藏南扎西康铅锌银锑多金属矿多期多阶段成矿特征及其指示意义

Multiphase and polystage metallogenic process of the Zhaxikang large-size Pb-Zn-Ag-Sb polymetallic deposit in southern Tibet and its implications

扎西康铅锌银锑多金属矿床是北喜马拉雅金-锑成矿带的典型代表,更是该成矿带内为数不多的已达到大型规模的矿床。扎西康矿床具有丰富的金属矿物和脉石矿物组合以及极为复杂的成矿期次,因而其成矿世代的系统划分不仅对该矿床成矿过程的认识和理解具有重要意义,而且对区带成矿作用的认识也具有十分重要的指示意义。文章在总结前人的认识基础之上,根据矿物共生组合和相互穿插关系,提出了新的成矿期次划分方案,将扎西康矿床的成矿世代分为3期、7阶段和13亚阶段,这种多期多阶段成矿特点显示出扎西康矿床的形成可能是多期流体叠加的结果,并提出晚期锑元素对先存铅锌矿体的叠加改造成因。研究表明这种叠加改造成矿作用在整个区带上具有普遍意义,指示了在特提斯喜马拉雅锑金成矿带可能具有寻找铅锌矿体的潜力。

Located in Tethys Himalayan sub-terrane, the Zhaxikang Pb-Zn-Ag-Sb polymetallic ore deposit is not only a representative ore deposit in the antimony-gold metallogenic belt but also among a few deposits that have reached large-scale reserves. The Zhaxikang deposit has abundant assemblages of ore minerals and gangue miner- als with complex ore-forming process, which indicates that recognition of ore-formaing stages and periods is very important for the study of the ore-forming process and also of indication significance for the understanding of the regional metallogenic belt. Based on summarizing the previous cognitions of the mineralization process as well as mineral paragenetic assemblages and crosscutting relationship of ore veins, the authors formulated a model for 3-period, 6-stage and 13-sub-stage complex ore-forming process, which indicates that the metallogenic process of the Zhaxikang deposit resulted from superimposition and remobilization of several stages of ore fluids, and the later antimony-bearing fluid was superimposed upon and reconstructed the pre-existent lead-zinc ore body. The overprinting and remobilization process has universal meaning for the study of the regional metallogenic belt and suggests the potential of finding lead-zinc deposits in the Tethys Himalayan Sb-Au metallogenic belt.