Petrologic and Geochemical Characteristics and Origin of Gusui Cherts,Guangdong Province,China

The characteristic structures of the Precambrian cherts from the Gusui section, Guangdong ,Chi-na, include bedded structure ,laminated structure ,massive structure and pseudobrecciated structure.The chert is characterized by consistently low abundance of TiO2,Al2O3 and most trace elements.Howevver ,it is enriched in Ba,As,Sb,Hg and Se.In Al-Fe-Mn ternary diagrams,it falls into the “hydrothermal field“ .Correspondence analysis and factor analysis show that many elements show up in the factor that represents the leaching of country rocks by hydrothermal solutions,and are the very characteristic element association fo the geochemically anomalous South China basement.Petrologic and geochemical evidence suggests a hydrothermal origin for the chert.The chert may have been formed in a Precambrian fift or an extension zone developed within the Yunkai marginal geosyncline, with a fault system linking it to an unknown heat source at depth.     

Physicochemical Conditions of Differential Mineralization of Au and As in Gold Deposits,Southwest Guizhou Province,China

The conditions under which gold and arsenic are enriched separately during mineralization in gold deposits in southwestern Guizhou Province were described and the thermodynamic calculations gave: 200–150°C at 400 × 10⁻⁶ -300 × 10⁶ Pa (corresponding to a depth between 1.6 km and 1.2 km); lgf o₂,−40 to -35 Pa; lgf s₂, -20 to−16 Pa; pH 5.0 -4.2 and Eh -0.53 V. This project was jointly supported by the National Natural Science Foundation of China and the Open Lab. of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences.     

Assessment of mercury mobility and bioavailability by fractionation method in sediments from coastal zone inundated by the 26 December 2004 tsunami in Thailand

The 26 December 2004 tsunami covered significant portion of a coastal zone with a blanket of potentially contaminated sediments. In this report are presented results on mercury concentrations in sediments deposited by the tsunami in a coastal zone of Thailand. Since the total mercury concentrations are insufficient to assess mercury mobility and bioavailability in sediment, its fractionation was applied. Sediments were sampled within 50 days after the event and analyzed by sequential extraction method. The procedure of sequential extraction involved five subsequent stages performed with solutions of chloroform, deionized water, 0.5 M HCl, 0.2 M NaOH, and aqua regia. The mean concentration of total mercury in sediments was 119 ± 50 ng g⁻¹ dry mass (range 66–230). The fractionation revealed that mercury is mainly bound to the least bioavailable sulphides 75 ± 6% (range 62–86), organomercury compounds 14 ± 7% (range 4–26), and humic matter 9 ± 7% (range 1–27). The lowest contributions bring fractions of water-soluble mercury 0.8 ± 1.0% (range 0.1–3.6) and acid soluble mercury 0.9 ± 0.5% (range 0.2–2.1). Although, the total mercury content is similar in a reference sample and in the tsunami sediments, the highly toxic organomercury fraction contribution is higher in the latter. The results were compared with chemical and sedimentological properties of the sediments but no significant correlations were obtained between them.     

The Relationship Between Mineralogical Characteristics and Isotopic Composition of Sphalerite,as Exemplified by the Huxu Deposit,China

The relationship between mineralogical characteristics and isotopic composition of sulfides has not received its proper share of attention from geologists, although many references are available concerning the application of sulfur isotopes to geological problems. Located in the vicinity of the contact region between the Yangtze Platform and the South China Caledonian Folding Zone, the Huxu deposit is hosted in a structural zone in quartz-diorite-porphyrite emplaced in Jurassic volcanic rocks. Sphalerite and galena are the principal ore minerals in the deposit. (1) Sphalerite is highly variable in color and this variation can be related to its chemical composition and sulfur isotopic characters. Dark colored sphalerites are poor in Zn and Ni, rich in Pb, Cu, Fe, Ag and Au and have high δ³⁴S values, while the opposite is true for light-colored ones. (2) δ³⁴S of sphalerite is negatively correlated with the contents of Zn and Ni and positively correlated with the contents of Pb, Cu, Ag and Au, with the absolute values of the correlation coefficients being greater than 0.7. The above two characters suggest that the sulfur isotopic composition of sphalerite is controlled not only by the physicochemical conditions under which the mineral was formed, but also by mineralogical characteristics of the host mineral. (3) Apparent correlations exist among the constituent elements in the sphalerite. For example, Zn is negatively correlated with Cu, Pb, Fe, Ag and Au and positively correlated with Ni. (4) Sphalerites of the same color in the same hand specimen always show similar characters with respect to trace element and sulfur isotopes. (5) Two distinct trends of evolution can be recognized between Zn and Cu, Zn and Pb, Zn and Ag and between these elements on one hand and δ³⁴S on the other, reflecting that the ore-forming solutions may have resulted from mixing of fluids of different origins. (6) Pb is uniformly distributed in sphalerite and shows positive correlations with Cu, Fe, Ag and δ³⁴S, suggesting isomorphic substitution in the sphalerite lattice. This project was financially supported by the Open Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences.     

