Metallogenic epoch of the oubulage copper-gold deposit in the alashan area,inner mongolia autonomous region北大核心

The Oubulage copper-gold deposit locates in the Alashan region of west Inner Mongolia Autonomous Region, was fourid recently in an assessment performed by team 511, Inner Mongolia Nonferrous Metals Geological Exploration Bureau. With large scale potentiality, the deposit distributes in lower Permian volcanic rock and subvolcanic rock, the main hosting rocks are quartz porphyry, dacitic melted volcanic breccia and liparitic volcanic breccia. Single zircon U-Pb and quartz 40Ar/39 Ar methods are applied to determine U-Pb ages of quartz porphyry vein of metallogenic epoch, and 40Ar/ 39 Ar age of ore-bearing quartz vein. The experiment results show that the age of quartz porphyry is 277. 4±3 Ma and the age of ore-bearing quartz vein is 264. 3±0. 5 Ma, indicating that Oubulage copper-gold deposit was formed in the late Hereynian Period. This copper-gold deposit and other gold deposits in the same area, such as Zhulazaga gold deposit and Hulunxibai gold deposit, all were formed in the late Hereynian Period, implying that Hereynian Period is a major copper-gold ore-forming epoch in the west of China.