西藏冈底斯成矿带南缘喜马拉雅早期成矿作用——来自冲木达铜金矿床的Re-Os同位素年龄证据  

Early Himalayan mineralization on the southern margin of the Gangdise metallogenic belt, Tibet, China: Evidence from Re-Os ages of the Chongmuda skarn-type Cu-Au deposit

作　　者：李光明[1] 刘波[2] 佘宏全[3] 丰成友[3] 屈文俊[4] 

机构地区：[1]中国地质科学院,北京100037 [2]中国地质调查局成都地质矿产研究所,四川成都610082 [3]中国地质科学院矿产资源研究所,北京100037 [4]中国地质科学院国家地质实验测试中心,北京100037

出　　处：《地质通报》2006年第12期1481-1486,共6页Geological Bulletin of China

基　　金：国家自然科学基金(编号:40272047);国家重点基础发展计划项目(编号:2002CB412609);中国地质调查局地质调查项目(编号:1212010630112)联合资助

摘　　要：采集冈底斯成矿带南部克鲁-冲木达铜金成矿亚带冲木达矽卡岩型铜金矿床的辉钼矿样品进行了Re-Os法精确同位素定年。该矿区辉钼矿的模式年龄介于37.63～41.19Ma之间,6件辉钼矿样品得到187Re-187Os等时线年龄为(40.3±5.6)Ma。该成矿年龄明显早于冈底斯成矿带中带和北带的驱龙、厅宫等斑岩铜矿床和甲马、知不拉、帮浦等矽卡岩型铜铅锌矿床的成矿年龄,而与冈底斯成矿带中广泛发育的碰撞期花岗质岩浆活动的年龄基本一致。据此认为,冲木达铜金矿床形成于喜马拉雅早期,与欧亚-印度大陆碰撞阶段的花岗质岩浆活动密切相关。Molybdenite samples were taken from the Chongmuda skarn-type Cu-Au deposit in the Kelu-Chongrnuda Cu-Au metallogemc subbelt in the southern Gangdise metallogenic belt and highly precise Re-Os dating was performed .on the samples. The Re-Os model ages of molybdenite of the deposit range from 37.63 to 41.19 Ma and six molybdenite samples yielded an ^187Re-^187Os isochron age of 40.3＋5.6 Ma. These ages are notably older than the mineralization ages of the porphyry copper deposits such as the Qulong and Tinggong deposits and skarn-type copper-polymetallic deposits such as the Jiama, Zhibula and Bangpu deposits in the Gangdise metallogenic belt, but are in the main consistent with the ages of the extensive collisional granitic magmatism in the Gangdise metallogenic belt. It follows thus that the Chongrnuda Cu-Au deposit formed in the early Himalayan and is closely related to granitic magmatism in the stage of Eurasia-India collision.

关 键 词：西藏 冈底斯成矿带 冲木达矽卡岩型铜金矿床 RE-OS年龄 喜马拉雅早期成矿作用 

分 类 号：P611[天文地球—矿床学] P618.2[天文地球—地质学]