Yajiangqiao granite pluton is a uranium producing granite body in the Central Hunan uranium metallogenic belt.In order to further evaluate the uranium metallogenic potential of granite bodies,LA-ICP-MS zircon U-Pb geochronology and trace element geochemistry studies were conducted on the granites of different stages.The diagenetic age and rock genesis type were analyzed,and the uranium ore-forming potential of the granite was further evaluated.The results indicate that the zircon age of the main granite in the Yajiangqiao pluton is(231.0±2.4)Ma,and the zircon ages of the complement granite are(229.3±1.4)Ma and(221.7±3.2)Ma.The pluton was formed in the Late Triassic and is a product of Late Indosinian magmatic activity.The trace elements in granite zircons exhibit typical characteristics of crustal magmatic zircons,with light rare earth elements depleted and heavy rare earth elements extremely enriched,positive Ce anomaly,strongly negative Eu anomaly.Under the tectonic background of post collision extension,by the combined effects of crustal thinning,pressure reduction,and mantle material upwelling occur,the crustal material of the Mesoproterozoic was partially melted to form the granitic magma.After the magma upwelling,emplacement,cooling and crystallization,the Yajiangqiao granite pluton formed.During the process of magma evolution,some parts of the source area were involved in mantle derived magma.The Yajiangqiao pluton is an Indosinian S-type granite with high zircon uranium content and low w(Th)/w(U)ratio,which is consistent with the characteristics of uranium-bearing granite.But the small exposed area of the pluton and low average uranium content are not conducive to the formation of large uranium ore field.
LA-ICP-MS Zircon U-Pb datinggeochemistryuranium-bearing graniteYajiangqiao graniteHunan Province
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