材料期刊网

包金山金矿位于湖南省双峰金矿带上，根据矿床地质特征将成矿作用划分为变质热液期、岩浆热液期和热液叠加期等3个成矿期，并将岩浆热液期细分为乳白色石英脉阶段(A)、烟灰色石英脉阶段(B)和碳酸盐?石英细脉阶段(C)3个矿化阶段。通过流体包裹体显微测温、包裹体成分分析及氢氧同位素组成分析来研究矿床成矿流体特征，并分析矿床成因。包裹体岩相学研究发现，A、B阶段的石英中发育3类包裹体：气液两相包裹体(I型)、水溶液?CO2包裹体(II型)和纯CO2包裹体(III型)。A阶段发育大量I型包裹体和极少量II型包裹体，均一温度集中于260~380℃，盐度为3.12%~15.42%；B阶段发育I型包裹体，II型及III型包裹体明显增多，均一温度集中于250~370℃，盐度为2.31%~12.29%。群体包裹体气相成分以H2O和CO2为主，还含有N2、CH4、H2、CO等，液相成分主要为Ca2+、Na+、Mg2+、SO42?、Cl?和NO3?。矿床主成矿期流体属低盐度、中高温、富CO2的Ca2+(Na+、Mg2+)-SO42?(Cl?、NO3?)-H2O-CO2体系，估算成矿压力为70~113 MPa，估算最大成矿深度为4.2km。氢氧同位素分析表明主成矿阶段的流体来源于原生岩浆水。矿床成因类型为变质热液叠加中温岩浆热液充填交代型矿床。

The Baojinshan gold deposit is located in Shuangfeng gold metallogenic belt of Hunan Province. According to geological characteristics of the deposit, three mineralization episodes were identified: metamorphic hydrothermal episode, magmatic hydrothermal episode and hydrothermal superposition episode, and 3 stages were subdivided from magmatic hydrothermal episode, namely milky quartz vein stage (A), smoky quartz vein stage (B) and carbonate-quartz veinlet stage (C). The characteristics of ore-forming fluid and ore genesis were discussed by using the fluid inclusion micro-thermometry, group inclusion composition analysis and H?O isotope analysis. Based on fluid inclusion petrography, three types of fluid inclusions are developed in stages A and B: aqueous inclusion (type I), CO2-aqueous inclusion (type II) and pure CO2 inclusion (type III). Mainly type I and few type II inclusions are present in stage A, having homogenization temperatures at 260?380 ℃, and the salinities ranging from 3.12% to 15.42%. In addition to development of type I inclusions, type II and III inclusions increase significantly in stage B, with homogenization temperatures ranging from 250℃to 370℃, salinities are in the range of 2.31%?12.29%. High density of H2O and CO2, followed by N2, CH4, H2 and CO were found as gas compositions in the inclusions. Liquid phase of fluid mainly comprise Ca2+, Na+, Mg2+, SO42?, Cl? and NO3?. Ore-forming fluid of main mineralization episode in Baojinshan gold deposit belongs to low salinity, medium-high temperature, CO2-rich Ca2+(Na+, Mg2+)-SO42?(Cl?, NO3?)-H2O-CO2 system. The calculated metallogenic pressures are in the range of 70?113 MPa, and the maximum estimated mineralization depth is 4.2 km. The result of hydrogen and oxygen isotope analysis shows that ore-forming fluid of main mineralization stage is mainly derived from magmatic fluid. Baojinshan deposit belongs to medium-temperature magmatic hydrothermal filling and metasomatic deposit along with superimposition of metamorphic hydrothermal.