西昆仑昆盖山北坡铜矿化点的地质特征及其找矿意义

Geological feature of copper mineralization and its ore-prospecting significance in Kungai Mountains, west Kunlun, China

昆盖山一带出露大套的石炭系火山岩,在野外剖面研究中发现了几处铜矿化的线索。详细的野外露头观察表明,铜矿化与火山角砾岩-凝灰岩、细粒花岗岩-细晶岩脉关系密切,伴有强烈的碳酸盐化、绿泥石化和绿帘石化;在不到300m长的剖面中,铜矿化体累积出露宽度大于8m。显微组成、结构分析表明,主要的金属矿物有辉铜矿、斑铜矿、蓝铜矿、铜蓝、钛铁矿等,显示为氧化—半氧化矿,上述铜矿物主要沿裂隙充填并明显破坏钛铁矿条带。5个捡块样品化学分析结果中铜最低品位0.11%,最高品位2.30%,均接近或高于边界品位,2个样品高于工业品位,此外伴生的银均高于铜矿床伴生的有益组分评价的参考值。矿化围岩的沉积组合反映其形成于较深海盆地的环境,为裂谷盆地构造背景。综合西昆仑的区域地质和已有的铜矿研究成果,认为该区具有形成大型铜矿床的地质背景。

During field investigation around Kungai Mountain area where there occur carboniferous lava strata, few copper mineralizations have been found. Through detailed outcrop observation, we have learnt that these copper mineralizations are closely related to volcanic breccia-tuff, granule granite and aplite, and have experienced intensive carbonatization, chloritization and epidotization. The total outcropping width is over 8m within a section less than 300m. According to the microscope research, major metallic minerals are chalcocite, bornite, azurite, covelline and ilmenit, belonging to oxidized to semi-oxidized ore. All the copper minerals above fill in the crakes and destroy the ilmenit band. The minimum copper content of five hand pick-up samples is 0.11% , while the maximum is 2.30%, all go beyond the cut-off grade, among which two are also beyond the industrial grade. Moreover, silver can be regarded as accompanying beneficial component. Sedimentation combination of the surrounding rocks suggests that they are formed in deep ocean basin environment, which belongs to rift valley basin. Based on the studies of regional geology and existing copper deposits, it is indicated that there is favorable geologic setting for a large-scale copper deposit in west Kunlun.