Океаническая кора, трансрегиональные зоны сдвига и Амеразийская микроплита в мел-кайнозойской геодинамике формирования океана в Арктике

Abstract

The author has reconstructed the structural-tectonic setting of the Late Cretaceous-Early Cenozoic stage of the geodynamic evolution of the Arctic Ocean. It is shown that the oceanic crust in the Eurasian and Canadian basins occupies a much smaller area than previously thought and was formed in both on blocks of the continental basement strongly stretched by Cretaceous rifting. Due to the processes, large and extended transregional shear zones were set in motion: the Chukchi-Canadian during the opening of the Canadian basin in the Early Cretaceous, and the continental marginal ones — Khatanga-Lomonosov and Northern Greenland-Canadian, the activation of shear movements in which is associated with the Late Cretaceous-Paleocene time, when the consistent formation of the Makarov and Eurasian basins took place. As a result new composite Amerasian microplate was detached and set in motion, which combined the blocks of Arctic Alaska, the Canadian Basin, the Chukchi Rise, the Alpha–Mendeleev Rise, the Podvodnikov and Makarov Basins, and the Lomonosov Ridge. The movement of the microplate along approximately parallel large shear zones at the edges of the Canadian Arctic and Siberian-Chukotka shelves was directed towards the Pacific subduction zone. The movement of the Amerasian microplate was accompanied by rifting and detachment of the Lomonosov Ridge from the Barents-Kara margin, opening of the Eurasian Basin in the rear of the ridge, and transform displacements — right-sided along the Khatanga-Lomonosov zone and left-sided along the North Greenland-Canadian fault zone. At the same time, as a result of the movement of the Amerasian microplate, the previously unified area of Cretaceous plateau basalts (HALIP) was broken, and the Central Arctic province of magmatism was separated and moved away from the Barents Sea province.