Geodynamic Model of Arctic Region Evolution in Mesozoic and Cenozoic as Result of Interaction between Deforming Plates and Upper Mantle Flows

Leopold Lobkovsky

Here we present a new geodynamic model of the Arctic, which is based on the presently evolving concept of the «tectonics of deforming lithosphere plates» together with the development of the upper mantle convection caused by subduction of the Pacific lithosphere under the Eurasian and North American lithospheric plates. Essentially instead of kinematic description of rigid plate rotation on Euler poles over the sphere (classic theory of plate tectonics) the new conception uses recent achievements in computer numerical analysis of 3D elasticplastic lithosphere deformations combined with numerical 3D modeling of underlying mantle flows. In our study the tectonic development of the Arctic Region in the Mesozoic and Cenozoic is reconstructed using consideration of Paleozoic evolution of the Arctida paleocontinent. Based on the available geological and geophysical data, it can be concluded that the Late Mesozoic and Cenozoic evolution of the central Arctic consecutively passed two main geodynamic phases. The first phase (Jurassic–Aptian) was characterized by the stress field with a substantial component of NW–SE extension, which led to the separation of the Chukotka–Alaska system of Arctida blocks from the North American continent, the southward movement of Chukotka, its collision with the Eurasian margin related to the closure of the South Anyui ocean, and opening of CA Basin. The second stage of evolution began in the Aptian (~120 Ma) with the formation of the postcollisional ~ E-W extensional stress field (e.g. Miller and Verzhbitsky, 2009). We believe that in the Aptian–Late Cretaceous this regime controlled rifting in the Central Arctic domain of the lithosphere, including the Makarov and Podvodnikov basins and the Alpha–Mendeleev Rise. In the Cenozoic, the effect of this stress field resulted in the opening of the oceanic Eurasia Basin and rifting of the Lomonosov Ridge apart from the Barents–Kara continental margin. The final closure of the South Anyui ocean in the Aptian time (Sokolov et al., 2002; 2009) led to the termination of spreading in the CA Basin and an abrupt deceleration of subduction-related mantle material sinking in the South Anyui Zone. The remained active subduction zone on the Pacific side created ~ E-W pulling effect in the lithosphere of the Eastern and Central Arctic. As a result, the blocks of formerly single Arctida began to move along the large strike–slip faults toward the Pacific. Namely that time, the stress field was rearranged by approximately 90 degrees. In general, the complex analysis of the geological evolution of the Arctic Region led us to conclusion that the main deep-water structural units of the lithosphere of the Central Arctic - Lomonosov Ridge and Alpha–Mendeleev Rise, as well as Makarov and Podvodnikov Basins, represent the rifted fragments of the Arctida paleocontinent.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013