The Hongniu-Hongshan deposit is a newly discovered porphyry-skam copper deposit in Zhongdian volcanic arc, which belongs to Southwest Sanjiang metallogenic belt. The deposit occurs within the hydrothermal alteration zone of the Yanshanian felsic intrusion which emplaced into Triassic carbonate and marble. The biotite and amphibole phenocryst in the quartz monzonite porphyry related to the mineralization contain abundant fluorine, respectively reached 1. 49% and 2. 62%, indicating that the magma are rich in water and fluorine. The quartz phenocryst show a skeletal texture, which indicate the magma undergone rapid rising, and the growth embayments, resorption surfaces, and high-K edge indicate the quartz phenocryst undergone autometasomatic process. In addition, the magmatic hydrothermal breccias in a drill core suggest that magmatic hydrothermal breccias were generated by explosive, fluid released from crystallizing porphyry, and there probably be concealed porphyry in the deep. The prograde stage coule be divided into three main substage: aluminum-riched garnets ( And(22-57)) and diopside (Hd(7-27)) in the first substage formed by diffusive metasomatism, and the fluid formed from high temperature magmatic degassing; Iron-riched garnets (And(75-98)) and pyroxenes (HD10-99) in the second substage formed by advective metasomatism, and the large scale fluid formed by magmatic fluid exsolution; The skarn mineral veins in the last substage probably formed from residual fluid of the metasomatism. The formation of skarn lead to the CO2 lost, mineral volume decreased, and open space created, permeability and porosity increased, which well-produced for mineralization. In the retrograde stage, the mineral assemblage mainly is epidote, amphibole, chlorite and sulfides. In the early retrograde stage, porosity decreased owning to hydrous minerals, fluid pressure increased leaded to fluid boiling and cryptoexplosion, as the result, the fluid temperature and pressure decrease, and copper precipitation. In the last stage, owning to the repeated boiling of fluid, formed open system, acidic magmatic fluid mixed with atmospheric water, copper precipitation.
