Mineralization age of the Hongshan gold deposit,East Tianshan, Xinjiang

Abstract：The Hongshan gold field is located at the north edge of the east section of the Qiugemingtashi-Huangshan ductile shear zone. The study of the genesis of the Hongshan gold deposit shows that its formation was strictly controlled by this ductile shear zone and that it belongs to a mylonite type or ultramylonite type deposit related to the ductile shear zone. Hornblende in granitic mylonite yields an Ar-Ar plateau age of 276.3 Ma, representing the upper limit of the ore-forming event of the Hongshan gold deposit. Sericite in gold ore samples give Ar-Ar plateau ages of 246.9 and 246.5 Ma, recording the age of the main mineralization stage of the gold deposit. The Ar-Ar plateau age of 246.5 Ma of the neogenic muscovite in mylonite is in agreement within error with that of the sericite in gold ore, which not only provides further evidence for the Hongshan gold deposit being of shear zone type origin but also puts a further constraint on the age of gold mineralization.