鄂尔多斯盆地特拉敖包铀矿床砂岩岩石-地球化学特征及其对铀成矿的指示OA

Lower Cretaceous Huachi-Huanhe Formation in the northwest Ordos Basin has recently been identified as a"new horizon"for uranium prospecting.The mineralized sand bodies of the Teraaobao uranium deposit are primarily located in the lower member of Huachi-Huanhe Formation,with ore bodies predominantly exhibiting stratiform morphology.However,systematic studies on the geological characteristics and metallogenic conditions of Teraaobao uranium deposit are few.At present,making the internal mechanisms of uranium enrichment remain unclear.This study conducted a comprehensive analysis of elemental geochemistry,carbon and oxygen isotopes,and whole-rock U-Pb dating on the mineralized sandstone layers to meticulously analyze the provenance of the sandstone and the origin of carbonates within the uranium ore layers.The results indicate that the primary provenance of the sandstone in Lower Cretaceous Huachi-Huanhe Formation is intermediate-acid igneous and metamorphic rocks from Yinshan mountain range.Notably,there is no direct correlation between carbonates and uranium mineralization.Instead,minerals such as pyrite,chlorite,and ilmenite play crucial roles as important uranium-adsorbing and reducing agents during the uranium mineralization process.Additionally,the sandstone of Huachi-Huanhe Formation has undergone reduction transformation by hydrocarbon-bearing fluids,a process closely associated with uranium mineralization.This new discovery provides fresh perspectives and insights for a deeper understanding of the uranium metallogenic mechanisms in Teraaobao uranium deposit.