黑龙江争光大型金矿成矿流体He-Ar-S同位素组成及成矿流体来源的示踪  

Source teacing and He-Ar-S isotopic compositions of ore-forming fluid in the Zhengguang large gold deposit,Heilongjiang Province

作　　者：刘宝山[1] 张春鹏[1] 程招勋 寇林林[1] 李成禄 韩仁萍[1] LIU Baoshan;ZHANG Chunpeng;CHENG Zhaoxun;KOU Linlin;LI Chenglu;HAN Renping(Shenyang Center,China Geological Survey,Shenyang 110034,Liaoning,China;Heilongjiang Institute of Natural Resources,Harbin 150036,Heilongjiang,China)

机构地区：[1]中国地质调查局沈阳地质调查中心,辽宁沈阳110034 [2]黑龙江省自然资源调查院,黑龙江哈尔滨150036

出　　处：《中国地质》2023年第3期952-961,共10页Geology in China

基　　金：国家重点研发计划课题典型矿集区三维地质结构与矿体定位(2017YFC0601305);中国地质调查局地质调查项目(DD20190156)联合资助。

摘　　要：【研究目的】黑龙江争光金矿床位于兴安地块东缘嫩江—黑河北东向断裂带西北侧的奥陶纪多宝山岛弧带上。本文通过对主成矿期的矿石样品研究,探讨了成矿流体的来源。【研究方法】选择9件主成矿期的黄铁矿和方铅矿进行了系统研究,测定了He、Ar和S同位素组成。【研究结果】其含金石英脉中黄铁矿和方铅矿的流体包裹体3He/4He=1.95×10^(-6)~5.03×10^(-6),^(40)Ar/^(36)Ar=349.1~453.9。幔源He占13.17%~44.67%,平均27.58%,显示了成矿流体以大气降水为主,但同时有地幔流体成分,表明金矿床成矿作用与地幔活动有着密切的关系。矿物δ^(34)S=-1.2‰~-3.9‰,平均-2.33‰,可能来自深源地幔流体,但其中有地壳流体的加入。【结论】洋壳向兴安地块俯冲,俯冲流体交代地幔楔发生部分熔融,流体上升至地表浅部与下渗的大气降水混合形成成矿流体,由于温度和压力的下降和流体沸腾作用导致成矿流体物理化学条件的改变,从而使成矿物质沉淀。[Objective]Zhengguang gold deposit in Heilongjiang Province is located in the Ordovician Duobaoshan island arc belt on the northwest side of Nenjiang—Heihe NE trending fault zone in the eastern margin of Xing'an block.By study of the ore samples in the main metallogenic period,we aim to explore the source of ore-forming fluids.[Methods]Nine ore samples from the main metallogenic stage were selected for systematic study of the He,Ar and S isotopic compositions.[Results]The results show that the ^(3)He/^(4)He and ^(40)Ar/^(36)Ar ratios for fluid inclusions of pyrite and galena in the gold-bearing quartz veins are 1.95×10^(-6)-5.03×10^(-6) and 349.1-453.9,respectively.The mantle-derived He accounting for 13.17%-44.67%,averagely 27.58%,indicating that the metallogenic fluid is mainly atmospheric precipitation,with the composition of mantle fluid as well,reflecting that the mineralization of gold deposit is closely related to mantle activity.Theδ^(34)S of minerals is-1.2‰--3.9‰,averagely-2.33‰,probably from deep mantle fluid,also with the addition of crustal fluid.[Conclusions]The oceanic crust subducted toward Xing’an block,with mantle wedge metasomatized by the subducted fluid,and resulted in partial melting and fluid rising to the shallow surface mixed with the downward precipitation to form the metallogenic fluids.The decrease of temperature and pressure and fluid boiling lead to the change of physical and chemical conditions of the metallogenic fluids and precipitate metallogenic materials.

关 键 词：He-Ar-S同位素 壳幔相互作用 争光大型金矿 地质调查工程 大兴安岭 

分 类 号：P597[天文地球—地球化学] P599[天文地球—地质学]