U-PB AGE OF ZIRCON AND MONAZITE FROM GRANITES OF THE KIROVOGRAD MASSIF

Previous studies using the TIMS method determined the age of zircon from granites of the Kirovograd (2065±20 Ma) and Bobrynets (2026±20 Ma) massifs [Shcherbak et al.] Similar ages of zircons from granites of the Kirovograd massif were obtained by LA-ICP-MS: 2062±11 Ma (quarry in Subottsi village), 2056±11 Ma (Elgran quarry). Much older ages of 2717±18 Ma for the nuclear parts of the crystals and 2267±20 Ma for the outer parts were obtained for zircon from granite of sample NU-15 (probably also from the Subottsi quarry) [Shumlyansky and , 2015]. At the same time, monazites are characterized by significantly lower age values - 2033.7 ± 2.9 Ma [Step. et al., 2021]. Mineralogical studies have shown that the reason for the difference in numerical age values is ancient radiogenic lead in the nuclear parts of zircon crystals.