) and forest biomass (the foliage of the forest tree species from 3063 plots was sampled). In groundwater field measurements of temperature, pH, conductivity, dissolved O₂, acidity, alkalinity were done. The evaluation was oriented to the natural radioactivity of the Slovak territory as follows: rocks (K, U, Th, U_tot and dose rate, 15,573 reference spectrometric points), radon risk and water (U_nat, ²²⁶Ra, ²²²Rn; 5271 samples). The main objective of the Geochemical Atlas was to construct single-component maps showing concentrations of chemical elements, compounds and measured parameters in the researched media of Slovakia at a scale of 1 : 1,000.000 and to create interactive databases of chemical composition and/or measured parameters of groundwater, biomass, rocks, soils, stream sediments and natural radioactivity, for the entire territory of the Slovak Republic. The single-component maps are not constructed in the part ‘Rocks’, where all the main rocks types of Slovakia are presented in the ‘Map of lithogeochemical rock types of Slovakia at a scale of 1: 500,000’. The edition of six atlases has been planned. In 1997 the first three atlases will appear (Groundwater, Biomass, Natural Radioactivity). Publishing of last three atlases (Rocks, Soils, Stream Sediments) is planned for 1998. Since the analytical works on stream sediments were finished during 1997, it was not possible to present here the results of that part of the Geochemical Atlas.     

Trace elements and ions in Italian bottled mineral waters: Identification of anomalous values and human health related effects

Microbiological studies have always had an important role in the evaluation of drinking water quality. However, since geological processes are the most important factors controlling the source and distribution of chemical elements in natural waters, the importance of geochemical data must not be underestimated. This study presents data on pH, conductivity and concentrations of 69 elements and ions (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Hg, Ho, I, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sc, Se, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn, Zr, Br⁻, HCO₃⁻, Cl⁻, F⁻, NH₄⁺, NO₂⁻, NO₃⁻, PO₄³⁻, SO₄²⁻, SiO₂) from 186 bottled mineral waters of 158 different Italian name brands. Analyses show a large range in concentrations for most of these elements, with variations up to four orders of magnitude. Our data demonstrate that some elements (such as Be), generally considered unlikely to occur, can instead reach surprisingly high levels in drinking water, and also how packaging can release some trace elements to the bottled water. Data analysis shows that the implementation of an international database of bottled water geochemistry and of potential toxicological effects is of paramount importance to provide a robust data set which would be useful to set international action levels and guidelines to secure bottled water quality, whose consumption has steadily increased in the recent years. A new formula to calculate nitrate and nitrite tolerable concentration levels in waters intended for human consumption is proposed, to take into account that about 5% of dietary nitrate in humans is converted to nitrite.     

Abundances of chemical elements of the granitoids in different geotectonic units of China and their characteristics

On the basis of actual analytical data of 767 composited samples collected mainly from about 750 large to middle representative granitoid bodies all over China, the average chemical compositions and element abundances of about 70 chemical elements of SiO₂, Al₂O₃, Fe₂O₃, FeO, MgO, CaO, Na₂O, K₂O, H₂O⁺, CO₂, TFe₂O₃, Ag, As, Au, B, Ba, Be, Bi, Cd, Cl, Co, Cr, Cs, Cu, F, Ga, Ge, Hf, Hg, Li, Mn, Mo, Nb, Ni, P, Pb, Rb, S, Sb, Sc, Se, Sn, Sr, Ta, Th, Ti, Tl, U, V, W, Zn, Zr, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y in alkalifeldspar granite, syenogranite and adamellite in 7 geotectonic units in China such as Tianshan-Xing’an orogenic series, Sino-Korean metaplatform, Kunlun-Qilian-Qinling orogenic series, Yunnan-Tibet orogenic series, Yangtze metaplatform, South China-Youjiang orogenic zone and Himalayan orogenic belt, are calculated and presented in this paper. In addition, the characteristics of petrochemical parameters, trace element contents and rare earth element distributions of different rock types of the granitoids in different geotectonic units are also sufficiently discussed. Translated from Acta Geologica Sinica, 2007, 81(1): 47–59 [译自: 地质学报]     

