Abstract:The Lishui gold mine in Jiangsu Province is a gold-tellurium deposit of silicified zone type occurring in a Mesozoic volcanic basin with its country rocks composed of a series of trachyandesitic volcanic complexes belonging to weakly alkaline type. The REE distribution pat tern suggests that these rocks were probably formed through the process of magmatic differentiation of the mantle-derived magma contaminated by crustal materials. The absence of calcite and the presence of a large amount of sericite imply that the wall fork alterations might have been developed in two stages. The earlier one is of carbonate- (quartz)-pyrite type with the pH condition probably around 7, while the late one is of quartz-sericite-pyrite assemblage formed under slightly acidic condition with pH<6.7. The mineralization of this deposit may be divided into four stages with each of them represented by a corresponding type of mineral assemblage: quartz-pyrite; quartz-pyrite-chalcocite; quartz-barite-pyrite; and quartz-pyrite-marcasite. The chief ore constituents are members of native gold-silver series, Au-Ag tellurides, sulfides, sericite quartz, etc. In the process of mineralization, large quantities of basic and alkaline components of the original rocks are removed with a relative concentration of Au, Ag, Te, Cu, Pb, Bi and As. During progressive alteration and mineralization, Auis gradually enriched. The temperatures for the mineralization are 320-120℃, and the pH values of the ore-forming fluids range from 4.1 to 5.6. The upper limit of logfO2 during the mineralization is estimated to be in the range of 36.3一-35. 3 at the earlier stage, and -34.4一-33.2 at the late stage. The gold ismainly derived form the upper mantle. In the process of mineralization gold might be transported in the form of thio or telluric comleixes. The chief factors controlling its precipitatio are pH, fO2 and temperature of the solution. Only at the late stage the lowering of pressure is effective in accelerating the speed of precipitation. Referring to the Au-Ag-Te phase diagram, the initial composition of the ore-bearing solution is almost confined to the region of AuTe-AuAg3Te2Au. Through the multiple stages of mineralization, the mineral assemblages of native gold, calaverite-petzite-native gold, sylvanite-native gold, hessite-sylvanite etc. were gradually precipitated, thus forming volcanic type Au-Te deposit rarely seen in China.
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汪建明，宁仁祖，丁浩华，张慧敏，丁桂春.1985.江苏省溧水硅化带型金一碲矿床的地球化学特征[J].矿床地质,4(4):57~67,88.1985.Geochemical characteristics of the Lishui silicified zone type gold-telluriumde-posit in jiangsu province[J].Mineral Deposits4(4):57~67,88
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