Abstract:The Yanzigou gold deposit in Danbacounty, Sichuan, is located in the Songpan-Ganzêorogenic belt. The ores can be divided into quartz vein gold ore and layered carbonaceous slate gold ore. Gold mineralization consists of pre-mineralization, main mineralization and post-mineralization periods. The fluid in the Yanzigou gold deposit is acidic and belongs to a CO2-H2O-NaCl system.Fluid inclusions can be divided into two types. Fluid inclusions in pre-mineralization and main metallogenic period have the typical characteristics of orogenic gold metamorphic hydrothermal fluid: medium homogenization temperature, low salinity, low density and high CO2. However, the fluid inclusions of post metallogenic period shows the characteristics of meteoric water, characterized with low homogenization temperature range, low salinity, low density and low CO2. During pre-mineralization and main mineralization periods,gold was mainly transported as \[Au(Cl)4\]- complex compound and \[Au(HS)2\]-, respectively. During the transition process from compression to transpression, the P-T conditions of fluids changed greatly, coupled with penetration of meteoric water into tensile fractures, resulting in boiling and mixing of fluids. With increasingof gold-sulfur complex content, and change of physical and chemical conditions such as PH, Eh, fO2, and fS, ore-forming materials started to precipitate and form ore bodies. According to the characteristics of the ore-forming fluids, the Yanzigou gold deposit belongs to orogenic gold deposit.