TECTONICS OF THE URALS AND THE BASEMENT OF WEST SIBERIA: GEOLOGY AND DEVELOPMENT FEATURES

K. S. Ivanov, V. A. Kontorovich, V. N. Puchkov, Yu. N. Fyodorov , Yu. V. Erokhin

Urals as a folded system had undergone two complete cycles of geodynamic development in the Riphean-Mesozoic time. The first cycle occurred in the Riphean and Vendian and ended by formation of the Timanides, the second one is dated as Paleozoic and early Mesozoic, corresponds to the Uralides, and can be divided into eight stages: (1) Continental riftogenesis (Cambrian - Early Ordovician). (2) Oceanic spreading (Middle-Late Ordovician). (3) Island arc (Late Ordovician - Early Carboniferous). (4) Early collision (Late Devonian-Early Carboniferous; between the Magnitogorsk island arc and the passive margin of Laurussia). (5) Late subduction with the crust consumption of the Paleouralian Ocean (Carboniferous). (6) Collision of Laurussian and the Kazakhstanian continents. (7) Limited post-collisional extension and superplume magmatism (Triassic). (8) Deformation in the Early Jurassic time. The basement of the western part of the West Siberian plate is a continuation of the structural zones of the eastern sector of Uralides, while the basement of the eastern part of the plate belongs to the Siberian craton and its folded margin. A huge block of the Kazakhstanides is situated to the east of the Uralides and pinches out to the north. These main domains of the basement are divided by two major ophiolite sutures. The Triassic rifting was marked by formation of graben systems composed of basalt-rhyolite complexes. Wide distribution of Triassic volcanogenic complexes within the basement of the West Siberian plate makes its principal difference from the Urals.

Key words: the Uralides, geodynamic cycle, the West Siberian Plate, basement tectonics, continental riftogenesis, Riphean, Mesozoic.

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