新疆阔尔真阔腊金矿床成矿流体包裹体研究

Ore-forming fluid inclusions of Kuoerzhenkoula gold deposit,Xinjing

新疆西北部阔尔真阔腊金矿床是产于海西期岛弧型钙碱性火山岩中的火山晚期热液型金矿床.流体包裹体研究表明,成矿阶段(Ⅰ)包裹体为气相包裹体,均一温度为308～396℃,盐度为5.86～8.41wt%NaCl;主成矿阶段(Ⅱ、Ⅲ)为气液包裹体,均一温度分别为209～276℃(Ⅱ)、119～198℃(Ⅲ),盐度分别为5.11～7.86wt%NaCl(Ⅱ)、2.74～6.17wt%NaCl(Ⅲ).石英流体包裹体成分测定采用分阶段法,有效地排除了不同成矿阶段包裹体成分的影响,准确地测出了成矿阶段(Ⅰ)和主成矿阶段(Ⅱ、Ⅲ)包裹体的成分,结果表明成矿流体具Na+-HS--Cl--H2O型中低温、低盐特征,金主要以金硫络合物的形式迁移,金矿化是在还原条件下进行.主成矿阶段包裹体中水的氢同位素组成为-83.97～-89.07‰,氧同位素组成为1.8～3.2‰,成矿流体是岩浆热液与古大气降水混合而成.流体混合及水-岩反应是造成本区金沉淀成矿的主要因素.

Kuoerzhenkuola gold deposit, located in calc-alkaline volcanic rock in Hercynian island arc, in northwest of Xinjiang, is volcanogenic late-stage hydrothermal ore deposit. The study of fluid inclusions indicates that inclusions in mineralizating early-stage are gaseous inclusions. The homogenization temperature ranges between 308 C and 396 C and The salinity is from 5.86 to 8.41wt% NaCl. The mineralizating major- stage (II, III) is gas-liquid inclusion. The homogenization temperature is 209degreesC similar to 276degreesC (II) and 148 similar to 180 degreesC (III) respectioely, and the salinity is 5.11 similar to 7.86wt% NaCl (II) 2.74 similar to 6.17wt% NaCl (III), respectioely. Composition of fluid inclusions in quartz is measured relatively according to different mineralizating stage, in order to rule out the influence of coexisting inclusions in different mineralizating stage. The result indicates that ore-forming fluid is a type of Na+ - HS- - Cl- - H2O fluid with medium-low temperature and low salinity. Au is transported by the type of auric-sulfur complex and the ore is formed in reduction condition. Hydrogen and oxygen isotopes of fluid inclusions in the mineralizating major- stage are -83.97 similar to89.07 and 1.8 similar to3.2, respectively, and show that the solutions were mainly originated from magmatic water and meteoric water. The fluid mixing and water-rock reaction have caused the deposition of Au.