Sandstone-hosted roll-type uranium deposits were found to occur in the Middle Jurassic Zhiluo Formation sandstone in Dongsheng area, north of the Ordos basin. The uranium occurs mainly as coffinite. Some of the coffinite is intergrown intimately with secondary pyrite, indicating simultaneous precipitation. The pyrite has δ
S values from −34‰ to +18‰, suggesting an origin of bacterial sulfate reduction. Calcite cement of the host sandstones has δ
C values from +0.3‰ to −27.6‰. The most negative δ
C value is more negative than those of terrestrial higher plants-derived organic matter in the Jurassic in the basin, thus the carbon of the calcite cement is likely derived from oil and natural gas, most likely from mixing of preexisting inorganically derived CO
and methane-derived CO
. The hypothesis is supported by the great, number of oil/gas inclusions found in the calcite cement and healed fractures through quartz grains. Interestingly, in the sandstone with high content of uranium, secondary pyrite has δ
S as light as −34‰, calcite cement has δ
C lower than −10‰. Thus, it can be concluded that sulfate reducing bacteria likely oxidized hydrocarbons, and directly or indirectly reduced uranium (VI) to uranium (IV).