Reaction transport numerical modeling on the zonation of skarn deposits: A case study of the Jiama porphyry-skarn Cu-polymetallic deposit in Tibet, China

　　
　　The skarn ore body of Jiama porphyry and skarn type copper-polymetallic mineral system, Tibet, China has a unique mineral zoning of metal and skarn minerals. At present, there are few numerical simulation studies on the mineralization of skarn deposits. In order to promote the dynamic and quantification of the mineralization process of the skarn deposit, a two-dimensional numerical simulation model coupling thermal transfer, fluid flow and chemical reaction has been established based on the exploration line profile and fluid inclusion data of the skarn ore body in the Jiama deposit, aiming at studying the formation mechanism of mineral zonation characteristics of the skarn ore body in the Jiama deposit. The model results show that the mineral zonation of skarn ore body in Jiama deposit is mainly controlled by favorable metallogenic temperature, redox state, pH value, HS^- concentration and Fe²⁺ concentration. Among them, the redox state controls the proportion of calcium-iron garnet and calcium-aluminum garnet in skarn garnet, the favorable temperature, pH value and HS^- concentration control the precipitation of lead, zinc and molybdenum, and the precipitation of copper is closely related to the concentration of Fe²⁺.