TECTONICS OF THE EASTERN ARCTIC AND ORIGIN OF THE AMERASIA BASIN
S.D. Sokolov1,*, L.I. Lobkovsky2,3, V.A. Vernikovsky4,5, V.A. Poselov6, O.E. Smirnov6, M.I. Tuchkova1, E.V. Shipilov7, N.O. Sorokhtin2, A.A. Baranov8, A.M. Bobrov8, S.M. Zholondz6
1Geological Institute, Russian Academy of Sciences, Moscow, Russia
2Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia
3Moscow Institute of Physics and Technology, Dolgoprudny, Russia
4Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, pr. Akademika Koptyuga 3, Russia
5Novosibirsk State University, Novosibirsk, Russia
6VNIIOkeangeologia, St. Petersburg, Russia
7Polar Geophysical Institute, Murmansk, Russia
8Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia
Keywords: Tectonics, geodynamics, Mesozoic, Eastern Arctic, Amerasia Basin, Chukotka, Arctic Alaska, Central Arctic uplifts
Abstract
We provide a brief description of the main structures in the Eastern Arctic, in the evolution of which two major stages have been distinguished and considered: the late Paleozoic–early Mesozoic and the Late Jurassic–Early Cretaceous. We have established the synchronicity of tectonic events on the Arctic margins of Northeast Asia and Arctic Alaska and within the structures of the Amerasia Basin, indicating the existence of a cause-and-effect relation between the compression (fold-and-thrust structures) and extension (rifting and spreading in the Canada Basin). We have proposed the tectonic models of the formation of fold-and-thrust structures in Chukotka and Arctic Alaska and have determined their similarities and differences. Paleotectonic reconstructions have been performed for 160 and 120 Ma. We present a critical review of the concepts about the formation of the structures in the Amerasia Basin and provide a subduction-convection geodynamic model according to the analysis of seismic tomography of the mantle and regional geology and tectonics data. This model was previously used to describe the Cretaceous and Cenozoic evolution of the Arctic lithosphere at a qualitative level. The model is based on the idea of the existence of a two-tier subduction system: a horizontally extended convection cell in the upper mantle, coupled with a conveyor mechanism of subduction of the Pacific lithosphere. As a result, there is a convergence of the “outer” Pacific subduction zone and the “inner” subduction zone located inside the South Anyui and Angayucham oceanic basins, which provides their closure and subsequent collision. Under the influence of the reverse upper mantle flow, scattered deformations of the Amerasia lithosphere occur, caused by viscous dragging with flows beneath the lithosphere, which is the reason for the diversity of the structures in the Amerasia Basin and the Canada Basin in particular. In addition, the developed geodynamic model is supplemented by a tectonic and magmatic mechanism of crustal subsidence and the formation of sedimentary basins.
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