阿尔金西段库木塔什萤石矿床成矿流体特征及成矿机制探讨OA北大核心CSTPCD

Kumutashi fluorite deposit is located in the Kaerqiaer super-large fluorite ore belt in the western Al-tyn Tagh,which is a newly discovered large fluorite deposit in recent years.The ore body is dominated by fluo-rite-calcite vein type,associated with lithium-bearing mica,and occurs in the NE and nearly EW faults of the Pa-leoproterozoic Altyn Tagh rock group.At present,the research on the characteristics of ore-forming fluid and ore-forming mechanism is relatively weak.Fluid inclusions in fluorite and calcite from different mineralization stages were studied by petrography,microthermometry,laser Raman spectroscopy,and hydrogen and oxygen isotopes.The ore-forming process can be divided into two stages:the early stage(Ⅰ)and the late stage(Ⅱ).The massive ores formed in the early stage are mainly gas-rich two-phase aqueous inclusions and CO2 three-phase inclusions with homogenization temperature ranging from 225.1 to 410.8℃,salinity from 5.20 to 9.63 wt%NaCleqv and density from 0.25 to 0.76 g/cm3;In the late stage,brecciated and stockwork ores were formed,and liquid-rich two-phase and gas-rich two-phase aqueous inclusions were mainly developed,with homogeniza-tion temperature ranging from 117.2 to 347.8℃,salinity from 0.53 to 12.73 wt%NaCleqv,and density from 0.40 to 0.91 g/cm3.The liquid phase of the inclusion is mainly composed of H2O with a small amount of CO2,and the gas phase is mainly composed of CO2 with a small amount of CH4,N2,H2 and H2S.In the early stage of mineral-ization,the fluid was a NaCl-H2O-CO2 hydrothermal system with medium-high temperature,medium-low salini-ty and low density,while in the late stage of mineralization,the fluid was a NaCl-H2O-CO2 hydrothermal sys-tem with medium-low temperature,low salinity and low density.The results of hydrogen and oxygen isotope studies indicate that the ore-forming fluids were derived from a mixture of magmatic hydrothermal and meteoric water.Fluorite precipitation in the early stage of mineralization was mainly due to the mixing of magmatic hy-drothermal solution and meteoric water,as well as water-rock reaction.In the late stage,fluid mixing further oc-curred,resulting in the decrease of temperature and the formation of brecciated and stockwork ores.Kumutashi fluorite deposit belongs to magmatic hydrothermal filling type vein fluorite deposit.