Elucidating the mineralization mechanisms of individual granitic stages and tracing magmatic evolution processes are critical for establishing mineralization models of large-scale batholiths.The Mufushan granitoid bat...Elucidating the mineralization mechanisms of individual granitic stages and tracing magmatic evolution processes are critical for establishing mineralization models of large-scale batholiths.The Mufushan granitoid batholith,renowned for multistage magmatism and large-scale rare metal mineralization,mainly comprises biotite,two-mica,and muscovite monzogranite.Existing research has predominantly focused on biotite and two-mica granite,whereas muscovite granite,as the most highly differentiated lithologic unit,remains understudied regarding its mineralization mechanisms and evolution characteristics.Focusing on two newly discovered Li-rich granites,namely tourmaline muscovite granite(TMG)from Shiniuchong and garnet muscovite granite(GMG)from Huanglongxiang,this study clarifies their intrusion ages,Li occurrence states and enrichment mechanisms,while establishing the magmatic evolutionary pathway.The results show that the U-Pb ages of columbite-tantalum and zircon are 130.2±1.0 Ma(TMG)and 138.2±1.0 Ma(GMG),respectively,confirming Early Cretaceous Li-rich magmatism.The Li concentrations in muscovite from the Li-rich muscovite granites are high(mean 3328 ppm),compared to those in Mufushan ordinary muscovite granites(<1500 ppm),but the dominant Li-bearing minerals are still classified as muscovite or phengite.Li enrichment of mica in this Li-rich granite system is controlled by the magmatic differentiation-dominated vector Si2LiAl-3,differing from that in cogenetic pegmatite systems,indicating distinct Li enrichment pathways between two mineralization processes and thereby endowing this system with the potential to evolve into granite-type Li deposits.Mica geochemistry and Rayleigh fractionation modeling indicate the Li-rich muscovite granites,along with biotite and two-mica granite in the Mufushan area,represent products of different stages of co-magmatic evolution.Crystal fractionation is the key mechanism controlling Li enrichment,requiring effective separation of at least 75%of the melt to drive preliminary Li enrichment in the highly differentiated granite.These findings significantly advance understanding of mineralization processes in large-scale batholiths,providing valuable insights for regional Li exploration.展开更多
基金supported by the National Key Research and Development Program(2024YFC2909300)the National Natural Science Foundation of China(42330806,U2444204,and 42472111)the Geological Survey Project grants from the China Geological Survey(DD20230289).
文摘Elucidating the mineralization mechanisms of individual granitic stages and tracing magmatic evolution processes are critical for establishing mineralization models of large-scale batholiths.The Mufushan granitoid batholith,renowned for multistage magmatism and large-scale rare metal mineralization,mainly comprises biotite,two-mica,and muscovite monzogranite.Existing research has predominantly focused on biotite and two-mica granite,whereas muscovite granite,as the most highly differentiated lithologic unit,remains understudied regarding its mineralization mechanisms and evolution characteristics.Focusing on two newly discovered Li-rich granites,namely tourmaline muscovite granite(TMG)from Shiniuchong and garnet muscovite granite(GMG)from Huanglongxiang,this study clarifies their intrusion ages,Li occurrence states and enrichment mechanisms,while establishing the magmatic evolutionary pathway.The results show that the U-Pb ages of columbite-tantalum and zircon are 130.2±1.0 Ma(TMG)and 138.2±1.0 Ma(GMG),respectively,confirming Early Cretaceous Li-rich magmatism.The Li concentrations in muscovite from the Li-rich muscovite granites are high(mean 3328 ppm),compared to those in Mufushan ordinary muscovite granites(<1500 ppm),but the dominant Li-bearing minerals are still classified as muscovite or phengite.Li enrichment of mica in this Li-rich granite system is controlled by the magmatic differentiation-dominated vector Si2LiAl-3,differing from that in cogenetic pegmatite systems,indicating distinct Li enrichment pathways between two mineralization processes and thereby endowing this system with the potential to evolve into granite-type Li deposits.Mica geochemistry and Rayleigh fractionation modeling indicate the Li-rich muscovite granites,along with biotite and two-mica granite in the Mufushan area,represent products of different stages of co-magmatic evolution.Crystal fractionation is the key mechanism controlling Li enrichment,requiring effective separation of at least 75%of the melt to drive preliminary Li enrichment in the highly differentiated granite.These findings significantly advance understanding of mineralization processes in large-scale batholiths,providing valuable insights for regional Li exploration.
