Permian and Triassic deposits of Siberian and Chukotka passive margins: sedimentation setting and provenanceстатья

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[1] Permian and triassic deposits of siberian and chukotka passive margins: sedimentation setting and provenance / M. I. Тuchkova, S. D. Sokolov, A. K. Khudoley et al. // ICAM VI Proceedings. — Petersburg: VSEGEI, 2014. — P. 61–96. The numerous current hypotheses on structural evolution of the present day Arctic require validation using data from regional geological studies. We are focusing on terrigenous deposits of Triassic age, which are the key to correlate geological events from the Eastern Arctic and the Verkhoyansk-Kolyma and Anyui-Chukotka fold systems. Triassic deposits of the Verkhoyansk–Kolyma fold system formed along the eastern margin of the Siberian continent. In the Anyui-Chukotka fold system, Triassic deposits accumulated on the southern margin of the Chukotka microcontinent. In present day structure heavily deformed sedimentary complexes of the two passive margins are brought closely together as a result of collision. The Siberian continent collided with the Kolyma – Omolon superterrane to form the Verkhoyansk–Kolyma fold belt. The Anyui- Chukotka fold system was formed as the result of collision between the Siberian continent and the Chukotka microcontinent associated with opening of the Canada Basin within the Amerasia Basin. The main results of our studies are: the directions of sedimentary supply and shelf zone progradation in the present day structure of theVerkhoyansk region and Chukotka differ by almost 180o. Changes in the sandstone mineral composition during the Triassic provide evidence of different source provinces for deposits of the Verkhoyansk and Chukotka passive margins. Changes in the chemical composition imply different evolutionary patterns of the rocks. Compositions of detrital zircon assemblages show dominant spikes of different ages: Verkhoyansk region is dominated by Proterozoic assemblages, and Chukotka by Phanerozoic ones. The level and type of deformation in both cases is represented by folds-and-thrusts of different vergence.

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