西昆仑苦子干碱性杂岩体富稀土霓辉正长岩成矿时代及矿物地球化学特征OA

[Objective]The Taxkorgan area in the western Kunlun Mountains,located on the Muztagh-Aksai Fe-Cu-Au-Pb-Zn metallogenic belt,serves as a significant base for iron and copper polymetallic resources in China.Recent discoveries indicate elevated rare earth element(REE)concentrations within its alkaline intrusive complexes,suggesting promising REE mineralization potential.The Kuzigan alkaline complex,the largest Cenozoic alkaline intrusive body in this region,remains poorly understood regarding its relationship with REE enrichment.[Methods]This study conducted petrographic analyses,whole-rock geochemistry,electron microprobe assays,and zircon LA-ICP-MS U-Pb geochronology on the Kuzigan alkaline complex.[Results]The complex comprises ore-bearing augite syenite,syenite,and granite.All rock types exhibit high total REE concentrations with light REE(LREE)enrichment.Bastnäsite and REE-rich apatite are identified in ore-bearing augite syenite,where bastnäsite crystallized later than rock-forming minerals,closely associated with hydrothermal activity.Zircon dating reveals emplacement ages of 10.9±0.1 Ma(syenite)and 10.2±0.1 Ma(ore-bearing augite syenite).Augite exhibits elevated Na2O and CaO contents,while apatite is characterized by high fluorine(F)and LREE2O3 concentrations.Titanite also shows F enrichment.[Conclusions]Alkaline fluids rich in Na+,K+,and F facilitated REE mobilization and precipitation through complexation,promoting mineralization.These findings suggest favorable prospects for REE exploration in the Kuzigan area.