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An investigation was carried out to determine the concentrations of heavy metals in the surface water, sediments, soils and plants. The main objective was to assess the environmental situation and evaluate the transfer of heavy metals from mining activities into the food chain. Total concentrations of Cu, Pb, Zn, Cd, and As were determined by AAS and Hg concentration by cold-vapour AAS. The results indicated a highly localised distribution pattern closely associated with the two pollution sources along the Lean river bank: strong acidity and a large amount of Cu in the drainage from the Dexing Cu mining area; and high concentrations of Pb and Zn in the effluents released from the smelters and mining, processing and extraction activities in the riparian zone. The results are discussed in relation to the need to deal with the observed deterioration in environmental quality., An investigation was carried out to determine the concentrations of heavy metals in the surface water, sediments, soils and plants. The main objective was to assess the environmental situation and evaluate the transfer of heavy metals from mining activities into the food chain. Total concentrations of Cu, Pb, Zn, Cd, and As were determined by AAS and Hg concentration by cold-vapour AAS. The results indicated a highly localised distribution pattern closely associated with the two pollution sources along the Lean river bank: strong acidity and a large amount of Cu in the drainage from the Dexing Cu mining area; and high concentrations of Pb and Zn in the effluents released from the smelters and mining, processing and extraction activities in the riparian zone. The results are discussed in relation to the need to deal with the observed deterioration in environmental quality.

The geology of seven large-scale Mississippi Valley-type deposits on the border between Sichuan and Yunnan is described and analyses of fluid inclusion leachates discussed. Previous studies had suggested that the ore-forming fluids were derived from meteoric waters but the leachates show Na/Br ratios within the range 75-358 and Cl/Br ratios 67-394, a variation trend coinciding with the seawater evaporation trajectory. The average ratios are 185 and 173 respectively, very close to the ratios (120 and 233) of residual sea water evaporated past the point of halite precipitation. However, fluid inclusions have absolute Na and Cl values much less than those of sea water, indicating that the brine has been diluted with water that oxygen and deuterium isotope values show was probably meteoric. Together the evidence suggests that highly evaporated sea water leached Pb, Zn and Fe before being mixed with descending meteoric water which resulted in ore formation., The geology of seven large-scale Mississippi Valley-type deposits on the border between Sichuan and Yunnan is described and analyses of fluid inclusion leachates discussed. Previous studies had suggested that the ore-forming fluids were derived from meteoric waters but the leachates show Na/Br ratios within the range 75-358 and Cl/Br ratios 67-394, a variation trend coinciding with the seawater evaporation trajectory. The average ratios are 185 and 173 respectively, very close to the ratios (120 and 233) of residual sea water evaporated past the point of halite precipitation. However, fluid inclusions have absolute Na and Cl values much less than those of sea water, indicating that the brine has been diluted with water that oxygen and deuterium isotope values show was probably meteoric. Together the evidence suggests that highly evaporated sea water leached Pb, Zn and Fe before being mixed with descending meteoric water which resulted in ore formation.

The main objective of the study was to investigate Ti, V, Cr, Mn, Cu, Pb, Zn and As in soil and sediment and to assess the degree of pollution in the area. It was found that soils and sediments were slightly contaminated. Geochemical maps of heavy metals showed contamination in the areas of vanadium-titanium-magnetite mining and smelting and the tailings dam. The sources of the selected elements were mainly dust from mining activities and other effluents. It was concluded that the area should be monitored regularly for trace metals, especially heavy metals., The main objective of the study was to investigate Ti, V, Cr, Mn, Cu, Pb, Zn and As in soil and sediment and to assess the degree of pollution in the area. It was found that soils and sediments were slightly contaminated. Geochemical maps of heavy metals showed contamination in the areas of vanadium-titanium-magnetite mining and smelting and the tailings dam. The sources of the selected elements were mainly dust from mining activities and other effluents. It was concluded that the area should be monitored regularly for trace metals, especially heavy metals.

The area includes a huge V-Ti magnetite deposit which provides 20% of China's iron, 64% of its vanadium and 53% of its titanium. The mining camp consists of six large-scale iron deposits hosted in basic-ultrabasic intrusions, numerous medium-sized coal, clay, dolomite and limestone deposits and minor graphite, manganese and barite. A total of 31 topsoil samples were systematically collected from smelting, mining, residential and agricultural districts. A normalisation procedure was adopted to establish environmental geochemical baseline models, from which regional geochemical baseline values of As, Cr, Cu, Ni, Pb and Zn were determined. Enrichment factors were used to anlayse the mechanism of trace-metal pollution in topsoil from anthropogenic sources. The results showed that the worst pollution has been caused by the coal mine, iron ore mine, smelter, tailings dam and power plant., The area includes a huge V-Ti magnetite deposit which provides 20% of China's iron, 64% of its vanadium and 53% of its titanium. The mining camp consists of six large-scale iron deposits hosted in basic-ultrabasic intrusions, numerous medium-sized coal, clay, dolomite and limestone deposits and minor graphite, manganese and barite. A total of 31 topsoil samples were systematically collected from smelting, mining, residential and agricultural districts. A normalisation procedure was adopted to establish environmental geochemical baseline models, from which regional geochemical baseline values of As, Cr, Cu, Ni, Pb and Zn were determined. Enrichment factors were used to anlayse the mechanism of trace-metal pollution in topsoil from anthropogenic sources. The results showed that the worst pollution has been caused by the coal mine, iron ore mine, smelter, tailings dam and power plant.

The three indicators are: the source of the ore-forming fluid, the migration of the fluid and the mineralisation from the fluid., The three indicators are: the source of the ore-forming fluid, the migration of the fluid and the mineralisation from the fluid.

Quartz from the disseminated ores and quartz associated with hydrothermal silicification was found to have a silicon isotopic composition and cathodoluminescence quite distinct from that of the wall rocks. Quartz associated with primary silicification was not luminescent, whereas that in wall rocks exhibited striking luminescence. From the silicon isotope values for primary silicification in host rocks of different ages, the process of silicon precipitation can be roughly approximated on the basis of dynamic fractionation of isotopes. The results show that fracture systems at deeper levels were more favourable to the deposition of SiO2, indicating that deep structures close to major fault systems would have high potential for the formation of large gold deposits., Quartz from the disseminated ores and quartz associated with hydrothermal silicification was found to have a silicon isotopic composition and cathodoluminescence quite distinct from that of the wall rocks. Quartz associated with primary silicification was not luminescent, whereas that in wall rocks exhibited striking luminescence. From the silicon isotope values for primary silicification in host rocks of different ages, the process of silicon precipitation can be roughly approximated on the basis of dynamic fractionation of isotopes. The results show that fracture systems at deeper levels were more favourable to the deposition of SiO2, indicating that deep structures close to major fault systems would have high potential for the formation of large gold deposits.

The No.302 uranium deposit is a granite type deposit with considerable vertical extension and relatively complete vertical zoning. Studies of the hydrothermal dikes reveal the existence of vertical zoning characterised by the presence of acidic and oxidised minerals in the upper part and alkaline and reduced minerals in the lower part. These are believed to have resulted from the mixing and boiling of hydrothermal solutions., The No.302 uranium deposit is a granite type deposit with considerable vertical extension and relatively complete vertical zoning. Studies of the hydrothermal dikes reveal the existence of vertical zoning characterised by the presence of acidic and oxidised minerals in the upper part and alkaline and reduced minerals in the lower part. These are believed to have resulted from the mixing and boiling of hydrothermal solutions.