The Research on Depositional Environment of Uranium Host Rock in the Northeast Ordos Basin

The sandstone-type uranium deposit is abundant in Northeastern Ordos Basin. Analysis of Jurassic uranium host rocks sand body distribution and sedimentary environment has some practical significance to ore prospecting in Dongsheng Area in the future. Based on previous studies, combined with the field geological investigation, this paper indicates that the uranium host rock is mostly coarse sandstone, containing a large number of plant detritus fossil, with erosion surface often found at the bottom, and the development of large trough, tabular cross-bedding. Through the analysis of the despositional framework and borehole columnar section of sand body along south-north direction, sand thickness and sedimentary environment distribution map of sand body in uranium host rocks are drawn. Sandstone thickness varies from 8 to 75m, and the morphology shows sheeted, zonal distribution on the whole. The thickest sand bodies are in Yaozhen Town-Xinjiezhen Town, which is up to 75m thick. The sand body is coarse and has a strong basal scouring erosion, especially in the Yan'an Formation. The sand body distribution and sedimentary environment all show that the braided river delta system distribute to one side of river channel, and such frequent branching is favorable for uranium deposit enrichment.