First evidence of Ediacaran magmatism in the geological history of the Mamyn Terrane of the Central Asian fold belt

Abstract

U–Pb geochronological studies reveal that the gabbro of the Mikitkin Massif and quartz diorite of the Ust’-Garin Massif of the Mamyn Terrane, which were provisionally assigned to the Early Proterozoic Garin Complex, have ages of 583 ± 6 Ma and 607 ± 8 Ma, i.e. Upper Riphean–Lower Vendian. The geochemical features of the magmatic rocks of the studied massifs indicate their suprasubduction origin. The parental melts of the magmatic rocks of the Garin Complex were formed in an active continental margin or ensialic island-arc setting due to melting of the subduction-modified depleted mantle source and the occurrence of contamination and fractional crystallization. These massifs were developed during the Ediacaran Stage of the geological evolution of the Mamyn Terrane and presumably reflect Neoproterozoic convergent geodynamic processes. These processes likely caused the ultimate formation of the Precambrian continental massifs in the eastern Central Asian fold belt, which were subsequently amalgamated into the structure of the epi-Paleozoic Amur microcontinent.