西藏努日矽卡岩型铜钨钼矿辉钼矿Re-Os定年及其地质意义  

Re-Os dating of molybdenite from Nuri Cu-W-Mo deposit and its geological significance

作　　者：张松[1,2] 郑远川[2] 黄克贤[3] 李为[3] 孙清钟[2] 李秋耘[3] 付强[3] 梁维[3] 

机构地区：[1]中国地质大学地学实验中心,北京100083 [2]中国地质科学院地质研究所,北京100037 [3]中国地质大学地球科学与资源学院,北京100083

出　　处：《矿床地质》2012年第2期337-346,共10页Mineral Deposits

基　　金：国家重点基础研究发展计划(973计划)"青藏高原南部大陆聚合和成矿作用"(2011CB403100);(973计划)三江特提斯复合造山与成矿作用(2009CB421008);中国地质调查局地质调查项目"青藏高原碰撞造山及成矿地质背景研究"(1212011121253);行业基金项目"中国大陆环境典型斑岩型矿床成矿规律和找矿模式"(2010011011)的联合资助

摘　　要：西藏努日层状矽卡岩型铜钨钼矿床是冈底斯东段南缘斑岩-矽卡岩铜多金属成矿带上规模最大的矿床。笔者对采自该矿床的9件不同产状、不同形态含钼矿石中的辉钼矿进行了Re-Os同位素组成分析,获得其模式年龄为23.46~24.77 Ma,等时线年龄为（23.36±0.49）Ma（MSWD=0.60）,模式年龄与等时线年龄结果基本一致。由于辉钼矿与黄铜矿、白钨矿呈共生关系,并考虑到该矿区内黄铜矿的年龄〔（23.75±0.18）Ma〕（作者未发表数据）,表明努日矽卡岩型铜钨钼矿床的成矿时代为23~24 Ma。结合前人研究资料可见,冈底斯南缘克鲁-冲木达斑岩-矽卡岩铜多金属成矿带从32 Ma至23 Ma发生了强烈的成矿作用。该成矿带的成矿时代明显有别于后碰撞期地壳伸展环境下形成的冈底斯斑岩铜矿带,显示出其为一套独立的成矿事件。该成矿事件可能主要受冈底斯南缘的晚碰撞走滑环境的控制。努日矿床成矿时代的确定及晚碰撞成矿事件的厘定,为今后研究和勘查该成矿带内同类型矿床提供了重要依据。The Nuri layered skarn Cu-W-Mo deposit is one of the most important deposits on the southern margin of the eastern Gangdese belt,Tibet.Molybdenite was separated from 9 samples collected from various types of ores.These molybdenite samples were dated by Re-Os isotopic analysis.Mode ages of the 9 samples vary from 23.46 Ma to 24.77 Ma.Meanwhile,these samples yielded an isochron age of（23.36±0.49） Ma（MSWD=0.60）.The isochron age should represent the formation age of the Nuri Cu-W-Mo deposit.Therefore,the Nuri ore deposit should have occurred at the late-collisional stage of the Indian-Asian collision process.Combined with the results of former researchers,Cu-W-Mo mineralization must have occurred during 32 Ma to 23 Ma in the Kelu Chongmuda area on the southern margin of the eastern Gangdise belt,which is different from the Gandise porphyry copper belt which was developed in a crustal extensional environment at the post-collisional stage.Mineralization of the Kelu Chongmuda belt might have been dominantly controlled by large-scale strike-slip faults system along the Yarlung Zangbo suture.Studies of the Nuri ore deposit indicate that intense Cu-W-Mo mineralization must have also taken place during the late-collisional stage of Indian-Asian collision in the Gangdese belt.

关 键 词：地球化学 辉钼矿 RE-OS同位素定年 层矽卡岩铜钨钼矿床 努日 冈底斯 西藏 

分 类 号：P618.41[天文地球—矿床学] P618.67[天文地球—地质学]