LA-ICP-MS zircon U-Pb dating of basalt and its geological significance in Huaniushan Pb-Zn deposit, Beishan area, Gansu, China

The Huaniushan Ag-Pb-Zn deposit is located in the Guazhou County, Beishan Mountain of Gansu Province. It is the only massive sulfide deposit of SEDEX type in Beishan Mountain, which occurred in the construction of light metamorphic clastic rocks or intermediate-basic volcanic rocks interbed clastic rocks-carbonate rocks. Without of the exact evidences about the isotopic geochronology and fossils, the metallogenic age of the deposit was disputed. The LA-ICP-MS zircon dating of basalt in the three ore area is researched, with 1071±5Ma. It is suggested that the expulsion activities of intermediate basic volcanic rocks in Huaniushan happened at late Jx era, and further showed that the Ag-Pb-Zn deposit formed in the extensional environment at the end of Jx period, related to the submarine volcanic action with the hydrothermal activities. It is compared with the some layer-controlled Pb-Zn polymetallic deposits, such as Hongshan Fe deposit in Beishan Mountain, Caixiashan Pb-Zn deposit in East Tianshan Mountain, Shidonggou deposit in the west segment of North Qilian Mountain and Dongshengmiao, Tanyaokou, Huogeqi deposits in the northwestern margin of the North China block. It is representative of the important mineralization period in the Beishan Mountain.