THE HISTORY OF THE KARAGAS SUPERGROUP EVOLUTION IN THE BIRUSA REGION: SYNTHESIS OF PALEOMAGNETIC AND SEDIMENTOLOGICAL DATA
D.V. Metelkina,b, V.V. Blagovidovb, and A.Yu. Kazanskya,b
a A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, prosp. Akad. Koptyuga 3, Novosibirsk, 630090, Russia
b Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
Keywords: Neoproterozoic, sedimentary basin, depositional environment, paleomagnetic pole, Siberian craton, Rodinia
Pages: 868-884
Abstract
We summarize the results of paleomagnetic and sedimentological studies of the Neoproterozoic rhythmic terrigenous-carbonate rock unit in the Karagas Supergroup, which were carried out in the middle reaches of the Biryusa and Uda Rivers. The paleomagnetic data are presented along with a detailed description of the studied sections and the specific sedmentological characteristics of the studied deposits. The new data refine the position of Late Precambrian paleomagnetic poles in Siberia and mark the paleogeographic and facies features of the rock unit formation. They also show that the rock unit was deposited much more rapidly than it was supposed earlier, in the environment of shallow-water sea basin on the margin of the Siberian continent. The origin and evolution of the Karagas sedimentary basin was governed by both global and regional tectonic factors. We associate the initiation of the basin with a global tectonic event, namely, the opening of ocean in southern Siberia during the break-up of Rodinia. Regional tectonic processes controlled the position of the Karagas sedimentary basin and its evolution. The position of the mean paleomagnetic pole (Plat = 3.9°, Plong = 292.3°, A95 = 7.1°) confirms the corresponding interval of the Neoproterozoic trend of APW in Siberia and proves the near-equatorial position of the continent in Karagas time.
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