东昆仑造山带岩浆型镍钴矿床地质特征、成因机制与找矿标志分析  

Geological characteristics,ore genetic mechanism and exploration indicators of magmatic nickel-cobalt deposits in the East Kunlun Orogenic Belt

作　　者：李华 蒋少涌[2] 李世金[3] 苏慧敏 董加祥 李元宝 陈晓琳 LI Hua;JIANG ShaoYong;LI ShiJin;SU HuiMin;DONG JiaXiang;LI YuanBao;CHEN XiaoLin(Qinghai Provincial Geological Survey Bureau,MNR Technology Innovation Center for Exploration and Exploitation of Strategic Mineral Resources in Plateau Desert Region,Xining 810000,China;State Key Laboratory of Geological Processes and Mineral Resources,School of Earth Resources,Collaborative Innovation Center for Exploration of Strategic Mineral Resources,China University of Geosciences(Wuhan),Wuhan 430074,China;Qinghai Provincial Non-ferrous Metal Geological and Minerals Exploration Bureau,Xining 810000,China;Geological Survey of Qinghai Province,Xining 810000,China)

机构地区：[1]青海省地质调查局,自然资源部高原荒漠区战略性矿产勘查开发技术创新中心,西宁810000 [2]中国地质大学(武汉)地质过程与矿产资源国家重点实验室,资源学院,紧缺战略矿产资源协同创新中心,武汉430074 [3]青海省有色地质矿产勘查局,西宁810000 [4]青海省地质调查院,西宁810000

出　　处：《岩石学报》2023年第4期1041-1060,共20页Acta Petrologica Sinica

基　　金：国家重点研发计划项目(2022YFC2903504);青海省地质勘查基金项目(2020021003ky003)联合资助。

摘　　要：东昆仑造山带位于中央造山带西段,属秦岭-祁连-昆仑成矿域的重要组成部分。近年来,在东昆仑地区发现了超大型的夏日哈木以及大型的石头坑德,以及浪木日等多个岩浆镍钴硫化物矿床,沿昆中断裂自西向东依次展布,主要含矿岩相为橄榄岩相和辉石岩相杂岩体,锆石U-Pb年代学限定它们形成于晚志留世-早泥盆世。岩石地球化学数据显示,含矿镁铁-超镁铁质岩体具有富集轻稀土元素和大离子亲石元素以及显著的Nb、Ta、Ti、P负异常等特征;Sr-Nd同位素研究指示岩浆源区来源于岩石圈地幔,岩浆演化过程中发生了橄榄石、斜方辉石、单斜辉石以及斜长石的分离结晶/堆晶作用,岩浆侵位过程中有明显地壳成分加入,成矿物质硫为壳-幔混源。夏日哈木和石头坑德橄榄石成分分析显示其Fo值分别为85~87和81~86,可作为评估成矿潜力的重要指标;矿区范围内黄铁矿化、黄铜矿化、磁黄铁矿化、镍黄铁矿化和次生镍华是重要的直接找矿标志;碳酸盐化、蛇纹石化、透闪石化、绿泥石化为重要的间接找矿标志。含矿超基性岩体多具有强磁性、高密度、低阻高极化,即“三高一低”异常组合,高强度异常、三级浓度分带明显,相互套合的Ni-Cu-Co异常浓集中心是重要的物化探找矿标志。The East Kunlun Orogenic Belt is located in the western part of the Central Orogenic Belt and is an important part of the Qinling-Qilian-Kunlun metallogenic belt.In recent years,several magmatic nickel-cobalt sulfide deposits,such as the giant Xiarihamu and the large Shitoukengde deposits,and the Langmuri deposit,have been discovered in the East Kunlun area,which are distributed from west to east along the Central Kunlun Fault.The main ore-bearing lithofacies are peridotite facies and pyroxenite facies complexes.Zircon U-Pb geochronology constrains their emplacement ages in the Late Silurian to Early Devonian.The whole-rock geochemical data show that the ore-bearing mafic-ultramafic rocks are characterized by enrichment of light rare earth elements and large ion lithophile elements,as well as significant negative Nb,Ta,Ti and P anomalies.The Sr-Nd isotope data indicate that the magmas were most likely derived from the lithospheric mantle.The fractional crystallization/cumulation of olivine,orthopyroxene,clinopyroxene and plagioclase occurred along with the process of magmatic evolution.Crustal contamination was involved in the magmatic and mineralization processes,and the ore-forming material sulfur has a mixed crust-mantle source.The olivine compositions of the Xiarihamu and Shitoukengde deposits show that their Fo values are within the range of favorable mineralization,which are 85~87 and 81~86 respectively.The direct mineralization indicators include pyritization,chalcopyritization,pyrrhotization,pentlanditization and secondary annabergitization.The indirect prospecting indicators are carbonation,serpentinization,tremolization and chloritization.The geophysical prospecting indicators include that the ultramafic rock body shows low and gentle positive anomaly,strong magnetism,high density,low resistivity and high polarization(the so-called“three high and one low”anomaly combination).The geochemical prospecting indicators include the well-defined co-existed Ni-Cu-Co anomaly,with the inner zone of Ni anomaly

关 键 词：东昆仑 基性-超基性岩 铜镍钴矿床 成矿模式 

分 类 号：P611[天文地球—矿床学] P618.62[天文地球—地质学] P618.63