Dating the Deli Pb–Zn deposit, Xidamingshan mining district, South China: Implications for regional exploration

Abstract

The Youjiang basin is a diamond-shaped Indosinian foreland basin formed during the subduction and merging of the South China plate into the Indo-Chinese plate. A large number of Indo-Chinese tectonic traces have been preserved in the basin. However, little has been reported about the syn-tectonic magma and its related mineralization in the basin. Sphalerites from the newly discovered Deli Pb–Zn deposit in the Xidamingshan mining district at the southeastern margin of the Youjiang basin were sampled for the Rb–Sr isochron dating. We obtained the isochron age of 207.1 ± 0.6 Ma (MSWD = 1.5) with initial Sr isotopic composition of 0.728379 to 0.739226. The Sr isotopic compositions are distinct from those of the Late Cretaceous felsic intrusions and the Late Jurassic high-Mg andesite in or around the Xidamingshan district but similar to those of the Late Triassic granites in the Guangxi province. The results indicate that the ore-forming age of the Deli Pb–Zn deposit may be closely related to the concealed Triassic granite. The Si–Ca fracture zone between the Devonian and Cambrian is a favorable location to search for Pb–Zn deposits in the Xidamingshan mining district. This work proves the Triassic Pb–Zn mineralization has occurred in the Xidamingshan mining district and Late Cretaceous magmatic-hydrothermal Bi–W–Zn–Pb–Ag mineralization in the west of it. It provides new ideas and directions for future exploration in the Xidamingshan mining district.

Keywords

• youjiang basin
• rb–sr dating
• organic matter
• late triassic
• deli pb–zn deposit
• mineralization