西藏雄村斑岩铜矿床辉钼矿Re-Os同位素体系  

The Re-Os isotope system of the Xiongcun porphyry copper-gold deposit, Tibet

作　　者：黄勇[1,2] 唐菊兴[3] 丁俊[2] 张丽[2] 郎兴海[1] 

机构地区：[1]成都理工大学,四川成都610059 [2]中国地质调查局成都地质调查中心,四川成都610081 [3]中国地质科学院矿产资源研究所,国土资源部成矿作用与资源评价重点实验室,北京100037

出　　处：《中国地质》2013年第1期302-311,共10页Geology in China

基　　金：国家自然科学基金(41172077);中国地质调查局地质大调查项目(1212011221073)共同资助

摘　　要：辉钼矿Re—os同位素测年是现今研究斑岩铜矿成矿时限最有效的手段。本文通过开展冈底斯成矿带雄村斑岩铜金矿辉钼矿Re—Os同位素年代学研究．并结合前人已发表的数据．认为雄村斑岩铜金矿床成矿时限为171～175Ma。I号矿体可能受到始新世大规模的岩浆活动扰动。辉钼矿在经历过后期热事件影响，在辉钼矿中形成有极微量富Re的K一硅酸盐矿物．I号矿体辉钼矿Re含量比Ⅱ号矿体以及Ⅲ号矿体中辉钼矿Re含量高出1～4倍。其Re一0s同位素年龄比真实年龄偏低．不能完全代表成矿年龄。同时通过与冈底斯成矿带斑岩一矽卡岩铜钼矿床，钼／钼铜矿床的对比研究后发现．雄村斑岩铜金矿中辉镅矿Re含量比同一成矿带上中新世斑岩铜铝矿床中辉钼矿Re含量高出一个数量级．比古新世一始新世斑岩钼矿／钼铜矿床中辉钼矿Re含量高出两个数量级。辉钼矿Re含量变化特征与成矿物质的来源、钼的浓度、成矿母岩组分以及成矿期间的物理／化学条件有关。Re-Os dating of molybdenite is an efficient means to restrict the time of mineralization. The age of mineralization of the Xiongcun porphyry copper-gold deposit is confined between 171 Ma and 175 Ma based on this study and other data available. No. I ore body of the Xiongcun deposit was affected by later magmtic thermal event. Molybdenite contains trace K-Si silicate enriched in Re. As a result of this event, the Re content of molybdenite is one to four times higher than that of molybdenite in No. Ⅱ ore body and No. Ⅲ ore body, and the age of molybdenite in No. I ore body is younger than the real age. The authors also compared the Re content of molybdenite between this deposit and other porphyry-skam deposits within this bek and found that the content of Re shows systematic variation. The Re content of the Xiongcun porphyry copper-gold deposit is one order of magnitude high than that of Miocene porphyry deposits and two order of magnitude higher than Paleocene to Eocene porphyry-skarn deposits. The Re variation is related to the source of metal, the content of molybdenum, the composition of magma and the physical/chemical condition of magmatic-hydrothermal solution.

关 键 词：RE-OS同位素 斑岩铜金矿床 岛弧型 雄村 冈底斯 西藏 

分 类 号：P597[天文地球—地球化学] P618.41[天文地球—地质学]