Home – Home – Jornals – Russian Geology and Geophysics 2018 number Неопубликованное

The article summarizes published and new geological, geochronological, biogeographical, paleomagnetic, and petrological-geochemical data to support the tectonic zoning of the Central Asian Fold Belt (CAFB) and its Vendian-Paleozoic geodynamic evolution as a complex folded structure consisting of deformed fragments of collisional and accretionary orogens. It has been shown that the Central Asian-Siberian Platform was formed in the zone of junction of the collisional and accretionary margins of the Siberian craton, similar to the modern tectonic interactions between the Indo-Atlantic and Pacific global tectonic segments of the Earth and Eurasia. It has been shown that in the Vendian and Early Ordovician, there were two active margins around the Siberian craton: the collisional Tuvo-Mongolian margin and the accretionary Kuznetsk-Altai margin, which separated the craton from the tectonic plates of the Paleo-Asian Ocean (Indo-Atlantic segment) and the Paleo-Pacific Ocean (Pacific segment), respectively.A distinctive feature of the Paleoasiatic Ocean plate is complex structure, which includes fragments of oceanic crust and Precambrian Gondwana microcontinents with fragments of the Grenville orogeny. Fragmentary Grenville zircons (1.3-0.9 billion years old) are widely found in the Vendian-Paleozoic sedimentary deposits of various geodynamic settings of the collisional orogen. A distinctive feature of the accretion orogen is the widespread presence of oceanic crust fragments and the absence of Precambrian blocks of Gondwana, and as a result, the absence of Granville-age clastic zircons in the Vendian-Paleozoic sedimentary rocks of various geodynamic settings. The Early-to-Middle Paleozoic Charysh-Terekta-Ulagan-Sayan-Olkhon suture-shear zone separates the collisional orogen from the shelf of the back arc basin located in the northern part of the Altai-Sayan folded region framed by the Siberian craton. The suture-shear zone consists of fragments of the Vendian-Early Paleozoic oceanic crust of the Back Arc basin, Ordovician blue shales and Ordovician-Silurian turbidites, Late Silurian-Devonian collisional metamorphic rocks and granites. Based on the structural position of the suture-shear zone and the data of petrological and geochronological studies, it is concluded that it is a subduction-collision complex formed at the site of the back-arc basin of the Vendian-Cambrian Tuva-Mongolian island arc. Late Paleozoic shifts and thrusts manifested themselves in the CAFB in the Late Devonian-Early Carboniferous as a result of the collision of the Kazakhstan-Baikal orogen (composite continent) with the Siberian craton with the formation of the North Asian continent, and in the Late Carboniferous-Triassic as a result of the collision of the East European and North Asian continents. As a result of collisional events, the initially linear structures of the collisional and accretionary orogens were deformed into large oroclinal folds, divided by shifts and thrusts into many fragments, where the Vendian-Paleozoic structures are complicated by thrust-fold deformations.