Age of Granites of the Kropyvnytsko-Bobrynetsky Massif (Ingul Megablock of the Ukrainian Shield)

The uranium-lead isotope systems of accessory monazites from porphyry-like and pegmatoid granites of the Kropyvnytsko-Bobrynets massif (Ingul megablock), which were opened by the Zhyvanivka quarry, located on the left bank of the Sugokleya River, southwest of the village of Zhyvanivka, were studied. For isotopic dating, multigrain monazite samples were taken manually under a binocular, and then the monofraction was separated by size by rolling on an inclined plane. The preparations with monofractions of monazite and zircon crystals, as well as polished grinds of porphyry-like and pegmatoid granites, were studied by optical microscopy. The results of the study of the mineral composition, petrographic and structural-textural features of granites are presented. The time of formation of the granites (2032-2036 Ma) exposed by the Zhyvanivsky quarry fits fully into the age interval of the formation of the Kropyvnytsky complex (2040-2020 Ma) of the Ingul megablock of the Ukrainian Shield in general and the granites of the Kropyvnytsky massif in particular.