The Genesis of Black Mudstone in Bashibulake Uranium Deposit in Tarim Basin and Its Indication for Uranium Mineralization
Bashibrak deposit is an important uranium deposit in Tarim Basin,which is characterized by diverse alteration types,high ore grade,and multi-layer tabular orebody.The distribution of uranium mineralization is closely related to the asphalt,but the age of asphalt and its relationship to uranium mineralization are still unclear,which restricts the interpretation of ore genesis and the next exploration direction.In this paper,gray black mudstone and gravel were selected as the research objects to determine the formation time of asphalt and its relationship with uranium mineralization,through field observation,rock mineralogy,and X-ray fluorescence spectroscopy measurements.The results show that black mudstone occurs in a thin layer inside the gravel layer,mainly composed of mud crystal dolomite,semi self shaped pyrite,and a large amount of block land-bitumen.Uranium minerals occur in black mudstone ores as a combination of coffinite,fine-grained pyrite and UO2/TiO2 mixture-asphalt minerals,and U is enriched synchronously with Pb,Zn,Cu,etc.The asphalt is the result of the oxidation and decomposition of the lower oil and gas migrated to the near shallow strata,formed during the early sedimentary diagenesis stage of the Kizilsu Group.Its formation is related to regional thermal events caused by magmatic activity in the southwestern region of Tarim during the late Early Cretaceous period(115～113 Ma).The key to the formation of this deposit is the rich U hydrocarbon fluid deposited in the early diagenetic stage.The mixing of the reductant basin fluid of the rich U hydrocarbon with the shallow formation water of the basin resulted in the large-scale precipitation of minerals such as U and Pb,Zn,Cu,Se,etc.,which also provided a foundation for the later surface oxidation transformation.
black mudstoneland-bitumenuranium mineralogyKezilesu GroupBashibulake
万方数据
维普
