CHARACTERISTICS OF CHLORITE IN THE YIMIN FORMATION AND ITS RELATIONSHIP WITH URANIUM MINERALIZATION IN THE KELULUN SAG,HAIL AR BASIN
In this study,chlorite within the grayish white,grayish green,and gray sandstone layers of the uranium-bearing Yimin Formation in the Kelulun Depression is examined using petrographic and in-si-tu electron microprobe analysis techniques to understand its characteristics and its relationship with urani-um mineralization.Chemical quantitative analysis is employed to investigate the types and forming condi-tions of chlorite,and its properties and connection with uranium mineralization are discussed.The results reveal two main types of chlorite:pore filling type and biotite alteration type.Based on Fe-Si diagrams,chlorite in the gray sandstone and some grayish-white sandstone is predominantly vermiculite,while most grayish-white and some grayish-green sandstone contain miculite,and a few samples of both grayish-white and grayish-green sandstone contain ferroclinochlorite.Result of the Mg/(Fe+Mg)-Al/(Al+Fe+Mg)relationship indicates that chlorite in different colors primarily originates from mafic fluid sources,with a minor contribution from argillaceous fluids.The empirical formula suggests chlorite formation tempera-tures ranging from 150 to 170 ℃ for grayish white sandstone,150 to 180 ℃ for grayish-green sandstone,and 170 to 200 ℃ for gray sandstone.Relationship diagrams between main cations and magnesium in chlo-rite confirm its formation through multi-stage hydrothermal fluid interactions.Chlorite associated with u-ranium mineralization in gray sandstone forms under more reducing conditions compared to grayish white and grayish green sandstone.Its formation mechanism involves dissolution-crystallization and dissolution-migration-crystallization processes.These chlorite processes and hydrothermal actions contribute to the activation,migration,adsorption,and precipitation of uranium.
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