40Ar‐39Ar Age of K‐feldspar from K‐feldspar Granite in the Qiaohuote Copper Deposit, Bayanbulak, Xinjiang, and Its Geological Significance

Abstract

Abstract By using the 40Ar‐39Ar chronological method to date K‐feldspar from K‐feldspar granite in the Qiaohuote copper district, the authors obtained a plateau age of 274.78±0.44 Ma and an isochron age of 272.7±3.0 Ma. Because there is no tectonic deformation overprinted or hydrothermal alteration in the K‐feldspar granite intrusion after its emplacement, the 40Ar‐39Ar age represents the crystallization age of K‐feldspar in K‐feldspar granite, i.e. the late crystallization age of the K‐feldspar granite intrusion, which indicates that the K‐feldspar granite formed in the intraplate extensional stage during the Early Permian. Moreover, based on the spatial relationship between the K‐feldspar granite intrusion and copper orebodies, variations of copper ore grade, REE characteristics of K‐feldspar granite and copper ores, and H and O isotopic compositions of fluid inclusions in copper ores, the metallogenesis of the Qiaohuote copper deposit is directly related to intrusive activities of the K‐feldspar granite, and thus the crystallization age of K‐feldspar in the granite approximately approaches the metallogenic epoch of the Qiaohuote copper deposit.