Abstract:

The Dashankou gold deposit in Hejing County, Xinjiang Province is located at the east part of the southern Tien Shan metallogenic belt, and near suture zone between the Tarim and KazakhstanErie Plates. The deposit  occurred in the SahentuohaiDashankou brittleductile shear zones, the gold orebody is hosted in the clastic rocks of the Dashankou Formation and the  Upper Silurianlower Devonian diorite porphyry and dacite porphyry, and the host rocks had undergone the brittleductile deformation. The boundaries between the ore bodies and wall rock are blurred. The ore bodies which are confined to the brittleductile deformation zone obviously show characteristic of thinout reappearing along its strike and tendency, presenting parallel slaty and lenticular ore grops or belts. The natural types of the ore are mainly goldbearing mylonite and quartz veins. The ore contains a small amount of pyrite. The fluid inclusions in the veinquartz of the main mineralization stage were studied. There are two major types of fluid inclusions at room temperature, i.e., the aqueous  and CO2bearing inclusions. The oreforming fluid mainly contains H2O and CO2, and the temperature is between 260320 ℃, the salinity peak is between 500%850% NaCleq., and the density between 075095 g/cm3. The oreforming fluids is mesothermal, low salinity and low density hydrothermal system. The oreforming pressure of 397810977 MPa and corresponding oreforming depths of 499900 km is estimated by the fluid inclusions. The oreforming fluid is a H2ONaCl system bearing CO2. The Dashankou gold deposit shows obviously characteristics of orogenic type of gold deposit with better exploration potentiality.

Key words: ore geolology, fluid inclusions, Dashankou gold deposit, orogenic type of gold deposit, Xinjiang