新疆伊宁县塔吾尔别克金矿床流体包裹体特征研究及矿床成因

A study of fluid inclusion characteristics and genetic type of the Tawuerbieke gold deposit in Yining County, Xinjiang

塔吾尔别克金矿床是西天山吐拉苏断陷盆地中一个重要的金矿床。矿体主要赋存于早石炭世二长斑岩及大哈拉军组第五岩性段安山岩、蚀变凝灰岩中,受断裂构造控制,矿床围岩蚀变作用普遍而强烈。矿石金属矿物主要为黄铁矿、自然金、赤铁矿和黄铜矿等,非金属矿物主要为石英、斜长石、方解石等。成矿过程大致划分为3个成矿阶段:1石英-黄铁矿阶段;2石英-硫化物脉阶段;3石英-碳酸盐阶段。石英及方解石中流体包裹体类型简单,主要为气液两相水包裹体和纯液相水包裹体。包裹体测试均一温度为100~196℃,流体盐度为0.0%~7.3%(质量分数,NaCl_(eq)),流体密度为0.9~1.0 g/cm^3,计算出成矿压力为5.2~81.9 MPa,对应成矿深度为0.5~7.4 km。塔吾尔别克金矿床成矿流体包裹体显示低温度、低盐度和较低密度的流体特征,表明成矿压力小和深度较浅。结合矿床地质特征、流体包裹体特征及前人研究成果,初步认为该矿床为浅成低温热液型金矿床。

The Tawuerbieke gold deposit is one of the important Au deposits in Tulasa fault basin of the West Tianshan Mountains. The rock types in the study area mainly consist of andesite, andesitic pyroclastic rocks of the Dahalajunshan Formation and monzonite porphyry rocks, by which the gold mineralization is hosted. The orebodies are controlled by faults, and alterations are strongly developed in the wall rocks. The metallic minerals mainly include pyrite, native gold, hematite and chalcopyrite, whereas non-metallic minerals comprise quartz, plagioclase and calcite. The mineralization can be divided into three stages, i.e., quartz and pyrite stage, quartz and sulfide vein stage, quartz and carbonate stage. The type of fluid inclusions in quartz and calcite is simple, mainly comprising vapor-liquid two-phase inclusions and pure liquid inclusions. The homogenization temperatures of inclusions vary from 100℃ to 196℃. The salinities are 0.0%~7.3% NaCleq. The densities range from 0.9 g/cm3 to 1.0 g/cm3. The estimated pressures of the ore-forming fluids range from 5.2 MPa to 81.9 MPa, corresponding to the depth of ore-forming range from 0.5 km to 7.4 km. The features of the inclusions demonstrate low temperatures, salinities and densities with small pressures and low depth. In combination with the characteristics of the ore geology, fluid inclusion and the previous results, the authors have reached the conclusion that the Tawuerbieke gold deposit is an epithermal gold deposit.