Age and Sources of the Protolith of Amphibolites of the Tulovchikha Formation in the Northeastern Bureya Continental Massif of the Central Asian Orogenic Belt

The results of mineralogical, geochemical, Sm‒Nd isotopic-geochemical studies of bulk composition of metamorphic rocks in the northeastern Bureya continental massif, as well as U‒Th‒Pb (LA-ICP-MS) geochronological studies of zircons extracted from them in order to determine the age and sources of their protolith are presented. It is established that the amphibolites of the Tulovchikha Formation are of primary magmatic origin, and their protolith is Late Tonian (about 760 Ma) rather than Early Precambrian, as it was traditionally believed. The obtained age estimate is the first for metamorphic rocks of the Tulovchikha Formation within the northeastern Bureya massif. Sm‒Nd isotopic-geochemical features of the amphibolites indicate melting of Neoproterozoic juvenile source and contamination of melts with Paleoproterozoic crustal material in a continental arc environment during the formation of initial melts for their protolith. The chronology of the late Tonian magmatism covering the Bureya, Songnen-Zhangguangcai Range, and Jiamusi-Khanka continental massifs of the eastern part of the Central Asian Orogenic belt is well consistent with stage of destruction of the Rodinia supercontinent.