湘东南将军寨钨矿花岗岩地球化学特征及铼-锇同位素定年
Geochemical Characteristics of Granites from the Jiangjunzhai Tungsten Deposit of Southeast Hunan Province and Its Re-Os Isotopic Dating
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摘要: 将军寨钨矿是湘东南白云仙矿田中一个典型的石英脉型黑钨矿床。岩石学和岩石地球化学研究表明，将军寨钨矿花岗岩体为一复式岩体，是同源岩浆演化的产物，具有壳源花岗岩的特征。文章研究了白云仙矿田将军寨钨矿花岗岩的地球化学特征，并进行石英脉型黑钨矿石中辉钼矿的铼-锇同位素定年，以精确厘定将军寨钨矿的形成时间，揭示湘东南地区钨、锡等有色金属成矿的时限及其地球动力学背景。铼-锇同位素定年结果表明，辉钼矿中铼的含量偏低，表明将军寨钨矿的成矿物质来源可能是以上地壳为主。4件辉钼矿样品的铼-锇同位素模式年龄为（151.3±2.5） Ma～（163.6±2.3） Ma，其等时线年龄为（169.6±2.7）Ma，这表明将军寨钨矿形成于燕山早期，为华南中生代大规模成矿作用的产物。Abstract: The Jiangjunzhai tungsten deposit is a typical quartz-wolframite deposit in Baiyunxian ore field. The granite body in the Jiangjunzhai tungsten deposit is a compound rockmass, which has the features of crust-derived type granite and is the product of comagmatic evolution. In this paper, the geochemical characteristics of granite in Jiangjunzhai tungsten deposit and the Re-Os isotopic dating of molybdenite from quartz-wolframite veins were studied and carried out, in order to elucidate the timing of mineralization and reveal the time limites and geodynamic setting of large-scale metallogeny in Southeast Hunan. Re-Os dating for four molybdenites yields a model age of (151.3±2.5) Ma～(163.6±2.3) Ma and an isochron age of (169.6±2.7) Ma, indicating that the Jiangjunzhai tungsten deposit was formed in the Early Yanshanian period and is the result of large scale mineralization in South China.
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