MULTISTAGE THRUST AND NAPPE TECTONICS IN THE SOUTHEASTERN PART OF EAST SAYAN AND ITS ROLE IN THE FORMATION OF GOLD DEPOSITS
I.V. Gordienko1, N.L. Dobretsov2, S.M. Zhmodik3, P.A. Roshchektaev4
1Geological Institute, Siberian Branch of the Russian Academy of Sciences, ul. Sakh’yanovoi 6a, Ulan-Ude, 670047, Russia
2Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, ul. Pirogova 1, Novosibirsk, 630090, Russia
3V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, ul. Pirogova 1, Novosibirsk, 630090, Russia
4OOO Rifei, ul. Babushkina 185, Ulan-Ude, 670047, Russia
Keywords: Thrust and nappe tectonics, geodynamics, ophiolites, island arcs, marginal sea, allochthonous terranes, collision zones, intraplate magmatism, genesis of gold deposits, East Sayan
Abstract
Comprehensive studies of structural geology and metallogeny, taking into account the authors’ previous works started as early as the last century, have shown that the southeastern part of East Sayan formed mainly in the Neoproterozoic-early Paleozoic in the settings of multistage thrust and nappe tectonics and tectonomagmatic restructuring of autochthonous and overthrust allochthonous oceanic (ophiolitic), island arc, and ocean-marginal terranes as well as amalgamation of accretion-collision and postcollisional igneous complexes that formed during the opening and subsequent closure of the Paleoasian Ocean marginal structures. In the middle and late Paleozoic, active intraplate volcanic and plutonic processes continued in the thrust/overthrust fault setting, which led to the formation of new dome-shaped nappe structures and the redistribution of ore matter (gold etc.) in large mineral deposits. The final structure of the East Sayan region formed during the late Cenosoic as a result of mountain uplifting and volcanic eruptions, including those in the valley of the Zhombolok River.
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