Characteristics of Host Sandbody and Its Uranium Metallogenic Potential of the Upper Member of Yimin Formation in Bei'er Depression, Hailar Basin

large-scale stable host sandbodies were discovered in the central Bei'er depression of Hailar Basin。The sandstone belonged to the longitudinal braided fluvial facies of the upper Yimin Formation in Low Cretaceous.It was at 200~500 m deep, and the whole thickness ranged from 50 m to 150m with a single being 5m. The lithology was composed mainly of glutenite and mediumcoarse sands followed of fine sandstone.The sandstone shows loose structure,excellent permeability, high debris content and low maturity of composition and structure.The ZTR index of 25%~52% and the unstable heavy minerals indicated that the sandstone deposit was adjacent to the provenance area.The clay minerals were characterized by abund antmont morillonite and little kaolinite.Rare content of carbon chips and pyrite indicated the alkaline groundwater condition.The average values of uranium, organic carbon, total sulfur and △Eh in primary sandstone were 4.91×10^-6, 0.08%, 0.03% and 16.25m vres pectively,suggesting that the reduction capacity of the internal uranium was low.Uranium mineralization mainly occurred in the gray sand bodies in both sides of the interlayer oxidation zone, with an average uranium content of 0.03~0.38kg/m²and the characteristics of low thickness,low grade and small scale.Through comprehensive analysis it is held that the host sandbody has a favorable metallogenic potential in interlayer oxidation uranium deposit.