Ore genesis of the Bayanbaolege Ag-Pb-Zn deposit, NE China: Constraints on LA-ICP-MS studies of cadmium and related trace elements in sulfides

The newly discovered Bayanbaolege Ag-Pb-Zn deposit is located in the Southern Great Hinggan Range metal-logenic belt, northeastern China, with 1440 t Ag, 380000 t Zn, 50000 t Pb, and a beneficial component of Cd (806 t Cd) and Ga (211 t Ga). The orebodies of this deposit occur as veins and are hosted mainly by a contact zone between the Permian silty slate and the granite intrusion, and have a closely spatio-temporal relationship with the early Cretaceous granodiorite porphyry intrusion. The mineralization process of the Bayanbaolege deposit can be divided into three mineralization stages including arsenopyrite-pyrite-quartz stage (stage I), pyrite-pyrrhotite-chalcopyrite stage (stage II) and galena-sphalerite-argentite-pyrite-calcite stage (stage III). LA-ICP-MS trace element mapping and spot analyses were conducted on the sphalerite and pyrite in stage III at the Bayanbaolege deposit. LA-ICP-MS trace element mapping and spot analyses were conducted on the stage III sphalerite and pyrite selected from the Bayanbaolege deposit in order to identify the occurrence form and distribution characteristics of critical metal elements, constrain the possible controls on the variation of trace elements, reveal the physi-cochemical condition of mineralization and provide new insights into the ore genesis. The results show that Ga, Ge, In, Cd, Mn, Cu, Ag and Co concentrations in sphalerite, and pyrite is the preferential host for Ge, As and Ni. The occurrence of Ga, Ge, In and Cd in sphalerite are mainly deposited in form of isomorphism. Physicochemical condition studies suggest that sphalerite precipitated from a medium-temperature hydrothermal system with the range from 190 degrees C to 291 degrees C (average at 230 degrees C) and accompanied with the intermediate fS2. Trace element concentrations of sphalerite are different from that of the MVT, VMS, SEDEX and skarn deposits. The results of this study, combined with the previous geological and physicochemical evidence, indicate that the Bayanbaolege Ag-Pb-Zn deposit deposit is an intrusion-related mesothermal hydrothermal vein-type deposit.