The Keyue Pb-Zn polymetallic deposit in southern Xizang is located in the eastern part of the Tethys Himalayan Sb-Au-Pb-Zn metallogenic belt,in which the lenticular or vein ore bodies strictly controlled by the NE-trending faults occur in the carbon-bearing calcareous slates of the Lower Jurassic Ridang Formation.The δ34S values of the sulfides from the ores range from 9.2‰ to 11.2‰,with an average of 9.85‰,similar to those of the Jurassic strata in the Ridang Formation,implying that S is mainly derived from the host strata.The sulfides from the ores give the lead isotopic ratios of 10.669-19.813 for 206Pb/204Pb,with an average of 19.740;15.823-15.979 for 207Pb/204Pb,with an average of 15.902,and 40.104-40.687 for 208Pb/204Pb,with an average of 40.410.These higher lead isotopic ratios bear a striking resemblance to those of the Himalayan crystalline basement,possibly indicating that the lead in the ores comes from the Himalayan crystalline basement.%藏南柯月铅锌矿床位于特提斯喜马拉雅构造域Sb-Au-Pb-Zn成矿带东段,矿体主要呈透镜状或脉状,严格受北东向断裂构造所控制,赋矿地层为下侏罗统日当组含碳钙质板岩.矿石硫化物硫同位素δ34S介于9.2‰～11.2‰之间,平均值为9.85‰,与区内日当组地层的δ34S值变化范围相似,表明成矿流体中的硫主要来源于容矿地层.矿石硫化物铅同位素组成为:206Pb/204Pb为19.669 ～ 19.813.平均值19.740;207 Pb/204Pb为15.823 ～ 15.979,平均值15.902;208 pb/204Pb为40.104～40.687,平均值40.410.其结果显示,矿石中的铅具有高放射性成因铅的特征,与喜马拉雅结晶基底的铅同位素组成具有相似的比值,表明矿石铅主要来源于喜马拉雅结晶基底.
展开▼
