扬子板块周缘MVT型铅锌矿床闪锌矿微量元素组成特征与指示意义:LA-ICPMS研究  

Trace elements in sphalerites from the Mississippi Valley-type lead-zinc deposits around the margins of Yangtze Block and its geological implications: A LAICPMS study

作　　者：吴越[1,2] 孔志岗 陈懋弘[4] 张长青[4] 曹亮[5] 唐友军[1] 袁鑫[1] 张沛 WU Yue;KONG ZhiGang;CHEN MaoHong;ZHANG ChangQing;CAO Liang;TANG YouJun;YUAN Xin;ZHANG Pei(MOE Key Laboratory of Exploration Technologies for Oil and Gas Resources,Yangtze University,Wuhan 430100,China;College of Resources and Environment,Yangtze University,Wuhan 430100,China;Faculty of Land Resource Engineering,Kunming University of Science and Technology,Kunming 650093,China;Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;Wuhan Center of Geology Survey,China Geological Survey,Wuhan 430205,China)

机构地区：[1]长江大学油气资源与勘探技术教育部重点实验室,武汉430100 [2]长江大学资源与环境学院,武汉430100 [3]昆明理工大学国土资源工程学院,昆明650093 [4]中国地质科学院矿产资源研究所,北京100037 [5]中国地质调查局武汉地质调查中心,武汉430205

出　　处：《岩石学报》2019年第11期3443-3460,共18页Acta Petrologica Sinica

基　　金：国家重点研发计划项目(2017YFC0602502);国家自然科学基金项目(41402063、41672093);中国地质调查局地质矿产调查项目(DD20160029);油气资源与勘探技术教育部重点实验室(长江大学)开放基金项目(KY-2018-05)联合资助

摘　　要：扬子板块周缘铅锌多金属成矿带内分布着数以百计的沉积岩容矿型铅锌矿床,它们不仅是我国主要的铅锌矿产地,同时也是重要的稀散元素(Ge、Ga等)生产基地。本次研究采用LA-ICPMS技术分别测定了扬子板块西南缘的会泽铅锌矿床、金沙厂铅锌矿床、大梁子铅锌矿床,扬子板块北缘的马元铅锌矿床以及扬子板块东南缘的凤凰茶田锌(铅)汞矿床中闪锌矿的微量元素组成,以揭示闪锌矿中微量元素(稀散元素)的富集规律和赋存状态,并为矿床成因类型的厘定及稀散元素矿产资源综合利用提供更多依据。LA-ICPMS微量元素测定结果显示闪锌矿中不同微量元素(稀散元素)分布不均匀,但这些矿床中闪锌矿总体以富集稀散元素Ge、Ga、Cd,贫In、Se、Tl、Te为特征,其Fe、Mn含量要明显低于与岩浆热液有关的高温闪锌矿,指示了扬子板块周缘铅锌矿床可能形成于中-低温成矿流体,而与岩浆热液无直接的成因联系,此外这些矿床中闪锌矿富Ge贫In的特征与其他的密西西比河谷型铅锌矿床(MVT)一致。同时,本次研究综合分析了闪锌矿中不同微量元素(稀散元素)之间的相关关系,并与闪锌矿微量元素LA-ICPMS时间分辨率特征相结合,研究表明:这些铅锌矿床中稀散元素Ge可能主要通过3Zn^2+■Ge^4++2(Cu^+,Ag^+)和2Zn^2+■Ge^4++□(晶体空位)的替代方式进入闪锌矿,Ga在闪锌矿中富集机理主要为2Zn^2+■(Cu,Ag)^++(Ga,As,Sb)^3+。此外,为进一步揭示不同成因类型铅锌矿床中稀散元素的富集规律,本文还系统对比了全球范围内不同类型铅锌矿床闪锌矿的稀散元素(均为LA-ICPMS数据)组成特征,并初步探讨了造成不同成因闪锌矿中稀散元素(Ge、Ga和In)差异性富集的主要控制因素,研究表明:(1) Ge在中低温盆地卤水成矿系统(MVT和SEDEX矿床)和岩浆-火山热液成矿系统(浅成脉状铅锌矿床和VMS矿床)形成的闪锌矿中均可能富集成矿,�There are hundreds of sedimentary rock-hosted Pb-Zn deposits in several Pb-Zn polymetallic metallogenic belts around the margins of the Yangtze Block. These Pb-Zn polymetallic metallogenic belts are not only the important production bases for the Pb and Zn metals,but also main suppliers for the dispersed elements such as the Ge and Ga in China. In this study,the technique of laser ablation-inductively coupled plasma mass spectrometry( LA-ICPMS) is employed to determine the trace elements( dispersed elements)composition in sphalerites from the Huize giant Pb-Zn deposit,the Jinshachang Pb-Zn deposit and the Daliangzi Pb-Zn deposit in the southwestern margin of the Yangtze Block,the Mayuan Pb-Zn deposit in the northern margin of the Yangtze Block as well as the Chatian Zn-( Pb)-Hg deposit in the southeastern margin of the Yangtze Block. The LA-ICPMS technique allows us to precisely identify the enrichment regularity and occurrence state of trace elements( dispersed elements) in these sphalerites,which could give some insight into the genesis of Pb-Zn deposits as well as provide basis for comprehensive utilization of dispersed elements mineral resources.The results show that although the distribution of trace elements( dispersed elements) in sphalerites form these Pb-Zn deposits are inhomogenous,the sphalerites are generally characterized by significant enrichment of dispersed elements Ge,Ga and Cd,and depletion of In,Se,Tl as well as Te. In addition,the contents of Fe and Mn elements in sphalerites of the Pb-Zn deposits around the margins of the Yangtze Block are significantly lower than that of the high-temperature sphalerites of magmatic-volcanic hydrothermal origin. These composition characteristics of trace elements( dispersed elements) in sphalerites indicate that these Pb-Zn deposits could be formed from the ore-forming fluids with medium-low temperature and there is no directly genetic relationship between the Pb-Zn deposits and magmatic activities. Moreover,the enrichment characteristics of trace elements in

关 键 词：扬子板块周缘铅锌矿床 闪锌矿 微量元素 稀散元素 LA-ICPMS 矿床成因类型 

分 类 号：P578.23[天文地球—矿物学] P595[天文地球—地质学]