西藏罗布真浅成低温热液型矿床地质特征及金银赋存状态  

Geological Characteristics and Occurrence State of Gold and Silver in the Luobuzhen Epithermal Deposit in Xizang

作　　者：刘晓峰 次琼 吴松[2] 李淼 侯依涛 孙文博 欧阳海涛 LIU Xiaofeng;CI Qiong;WU Song;LI Miao;HOU Yitao;SUN Wenbo;OUYANG Haitao(No.2 Geological Party,Xizang Autonomous Region Geological and Mineral Exploration and Development Bureau,Lhasa 850003,Xizang,China;School of Earth Science and Recourses,China University of Geosciences(Beijing),Beijing 100083,China;Mineral Resources and Reserves Evaluation Center of MNR,Beijing 100035,China)

机构地区：[1]西藏自治区地质矿产勘查开发局第二地质大队,西藏拉萨850003 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]自然资源部矿产资源储量评审中心,北京100035

出　　处：《黄金科学技术》2025年第1期1-18,共18页Gold Science and Technology

基　　金：西藏自治区科技计划科技重大专项课题“西藏冈底斯斑岩铜矿成矿规律及资源潜力评价”(编号:XZ202401YD0006)资助。

摘　　要：罗布真浅成低温热液型金银矿床位于冈底斯成矿带西段,金资源量约为8 t,矿体分布在英安岩与花岗闪长岩接触的强硅化蚀变带。该矿床成矿作用可划分为3个阶段:石英—黄铁矿阶段(Ⅰ)、石英—多金属硫化物阶段(Ⅱ)和石英—碳酸盐脉阶段(Ⅲ)。通过毒砂温度计相图估算出Ⅰ阶段和Ⅱ阶段的形成温度为(366±4)℃和(263.5±80.5)℃。电子探针分析结果表明:罗布真矿床银主要以可见银赋存于碲银矿中或以不可见银赋存于含银黝铜矿中,少量分布于闪锌矿、黄铜矿和黄铁矿中,其中在含银黝铜矿、闪锌矿、黄铜矿和黄铁矿中以类质同象形式存在,在方铅矿中主要以超显微包体银存在;金主要以不可见金形式赋存于微粒(<50μm)黄铁矿中,其中Ⅰ阶段金主要以固溶体金或晶格金形式赋存,Ⅱ阶段金主要以纳米级微颗粒金形式赋存。罗布真Au和Ag元素的富集和活化受硫逸度、温度和pH值等多种因素的影响,硫化作用是金银沉淀的主要机制。The Luobuzhen gold and silver epithermal deposit is located in the southwestern part of the Zhunuo ore concentration area,within the western segment of the Gangdese metallogenic belt in Tibet.This deposit,containing approximately eight tons of gold resources and associated with silver(Ag),lead(Pb),and zinc(Zn),is hosted within the continental volcanic rocks of the Pana Formation,part of the Linzizong Group.Its occurrence is controlled by a fault fracture zone exhibiting a near east-west trending.The Luobuzhen region exhibits silicification,sericitization,clay alteration,and propylitization,with ore bodies predominantly located within the intensely silicified alteration zone at the contact interface between dacite and granodiorite.The mineralization process can be divided into three distinct stages:The quartz-pyrite stage(StageⅠ),the quartzpolymetallic sulfide stage(StageⅡ),and the quartz-carbonate vein stage(StageⅢ).Notably,StageⅡrepresents the primary ore-forming phase.The formation temperatures for stagesⅠandⅡwere determined to be(366±4)℃and(263.5±80.5)℃,respectively,using arsenopyrite thermometry.Electron probe micro-analysis(EPMA)data indicates that silver in the Luobuzhen deposit predominantly occurs in tellurite as visible silver,in silver-bearing tetrahedrite as invisible silver,and to a lesser extent in sphalerite,chalcopyrite,and pyrite.Silver is present as an isomorphic component within silver-bearing tetrahedrite,sphalerite,chalcopyrite,and pyrite,while in galena,it occurs as micro-inclusion silver.Gold predominantly exists as“invisible gold”within particulate(<50μm)pyrite.In stageⅠ,gold primarily manifests as solid solution gold or lattice gold,whereas in stageⅡ,it is mainly found as nanoscale micro-particulate gold.The activation and concentration of metal elements in the Luobuzhen deposit are attributed to the synergistic effects of various factors,including sulfur fugacity,pH value and temperature within the fluid system.The primary mechanisms responsible for the precipit

关 键 词：赋存状态 矿物温度计 浅成低温热液矿床 罗布真 冈底斯西段 西藏 

分 类 号：P618.5[天文地球—矿床学]