大别造山带汞洞冲铅锌矿床矿物学特征和铅同位素研究  

Mineralogical characteristics and Pb isotopes of Gongdongchong lead-zinc polymetallic deposit,Dabie orogenic belt

作　　者：吴皓然 谢玉玲[1] 王莹[1] WU Haoran;XIE Yuling;WANG Ying(School of Civil and Resources Engineering,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学土木与资源工程学院,北京100083

出　　处：《地质通报》2020年第2期338-352,共15页Geological Bulletin of China

基　　金：中国地质调查局项目《安徽大别山成矿带钼矿成矿规律与成矿预测》(编号:2014-01-020-010)。

摘　　要：汞洞冲矿床位于大别造山带北麓,是以热液角砾岩型铅锌为主的多金属矿床。岩矿相显微鉴定、SEM/EDS及电子探针分析结果表明,矿床中Ag以独立银矿物相为主(硫锑铜银矿和含银黝铜矿),呈粒状、柱状、板状、不规则状等,以显微或亚显微状被包裹于先期形成的方铅矿中,金属硫化物中不可见银极少。结合矿床金属硫化物铅同位素结果表明,矿床的形成与燕山期岩浆活动密切相关,成矿物质具有壳幔混合的特征。自岩浆出溶的Pb、Zn、Ag等金属离子在成矿早期以氯络合物的形式迁移,随着成矿热液温度、盐度、fO2降低,以及pH值的升高,Pb、Zn氯络合物因稳定性降低而解体形成铅锌角砾型矿石,而Ag则形成硫氢络合物继续存在,当温度继续降低后发生分解沉淀,Ag^+与Sb^3+、As^3+、Cu^+结合形成大量独立银矿物。The Gongdongchong Pb-Zn deposit,located on the north border of Dabie orogenic belt,Jinzhai County,Anhui Province,is a representative hydrothermal breccia-type lead-zinc polymetallic deposit in the Dabie Mountain region.The results of microscopic identification,SEM/EDS and EPMA of ore minerals indicate that silver exists mainly in the form of independent silver-bearing minerals,such as polybasite and Ag-tetrahedrite,which occur mainly in galena as micro-inclusions in the granular shape,columnar shape,lath shape and irregular form.The data 206Pb/204 Pb(17.804~17.947),207 Pb/204 Pb(15.567~15.669)and 208Pb/204 Pb(38.496~38.886)of sulfides suggest that the ore-forming metals were derived from crust-mantle mixed source,being closely related to the Yanshanian magmatic activity.Metal ions such as Pb,Zn and Ag which were dissolved from magma migrate as chlorine-complex in the early stage of mineralization.As the temperature,salinity and fO2 dropped and pH rose,Pb,Zn-chloride-complex was decomposed to form a lead-zinc breccia ore due to the decrease in stability in the ore-forming hydrothermal solution,while the Ag-ions formed sulfur-hydrogen-complex.When the temperature fell,the Ag-sulfur-hydrogen-complex were decomposed and precipitated.Meanwhile,Ag^+combined with Sb^3+,As^3+,and Cu^+to form a large amount of independent silver-bearing minerals.

关 键 词：汞洞冲铅锌矿床 银赋存状态 电子探针 PB同位素 大别造山带 

分 类 号：P618.4[天文地球—矿床学] P597[天文地球—地质学]