New results of zircon study (U–Pb method, SHRIMP II) from metavolcanic rocks of the upper structural-compositional unit of the Maksyutov complex, Sakmara River, the area of settlement of Novotroitsky, are presented. It is established that zircon from metavolcanic rocks forms three age groups. Ancient Early Proterozoic (2060 ± 22 Ma) continental-type zircon is xenogenic. Igneous Early Cambrian (517 ± 7 Ma) zircon registers the crystallization of oceanic basalt. Metamorphic Early Devonian (411 ± 5 Ma) zircon reflects progressive metamorphism at a temperature of 395–418°C.
Valizer et al. (Sun,) studied this question.