Gold and silver occurrence and its genesis in the Mozigou gold deposit, Danba area, western Sichuan, China

Mozigou gold deposit is located in the margin of the Yangtze and east of Songpan-Ganzi orogenic belt, Danba County, Sichuan Province, with Devonian Weiguan Formation Carbonaceous slate as its ore-bearing country rocks. Mineralization can be divided into sedimentary mineralization, hydrothermal ore-forming period and hypergene weathering period.And the hydrothermal ore-forming is the main period of gold mineralization. The authors studied the deposition of gold, silver occurrence status, and the main characteristics of gold-bearing minerals by means of microscopic observation, scanning electron microscopy, electron probe composition analysis, and mineral crystal chemical formula calculation. Thus we found out gold was mainly inclusion, fracture and intergranular gold. Silver is main form of isomorphic occur in Galena and Sulphosalts. Gold-bearing minerals pyrite had biological structures, which indicated that bio-mineralization played an important role during the formation stage of gold deposits. Ores are controlled by specific strata and fractures, and have endured strong wall-rock alteration. According to the deposit characteristics of tectonic environment, ore-rock, structural control, layer position control and mineral paragenesis etc., authors can ascertain the Mozigou gold deposit can be regarded as micro-disseminated gold deposits, and the type is sedimentary-hydrothermal reworked deposits.