A national-scale geochemical and mineralogical survey of soils of the conterminous United States

In 2007, the US Geological Survey initiated a low-density (1 site per 1600 km², c. 4800 sites) geochemical and mineralogical survey of soils of the conterminous USA. The ideal sampling protocol at each site includes a sample from 0–5 cm depth, a composite of the soil A horizon, and a sample from the soil C horizon. The <2-mm fraction of each sample is analyzed for Al, Ca, Fe, K, Mg, Na, S, Ti, Ag, Ba, Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Ga, In, La, Li, Mn, Mo, Nb, Ni, P, Pb, Rb, Sb, Sc, Sn, Sr, Te, Th, Tl, U, V, W, Y and Zn by inductively coupled plasma-mass spectrometry and inductively coupled plasma-atomic emission spectrometry following a near-total digestion in a mixture of HCl, HNO₃, HClO₄ and HF. Separate methods are used for As, Hg, Se and total C on this same size fraction. The major mineralogical components are determined by a quantitative X-ray diffraction method. Sampling was completed in 2010 with chemical and mineralogical analysis currently underway. Preliminary results for a swath from the central USA to Florida clearly show the effects of soil parent material and climate on the chemical and mineralogical composition of soils. A sample archive will be established and made available for future investigations.     

Geochemical constraint on origin and evolution of solutes in geothermal springs in western Yunnan,China

Geothermal resources are very rich in Yunnan, China. However, source of dissolved solutes in geothermal water and chemical evolution processes remain unclear. Geochemical and isotopic studies on geothermal springs and river waters were conducted in different petrological-tectonic units of western Yunnan, China. Geothermal waters contain Ca–HCO₃, Na–HCO₃, and Na (Ca)–SO₄ type, and demonstrate strong rock-related trace elemental distributions. Enhanced water–rock interaction increases the concentration of major and trace elements of geothermal waters. The chemical compositions of geothermal waters in the Rehai geothermal field are very complicated and different because of the magma chamber developed at the shallow depth in this area. In this geothermal field, neutral-alkaline geothermal waters with high Cl, B, Li, Rb Cs, As, Sb, and Tl contents and acid–sulfate waters with high Al, Mn, Fe, and Pb contents are both controlled by magma degassing and water–rock interaction. Geothermal waters from metamorphic, granite, and sedimentary regions (except in the Rehai area) exhibit varying B contents ranging from 3.31 mg/L to 4.49 mg/L, 0.23 mg/L to 1.24 mg/L, and <0.07 mg/L, respectively, and their corresponding δ¹¹B values range from −4.95‰ to −9.45‰, −2.57‰ to −8.85‰, and −4.02‰ to +0.06‰. The B contents of these geothermal waters are mainly controlled by leaching host rocks in the reservoir, and their δ¹¹B values usually decrease and achieve further equilibrium with its surrounding rocks, which can also be proven by the positive δ¹⁸O-shift. In addition to fluid–rock reactions, the geothermal waters from Rehai hot springs exhibit higher δ¹¹B values (−3.43‰ to +1.54‰) than those yielded from other areas because mixing with the magmatic fluids from the shallow magma. The highest δ¹¹B of steam–heated waters (pH 3.25) from the Zhenzhu spring in Rehai is caused by the fractionation induced by pH and the phase separation of coexisting steam and fluids. Given the strong water–rock interaction, some geothermal springs in western Yunnan show reservoir temperatures higher than 180 °C, which demonstrate potential for electricity generation and direct-use applications. The most potential geothermal field in western Yunnan is located in the Rehai area because of the heat transfer from the shallow magma chamber.     

