Central Ukraine Uranium Province: The Genetic Model

This paper presents a descriptive genetic model of the Central Ukraine Uranium Province (CUUP), the largest U Province related to Na-metasomatism around the world. It is located in the Palaeoproterozoic metamorphic-magmatic complexes of the Ukrainian Shield. Na-metasomatic alterations are fault-controlled, regionally extended along crustal scale tectonic fault structures. Economic U-mineralization follows brittle deformations in extensive areas of multistage metasomatites spatially controlled by ductile to brittle deformation structures. The Na-metasomatism model suggests interaction of the host rocks with heated marine water infiltrating along the structures. U mineralization is related to later percolation of hydrothermal fluids resulting in Ca- and K-metasomatic alterations. ⁸⁷Sr/⁸⁶Sr, δ¹³C and δ¹⁸O isotopic data characterize a deep crustal source for the mineralizing hydrothermal fluids related to the crust dehydration during metamorphism. An enrichment in HFSE and LILE may indicate their derivation from the last stage granitic melts enriched in incompatible elements and reflecting melting within zones of contrasting thickness in the lithosphere induced by a mantle plume and evidenced by successive magmatic events from regional injection of basic dyke swarms to decompression melting with emplacement of a large A-type granitic batholith. (author)