Characteristics of the “multi-layer”mineralization and alteration of lead-zinc deposits in the northeastern Yunnan ore concentration area and their significances for prospecting mineral resources

The “multi-layer”ore-hosting characteristics of lead-zinc deposits in the northeastern Yunnan ore concentration area are very special. Taking the Maoping germanium-rich lead-zinc deposit as the main research object of this paper, by comparing typical deposits including the Maozu, Lehong, Huize, Fulechang, Lemachang deposits in the ore concentration area, we have summarized characteristics and regulations of mineralization and alteration occurred in different strata in the ore concentration area, have revealed the mechanisms of mineralization and alteration occurred in various strata, and have established the zoning model of mineralization and alteration for those deposits. The main types of hydrothermal alteration of various lead-zinc deposits in this area include dolomitization, calcitization, pyritization, silicification and baritalization. Fluorination is developed in the Sinian Dengying Formation. There is relatively developed pyritization, with small scale silicitization and barittization and without fluorination in Devonian, Carboniferous and Permian strata. It is concluded that the variation of alteration types is related to the properties of wallrocks and ore-forming fluids, from west to east of the region (Maozu → Huize, Maoping → Fulechang), the silica contents in ore-hosting strata were gradually decreased, while contents of calcium and magnesium were increased, the silicification and barittization were weakened, while the dolomitization, calcitization and pyritization were strengthened. The porosity and permeability of the wallrock and the effect of faulting structures mainly affect the degree and distribution area of alteration. This study will be helpful for expanding the prospecting space of lead-zinc deposits in the area, and is of theoretical and practical significances for the prospecting and exploration of mineral resources.