Alteration Zoning Characteristics and Genesis of the Hetaoping Pb-Zn Polymetal Deposit in Baoshan, Western Yunnan

The Hetaoping lead-zinc deposits, located in Baoshan area, western Yunnan, is occurred within the northern part of Bashan-Yongde virgation in Fugong-Zhenkang fold belt, which is situated in the southern section of Gangdese-Nyainqentanglha fold systems. The ore body is occurred along N-S fault and interstratified fracture zone, with layer, lentoid and vesicular shapes. The ore-forming rock is skarn within fracture zone and marble limestore and argillaceous limestone in upper Cambrian Hetaoping group. The ore-controlling tectonic are N-S F1 fault and NN-W secondary faults, where develop hydrothermal Zn, Pb, Ag, Cu, Fe and Au deposits. According the veins cutting relationships, minerals assemblages and origin characters, the hydrothermal process can be divided into seven mineralization stages, in which the third, fourth and five stages are main Zn mineralized phases. The main types of alterations closely related to mineralization are skarnization, silicification, calcilization and pyritization. The alteration mapping has been carried out, the altered minerals assemblages of V1 ore body in DK15 have been analyzed, and the zoned alteration process has been revealed. From the deep to surface, ore-forming elements have a zoning feature of Cu(Fe)→Cu, Zn(Fe)→Pb, Zn (Cu, Au, Ag)→Au; From ore body to wall-rock, ore-forming elements have a changing trend of CuZn(Fe)or CuPbZn→PbZn (Cu, Au, Ag)→Au, shoeing the superimposition and zonation characters of hydrothermal fluid. These results suggest that the hydrothermal fluid has a migrated trend from the northeast to southwest. In brief, the Hetaoping Pb-Zn deposit is a skarn-type deposit formed by the multiple superimposition of hydrothermal fluid, which has association with the skarnization of deep magma in early stage and is related to the middle-and low-temperature hydrothermal mineralization in late stage. This deposit can be served as an important example of multiple mineralized deposits.