广西泗顶铅锌矿成矿流体特征研究

Study on fluid inclusions characteristics of the Siding lead-zinc deposit in Guangxi

通过对广西泗顶铅锌矿的流体包裹体研究,得出该矿区流体包裹体主要为单相LH2O和气-液两相H2O-NaCl两种类型。显微测温实验结果表明:陡倾斜脉状矿体流体包裹体均一温度主要集中于84.3℃~117.6℃,盐度w(NaCleq)主要为0.87%~2.72%,密度为0.936~0.988g/cm3;似层状矿体流体包裹体的均一温度为70.1℃~305.4℃,主要集中在98.1℃~152.6℃和213.7℃~239.1℃两个温度段,盐度w(NaCleq)主要为0.53%~1.91%和7.31%~10.62%,密度介于0.851~0.989g/cm3之间。依据流体温度和盐度空间分布变化规律,并结合前人对硫同位素地球化学特征的研究,认为:陡倾斜脉状矿体的形成是由远源含矿流体,金属以硫络合物的形式迁移,在有机质还原剂作用下硫酸盐被还原,生成还原硫,金属硫化物沉淀;而似层状矿体的形成分两种情况:硫酸盐的还原机制;两种流体的混合机制,使金属硫化物沉淀。

This study was focused on the fluid inclusion trapped in calcite form of the Siding lead-zinc deposit in Guangxi. These inclusions can be divided into LH2O type and H2O-NaCl type. Microthermometric result showed that the primary fluid inclusions from the steeply inclined orebody of vein type had a homogeneous temperature range of 84.3℃-117.6℃ and a salinity of 0.87%-2.72% （NaCleq）with a density in the range of 0.936-0.988g/cm^3. The fluid inclusions of semi-layered orebody had a homogeneous temperture range of 70.1℃-305.4℃ , which were mainly concentrated in two stages of 98.1℃-152.6℃ and 213.7℃-239.1℃. Their salinity was concentrated in0.53%-1.91% and 7.31%-10.62% NaCleq with a density of 0. 851 to 0.989g/cm^3. In summary,the ore-forming fluids of the Siding deposit can be divided into two sta-ges, both having lower salinity and density. According to the variation of fluid temperature and salinity in spatial distribution and the previous study of geochemical characteristics of sulfur isotope,it is considered that the formation of the steep dip vein orebody is formed from the ore bearing fluid in the far source, the metal is migrated in the form of sulfur complex and the sulfate is reduced by the organic reductant, resulting in the reduction of sulphur and the precipitation of the metal sulfide. But the formation of the lamellar orebodies is divided into two kinds： the reduction mechanism of sulfate and the mixing mechanism of the two kinds of fluids, which all lead the metal sulfide to precipitate.