Green altered sandstone related to hydrocarbon migration from the uranium deposits in the northern Ordos Basin, China

•Diagenetic green altered sandstone related to hydrocarbon migration was recognized.•Chemical reduction caused the mobilization of Fe via dissolution of hematite.•Incorporation of the mobilized Fe into diagenetic chlorite imparts the green color.•The green altered sandstone was the product of hydrocarbon-water-rock interactions under sulfur-depleted, reducing conditions.•Hydrocarbon-induced alterations can serve as exploration guides for sandstone-hosted uranium deposits.