Chemical and isotopic (B, Sr) composition of alluvial sediments as archive of a past hydrothermal outflow

The geochemical and isotopic signature of Quaternary alluvial sediments filling a post-orogenic basin along the Tyrrhenian coasts of Italy (Cornia Plain, Tuscany) was investigated to unravel possible interactions with geothermal fluids from the Larderello geothermal field. Two cores located in the upper (UCP) and lower (LCP) sector of the plain were sampled to depths of up to 80 m. A third core in a neighbouring area not affected by geothermal activity was also sampled (Arno plain at Pisa), and its sediment composition was used as reference. The Cornia sediments (fraction < 65 μm) show high B, Cs and Sb concentrations related to a peculiar chemical enrichment of the clay fraction. They also show remarkable enrichments in As (up to 1000 μg g^− 1) reflecting a contribution from local ore deposits.⁸⁷Sr/⁸⁶Sr ratios, ranging from 0.71022 to 0.71698, reveal the nature of the weathered mother rocks of the alluvial sediments, whereas the boron isotopic composition, varying from − 20‰ to − 10‰, suggests an interaction between the clay fraction and boron-rich fluids at temperatures greater than 50 °C. This implies that hydrothermal fluids widely circulated within the Cornia basin in the past, ultimately leading to the geochemical anomalies currently recorded in local sediments.Although natural (geogenic) in origin, these anomalies cause severe problems to the regional water management (groundwater exploitation) through leaching of trace elements into circulating groundwater, a phenomenon which has to be carefully studied and monitored.     

Hydrochemistry of Salt Lakes of the Qinghai-Tibet Plateau, China

The authors have carried out scientific investigations of salt lakes on the Qinghai-Tibet Plateau since 1956 and collected 550 hydrochemical data from various types of salt lakes. On that basis, combined with the tectonic characteristics of the plateau, the hydrochemical characteristics of the salt lakes of the plateau are discussed. The salinity of the lakes of the plateau is closely related to the natural environment of lake evolution, especially the climatic conditions. According to the available data and interpretation of satellite images, the salinity of the lakes of the plateau has a general trend of decreasing from north and northwest to south and southeast, broadly showing synchronous variations with the annual precipitation and aridity (annual evaporation/annual precipitation) of the modern plateau. The pH values of the plateau salt lakes are related to both hydrochemical types and salinities of the lake waters, i.e., the pH values tend to decrease from the carbonate type → sodium sulfate subtype → magnesium sulfate subtype → chloride type; on the other hand, a negative correlation is observed between the pH and salinities of the lakes. Geoscientists and biological limnologists generally use main ions in salt lakes as the basis for the hydrochemical classification of salt lakes. The common ions in salt lakes are Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl^? SO₄ ^2?, CO₃ ^2?, and HCO₃ ^?. In this paper, the Kurnakov-Valyashko classification is used to divide the salt lakes into the chloride type, magnesium sulfate subtype, sodium sulfate subtype and carbonate type, and then according to different total alkalinities (K _C = Na₂CO₃ + NaHCO₃/total salt × 100%) and different saline mineral assemblages, the carbonate type is further divided into three subtypes, namely, strong carbonate subtype, moderate carbonate subtype and weak carbonate subtypes. According to the aforesaid hydrochemical classifications, a complete and meticulous hydrochemical classification of the salt lakes of the plateau has been made and then a clear understanding of the characteristics of N–S hydrochemical zoning and E-W hydrochemical differentiation has been obtained. The plateau is divided into four zones and one area. There is a genetic association between certain saline minerals and specific salt lake hydrochemical types: the representative mineral assemblages of the carbonate type of salt lake is borax (tincalconite) and borax-zabuyelite (L₂CO₃) and alkali carbonate-mirabilite; the representative mineral assemblages of the sodium sulfate subtype are mirabilite (thenardite)-halite and magnesium borate (kurnakovite, inderite etc.)-ulexite-mirabilite; the representative mineral assemblages of the magnesium sulfate subtype are magnesium sulfate (epsomite, bloedite)-halite, magnesium borate-mirabilite, and mirabilite-schoenite-halite, as well as large amount of gypsum; The representative mineral assemblages of the chloride type are carnallite-bischofite-halite and carnallite-halite, with antarcticite in a few individual salt lakes. The above-mentioned salt lake mineral assemblages of various types on the plateau have features of cold-phase assemblages. Mirabilite and its associated cold-phase saline minerals are important indicators for the study of paleoclimate changes of the plateau. A total of 59 elements have been detected in lake waters of the plateau now, of which the concentrations of Na, K, Mg, Ca, and Cl, and SO₄ ^2?, CO₃ ^2?, and HCO₃ ^? ions are highest, but, compared with the hydrochemical compositions of other salt lake regions, the plateau salt lakes, especially those in the southern Qiangtang carbonate type subzone (I₂), contain high concentrations of Li, B, K, Cs, and Rb, and there are also As, U, Th, Br, Sr, and Nd positive anomalies in some lakes. In the plateau lake waters, B is intimately associated with Li, Cs, K and Rb and its concentration shows a general positive correlation with increasing salinity of the lake waters. The highest positive anomalies of B, Li, Cs, and K center on the Ngangla Ringco Lake area in the western segment of the southern Qiangtang carbonate type subzone (I₂) and coincide with Miocene volcanic-sedimentary rocks and high-value areas of B, Li, and Cs of the plateau. This strongly demonstrates that special elements such as B, Li, and Cs on the plateau were related to deep sources. Based on recent voluminous geophysical study and geochemical study of volcanic rocks, their origin had close genetic relation to anatectic magmatism resulting from India–Eurasia continent–continent collision, and B–Li (-Ce) salt lakes in the Cordillera Plateau of South America just originated on active continental margins, both of which indicate that global specific tectonically active belts are the main cause for the high abundances of B, Li, and Cs (K and Rb) in natural water and mineralization of these elements.     