Genetic Type and Metallogenic Mechanism of Bankuan Gold Deposit in Special Reference to the Studies of Fluid Inclusions and Isotopes in Minerals

Auriferous quartz veins in the Bankuan gold deposit occur in the interlayer broken zone of the basal conglomerate of the Tietonggou Formation or at the unconformity between the Tietonggou Formation and the crystalline basement.The composition of fluid inclusions in the minerals indicates that the nature and composition of ore-forming hydrothermal solutions show a drastical change soon after the solutions reached the Tietonggou Formation from the crystalline basement,resulting in gold precipitation.So the Bankuan gold deposit can be assigned to the conglomerate stata-bound-type deposits.137 thermometric data are concentrated in the three ranges 400-340℃,330-220℃ and 180-160℃,representing three episodes of metalogenesis,Oxygen isotope studies demonstrate the evolution of ore-forming hydrothermal solutions from early metamorphic to late meteoric,Diversity of ore-forming materials dominated by deep-source material is supported by sulphur and lead isotope data.From the above discussions it may be concluded that the deposit formed by metamorphism induced as a result of Mesozoic northward intracontinental subduction along the Machaoying fault.     

Therm odynamics of Diagenetic Fluid and Fluid／Mineral Reactions in the Eogene Xingouzui Formation,Oil Field T,Jianghan Basin

This study focuses on the thermodynamics of diagenetic fluid from the Eogene Xingouzui Formation which represents the most important reservoir in Field Oil T in the Jianghan Basin. The measured homogenization temperatures (110–139 °C) of fluid inclusions in diagenetic minerals fell within the range of 67 –155 °C at the middle diagenetic stage. The pressure of diagenetic fluid is estimated at 10.2 –56 MPa. The activity of ions in the fluid shows a tendency of Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ > Fe³⁺ > Fe²⁺ for cations, and HCO ₃ ⁻ > SO ₄ ²⁻ > F⁻ > Cl⁻ > CO ₃ ²⁻ for anions. For the gaseous facies, there is a tendency of CO₂> CO> H₂S> CH₄> H₂. According to the thermodynamic calculations, the pH and Eh of the fluid are 5.86–6.47 and −0.73–−0.64V, respectively. As a result of the interaction between such a diagenetic fluid and minerals in the sediments, feldspars were dissolved or alterated by other minerals. The clay mineral kaolinite was instable and hence was replaced by illite and chloritoid. This project was jointly funded by the National Natural Science Foundation of China (49133080) and the Open Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences.     

广西东平地区碳酸锰矿床Ga含量高异常的发现及成因初探

Ga是一种典型的稀有分散元素,主要产于铝土矿、闪锌矿及煤矿之中。最近,在广西东平地区下三叠统北泗组碳酸锰矿床中发现Ga高异常含量,w(Ga)介于5.16×10~(-6)~82.80×10~(-6)之间,平均为33.76×10~(-6),达到了Ga工业品位标准;锰矿层和围岩中w(Ga)平均分别为46.40×10~(-6)、19.31×10~(-6),高于国内外已报道的大部分锰矿床。文中根据北泗组碳酸锰矿床地球化学特征,揭示了该锰矿床为热水沉积;同时,结合现代大洋铁锰沉积有关Ga的最新报道,提出北泗组碳酸锰矿床中Ga的赋存与含锰矿物密切相关,其来源与海底热液活动有关。最后,文中还利用Mn/Fe-Ga、Co-Ga关系图判别了古代铁锰沉积的成因类型。     

The 7^th International Symposium on Environmental Geochemistry, September 24-27, 2006, Beijing, China

Preface The International Symposium on Environmental Geochemistry, first held in London, Great Britain in 1985, has become a premier international forum for the presentation and discussion of advances in scientific understanding of environmental geochemistry. The 7^th International Symposium on Environmental Geochemistry is being held in Beijing, China. The symposium is sponsored by the State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences and the Chinese Society for Mineralogy, Petrology and Geochemistry.     

