Concentrations of organic matter, iron and manganese in the deep sea surface sediments in the Nansha Islands sea area, South China Sea are measured. Horizontal and vertical distributions of iron and manganese are disc...Concentrations of organic matter, iron and manganese in the deep sea surface sediments in the Nansha Islands sea area, South China Sea are measured. Horizontal and vertical distributions of iron and manganese are discussed. The vertical distribution of iron and manganese in the sediments results from reduction, diffusion, and redeposition of manganese (or iron) oxide and hydroxide in the sediment. There are the maxima of iron and manganese in solid phase in the top of the sediment, which is caused by the penetration of O2 and the upward flux of Mn2+ ( or Fe2+ ). Manganese bacteria play a very important role in the cycle of solid-phase iron and manganese in the ocean environment. Manganese bacteria oxidize Mn2+ ( or Fe2+ ) in dissolved state to Mn4+ ( or Fe3+ ) in oxidized state under the aerobic condition, whereas they reduce iron and manganese in anaerobic conditions.展开更多
This paper reports the variation rules for the typomorphic parameters of the pyrite and the gold enrichment rules of the Denggezhuang quartz vein gold deposit at a large-depth scale, providing the mineral signs for de...This paper reports the variation rules for the typomorphic parameters of the pyrite and the gold enrichment rules of the Denggezhuang quartz vein gold deposit at a large-depth scale, providing the mineral signs for deep prospecting prediction through detailed study of the characteristics of crystal＇ habits, chemical composition, the thermoelectricity of pyrites, and min- eralogical mapping. This paper primarily discusses the correlation between the mineralization intensity and the space-time evolution of the mineralogical parameters, clarifies the physicochemical conditions during gold mineralization, and provides information useful for deep mineralization prediction. We demonstrate that the crystal habits of the pyrites are very complex, primarily occurring as （ 100）, （210）, and their combinate form. （210） and （ 100）＋（210） have positive correlations with gold mineralization, and （ 100）＋（210） therefore can be useful for locating rich ore segments. The composition of pyrites is charac- teristically poor in S and rich in As. Their typical trace elements are composed of Mo, As, Pb, Cu, Bi, Zn, Au, Co, Se, Sb, Ag, Ni, Cr, and Te. The average contents of trace elements in pyrites from various stages show that the crystallizing temperature gradually decreased from an early stage to the metallogenic episodes. The precipitation and accumulation of Au and Ag occur primarily in the quartz-pyrite stage （III） and the polymetal minerals stage （IV）. The occurrence rate of P-type pyrites （P（%）） is 83.52%. There is a larger dispersion of the thermoelectrical coefficient of pyrite （a） in the Denggezhuang gold deposit than in other deposits in the Jiaodong Peninsula. The electrical conductivity assemblage of pyrites from I to V is characterized by P〉N〉P〉N〉P〉〉N〉P〉〉N〉P〉N, which is usually considered beneficial for mineralization. The relative contents of As＋Sb＋Se＋Te and Co＋Ni are closely correlated to P-type and N-type average values and their occurrence rates. According to the crystallizing temperature of pyrite, the mineralization intensity, and the denudation degree, the mineralization temperature of the Denggezhuang gold deposit is in the range of 150-322~C and is of a medium-low temperature. The orebody has already become denuded to the top-middle of the orebody, and the size of the orebody is larger than 900 m. Based on the vertical zon- ing of the thermoelectrical coefficients of pyrites and P-type pyrite mapping, it is suggested that the segment between -425 and -800 m may have exploration potential to the northeast of line 94 of the No. I2.2 orebody.展开更多
基金supported by the National Natural Science Foundation of China(contract No.49706065)the Special Foundation of National Social Common Wealth Research(contract No.2001DIA50041)ZKCX2-SW-212 by Chinese Academy of Science
文摘Concentrations of organic matter, iron and manganese in the deep sea surface sediments in the Nansha Islands sea area, South China Sea are measured. Horizontal and vertical distributions of iron and manganese are discussed. The vertical distribution of iron and manganese in the sediments results from reduction, diffusion, and redeposition of manganese (or iron) oxide and hydroxide in the sediment. There are the maxima of iron and manganese in solid phase in the top of the sediment, which is caused by the penetration of O2 and the upward flux of Mn2+ ( or Fe2+ ). Manganese bacteria play a very important role in the cycle of solid-phase iron and manganese in the ocean environment. Manganese bacteria oxidize Mn2+ ( or Fe2+ ) in dissolved state to Mn4+ ( or Fe3+ ) in oxidized state under the aerobic condition, whereas they reduce iron and manganese in anaerobic conditions.
基金financially supported by the Key Program of National Natural Science Foundation of China(Grant No.90914002)the Ore-Prospecting Project for Critical Mines(Grant No.20089937)+1 种基金Scheduled Program of China Geological Survey(Grant No.1212011220926)the Institution of Higher Education Innovation and Intelligence Attraction Program(Grant No.B07011)
文摘This paper reports the variation rules for the typomorphic parameters of the pyrite and the gold enrichment rules of the Denggezhuang quartz vein gold deposit at a large-depth scale, providing the mineral signs for deep prospecting prediction through detailed study of the characteristics of crystal＇ habits, chemical composition, the thermoelectricity of pyrites, and min- eralogical mapping. This paper primarily discusses the correlation between the mineralization intensity and the space-time evolution of the mineralogical parameters, clarifies the physicochemical conditions during gold mineralization, and provides information useful for deep mineralization prediction. We demonstrate that the crystal habits of the pyrites are very complex, primarily occurring as （ 100）, （210）, and their combinate form. （210） and （ 100）＋（210） have positive correlations with gold mineralization, and （ 100）＋（210） therefore can be useful for locating rich ore segments. The composition of pyrites is charac- teristically poor in S and rich in As. Their typical trace elements are composed of Mo, As, Pb, Cu, Bi, Zn, Au, Co, Se, Sb, Ag, Ni, Cr, and Te. The average contents of trace elements in pyrites from various stages show that the crystallizing temperature gradually decreased from an early stage to the metallogenic episodes. The precipitation and accumulation of Au and Ag occur primarily in the quartz-pyrite stage （III） and the polymetal minerals stage （IV）. The occurrence rate of P-type pyrites （P（%）） is 83.52%. There is a larger dispersion of the thermoelectrical coefficient of pyrite （a） in the Denggezhuang gold deposit than in other deposits in the Jiaodong Peninsula. The electrical conductivity assemblage of pyrites from I to V is characterized by P〉N〉P〉N〉P〉〉N〉P〉〉N〉P〉N, which is usually considered beneficial for mineralization. The relative contents of As＋Sb＋Se＋Te and Co＋Ni are closely correlated to P-type and N-type average values and their occurrence rates. According to the crystallizing temperature of pyrite, the mineralization intensity, and the denudation degree, the mineralization temperature of the Denggezhuang gold deposit is in the range of 150-322~C and is of a medium-low temperature. The orebody has already become denuded to the top-middle of the orebody, and the size of the orebody is larger than 900 m. Based on the vertical zon- ing of the thermoelectrical coefficients of pyrites and P-type pyrite mapping, it is suggested that the segment between -425 and -800 m may have exploration potential to the northeast of line 94 of the No. I2.2 orebody.