An Assessment of Performance in the Routine Analysis of Silicate Rocks Based on an Analysis of Data Submitted to the GeoPT Proficiency Testing Programme for Geochemical Laboratories (2001–2011)

Data reported by laboratories contributing to the GeoPT proficiency testing programme for geochemical laboratories over the period from 2001 to 2011 have been assessed to identify the elements and concentration ranges over which analytical performance can be considered satisfactory. Criteria developed in the paper indicated that performance in the content determination of the elements/constituents SiO₂, Al₂O₃, MnO, Cs, Dy, Er, Eu, Ga, Hf, Ho, Lu, Nd, Pr, Sm, Sr, Tb, Tl, Tm, U, Y, Yb and Zn was satisfactory over the full concentration range assessed. The elements/constituents TiO₂, Fe₂O₃(T), MgO, CaO, Na₂O, K₂O, P₂O₅, Ba, Be, Cd, Ce, Co, Gd, La, Li, Nb, Rb, Sb, Sc, Sn, Ta, Th, V and Zr showed some degradation in performance at lower concentration levels (approaching the detection limit of some techniques). Performance in determining LOI, As, Bi, Cr, Cu, Ge, Mo, Ni, Pb and W was in general unsatisfactory over the full concentration range assessed. Other elements (especially Fe(II)O, H₂O⁺, CO₂, Ag, Au, B, Br, Cl, F, Hg, I, In, Ir, N, Os, Pd, Pt, Re, Rh, S, Se, Te) could not be evaluated as they were not routinely reported by laboratories participating in the GeoPT programme, often because they are present in silicate rocks at sufficiently low concentrations to require a pre‐concentration stage. Some suggestions are made for the causes of unsatisfactory performance, but further progress will require a detailed assessment of the methods used by participating laboratories, which will form the subject of a further paper.     

