THE GEOLOGIC FEATURES OF BEIDACHENG GOLD DEPOSIT, AOHAN AUTONOMOUS COUNTY, INNER MONGOLIA

Beidacheng gold deposit occurs in the metamorphic rocks of the Archean Xiaotazi formation of Liaohe group and was controlled by NE ductile-brittle shear belt. The ore body presents as vein structure. Two mineralized types are pyrite-quartz vein and altered rocks. The mineralization has positive relations with alteration. Ore sources are provided by the Archean amphibolitic formation, and have genetic relationship with Yanshan supergene-ultra-supergene quartz-orthophyre and rhyolite porphyry. Sulphur isotopic compositions correspond to meteoritic sulfur. The mineralization temperatures are mainly between 120℃ to 270℃. It belongs to magmatic metamorphic hydrothermal reconstruction Au deposit of medium-lower temperature.