~(40)Ar/~(39)Ar Dating of Adularia from the Bitian Gold—Silver—Copper Deposit, Fujian Province

The age of adularia from gold-bearing quartz vein of the Bitian gold—silver—copper deposit in Fujian Province was analyzed by using the 40Ar/ 39Ar fast neutron activation dating technique, which yielded a plateau age of 91.47±0.39 Ma and an isochron age of 91.38±0.21 Ma. The plateau age and isochron age of adularia are almost coincident, indicating a well-defined dating result. Therefore, the plateau age of 91.47±0.39 Ma represents the formation age of Au—Ag mineralization in the Bitian deposit. This result suggests that the Au—Ag mineralization of the Bitian sericite—adularia-type deposit occurred later than the formation of the Late Cretaceous volcanic eruption sequences, and the Au-Ag mineralization related to the sub-volcanic intrusions and NW-trending fractures in the Bitian area is the latest Au—Ag mineralization in the Zijinshan—Bitian porphyry—epithermal metallogenic system.