赣中金滩岩体印支晚期二云母花岗岩年代学、地球化学特征及地质意义OA

Located in central Jiangxi Province,Jintan pluton is a complex pluton formed in Indosinian period and one medium-sized Xiali uranium deposit has been identified in the pluton,However,studies on the uranium-bearing granites are seldom reported.This paper investigated the petrographic,geochronological,and geochemical characteristics of two-mica granites in the pluton and explored their genetic relationship with uranium mineralization.Particular attention was given to the petrogenesis,source characteristics,tectonic setting,and mineralization association.Zircon U-Pb dating yields the crystallization ages of 215.5 Ma±1.0 Ma and 215.0 Ma±1.7 Ma,indicating the granite emplaced during Late Indosinian period.These granites are characterized by high silica and alkali contents,with peraluminous compositions.Geochemical analyses reveal that the granites are enriched in large-ion lithophile elements(Rb,U,Th)and depleted in high-field-strength elements(Ba,Sr,Eu),which are consistent with those of Indosinian S-type granites in South China.The elevated Rb/Sr and Rb/Ba ratios,together with low CaO/Na2O values,suggested the two-mica granite were derivated from the partial melting of argillaceous crustal sources which originated from the Paleoproterozoic crustal materials in a post-orogenic extensional tectonic setting.These granites were found with the uranium concentrations ranging from 11.11×10-6 to 42.27×10-6,and might have provided uranium source for the subsequent uranium mineralization events.