Characteristics and metallogenesis of ore-bearing sandstone in the Tarangaole sandstone type uranium deposit, Ordos Basin

This paper is the result of mineral exploration engineering.

Objective  In recent years, sandstone type uranium deposits have developed rapidly in North China. The geological exploration of sandstone type uranium deposits in the Tarangaole area has made significant discoveries. Through the study of sandstone type uranium deposits in the Tarangaole area, it is helpful to better explore the distribution rules of deep sandstone type uranium deposits and the occurrence patterns of petrology and mineralogy. The stratigraphic structure of Tarangaole is similar to that of Na Linggou and Da Ying uranium deposits, but the rock characteristics of ore bearing strata and the occurrence of uranium minerals in the study area are not clear.

Methods  In this paper, through core observation, systematic sampling and detailed identification under microscope, the uranium ore in Tarangaole area was analyzed by EPMA.

Results  The results show that the sandstones in the lower member of Zhiluo Formation of Middle Jurassic are mainly feldspathic lithic sandstone and lithic arkose, With low compositional maturity and structural maturity, and have the characteristics of near provenance deposition.

Conclusions  The results of electron microprobe analysis show that the main uranium minerals are pitchblende, uranite and a small amount of ilmenite. The backscatter images show that uranium deposits are mostly distributed together with pyrite and organic matter minerals, indicating that pyrite and organic matter minerals provide reducing agents for the formation of uranium minerals.The development of dissolution and epigenetic alteration during diagenesis provides favorable conditions for uranium enrichment and precipitation. By observing thealteration phenomena and the characteristics of altered minerals in sandstone of ore bearing Tarangaole bed, it is shown that the clay minerals transform each other under certain physical and chemical conditions. The change of geochemical environment causes the mutual transformation of clay minerals and further changes the geochemical environment of ore-bearing sand bodies.