Shestopalova O. Geochronology of Korsun-Novomirgorod Pluton

The thesis is devoted to isotopic-geochronological study of rocks that make up the Korsun-Novomirgorodsky pluton (KNP). In the course of research, the age of formation of intrusive phases of KNP and the origin of sources(crust-mantle) of initial melts for gabbroids and rapakivi granites were determined. The age of intrusion of KNP is 1.80-1.74 Ga. Three stages of formation have been determined for the main pluton rocks: white anorthosites - 1.80-1.79 Ga; аnorthosites and gabbro-anorthosites of main volume of basic massifs were formed in the interval of 1.77-1.74 Ga; the KNP granitoids were formed in a short time, or with a slight interruption of the intrusive phases in the interval of (1.754-1.748 Ga) years ago. The crust material played significant role in the formation of rock melts of the KNP. This is evidenced by the studies of Rb-Sr and Sm-Nd isotopic systems and the presence of the relic nuclei in zircon. The obtained results testify to the paragenetic connection (mantle source of energy and fluids) during the formation of the rocks of the KNP and the uranium-ore mineralization of the albite-uranium type. This is confirmed by their synchronous formation and well agrees with the results of the investigation of Rb-Sr isotopic systems.