Abstract:

The Zhouzhuang AgPbZn ore deposit was recently discovered in the southwestern Henan Province where there are some other AgPbZn ore deposits. It occurred in an interplate tectonicmagmatic geological environment after Indosinian orogeny. The orebody is mainly in the Erlangping Group and the veins of quartz(AgPbZn) sulfides filled in the fault fractures whose strikedirections are perpendicular to the orogenic belt. The AgPbZn hydrothermal mineralization shows three stages: the early stage is characterized by quartzpyrite; the main stage is quartz (AgPbZn) sulfide; and the late stage is quartzcalcite. Three types of fluid inclusions were trapped in the quartz in the AgPbZn ores; they are the water solution, the CO2H2O, and the daughter mineralbearing inclusions. The oreforming fluid temperatures of the early, the main and the late mineralization stages are 310270 ℃, 230200 ℃, and 180150 ℃, respectively. The oreforming fluid salinity of the early stage is 10%6% NaCleq., the main stage is 18%14% NaCleq., and the late stage 12%8% NaCleq.. The temperature decreased, and the salinity increased first and then decreased during the mineralization. The mineralization were accompanied with the rising of the crust; the oreforming fluid pressures in the early, the main and the latemineralization stages are 270235 MPa, 230200 MPa, and 79.3939.37 MPa, respectively; and the corresponding depths are 108.7 km, 8.57.4 km, and 2.91.5 km, respectively. The δDH2O VSMOW decreased from -59‰-70‰ to -70‰-82‰ and the δ18OH2O VSMOW also decreased from 5.19‰6.53‰ to 2.32‰2.46‰ when the mineralization developed from the early to the main stage, and the δ18OH2O VSMOW further decreased to -0.05‰ in the late mineralization stage. The oreforming fluid was mainly from the magma or the metamorphic water, and mixed by some meteoric water in the late stage. This study gives some new information for understanding the metallogeny of AgPbZn in southwestern Henan Province.

Key words: ore geology, fluid inclusions, O and Hisotopes, AgPbZn ore veins, Zhouzhuang AgPbZn ore deposit, southwestern Henan Province