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 rnthe 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.
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