Precambrian Terranes of the Central Asian Orogenic Belt: Comparative Characteristics, Types, and Peculiarities of Tectonic Evolution

Resumo

The structure and peculiarities of the tectonic evolution of Precambrian terranes included in the structure of Paleozoides in different parts of the Central Asian orogenic belt are reviewed; types and comparative characteristics of Precambrian terranes are provided. We shed light on two types of Precambrian terrane structures: essentially juvenile Neoproterozoic crust (1); Mezo- and Early Neoproterozoic crust formed due to reworking of Early Precambrian formations (2). Terranes with juvenile Neoproterozioc crust, located in the Central and Eastern parts of the Central Asian orogenic belt, were generated in the oceanic sector of the Earth. Their formation was related to the Early- and Late Neoproterozoic cycles of tectogenesis up to 200 Ma each. Terranes with Mezo- and Early Neoproterozoic crust, found mainly in the west of the Central Asian orogenic belt, were generated in the continental sector of the Earth during the Neoproterozoic and their evolution occurred mainly in intracontinental environments. During the evolution of all of the considered terranes in an interval of 800‒700 Ma, an event associated with rift zone formation and intraplate magmatism was revealed: it coincided with the breakup of the supercontinent of Rodinia. The conducted research makes it possible to relate the formation history of the Precambrian terranes of the Central Asian orogenic belt to processes that took place at the margin of the Syberia-Tarim part of Rodinia and the adjacent sector of the paleocean.