穷布拉克铜矿床是新疆阿吾拉勒铁铜成矿带西段规模最大的一个铜矿床.本文对该矿床Ⅰ号矿体3种矿石中的方解石脉开展了流体包裹体和稳定同位素研究,结果表明:3种矿石的包裹体均为气液两相包裹体,流体体系为NaCl-H2O体系.包裹体的均一温度为85～343℃,盐度范围为(1.57～17.79) wt％NaCl eq.,密度为0.7～1.05 g/cm3.方解石的δ 13C值为-3.2‰～-6.5‰,平均-4.08‰,显示出幔源的特征.成矿流体的δ18O值为0.45‰～4.44‰.硫化物δ 34S值变化范围较大,为-10.5‰～5.5‰.Ⅰ号矿体与矿区内的火山热液型矿体具有相似的流体包裹体和稳定同位素特征,沉积特征不明显,并非沉积-改造型,与其他矿体具有相同的成因类型.成矿流体由火山热液和参与了水-岩反应的大气水两种流体混合而成,以火山热液占主导地位.矿物沉淀主要与流体混合后缓慢降温有关,但混合后的稀释作用以及水-岩反应导致pH值升高可能也起到了一定作用.%The Qiongbulake copper deposit is the largest deposit in western Awulale Mountain copper belt of Xinjiang. Three ore types from No.l ore body were selected for fluid inclusion and stable isotope studies. The results reveal that all the fluid inclusions are of L—V type and NaCl—H2O system. Fluid inclusions associated with calcite display moderate—low homogenization temperatures (85℃～343cG),moderate — low salinities (1.57～17.79 wt%NaCl eq.) and low densities (0.7g/cm3～1.05 g/cm3). The petrographic characteristics of the fluid inclusions in the three ore types are similar to each other, whereas some differences do exist for the homogenization temperatures and alkalinities. Carbon isotope determinations of calcite show δ13 CPDB values of —3.2‰—6.5‰, suggesting that the carbon was derived from the mantle. Oxygen isotope determinations of the fluids show δ 18OSmow values of 0.45%o～4.44%o. Sulfur isotope determinations of sulfides show δ 34SvDt values of —10.5%o～ 5.5%o. The No. 1 ore body and other volcanic hydrothermal ore bodies have similar fluid inclusion and stable isotope characteristics. Therefore, the No. 1 ore body is not of sedimentation —transformation genesis but of volcanic hydrothermal genesis. The mixing of volcanic hydrothermal solution and circulated meteoric water was probably responsible for ore genesis. The slow cooling of ore—forming fluid played the most important role in the deposition of minerals. However, the effect of dilution and the increase of pH were not negligible.
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