福建碧田金银铜矿床冰长石的^(40)Ar/^(39)Ar年龄

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

采用 4 0 Ar/ 39Ar快中子活化年代学方法对采自碧田金银铜矿床的冰长石进行了年龄测定。结果表明 ,冰长石年龄为 91 .4 7± 0 .39Ma,代表了碧田矿床金—银矿化的形成时代。作为紫金山—碧田地区大规模铜金 (银 )矿化作用冰长石—绢云母型浅成低温热液贵金属矿床的典型代表 ,碧田矿床成矿年龄的确定 ,为本区不同类型铜金 (银 )矿床时空关系和成因机制的探讨提供了重要的依据。

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.