Special rock and mineral characteristics of uranium mineralization in red variegated sedimentary formations:Taking the uranium occurrence of Neogene Jidike Formation in Kuqa Depression as an example
In recent years,the exploration of sandstone-type uranium deposits in the northern part of China has made breakthroughs in the Mesozoic and Cenozoic red-colored sedimentary formations.However,there is a great controversy about the mechanism of uranium mineralization in red beds,which has become a hot topic of current research.A large amount of uranium mineralization outcrop information is developed in the Neogene red layer in the Kuqa Depression.Carrying out relevant research is very helpful in analyzing the uranium enrichment mechanism in the red variegated layer.Through systematic sedimentology,petrology and mineralogy,the uranium mineralization spots in the red variegated layer of the Jidike Formation were dissected,and a relatively special type of uranium mineralization was discovered:the mineralized layer was located in a lacustrine sedimentary environment under an arid background.It is produced in a large set of red mudstone in the shape of a thin layer of lens.The mineraliza-tion lithology is gray-green marl and develops a large number of reddened siliceous masses.The mineralization has layer-controlled characteristics and is closely related to the siliceous masses.The siliceous mass has a combination of reddish microcrystalline quartz,fluorite,uranite,calcite and a small amount of natural arsenic,chalcopyrite and barite intergrowth minerals.The siliceous mass is very similar to the granite-type siliceous vein uranium mineraliza-tion in South China,showing the characteristics of deep hydrothermal origin.It is comprehensively judged that this mineralized layer has dual effects of sedimentation and hydrothermal fluid,and is a special hot water deposition type uranium mineralization.This type of uranium mineralization discovery provides direct and strong evidence that deep hydrothermal fluids could carry uranium into sedimentary basins to undergo uranium mineralization,and improve the theory of sedimentary uranium mineralization in continental basins.
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