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

连山关铀矿床具有特殊的铀矿物组合,即晶质铀矿-沥青铀矿-铀石组合。其中主要矿物晶质铀矿和沥青铀矿的硬度、比重、反射率和晶胞参数都较其它矿床中这两种矿物的参数为大,含氧系数则较小。这表明铀矿物是在较高温度和强还原条件下形成。尤其有一部分具有胶状构造外表特征的沥青铀矿样品的各项参数均与晶质铀矿一样。其原因是,1.946Ga形成的铀矿物受到了1.829Ga混合岩化作用以及中生代活化作用的改造,使沥青铀矿重结晶,形成具有沥青铀矿假象的晶质铀矿。这种特征是该区太古宙古陆发生活化的标记,是华北地台活化古陆所特有的铀矿物组合特征。

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.