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The Dongshang Uranium Deposit is situated in the southern section of the Ganfang Pluton in the Jiuling Orogenic Belt of northwestern Jiangxi Province. The U-bearing granites consist mainly of medium- to coarse-grained, porphyritic biotite(binary) granite. Through zircon and monazite U-Pb geochronology, petrology, and rock geochemistry studies, the U-bearing granites' age, source characteristics, and rock genesis were determined, and their uranium metallogenic potential was also discussed. The LA-ICP-MS analysis showed that the zircon U-Pb intercept and weighted average ages are both 152±1 Ma, and the monazite U-Pb intercept and weighted average ages are 151±1 Ma and 151±2 Ma, respectively, indicating the formation of the U-bearing granites during the early Yanshan period. The major elements exhibit the characteristic of high silica content (SiO2 ranging from 72.1% to 75.6%), high alkalis content (K2O+Na2O ranging from 7.26% to 8.43%), potassium-rich and sodium-poor (K2O/Na2O=1.07 to 1.42), high aluminum (A/CNK=1.12 to 1.29), low titanium content (TiO2 ranging from 0.07% to 0.17%), and iron-poor magnesium (FeOT ranging from 0.75% to 1.28%, MgO ranging from 0.19% to 0.31%), classifying the U-bearing granites as high potassium calcalkaline peraluminous granites. Trace elements Ba, Sr, Nb, and Ti are depleted, while Rb, U, Pb, and Ta are enriched, representing a typical low Ba, Sr granite. The total rare earth elements (ΣREE) are relatively low (∑REE=21.6×10−6 to 50.7×10−6), exhibiting a right-dipping light rare earth enrichment pattern with a prominent negative Eu anomaly, which belongs to S-type granites. Based on geochronology and rock geochemical features, it's suggested that the Dongshang U-bearing granites were formed during the syn-collision compressional setting, resulting from the partial melting of the muscovite-rich metapelites of the Anlelin Formation in the Neoproterozoic Shuangqiaoshan Group. High uranium content, high Rb/Sr ratios, Th/U ratios less than 3, and high zircon uranium contents indicate the potential for uranium ore-forming conditions within these granites. |