Geochemistry and Sr-Nd isotope systematics of metabasites in the Tunchang area, Hainan Island, South China: implications for petrogenesis and tectonic setting

Summary The metabasites in Tunchang area, East-central Hainan Island, South China generally display strongly LREE-depleted patterns, extremely low HFSE concentrations and relatively high LILE contents; a few boninite-like samples have a concave-up, slightly LREE-enriched pattern. The low but variable Ti/V ratios between 6 and 20, and the high mg-numbers and Cr, Co, Ni contents, are indicative of plume-influenced intraoceanic arc magmas. It accord with this model are moderately high ɛ_Nd(t) values ranging from +2.16 to +6.75, and ⁸⁷Sr/⁸⁶Sr_i values ranging from 0.70239 to 0.70824. These geochemical features imply that the protoliths for the Tunchang area metabasites are relics of an intra-oceanic island arc and the parental melts of these rocks were generated from a depleted, primitive mantle arc source rather than from a N-MORB source in a supra-subduction zone-like setting. The minor geochemical differences between the two identified groups of metabasites are due to a combined result of the variable degree of partial melting and the crystal fractionation of clinoproxene ± olivine ± plagioclase. The Tunchang area metabasites are distinctive in geochemical and isotopic compositions, and likely also in age from the Bangxi area metabasites in the northwestern part of Hainan Island. We assume that the NE–SW trending Baisha Fault Zone likely marks an early suture zone due to the collision of an Early Paleozoic intra-oceanic arc with the South China continent. In contrast, the Bangxi area metabasites more likely are formed in an extensional back-arc basin due to subduction of the Paleo-Tethys beneath the South China continental margin during the Late Paleozoic. Present address: Chinese Academy of Sciences, Guangzhou Institute of Geochemistry, Guangzhou, Guangdong Province 510640, People’s Republic of China Authors’ addresses: Deru Xu, Bin xia, Pengchun Li, Guanghao Chen, Tao Chen, Key Lab of Marginal Sea Geology, Chinese Academy of Sciences, Guangzhou Institute of Geochemistry, Guangzhou, Guangdong Province 510640, People’s Republic of China; Bakun-Czubarow Nonna, Bachlinski Robert, Polish Academy of Sciences, Institute of Geological Sciences, Institute of Geological Sciences, ul. Twarda 51/55, 00-818 Warszawa, Poland     

Silicon Isotope Geochemistry of Micro—Fine Disseminated Gold Deposits in SW Guizhou and NW Guangxi,China

Quartz was studied with respect to its silicon isotopic composition and cathodoluminescence in micro-fine disseminated gold deposits in SW Guizhou and NW Guangxi.The results showed that quartz in wall rocks.ores and that in association with hydrothermal silicification are distinctive in silicon isotopes and cathodoluminescence characters.Quartz in association with primary silicification is non-luminescent while that in wall rocks and associated with secondary silicification exhibits striking luminescence.Based on the dynamic fractionation of silicon isotopes,it is suggested that the mineralization was accompanied by rapid transport of aprimary siliceous fluid along the major deep fault system into subordinate faults before ore components deposited in favorable strata via penetration and metasomatism.Therefore,a deep origin is implicit for gold deposits of this type.     

Sphalerite Chemistry,Niujiaotang Cd—Rich Zinc Deposit,Guizhou,Southwest China

Sphalerite in the Niujiaotang Cd-rich zinc deposit, Duyun, Guizhou is characteristically light-yellow in color with significant enrichment of cadmium which ranges from 0.83% to 1.97% (averaging 1.38%) in concentration in the mineral, corresponding to an enrichment coefficient as high as 30. 47 to 72. 96. In comparison with other major Pb−Zn deposits in the world (the Mississippi Valley deposits, and the Fankou and Jinding deposits in China) the Niujiaotang deposit isn ⁻ n×10 times richer in cadmium. Sphalerite in the deposit is also rich in Ga and Ge, but poor in In, Mn and Fe, suggesting some special mechanisms that govern the geochemical behavior of these trace elements. Except for a minor amount of independent minerals like greenockite, cadmium occurs mainly as isomorphous impurity in the crystal lattice of sphalerite. During weathering and leaching under supergene condition, cadmium was separated from Zn, resulting in some secondary minerals of Cd, including oxides and otavite. This project was jointly supported by the National Natural Science Foundation of China (No. 496-33110) and the Laboratory Foundation of Ore Deposit Geochemistry of Chinese Academy of Sciences.     

