庐枞盆地北东缘西湾铅锌矿床原生晕地球化学特征及其对矿体圈连的指示意义

Geochemical characteristics of primary halo of Xiwan lead-zinc deposit,northeastern margin of Luzong Basin and its significance to orebody delineation

西湾铅锌矿床位于长江中下游成矿带庐枞盆地北东缘,其赋矿围岩破碎溶蚀现象明显,地层和矿体产状难以辨识。为了准确圈连矿体,以原生晕地球化学特征研究为基础,以热液矿床原生晕找矿理论为指导,通过对西湾矿区钻孔岩石光谱样品进行测试,绘制原生晕剖面等值线图,研究原生晕浓度分带和轴向分带特征,探讨原生晕地球化学特征及其对矿体圈连的指示意义。聚类分析和因子分析发现,As、Sb、Pb、Zn、Ag、Mo与铅锌矿成矿关系密切。16号勘探线原生晕浓度分带和轴向分带特征表明:前缘晕指示元素为As、Sb,近矿晕指示元素为Pb、Zn、Ag,尾晕指示元素为Mo;轴向分带特征反映Ⅲ号矿体具“反分带”现象。轴向分带和指示元素的变化特征说明,西湾铅锌矿床成矿作用复杂,推测为多期次成矿或矿体沿倾向还有延伸。As、Sb、Pb、Zn、Ag、Mo的浓度分带特征对矿体的圈连具有较好的指示意义。

Xiwan lead-zinc deposit is located in the northeaster margin of Luzong Basin,the Middle-Lower Yangtze metallogenic belt.It is difficult to identify the occurrence of strata and orebodies because of the heavy destroyed and corroded ore-bearing rocks.Therefore,in order to accurately delineate the orebodies,the primary halo geochemical characteristics are studied following the primary halo prospecting theory of hydrothermal deposits.Samples are collected from the boreholes of the No.16 exploration line in Xiwan mining area,the contour map of the primary halo profile is drawn according to the spectral test results,the concentration zoning and axial zoning characteristics of the primary halo are distinguished and their indicative significance to delineating and connecting the orebodies are also discussed.Cluster analysis and factor analysis based on those different characteristics suggest that As,Sb,Pb,Zn,Ag and Mo are closely related to lead-zinc mineralization.Research on concentration zoning of primary halo in Xiwan lead-zinc deposit reveals that the front halo is indicated by As and Sb,the near-ore halo is indicated by Pb,Zn and Ag,and the tail halo is indicated by Mo.The axial zoning characteristics of primary halo reflect that the No.Ⅲ ore bodies which shows features of“reverse zoning”.The change of the axial zoning and indicator elements indicate that the mineralization of Xiwan Pb-Zn deposit is complex,which is speculated to be multi-stage mineralization or orebody extendalong the trend.Furthermore,zoning characteristics of concentrations of As,Sb,Pb,Zn,Ag and Mo have objective and intuitive significance for the delineation and connection of the orebodies.