Metallogenic condition and prospecting orientation for deep sandstone-hosted uranium deposits in Mesozoic-Cenozoic basins of North China

The exploration of sandstone-hosted uranium deposits has only been focused on the basin margins with the depth less than 700m because of restrictions of mining technology, cost and metallogenic theory. The prospecting potentiality of deep uranium deposits in basins has always been ignored. In this study, favorable sedimentary structure, tectonic movement, geological fluid and reduction condition of deep sandstone-hosted uranium deposits were discussed based on the summary of tectonic settings and uranium-bearing strata of known shallow sandstone-hosted uranium deposits in Mesozoic-Cenozoic basins in North China and new findings from the exploration of deep sandstone-hosted uranium deposits in recent years. Meanwhile, prospecting potentiality of deep sandstone-hosted uranium deposits was assessed and two directions were preferentially pointed out:(1) at the margin slope of the basin, the "red and black" strata series should be preferentially targeted in search for the potential deep deposits whose formation conditions are similar to the conditions of the shallow deposits; (2) at the center of the basin, emphasis should be put on the red layer with positive structure and sand body developed areas in the deep buried basin. These suggestions have been proved to be effective in the uranium investigation in Songliao basin.