安徽西湾铅锌矿床闪锌矿原位微量元素组成及成矿流体特征  

In situ trace element composition of sphalerite and ore-forming fluid characteristics of Xiwan Pb-Zn deposit, Anhui Province

作　　者：兰秉玉 袁峰[1,2,3] 邓宇峰 程培生[4] 李晓晖 张建明[4] 李壮[4] LAN BingYu;YUAN Feng;DENG YuFeng;CHENG PeiSheng;LI XiaoHui;ZHANG JianMing;LI Zhuang(School of Resources and Environmental Engineering,Hefei University of Technology,Hefei 230009,Anhui,China;Ore Deposit and Exploration Centre(ODEC),Hefei University of Technology,Hefei 230009,Anhui,China;Anhui Research Center for Mineral Resources andMine Environment Engineering Technology,Hefei University of Technology,Hefei 230009,Anhui,China;Geological Exploration Technology Institute of Anhui Province,Hefei 230031,Anhui,China)

机构地区：[1]合肥工业大学资源与环境工程学院,安徽合肥230009 [2]合肥工业大学,矿床成因与勘查技术研究中心,安徽合肥230009 [3]合肥工业大学安徽省矿产资源与矿山环境工程技术研究中心,安徽合肥230009 [4]安徽省勘查技术院,安徽合肥230031

出　　处：《矿床地质》2023年第1期192-210,共19页Mineral Deposits

基　　金：国家自然科学基金项目(编号:41820104007、42072321);安徽省地勘基金重点项目“无为县西湾铁多金属矿普查”(编号:2018-1-1);安徽省公益性质工作项目“安徽省铅锌矿中关键金属镉的资源潜力调查评价”(编号:2021-g-2-11)联合资助。

摘　　要：安徽西湾铅锌矿床位于长江中下游成矿带庐枞矿集区北部,是近年来在该地区发现的首个赋存于三叠系周冲村组碳酸盐地层中的大型隐伏铅锌矿床,目前该矿床的成矿流体演化及矿床成因研究较为薄弱,制约了该地区铅锌矿床成矿理论与地质勘探。文章根据矿床地质特征,结合镜下鉴定,认为矿床中硫化物主要形成于石英碳酸盐硫化物阶段及碳酸盐硫化物阶段。闪锌矿原位微量元素分析和包裹体测温数据显示,石英碳酸盐硫化物阶段闪锌矿Fe、Mn含量相对较高,Ga、Ge、Cd含量相对较低,该阶段闪锌矿的均一温度为207~236℃,流体盐度w(NaCleq)范围为7.45%~11.81%;碳酸盐硫化物阶段的闪锌矿相对贫Fe和Mn,Cd、Ga和Ge含量相对较高,其闪锌矿均一温度为164~189℃,流体盐度w(NaCleq)为0.88%~5.56%。此外,西湾矿床西南部的样品以石英碳酸盐硫化物阶段的闪锌矿为主,而东北部的样品以碳酸盐硫化物阶段为主,流体包裹体均一温度结果表明矿床成矿温度从西南(183~240℃)向东北方向呈降低趋势(160~209℃),说明成矿流体由西南向东北方向移动。西湾矿床闪锌矿Zn/Cd比值(平均146)与矽卡岩矿床Zn/Cd值(104~214)相符,远低于火山沉积型矿床闪锌矿Zn/Cd值(417~531)及沉积岩容矿的矿床闪锌矿Cd/Zn值(250~330),且石英碳酸盐硫化物阶段闪锌矿In/Ge变化范围大(0.01~571)、Cd/Fe小于1,w(Mn)为(105~3201)×10-6的特征也与远源矽卡岩型矿床闪锌矿特征相符。结合矿床地质特征,文章认为西湾铅锌矿床应属于远源矽卡岩矿床。The Xiwan Pb-Zn deposit is located in the North of the Luzong basin in the Middle-Lower Yangtze River Metallogenic Belt. It is the first large-scale concealed Pb-Zn deposit hosted in the Triassic Zhouchongcun Formation in the Luzong basin discovered in recent years. Because the genesis is not clear, which restricts the understanding of Pb-Zn metallogenic theory and geological exploration in this area. According to the geological characteristics of the deposit and microscopic identification results, we think that the main mineralization was produced in quartz-carbonate sulfide stage and carbonate-sulfide stage. Trace element analysis and homogenization temperature of fluid inclusions show that sphalerites in quartz-carbonate sulfide stage are relatively rich in Fe and Mn,low in Ga, Ge and Cd. The homogenization temperature of sphalerite in quartz-carbonate sulfide stage is 207~236℃ with salinity w(NaCleq) of 7.45%~11.81%. The sphalerites of carbonate-sulfide stage are poor in Fe and Mn, rich in Cd, Ga and Ge. The homogenization temperature of sphalerite in this stage is 164~189℃, and the fluid salinity w(NaCleq) is 0.88%~5.56%. The sphalerite in the Southwest part of the deposit was dominantly formed in the quartz-carbonate sulfide stage, whereas that in the Northeast part was formed in the carbonate-sulfide stage.It also shows that the ore-forming temperature decreases from the southwest(183~240℃) to the Northeast(160~209℃), indicating that the ore-forming fluid migrates from the Southwest to the Northeast. The Zn/Cd value(average 146) of sphalerite are similar to skarn deposit, different from those of volcanic-sedimentary deposit(417~531) and sedimentary-hosted deposit(250~330). The In/Ge(0.01~571) and Cd/Fe(<1) ratios and Mn content((105~3201)×10-6) of the sphalerite in the quartz-carbonate sulfide stage are also similar with the distal skarn deposit. We therefore think that the Xiwan Pb-Zn deposit should be a distal skarn deposit.

关 键 词：地球化学 闪锌矿 LA-ICP-MS 远源矽卡岩矿床 西湾铅锌矿床 

分 类 号：P618.42[天文地球—矿床学] P618.43[天文地球—地质学]