投稿时间：2012-04-19
修订日期：2012-11-01
中文摘要:莲花山铜矿床产于中生代火山盆地隆坳转换部位,是大兴安岭中段铜多金属成矿带上的重要矿床之一。根据野外观察与室内鉴定,将矿化过程从早到晚划分为4个阶段,分别为早期的黄铁矿-石英阶段、中期的石英-硫化物阶段、中晚期的多金属硫化物阶段与末期的石英-碳酸盐阶段。研究表明,流体包裹体类型有纯气相、纯液相、气液两相和含子晶多相包裹体,矿化早期4类包裹体均有发育,中、中晚与末期主要发育气液两相包裹体。从早到晚,均一温度分别为340～420℃、220～310℃、140～200℃、～130℃。早期含子晶包裹体w(NaCleq)为34.5%～48.9%,气液两相包裹体w(NaCleq)为3.85%～7.15%,中、中晚期包裹体w(NaCleq)变化于5.25%～8.54%之间,未测到末期的盐度。初步厘定早期中高温、高盐度、富CO2的氧化含矿流体"沸腾",CO2逸出,演化为中阶段中温、低盐度流体,pH值升高,黄铜矿、黄铁矿大量沉淀,中晚期大气降水开始混入,形成以方铅矿与闪锌矿为主的多金属硫化物,末期流体成分则接近于循环天水;进而确定该矿床是与次火山岩相关的浅成热液高硫化型铜矿床。
Abstract:The Lianhuashan Cu deposit, one of the important deposits in the polymetallic metallogenic belt of the Da Hinggan Mountains, occurs in the uplift-depression conversion part of the Mesozoic volcanic basin. The mineralization process can be classified into four stages from early to late based on field geology and mineral assemblages: (early) pyrite-quartz phase, (middle) quartz-sulfides phase, (middle-late) polymetallic sulfides phase, and (late) quartz-carbonate phase. In addition, there are four types of fluid inclusions in the early stage, i.e., pure volatile inclusions, pure liquid inclusions, aqueous inclusions, and daughter crystal-bearing inclusions. Studies indicate that all the four kinds of fluid inclusions existed in the early stage, whereas only aqueous inclusions were observed in the middle-late stages. The homogenization temperature of the formation from the early phase to the late phase is in order of 340～420℃, 220～310℃, 140～200℃, and ～130℃. Salinities w(NaCleq) in the early stage are 34.5%～48.9% and 3.85%～7.15% for daughter crystal-bearing inclusions and aqueous inclusions, respectively, whereas salinities w(NaCleq) in the middle and middle-late stages are 5.25%～8.54% for aqueous inclusions. No data were detected for the late stage. The authors have obtained the following preliminary understanding: the early phase was a stage of oxidized ore-bearing fluids characterized by high temperature, high salinity, and enrichment of CO2. It transformed into the second phase with medium temperature, low salinity fluids and rising pH values, and abundant chalcopyrite and pyrite started to precipitate at this phase. In the middle-late stage, lots of galena and sphalerite and other sulfides began to form as a result of the mixture of meteoric water. In the late phase, the fluid compositions were very close to those of the cyclic meteoric water. It is thus suggested that this copper deposit is one of the epithermal high sulfidation deposits and its formation was closely related to subvolcanic activity.
keywords:geochemistry fluid inclusion fluid evolution Lianhuashan Cu deposit middle Da Hinggan Mountains
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中图分类号：P618.41
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基金项目:本文得到国家自然科学基金(40772052; 41172072)和中国地质调查局计划工作项目(资[2010]26-06)联合资助
引用文本：
白令安,孙景贵,孙庆龙,古阿雷,赵克强,门兰静.2012.大兴安岭中段莲花山铜矿床成矿流体性质与矿床成因研究[J].矿床地质,31(6):1249~1258BAI LingAn,SUN JingGui,SUN QingLong,GU ALei,ZHAO KeQiang,MEN LanJing.2012.Ore-forming fluids and genesis of Lianhuashan Cu deposit in middle Da Hinggan Mountains[J].Mineral Deposits31(6):1249~1258
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