投稿时间：2014-07-25
修订日期：2015-03-05
网络发布日期：2015-07-02
中文摘要:地处藏北高原的班公湖-怒江铜矿带是继藏东的玉龙斑岩铜矿带和藏南的冈底斯斑岩铜矿带之后, 在青藏高原上发现的第三条铜矿带。与前两条斑岩铜矿带不同的是, 班公湖-怒江铜矿带的铜矿床类型具有多样性, 包括: ① 多龙、雄梅斑岩型铜金矿床; ② 尕尔穷-嘎拉勒斑岩-矽卡岩型铜金矿床; ③ 拨拉扎斑岩型铜钼矿床; ④ 舍索矽卡岩型铜(铅锌)多金属矿床。不同类型铜矿床的成矿时代集中在120～90 Ma之间, 约30 Ma间隔内。文章通过沉积岩岩相学、火成岩岩石地球化学以及锆石U-Pb与辉钼矿Re-Os同位素年代学的综合研究, 指出班公湖-怒江中特提斯洋盆的闭合时间为早白垩世初(140～130 Ma之间), 班公湖-怒江成矿带上的铜矿床都形成于碰撞后造山环境。该成矿带与铜矿化有关的侵入岩主要为花岗闪长(斑)岩和石英闪长(玢)岩, 在岩石地球化学上, 富集大离子亲石元素(Rb、Th、U、Ba、K、Pb), 亏损高场强元素(Nb、Ta、Ti), 显示出俯冲组分对岩浆生成过程产生的重要影响, 与碰撞后岩浆作用特征相吻合。除了班公湖-怒江铜矿带外, 青藏高原上的另外两条斑岩铜矿(即臧东的玉龙斑岩铜矿带和臧南的冈底斯斑岩东矿带), 也是形成于洋盆闭合之后的造山带碰撞后环境, 因此, 青藏高原可以说是地球上碰撞后铜矿床的天堂。
Abstract:The Bangong Co-Nujiang copper ore belt occurs in northern Tibetan Plateau and is the third copper belt discovered in the Tibetan Plateau after the Yulong porphyry copper belt in the eastern plateau and the Gangdise porphyry copper belt in the southern plateau. Unlike the other two porphyry copper belts, the Bangong Co-Nujiang copper ore belt exhibits diverse copper genetic types and metal element assemblages. These deposits include Duolong-Xiongmei porphyry Cu-Au deposit, Gaerqiong-Galale porphyry-skarn Cu-Au deposit, Bolazha porphyry Cu-Mo deposit and Shesuo skarn Cu (Pb-Zn) polymetallic deposit. Ore-forming process of all these copper ore deposits took place within a period of approximately 30 Ma, i.e., from 120 Ma to 90 Ma. Through a comprehensive study of sedimentary facies, the petrogeochemistry of igneous rock and the isotopic chronology of zircon U-Pb and molybdenite Re-Os, the authors hold that the closure of the Bangong Co-Nujiang middle Tethys oceanic basin most likely occurred at the initial stage of the early Cretaceous epoch (140～130 Ma) and that the copper ore deposits of the Bangong Co-Nujiang copper belt formed in a post-collisional orogenic environment. The Cu mineralization-associated intrusions are mainly granodiorite (porphyry) and quartz diorite (porphyrite). These intrusions are geochemically enriched in large ion lithophile elements (LILEs) Rb, Th, U, Ba, K, Pb and depleted in high field strength elements (HFSEs) Nb, Ta, Ti, reflecting a considerable influence of subducted components on magma generation. In addition to the Bangong Co-Nujiang copper ore belt, the other two porphyry copper belts in the Tibetan Plateau, i.e., the eastern Yulong belt and the southern Gangdise belt, were also formed in a post-collisional environment after the closure of the oceanic basin. It is therefore considered that the Tibetan Plateau is a paradise of post-collisional copper ore deposits.
keywords:geology post-collisional magmatism post-collisional copper deposit Bangong Co-Nujiang copper belt Tibetan Plateau
文章编号：
中图分类号：P618.41
文献标志码：
基金项目:本文得到国家科技支撑计划项目（编号: 2011CB403203）和中国地质调查局青藏专项（编号: 12120113037300）联合资助
引用文本：
曲晓明,范淑芳,马旭东,宋扬.2015.西藏班公湖-怒江成矿带上的碰撞后铜矿床[J].矿床地质,34(3):431~448QU XiaoMing,FAN ShuFang,MA XuDong,SONG Yang.2015.Post-collisional copper ore deposits along Bangong Co-Nujiang metallogenic belt, Yibetan Plateau[J].Mineral Deposits34(3):431~448
图/表