流域上游基岩与下游冲积平原土壤化学组成的对比

对海河水系流域、鄱阳湖水系流域上游的基岩与下游的冲积平原土壤之间化学组成的对比研究显示,下游冲积物土壤的化学组成明显地受源岩成分、形成过程和形成环境的影响。流域上游基岩的一些特征元素在冲积物土壤中被明显地继承,如海河流域基岩和土壤中的CO2、CaO、MgO、FeO、Sr,鄱阳湖流域基岩和土壤中的W、Sn、Bi、U、Th、Pb、Rb、Tl、As、Sb、Se、Hg、Nb、Ta、Hf、B、Be、Ge、Pt、Pd、Y。受形成过程和形成环境的影响,处于暖温带半湿润季风气候下的海河流域冲积平原土壤以极富集CO2、CaO、Na2O、Cl,显著富集MgO、FeO、Sr,富集P、S为特征;而处于亚热带湿润季风气候下的鄱阳湖流域冲积平原土壤则以显著富集Hg、Se和富集Al2O3、Fe2O3H2O^＋、W、Sn、Bi、Mo、U、Th、Pb、Rb、Cs、Tl、Li、Be、B、Ga、Ge、Nb、Ta、Zr、Hf、As、Sb、Co、Cr、Ti、V、Zn、Pt、Pd、REE、Y为特征。无论是海河流域还是鄱阳湖流域的冲积平原土壤,均富集As、Sb、Hg、B、Cl、W、Sn、Bi、Pb、Se、Ge、Li、Cs、Cu、Au、Fe2O3、V、Cr、Ni、Zr、Hf、Y。     

五台山—恒山绿岩带Au-Ag-Cu成矿作用地球化学特征

五台山—恒山绿岩带Ａｕ、Ａｇ、Ｃｕ矿床可分为二大类型：（１）再生型金银铜矿，产在包括岩浆岩在内的各类岩石断裂构造中，与岩浆期后热液有关；（２）变生型金银铜矿，产于各类变质岩中，具有层控特征（即绿岩型金矿）。在地球化学特征上，再生型矿床与变生型矿床相比，矿体及围岩中Ｍｏ、Ａｇ、Ｐｂ、Ｚｎ、Ｃｄ等成矿及伴生元素明显富集；Ｋ２Ｏ、Ｒｂ、Ｓｒ、Ｂａ、Ｔｈ、Ｕ也明显富集，是后期岩浆热液作用的结果；Ｈｇ、Ｆ的明显富集则与后期构造活动有关；Ｚｎ／Ｃｄ比值较低，说明受到后期岩浆侵入影响；Ｔｈ／Ｕ比值低，可能指示富钙的酸性岩环境。再生型Ａｕ矿化的元素组合为Ｃｄ、Ａｓ、Ｎｉ、Ａｇ、Ｓｂ、Ａｕ、Ｈｇ（Ｂｉ），再生型Ａｇ矿化的元素组合为Ａｓ、Ｓｂ、Ａｇ、Ｃｄ、Ｃｕ、Ｎｉ（Ｍｏ、Ｐｂ、Ｚｎ、Ｂｉ），变生型Ａｕ矿化的元素组合较简单，只为Ａｕ、Ｈｇ、Ａｓ或Ａｕ、Ｃｕ。上述地球化学特征不仅可以有效地区分矿化类型，而且可以作为地球化学找矿和评价的指标     

Analysis of a weathered profile on sulfide mineralization at Mugga Mugga, Western Australia

The mineralogy and geochemistry of the massive pyrite-pyrrhotite mineralization, which contains minor magnetite, sphalerite and galena, the weathered profile and surface gossan at Mugga Mugga in Western Australia have been examined. Reactions between amphibolite wall rocks and acid waters from the oxidation of the iron sulfides have resulted in distinct mineralogical zonation of the weathered profile which is further modified near the surface by lateritization. At the base of the weathered zone an opaline chert (Opal-CT) has been precipitated from fluctuations of the water table. A gossanous zone from 25.14–68.80 m with boxworks after massive pyrite is modified by abundant kaolinite, dickite and an alunite-type mineral derived from amphibolite wall rocks, while above 25.14 m both plinthite and mottled clay zones of a laterite profile are evident. Some characteristics of a mature gossan profile – sulfate-phosphate-arsenate near the base, a carbonate zone higher in the profile, and an oxide zone near the surface – overprint the gross zonation.At the interface between sulfide and weathered rock Mg, Ca, K, S, Zn, Cd, Hg, Ba are depleted, As, Sb, Mo, Cr and V contents increase and in the weathered zone, SiO₂, TiO₂, P₂O₅, SO₃, Pb, Zn, Hg, Sb, Co, Ni, W, Ba, Sr and Zr decrease up the profile whilst Al₂O₃, Fe₂O₃, CO₂, Cu and As increase. Of the elements associated with the massive pyrite (Pb, Zn, Cu, Ag, As, Cd, Hg, Sb, Co, Ni) anomalous concentrations of Pb, Cu, Ag, As and Sb occur in the surface gossan despite the possibility of complete leaching by highly acidic solutions. These anomalies are similar to those found in gossans over pyrite mineralization elsewhere in the Yilgarn Block.     

