赣中金滩岩体产铀花岗岩磷灰石地球化学特征及地质意义OA

Jintan pluton is an Indosinian multi-stage and multi-phase composite pluton in central Jiangxi Province.It currently hosts the medium-sized Xiali uranium deposit and several uranium occurrences,including Xingjiazhou and Chouxi,and is therefore a uranium-bearing granitic pluton.In this paper,the garnet-bearing two-mica granite from Jintan pluton was selected for investigation.In situ major-and trace-element compositions of apatite were analyzed by Electron Probe Microanalysis(EPMA)and Laser Ablation Inductively Coupled Plasma Mass Spectrometry(LA-ICP-MS),aiming to constrain the petrogenesis of the granite and its implications for uranium mineralization.Our results show that,based on apatite geochemical parameters including REE distribution patterns,F/Cl,Sr/Mn,(Ce/Yb)N,Th/U,and Sr/Y ratios,the garnet-bearing two-mica granite is classified as S-type granite.The apatite is characterized by high F and low Cl contents,suggesting that the granite was derived from partial melting of continental crustal materials.The strongly negative Eu anomalies,weakly positive Ce anomalies,low SO ₃ contents,and high Mn contents of apatite reflect a low oxygen fugacity environment during magmatic evolution.The coupling of high degrees of fractional crystallization and low oxygen fugacity not only facilitated the crystallization and precipitation of uraninite at the magmatic stage,but also provided fundamental metallogenic conditions for the extraction of uranium by later hydrothermal activity.Comprehensive analysis indicates that the geochemical characteristics of apatite can effectively constrain the petrogenesis of the uranium-bearing granite and offer valuable geochemical proxies for improving our understanding of hydrothermal uranium mineralization mechanisms.