Home – Home – Jornals – Russian Geology and Geophysics 2006 number 1

We discuss the structure of the Yenisei Ridge fold and thrust belt, its Paleoproterozoic and Neoproterozoic geodynamic evolution, and the related granitoid magmatism. Many previous studies interpreted the Yenisei Ridge as a fold belt upon Archean and Paleo-Proterozoic basement composed of high-grade metamorphic and igneous rocks discordantly overlain by Mesoproterozoic-Neoproterozoic sediments metamorphosed under greenschist-facies conditions. We used the available and new geological, petrological, geochemical, and U-Pb zircon data to reveal several terranes of different ages and compositions which were assembled in the course of Paleoproterozoic and Neoproterozoic collision-accretionary movements on the western periphery of the Siberian craton. We suggest that the fold and thrust belt evolved in four major tectonic stages at 1900-1840, 880-860, 760-720, and 700-630 Ma. The earliest event was associated with high-grade metamorphism (granulite to amphibolite facies) and emplacement of the Taraka granites within the Angara-Kan terrane. The following event occurred at 880-860 Ma, but the Eruda, Kalamy, and Teya granites had rather emplaced beyond the Yenisei Ridge within the Central Angara terrane before it collided with Siberia. The latter collision (the third event) was apparently responsible for the Chirimba, Ayakhta, and Glushikha granites (760-720 Ma). The fourth event in the Neoproterozoic-Vendian (700-630 Ma) is constrained by the age of island-arc and ophiolite complexes and their obduction onto the Siberia cratonic margin. The same activity (650-630 Ma) in the central part of the fold and thrust belt produced the Tatarka complex composed of A -type granites, nepheline syenites, and carbonatites of mantle and crust-mantle origin.