Sedimentary rock-hosted gold mineralization at Zalaa Uul, Khentii Range, northeastern Mongolia

The recently discovered Zalaa Uul occurrence exhibits gold concentrations averaging about 1 ppm in silicified breccias as wide as 100 m. Most mineralization is hosted in brecciated siltstone, shale, and calcareous sandstone of the Permian Ulz Formation that exhibits multiple stages of silicification. Rock geochemistry indicates: (1) gold is strongly associated with arsenic and silver; (2) antimony, tellurium and thallium are locally anomalous but poorly correlated with gold; (3) mercury is spatially correlated with copper; and (4) Ag:Au ratios are low (≤3). A low-level Cu–(Hg + Sb, ±Au + As) anomaly occurs over an hypothesized feeder breccia. The feeder breccia occupies a major northwest-dipping reverse fault zone between dominantly greenschist-facies phyllite and schist of the Upper Proterozoic Toshint Formation and unmetamorphosed marine clastic rocks of the permian Ulz Formation. Ground magnetometer surveys identified a magnetic body, thought to represent part of an intrusive complex at depth, within the reverse fault zone, down-plunge from the ∼70° northwest-dipping feeder breccia. Altered rhyolite dikes crop out in the vicinity of the feeder breccia. The potentially economic gold grades are 2 to 3 km outboard of the feeder breccia and may represent the distal Au + As zone of an intrusion-related mineralizing system. Alteration, regional structural and geophysical setting, host rocks and trace element geochemistry, and finely disseminated nature of gold particles are similar to Carlin-type gold systems in the Great Basin of the western USA, but local geology, magnetically mapped intrusive bodies, and trace element zonation suggest affinity with some intrusion-related gold systems. Received: 28 February 1999 / Accepted: 3 March 2000     

Organic Geochemistry of Lead—Zinc Polymetallic Dposits,Northern Guangdong

The characters of organic matter in rocks and ores in the Fankou and Dabaoshan deposits are systematically studied with regard to their implications for mineralization.The results show that kerogens in this area faaa mainly into the plutonism field in Van Krevelen‘s diagram.Reflectivity of the organic substance was measured to be 3.06%(Fankou)and 1.67%(Dabaoshan),corresponding to the paleo-geotemperatures of 232℃ and 184℃ respectively.The same types of porphyrins and hydrocarbons were recognized in the rocks and ores and hydrocarbon-bearing inclusions are widespread in quartz and calcite,particularly in Dabaoshan,It is thought that the orgain matter must have played a critical role in diagenesis and metallization in these deposits and that the hydrothermal solution was most likely to be the type of water-oil hot brine.     

Ore Zoning and Dynamics of Ore—Forming Processes of Yinshan Polymetallic Deposit in Dexing,Jiangxi

The Yinshan deposit,one of the large-scale Cu-Pb-Zn-Au-Ag polymetallic deposits,may be named a middle-low temperature subvolcanic hydrothermal deposit and referred to as the “transitional deposit“linking mineralization of the epithermal and porphyry coppertypes.In this paper,the characteristics and structures of ore zoning are briefly described.On the basis of the dynamics of ore-forming processes and applying computer numerical simulation technique,the mechanism of ore zoning is discussed and a concealed igneous body controlling ore deposition at depth of the Yinshan mine is predicted.     

Microthermometric measurement of fluid inclusions and its constraints on genesis of PGE-polymetallic deposits in Lower Cambrian black rock series, southern China

