METALOGENIC THETHORIUM AND URANIUM OF INTERBLOK ZONES OF THE UKRAINIAN SHIELD (BY EXAMPLE OF BILOTSERKIVSKO-ODESKA ZONES)

Abstract

The peculiarities of the geological structure and geodynamic development of the Bilotserkivsko-Odeska interblock zone are considered. Possible connection of thorium-uranium mineralization with concrete dislocation structures and petrological processes is established. Some search criteria for thorium-uranium ores are given. The structural pattern of the Bilotserkivsko-Odeska zone is shown to be formed in several phases of structural- material transformation of the crystalline base under sheared conditions with changes in the tectonic pressure directions and P-T realisation condi- tions. In particular, such transformations of the first seven phases (Precambrian) took place under the R-T conditions, from granulite to green-shaft facies of metamorphism. Later transformations of the crystalline base took place under cold conditions. The final formation of the structural pattern of the Bilotserkivsko-Odeska zone occurred in the Paleoproterozoic, and the later tectonic violations (formed in cold conditions) did not significantly change the structure pattern of the established timestamp. U-, Th-ore bodies of the Bilotserkivsko-Odeska zone of all hierarchical levels are regular components of the structural patterns of the shear. The U and Th content of the granitoids increases with each phase of the structural-material trans- formations, while in the host-rock it decreases. The most significant U-Th concentrations are confined to the δ- and T-structures of the Paleoprotero- zoic structural pattern of this zone, which is the result of at least six stages of structural-material transformations of the crystalline base. All this indicates that the U-, Th-ore and ore-bearingbodies have the same history of formation – several phases of structural and material transformations of the crystalline basis, i.e. the ore substance was removed from the crystalline base rock, transformed (together with the non-metallic components), moved, and acquired new material and spatial forms, adapting to the corresponding R-T and kinematic conditions provoked by tectonic impulses, the number of which was at least eight.Therefore, the ore-prospective bodies occupy certain structural cells in the Paleoproterozoic structural pattern of the Bilotserkivsko-Odeska interblock zone – the pre-shift pressure shadows. We consider this affinity to be the leading search criterion.