连山关铀矿床特殊的工业铀矿物组合及其特征和意义

THE UNIQUE ECONOMIC URANIUM MINERAL ASSEMBLAGE IN LIANSHANGUAN URANIUM DEPOSIT AND ITS CHARACTERISTICS AND SIGNIFICANCE

Located in Liaoning province, North China, the Lianshanguan uranium deposit is characterized by its unique uranium mineral assemblage, i. e. uraninite-pitchblende-coffinite assemblage. Compared with those in other uranium deposits, the uraninite and pitchblende in Lianshanguan deposit have higher values of hardness, specific gravity, reflectance and cell parameter and lower value of oxygen coefficient, indicating that the uranium minerals were formed under relatively high temperature and intensely reducing conditions. Particularly part of pitchblende samples with colloidal structure features have the same physical and optical features as uraninite. The reason for this is that the uranium minerals formed at 1946 Ma experienced migmatization at 1829 Ma and the transformation of remobilization during Mesozoic period giving rise to the recrystallization of pitchblende and the formation of uraninite with pseudomorph of pitchblende. The uraninite-pitchblende-coffinite assemblage is an unique one and inherent for the remobilized old landmass of North China Platform, and the recrystallization of pitchblende and the uraninite with pseudomorph of pitchblende marks the remobilization of the Archean old landmass in the region.