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

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.