The structures of the lateral extrusion of the western part of the Altai-Sayan folded area

The article deals with the tectonic structure of the Altai and conjugate regions of the Western part of the Altai-Sayan folded area (ASFA) in the context of its General geotectonic position in the Central Asian folded belt. Selected major structures of the lateral extrusion of first and second order, formed on the General contraction of this part of the accretionary margins of the epikaledonian Siberian paleocontinent in the middlepaleozoic-mesozoic time. The structures of the lateral extrusion of the first order include large and complex structures of the Salair and Western-Sayan blocks and a smaller Kulundian massif. As the structure of the second order, formed with a horizontal displacement of the structures of the first order, considered Kaimsko-Katunian group of blocks, Mrasskian block and the group of smaller blocks of the second order of the Westen-Sayan block (Ulaganian and Oroyki blocks of the second order). The time of the beginning of formation of the collisoin shear-thrust structure of the Altai region corresponds to the beginning of the development of the geodynamic regime of the active continental margin in the large part of the Western Altai-Sayan folded area and is defined as early Devon. Early period of most intensive horizontal displacements of the blocks with the development of thrust zones and large-amplitudian strike-slip faultes corresponds to Telbessian Orogenya in the mid-late Devonian time. During this period of time, the structures of the first order lateral extrusion were mainly formed. At a later stage, corresponding to the collision of continents and the Ural-lion Orogenia in the second half of carboniferous and at the beginning of Permian, mainly formed the structure of the lateral extrusion of the second order, which in some districtes was accompanied by a reverse effect. The subsequent Late- Triassic-Early-Jurassic and Early-Cretaceous compression periods did not have a significant impact on the overall structure of the region.

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