LATE CAMBRIAN-ORDOVICIAN TECTONICS AND GEODYNAMICS OF CENTRAL ASIA
N.L. Dobretsov, M.M. Buslov
Institute of Geology and Mineralogy, Siberian Branch of the RAS, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
Keywords: Accretion-collision processes, Gondwana-derived microcontinents, island arc, orogen, mantle plume
Pages: 71-82
Abstract
In the Late Cambrian-Ordovician, Gondwana-derived microcontinents such as Kokchetav, Altai-Mongolian, Tuva-Mongolian, and Barguzin, as well as the Kazakhstan-Tuva-Mongolian island arc or a system of island arcs were involved in intense accretion-collision processes in similar geodynamic settings on a vast territory of Central Asia - from West Kazakhstan to Lake Baikal. The processes were likely to be the result of a large rebuilding of the Earth's crust possibly related to the increased mantle impact on the lithosphere as they were simultaneous to the opening of the Uralian and Mongolian-Okhotsk (Turkestan) Oceans. The 970-850 Ma breakup of Rodinia and the 760-700 Ma important tectonic events were followed by the Late Cambrian-Early Ordovician plume magmatism impulse at 500-480 Ma, which led to the opening of new oceans and accelerated the accretion of the Gondwana-derived blocks to the island arc and subsequent formation of an extended - more than 6000 km long - Kazakhstan-Baikal orogenic belt.
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