Lithologic characteristics and modes of occurrence of uranium of the target strata in the Nalinggou uranium deposit of Ordos Basin

The lower part of the first member of Zhiluo Formation of Middle Jurassic is the main uranium ore-bearing layer of the Nalinggou uranium deposit. Because of the formation has braided river sedimentary system features such as good sand body connectivity and permeability, rich reducing substances (charcoal and pyrite), it has good conditions for uranium mineralization. Using multiple testing means such as microscope microscopy, X-ray diffraction analysis, scanning electron microscopy analysis, the authors studied sandstone rock characteristics. Alteration phenomena and altered mineral characteristics of the uranium target strata was observed. the conversion relationship in clay minerals, biotite and other minerals was explored. Component analysis was conducted, and existing forms of uranium mineral in the Nalinggou uranium deposit were investigated using α track etching, electron microprobe analysis and tensile test. By discussing the relationship between petrologic features and existing form of uranium minerals in the ore-hosting horizon, it is found that the enrichment of U, occurrence of U and component type of U were closely related to the exchange of material in the mineral alteration transformation, and uranium mineralization in Nalinggou area was controlled by paleo-interlamination oxidized zone and was affected by the later hydrothermal fluid.