西藏雅鲁藏布江南岸若措早侏罗世含矿斑岩的锆石U-Pb年龄及地质意义

发布时间：2018-05-05 08:17

本文选题：西藏 + 雅鲁藏布江　；参考：《矿物岩石》2017年04期

【摘要】：针对西藏雅鲁藏布江南岸若措地区矿化斑岩的岩相学、年代学和地球化学特征,研究旨在探讨与新特提斯洋早期俯冲作用有关的岩浆和成矿作用,拓宽侏罗纪斑岩型矿床找矿思路。样品锆石LA-ICP-MS U-Pb定年结果显示矿化角闪石英闪长斑岩结晶年龄为181.70 Ma±2.90 Ma,成岩时代为早侏罗世;微量元素地球化学特征显示富集大离子亲石元素(LILEs:如Rb,Sr和U)和轻稀土(LREEs),亏损高场强元素(HFSEs:如Nb,Ta和Ti)和重稀土(HREEs),结合微量元素构造环境判别图解,暗示其形成于新特提斯洋北向俯冲相关的岩浆弧环境。同时岩石以高Sr(344×10~(-6)~571×10~(-6))、Sr/Y(37.69~46.36)和Mg#值(44~54),低Yb(0.93×10~(-6)~1.31×10~(-6))和Y(9.12×10~(-6)~13.02×10~(-6))为特征,这与起源板片部分熔融的埃达克岩地球化学特征一致,暗示母岩浆主要起源新特提斯洋洋壳的部分熔融。综合分析认为雅鲁藏布江北岸和雅鲁藏江南岸均具有寻找侏罗纪斑岩型矿床的潜力,矿产勘查工作的重点是侏罗纪斑岩体与火山-沉积岩盖层的耦合区域。
[Abstract]:In view of the petrographic, chronological and geochemical characteristics of mineralized porphyry in the Ruoco area on the south bank of the Yarlung Zangbo River, Tibet, the purpose of this study is to explore the magmatic and metallogenic processes related to the early subduction of the NeoTethys Ocean. To broaden the exploration ideas of Jurassic porphyry deposits. The zircon LA-ICP-MS U-Pb dating results show that the crystallization age of the mineralized hornblende quartz diorite is 181.70 Ma 卤2.90 Ma, and the diagenetic age is early Jurassic. The geochemical characteristics of trace elements show that they are enriched in large ion lithophile elements, such as RbLi Sr and U) and light rare earth element LREEsN, and depleted in high field strength elements such as NB, Ta and Ti) and heavy rare earth elements, HREESS, combined with trace element tectonic environment discriminant diagrams. It suggests that it was formed in the magmatic arc environment associated with the new Tethys northerly subduction. At the same time, the rocks are characterized by high Sr(344 脳 10 ~ (10) ~ (-6) ~ (571 脳 10 ~ (10) ~ (-6) ~ (1) and Mg# value ~ (44) ~ (54), low Yb(0.93 脳 10 ~ (10) ~ (6) ~ (1. 31 脳 10 ~ (1) ~ (6) and YT ~ (9.12 脳 10 ~ (-10) ~ (-613.02) 脳 10 ~ (10) ~ (-6), which is consistent with the geochemical characteristics of the adakite, which indicates that the mother magma mainly originated from the partial melting of the NeoTethys oceanic crust. It is considered that the north bank of Yalu Zangbo River and the south bank of Yalu Zangbujiang River have the potential to search for Jurassic porphyry deposits, and the emphasis of mineral exploration work is on the coupling area between Jurassic porphyry body and volcanic-sedimentary cover.
【作者单位】：成都理工大学地球科学学院国土资源部构造成矿成藏重点实验室;中国地质科学院矿产资源研究所;
【基金】：国家自然科学基金项目(41502079) 国土资源部公益性行业专项内生金属矿床成矿机制研究国家重点实验室开放研究基金项目(2017-LAMD-K04) 矿床地球化学国家重点实验室开放研究基金项目(201503) 四川省青年基金项目(2014JQ0047) 四川省教育厅自然科学重点项目(15ZA0073)
【分类号】：P588.1;P612

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