Object of investigation - crystalline rocks from deposits of uranium-potassic and uranium-sodic associations of Precambrian complexes of Ingul megablock, the Ukrainian Shield. The aim of the work - to develop mineralogical-geochemical and secular criteria of searches for uranium deposits of potassic-uranium (K-U) and sodic-uranium (Na-U) associations in Precambrian complexes of Ingul megablock of the Ukrainian Shield (USh). Methods of investigations - uranium-lead isotopic method, rubidium-strontium isotopic method, methods of optical and electronic microscopy, field searches. For the first time, scandium bearing pyroxene has been found in uranium ores (Vatutinka deposit, horizon 542) by microprobe investigations of albitites of Kirovograd block. Unlike scandium-bearing acmite of Zheltaya Rechka deposit, Sc2O3 content of which hardly reaches the first tenth of percent, aegirine-diopsides of Vatutinka show the presence of several percents of Sc2O3 and in some phases it exceeds 10 weight %. Isotopic Rb-Sr investigations of rocks of granite-albitite series testify for deep source of hydrothermal solutions, which interaction with granitoides and gneisses have resulted in the formation of uraniferous albitites. Uranium mineralization of uranium-sodic associations is supposed to be confined to deep faults of mantle origin. As a result of geological searches and uranium-lead isotopic dating, it is established that formation of uranium-thorium-rare-earth mineralization of potassic-uranium associations occurs during one stage at 2,03 billion years. This stage starts from granitoide formation with following metasomatic alterations of host rocks under fluids activity and finished by the formation of mineralization itself. Following criteria of localisation of uranium ore mineralization are established: a) sodic-uranium association: 1. Structural-tectonic (albitites and uranium ore mineralization are confined to the zones of deep faults). 2. Mineralogical (vertical mineralogical zonation). 3. Isotopic-geochemical (zones with the highest uranium contents are characterized by the lowest values of 87Sr/86Sr ratios). b) potassic-uranium association: 1. Structural (zones of uranium ore mineralization are spatially confined to the bodies of parental granitoides). 2. Mineralogical (hypogene uranium minerals of К-U associations are characterized by more high content of thorium and rare-earths).
2010 to 2012