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MRD-12 Fluvial palaeo-systems: Evolution and mineral deposits
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A special kind of sandstone type uranium deposit related to Jurassic paleochannel systems in northeastern Ordos basin, China
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Ziying Li, Beijing Research Institute of Uranium Geology (China)
Yangquan Jiao, China Geological University, Wuhan (China)
Xiheng Fang, Beijing Research Institute of Uranium Geology (China)
Yuliang Xia, Beijing Research Institute of Uranium Geology (China)
Anping Chen, Geological Exploration Team 208 (China)
Ke Zhang, Zhongshan University (China)
Ye Sun, Beijing Research Institute of Uranium Geology (China)
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The Dongsheng sandstone type uranium deposit is a large one discovered in recent years in northeastern Ordos basin, China. It is a special kind of sandstone type uranium deposit, different from other ordinary sandstone type deposits because of its unique signatures. It is generally controlled by a transitional zone between greenish and grayish sandstones, both of those two kinds of sandstones now indicate reduced geochemical environments.
The greenish color of the paleo-oxidized sandstones mainly results from chloritization and epidotization related to oil and gas secondary reduction processes. The deposit genetically is different from ordinary sandstone uranium deposits, which is of more complex origin, undergoing not only paleo-oxidization mineralization process, but also oil-gas fluid and hydrothermal reworking processes.
It is spatially related to Jurassic Zhiluo Formation with braided paleochannel systems, The uranium mineralization zone with higher grade usually exists in the branching area of the distributary channels of main braided streams, whose sandstone heterogeneity shows a transfer sedimentary facies from the braided stream sedimentary system to the braided delta sedimentary system. Statistical results show that medium-grained and fine-grained sandstones are the most favorable rock types for uranium mineralization.
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