Systematic microthermometric measurements of fluid inclusions in the PGE-polymetallic deposits hosted in the Lower Cambrian black rock series in southern China were performed, and the results suggest: (1) there exist two types of fluid inclusions. TypeⅠis of NaCl-H2O system with low-medium salinity, and its homogenization temperatures (Th) and salinities are 106.9- 286.4℃ and ( 0.8- 21.8) wt%NaCl eq. respectively; TypeⅡ is of CaCl2-NaCl-H2O system with medium-high salinities, and its homogenization temperatures and salinities range from 120.1℃ to 269.6℃ and ( 11.4- 31.4) wt%NaCl eq., respectively. The typeⅡ fluid inclusions have been discovered for the first time in this kind of deposits; (2) two generations of ore-forming fluids were recognized. Characteristics of fluid inclusions in the PGE-polymetallic ores and carbonate-quartz stockworks in the underlying phosphorites are almost of no difference, they may represent ore-forming fluids at the main metallogenic stage. The peak value of homogenization temperature of those fluid inclusions is about 170℃, while their salinities possess a remarkable bimodal distribution pattern with two peak values of (27-31) wt%NaCl eq. and (4-6) wt%NaCl eq. On the contrary, fluid inclusions in the carbonate-quartz veins in the hanging wall may represent ore-forming fluids at the post-metallogenetic stage. The homogenization temperatures and the peak values of salinities are mostly 130-170℃ and (12-14) wt%NaCl eq., respectively; (3) nobel gas isotopic composition analyses in combination with the microthermometric measurements of fluid inclusions suggest that the ore-forming fluids at the main metallogenetic stage were probably derived from mixing of basinal hot brines with the CaCl2-NaCl-H2O system and seawater with the NaCl-H2O system; (4) in the Early Cambrian, the basinal hot brines were trapped in the Caledonian basins, which were distributed along the southern margin of the Yangtze Craton, and where giant thick sediments were accumulated, and expelled and migrated laterally along the strata because of the pressure caused by overlying sediments. The basinal hot brines absorbed Ni, Mo, V, PGE from the surrounding rocks and were transformed into ore-bearing hydrothermal fluids with the CaCl2-NaCl-H2O system and medium-high salinities, then ascended along faults and mixed with seawater of the NaCl-H2O system, and finally PGE-polymetallic deposits or occurrences were formed in the black rock series.     

Mercury mobility and bioavailability in soil from contaminated area

The mobility and bioavailability of mercury in the soil from the area near a plant using elemental mercury for manufacturing thermometers, areometers, glass energy switches and other articles made of technical glass has been evaluated. Mercury has been determined by sequential extraction method and with additional thermo desorption stage to determine elemental mercury. The procedure of sequential extraction involves five subsequent stages performed with the solutions of chloroform, deionized water, 0.5 M HCl, 0.2 M NaOH and aqua regia. The mean concentration of total mercury in soil was 147 ± 107 μg g⁻¹ dry mass (range 62–393), and the fractionation revealed that mercury was mainly bound to sulfides 56 ± 8% (range 45–66), one of the most biounavailable and immobile species of mercury in the environment. The fractions that brought lower contribution to the total mercury content were semi-mobile humic matter 22 ± 9% (range 11–34) and elemental mercury 17 ± 5% (range 8–23). The contributions brought by the highly mobile and toxic organomercury compounds were still lower 2.3 ± 2.7% (range 0.01–6.5). The lowest contributions brought the acid-soluble mercury 1.5 ± 1.3% (range 0.1–3.5) and water-soluble mercury 1.0 ± 0.3% (range 0.6–1.7). The surface layer of soil (0–20 cm) was characterized by higher mercury concentrations than that of the subsurface soil (60–80 cm), but the fractional contributions were comparable. The comparison of mercury fractionation results obtained in this study for highly polluted soils with results of fractionation of uncontaminated or moderately contaminated samples of soil and sediments had not shown significant statistical differences; however, in the last samples elemental mercury is usually present at very low concentrations. On the basis of obtained correlation coefficients it seems that elemental mercury soils from “Areometer” plant are contaminated; the main transformation is its vaporization to atmosphere and oxidation to divalent mercury, probably mainly mediated by organic matter, and next bound to humic matter and sulfides.     

Evidence for a magmatic origin for Carlin-type gold deposits: isotopic composition of sulfur in the Betze-Post-Screamer Deposit, Nevada, USA

We report here new sulfur isotope analyses from the Betze-Post-Screamer deposit, the largest Carlin-type gold deposit in the world. Carlin-type deposits contain high concentrations of arsenic, antimony, mercury, tellurium and other elements of environmental interest, and are surrounded by large volumes of crust in which these elements are also enriched. Uncertainty about the source of sulfur and metals in and around Carlin-type deposits has hampered formulation of models for their origin, which are needed for improved mineral exploration and environmental assessment. Previous studies have concluded that most Carlin-type deposits formed from sulfide sulfur that is largely of sedimentary origin. Most of these studies are based on analyses of mineral separates consisting of pre-ore diagenetic pyrite with thin overgrowths of ore-related arsenian pyrite rather than pure, ore-related pyrite. Our SIMS spot analyses of ore-related pyrite overgrowths in the Screamer zone of the Betze-Post-Screamer deposit yield δ³⁴S values of about −1 to 4‰ with one value of about 7‰. Conventional analyses of realgar and orpiment separates from throughout the deposit yield δ³⁴S values of about 5–7‰ with one value of 10‰ in the Screamer zone. These results, along with results from an earlier SIMS study in the Post zone of the deposit and phase equilibrium constraints, indicate that early arsenian pyrite were formed from fluids of magmatic origin with variable contamination from sulfur in Paleozoic sedimentary rocks. Later arsenic sulfides were formed from solutions to which sulfur of sedimentary origin had been added. The presence of Paleozoic sedimentary sulfur in Carlin-type deposits does not require direct involvement of hydrothermal solutions of sedimentary origin. Instead, it could have been added by magmatic assimilation of Paleozoic sedimentary rocks or by hydrothermal leaching of sulfur from wall rocks to the deposit. Thus, the dominant process delivering sulfur, arsenic, gold and mineralizing fluids to Carlin-type systems and their surrounding country rocks was probably separation of fluids from a magmatic source. Editorial handling: G. Beaudoin     

