ABSTRACT

The distribution of epithermal base metal deposits in the Lanping basin, Yunnan province, SW China is controlled by Cenozoic thrust-nappe systems. The Baiyangping and Wudichang Ag-bearing polymetallic deposits are representative of the epithermal base metal deposits in the Lanping basin. Hydrothermal calcites associated with base metal sulfides in these two deposits yield similar Sm-Nd isochron ages of 30.1 ± 1.9 to 27.4 ± 1.8 Ma, respectively. These results indicate that the ages of mineralization of the Baiyangping Cu-Ag-Co and Wudichang Pb-Zn-Ag ore deposits are contemporaneous with the Cenozoic Indo-Asian continental collision. Such temporal correlation, combined with the apparent regional structural control of the distribution of these type of deposits suggests that Cenozoic thrust-nappe tectonics and associated hydrothermal activity played an important role in the formation of the epithermal Ag-bearing polymetallic base metal ore deposits in the Lanping basin.