Mayoum Gold deposit is located in the western part of the Brahmaputra suture zone, Tibet, as an important independent rock gold deposit. The present paper first found that the CO2 fluid inclusions have the characteristics of the critical uniform by temperature test. The ore-forming fluids are supercritical fluids。The results show that the ore-forming fluids are low salinity supercritical CO2-H2O fluids. Supercritical fluids may exsolute from the magma, and then extract the elements such as gold from the rock. Fluids experienced phase separation, heterogeneity capture, across the critical point, precipitation adding processes. Ore-forming fluids across the critical point precipitate ore-forming elements, and form the early mineralization body. Fluids mix with the precipitation eventually, which lead to mass ore precipitation during the late ore forming stage.
