投稿时间：2017-03-13
修订日期：2018-02-26
网络发布日期：2018-07-12
中文摘要:努日矿床是近年来在西藏冈底斯成矿带南缘发现的一个大型铜钼钨矽卡岩型矿床，由于成矿斑岩一直未能确定，一定程度上制约了区域成矿规律的总结和找矿方向的确定。文章基于野外地质观察和岩体成岩时代研究，识别出与成矿有关的一期花岗闪长斑岩体，锆石LA-ICP-MS U-Pb年代学研究显示其成岩时代为（24.94±0.28）Ma，略早于矿体的成矿年龄（23.62 Ma），结合岩体蚀变、矿化及围岩特征，确认其为成矿斑岩体。岩石地球化学特征表明其具高Sr、低Y、无Eu异常的特征，Rb-Sr、Sm-Nd、Pb同位素组成与冈底斯带中新世成矿岩体基本一致，说明其岩浆源区具壳幔混合来源的特征，岩浆相对富集放射性成因Pb同位素，暗示其演化中混染了较多古地壳物质，有效解释了矿床铜-钼-钨矿物组合。矿区成矿斑岩体的发现证实了努日矿床属于斑岩成矿系统中的矽卡岩矿床，岩浆形成于加厚下地壳部分熔融，上升演化过程中与上覆古老拉萨地壳发生过同化混染作用，是岩浆热液与比马组灰岩持续演化的结果。本研究对在冈底斯南缘寻找努日式矿床具有较好的借鉴意义。
Abstract:The Nuri deposit is a newly explored Cu-Mo-W deposit on the southern margin of the Gangdise metallogenic belt. However, the metallogenic porphyry has not been determined, and the nature of the ore-forming stock is still unknown, which has restricted the summary of the metallogenetic regularity. Based on detailed field investigation and studies of the mineralogenetic epoch, the authors first identified a porphyry stock which had close relationship with mineralization. The LA-ICP-MS zircon U-Pb age is (24.94±0.28) Ma, slightly older than Cu-W-Mo minera-lization age. The porphyry stock is considered to be the metallogenic porphyry according to the alteration, mineralization and skarn mineral zoning characteristics. This stock exhibits high Y, low Y and no Eu anomaly characteristics. The composition of the Rb-Sr, Sm-Nd and Pb isotopes is consistent with that of the Miocene porphyries, which shows the crust-mantle mixing resource characteristics. Relatively higher concentration of radiogenic Pb isotopes indicates the more ancient crustal material mixture during the magma evolution, which may effectively explain the Cu-Mo-W mineral combination. The discovery of the ore-forming porphyry first confirms that it was formed in the porphyry system. The magma was derived partly from the melt of thickened lower crust that experienced assimilation process with the upper ancient crust during magma upwelling. The mineralization resulted from the continuous evolution of the magmatic hydrothermal solution and the Bima Formation. This study provides further meaningful information for regional exploration.
keywords:geochemistry zircon U-Pb dating Sr-Nd-Pb-Hf isotope Nuri skarn deposit Gangdise metallogenic belt Tibet
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基金项目:本文得到国家重点研发计划"青藏高原典型矿集区透明化与矿体定位预测"（编号：2016YFC0600308）和"冈底斯-喜马拉雅铜矿资源基地调查"项目（编号：DD20160015）联合资助
引用文本：
王勤,黄勇,董随亮,闫国强,游钦,江化寨,张凯.2018.冈底斯成矿带东段努日矿床成矿斑岩年代学、地球化学及其意义[J].矿床地质,37(3):571~586WANG Qin,HUANG Yong,DONG SuiLiang,YAN GuoQiang,YOU Qin,JIANG HuaZhai,ZHANG Kai.2018.Zircon LA-ICP-MS U-Pb geochronology, geochemistry and implications of ore-forming porphyry in Nuri skarn Cu-Mo-W deposit, eastern Gangdise[J].Mineral Deposits37(3):571~586
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