江西石城姜坑里铌钽矿床独居石U-Pb年龄、地球化学特征及找矿指示OA

The Yanshanian granites widely distributed in Southern Jiangxi serve as important metallogenic hosts for granite-type rare metal deposits.Taking the Jiangkengli Nb-Ta deposit in Shicheng as the research object,this study systematically compares the geochemical differences between mineralized and non-mineralized granites through field geological surveys,petrographic analysis,whole-rock geochemical testing,and U-Pb chronology.The results show that the mineralized granites are predominantly sodic calc-alkaline series,which are significantly enriched in Al2O3,TFe2O3,and MnO compared with non-mineralized granites.They are characterized by low total rare earth elements(ΣREE＜20× 10-6),low Nb/Ta(＜3),low Zr/Hf(＜5),and high Rb/Sr(＞150),based on which quan-titative discrimination indices for mineralized granites are established.Isotopic chronology reveals that the monazite U-Pb age of zinnwaldite-albite granite is 144.9±0.8 Ma.Combined with regional metallogenic age comparisons,it is inferred that 145～140 Ma represents a unique Nb-Ta mineralization period in Southern Jiangxi.The ore-forming mechanism indicates that the deposit formed through the synergistic evolution of highly differentiated magma and F/Li-rich fluid alteration.This study provides key geological references for rare metal prospecting in Southern Jiangxi.