江西冷水坑矿田下鲍Ag-Pb-Zn矿床地质特征及银的赋存状态研究

下鲍大型Ag-Pb-Zn矿床位于江西冷水坑矿田西南部。矿床地质研究表明,成矿作用可以分三个阶段:(Ⅰ)闪锌矿-黄铁矿阶段;(Ⅱ)方铅矿-闪锌矿-银矿物阶段;(Ⅲ)黄铁矿-石英(方解石)阶段。岩矿石光薄片鉴定和电子探针分析表明,下鲍矿床主要金属硫化物为闪锌矿、方铅矿、黄铁矿及银矿物。电子探针分析显示,银主要以独立银矿物形式存在,金属硫化物中不可见银极少。银矿物种类主要为螺状硫银矿和自然银,呈裂隙银赋存于铁锰碳酸盐中或呈粒间银分布于铁锰碳酸盐粒间和早期硫化物晶隙间;另有少量硫银锡矿、含银黝铜矿、淡红银矿、金银矿及深红银矿、硫砷铜银矿等银矿物,呈亚显微粒状赋存于铁锰碳酸盐粒间或呈固溶体分离结构赋存于方铅矿、闪锌矿等硫化物中。主要银矿物大量赋存于铁锰碳酸盐中,表明银矿化与铁锰碳酸盐可能存在成因联系。

Geological characteristics and occurrence of silver in Xiabao Ag-Pb-Zn deposit, Lengshuikeng ore field, Jiangxi Province, East China

The Xiabao large-scale Ag-Pb-Zn deposit is located in the southwestern Lengshuikeng ore field,Jiangxi Province.The major mineralization can be divided into three stages:sphalerite-pyrite polymetallic stage(stageⅠ);galena-sphalerite-silver minerals polymetallic stage(stageⅡ);pyrite-quartz(calcite)stage(stageⅢ).The major ore minerals include sphalerite,galena,pyrite and silver minerals are studied in this paper on petrography and analyzed with Electron Probe Micro Analysis(EPMA).The EPMA also indicates that the most Ag presented in the ores occurs mainly as independent silver minerals,and rare Ag in sulfides.The dominant silver minerals are akanthite and native silver,which occur in the crevasse of ferromanganese-carbonate as crevasse silver or in the clearance of ferromanganese-carbonate and early sulfides as intergranular silver.In addition,there are also some micro canfieldites, Ag-bearing tetrahedrite,proustite,küstelite,aerosite,and eugenite,which occur in the clearance of ferromanganese-carbonate as submicroscopic structure or in galena,sphalerite or other sulfides as unmixing of solid solution structure.The fact that a large number of major silver minerals occur in ferromanganese-carbonate probably indicates a genetic relationship between silver mineralization and ferromanganese-carbonate.