Abstract:

Huaaobaote Pb-Zn-Ag polymetallic deposit, a hydrothermal vein-type deposit, is tectonically located at the central and southern Daxinganling Mountains Metallogenic Belt. In combination with the alteration and mineralization characteristics, the paragenetic sequence of ore minerals and gangue minerals, the metallogenic stages could be divided into Quartz-Pyrite, Sphalerite-Galena and Arsenopyrite-Pyrite ones. By the study of fluid inclusions, it was shown that the ore-forming fluid are characterized by middle-low temperature (146.7-274.3℃), low salinity (0.54%-8.52%) and low density (0.790-0.943 g/cm³). The estimated metallogenic pressure and the metallogenic depth reflect that the deposit was formed in a mesogene-hypergene environment. With sulfur, lead isotopic analytical results of metal sulfides, it was shown that the source of ore-forming materials had the characteristics of a crust-mantle mixed source. The δ¹⁸O_SMOW and δD of the ore-forming fluid range from -11.78‰ to -6.01‰ and from -110.90‰ to -70.30‰, respectively. It was concluded  that the oreforming fluid of the deposit was mainly derived from mixing of magmatic water and meteorite water. In combination with regional geological features and tectonic evolution, it is considered that this middle-low-temperature hydrothermal vein-type Pb-Zn-Ag polymetallic deposit was formed under the stretch orogenic structure system, among southern Daxinganling in the Mesozoic Era, and controlled by the multiple geological factors, such as deep faults, the Early Cretaceous tectonic-magmatic activities and the Shoushangou Group.

Key words: Huaaobaote, polymetallic deposit, fluid inclusions, S, Pb, H, O isotopes, genetic study