Boron isotope composition of geothermal fluids and borate minerals from salar deposits (central Andes/NW Argentina)

We have measured the boron concentration and isotope composition of regionally expansive borate deposits and geothermal fluids from the Cenozoic geothermal system of the Argentine Puna Plateau in the central Andes. The borate minerals borax, colemanite, hydroboracite, inderite, inyoite, kernite, teruggite, tincalconite, and ulexite span a wide range of δ¹¹B values from −29.5 to −0.3‰, whereas fluids cover a range from −18.3 to 0.7‰. The data from recent coexisting borate minerals and fluids allow for the calculation of the isotope composition of the ancient mineralizing fluids and thus for the constraint of the isotope composition of the source rocks sampled by the fluids. The boron isotope composition of ancient mineralizing fluids appears uniform throughout the section of precipitates at a given locality and similar to values obtained from recent thermal fluids. These findings support models that suggest uniform and stable climatic, magmatic, and tectonic conditions during the past 8 million years in this part of the central Andes. Boron in fluids is derived from different sources, depending on the drainage system and local country rocks. One significant boron source is the Paleozoic basement, which has a whole-rock isotopic composition of δ¹¹B=−8.9±2.2‰ (1 SD); another important boron contribution comes from Neogene-Pleistocene ignimbrites (δ¹¹B=−3.8±2.8‰, 1 SD). Cenozoic andesites and Mesozoic limestones (δ¹¹B≤+8‰) provide a potential third boron source.     

Are C1 chondrites chemically fractionated? a trace element study

Six C1 chondrite samples and a C2 xenolith from the Plainview H5 chondrite were analyzed by radiochemical neutron activation for the elements Ag, Au, Bi, Br, Cd, Ce, Cs, Eu, Ge, In, Ir, Lu, Nd, Ni, Os, Pd, Pt, Rb, Re, Sb, Se, Sn, Tb, Te, Tl, Yb, and Zn. The data were combined with 9 earlier analyses from this laboratory and examined for evidence of chemical fractionation in C1 chondrites.A number of elements (Br, Rb, Cs, Au, Re, Os, Ni, Pd, Sb, Bi, In, Te) show small but correlated variations. Those of the first 8 probably reflect hydrothermal alteration in the meteorite parent body, whereas those of Sb, Bi, In, and Te may at least in part involve nebular processes. Br and Au show systematic abundance differences from meteorite to meteorite, which suggests hydrothermal transport on a kilometer scale. The remaining elements vary from sample to sample, suggesting transport on a centimeter scale.There is no conclusive evidence for nebular fractionation affecting C1 's. Though C1 chondrites have lower $\text{Zr}\text{Hf}$ and $\text{Ir}\text{Re}$ ratios than do other chondrite classes, these ratios vary in other classes, suggesting that those classes rather than C1's are fractionated. Three fractionation-prone REE—Ce, Eu, and Yb have essentially the same relative abundances in C1's and all other chondrite classes, and hence apparently are not fractionated in C1's. We did not confirm the large Tb and Yb variations in C1's reported by other workers.We present revised mean C1 abundances for 35 elements, based on the new data and a critical selection of literature data. Changes are generally less than 10%, except for Br, Rb, Ag, Sb, Te, Au, and the REE.The Plainview C2 xenolith has normal trace element abundances, except for 3 elements falling appreciably above the C2 range: Rb, Cs, and Bi. Hydrothermal alteration may be the reason for all 3, though nebular fractionation remains a possibility for Bi.