Heavy metal concentrations in shallow marine sediments affected by submarine tailings disposal and artisanal gold mining,Buyat-Ratototok district,North Sulawesi,Indonesia

Trace element concentrations in shallow marine sediments of the Buyat-Ratototok district of North Sulawesi, Indonesia, are affected by submarine disposal of industrial gold mine tailings and unregulated dumping of tailings and wastewater from small-scale gold mining using mercury amalgamation. Industrial mine tailings contained 590–690 ppm arsenic, 490–580 ppm antimony, and 0.8–5.8 ppm mercury. Tailings-affected sediment As and Sb concentrations were 20–30 times higher than in muddy sediments not contaminated with tailings, and 50–60 times higher than pre-mining average. Highest mercury concentrations were observed in sediments affected by small-scale mining using mercury amalgamation (5–29 ppm). Concentrations of most other trace elements were comparable in sediments affected by both types of mining and were slightly higher than regional averages for sediments collected before the onset of industrial mining. Elevated concentrations of both As and Sb in approximately equal proportions suggest tailings dispersal of at least 3.5 km. Mercury released from artisanal gold mining dispersed up to 4 km from river mouths. Slight increases in concentrations of non-mercury trace elements in areas affected by artisanal mining over pre-industrial mining concentrations were probably caused by increased rates of erosion. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Arsenic and mercury contamination in 31 cores taken in 1965, St. Anna Trough, Kara Sea, Arctic Ocean

 Several cores of 31 collected in 1965 in the St. Anna Trough, Kara Sea, have very high concentrations of Hg and As in surface/near-surface samples. Mercury contents range from 94 to 3915 ppb with a mean of 444 ppb and a baseline value of 314 ppb. Arsenic contents range from 5 to 710 ppm with a mean of 51 ppm and a baseline value of 23 ppm. The Hg and part of the As loading is likely anthropogenic from industrial activities in Siberia via atmospheric emission and deposition onto catchments. This is followed by mobilization into fluvial systems and is added to by industrial effluent discharge. Post-depositional diagenesis from depth in the cores contributes to high As values. A north-flowing bottom current transports Hg- and As-bearing suspended material from the Ob River sea discharge zone to depositional environments in the St. Anna Trough. Dumping of military materials and other wastes into the Kara Sea from the late 1940s to 1991 has likely added to Hg and As loading in the trough sediments. The bioavailability of mercury from suspended materials may be the reason why higher than normal levels of these potentially toxic elements are found in European Arctic seabirds, ringed seal and polar bear. Received: 12 December 1999 · Accepted: 23 May 2000     

Detrital transport of metals by glaciers, an example from the Pinchi Mine, central British Columbia

 Abundant cinnabar (HgS) mineralization is associated with the Pinchi Fault in central British Columbia. Two formerly producing mercury mines have been developed on this fault: Pinchi and Bralorne Takla. The mercury content of till (a sediment type directly deposited by glaciers) in the area of this fault is primarily controlled by the occurrence of cinnabar mineralization in bedrock and the direction of ice flow. Cinnabar-bearing bedrock was eroded by glaciers, transported in the direction of ice flow, and deposited "down-ice" from its source. An example of such a dispersal train is documented for the Pinchi Mine area where mercury ore was transported over a distance of 12 km, as measured in the clay-sized fraction (< 0.002 mm) of till, and could have been transported over 24 km according to heavy mineral concentrates (specific gravity >3.3) of this same sediment. Antimony, chromium, and nickel dispersal trains were also detected in the region. These data indicate that natural glacial processes can result in the "mobilization" of metals in the surficial environment, a factor which has to be considered at mine sites in glaciated terrain, where mine reclamation and remediation measures are now required. Received: 31 October 1996 · Accepted: 27 May 1997