Roles of Postcollisional Granitoids and Aptian–Albian Extension in Tectonic Evolution of Mesozoic Structures on Chukchi Peninsula, Northeastern Russia

Resumo

New U–Pb SIMS zircon datings from granitoid plutons and dikes of Western Chukotka, together with data obtained earlier, confirm that postcollisional granitoid magmatism and dike intrusion occurred in the Aptian–Albian (117–105 Ma ago) and marked a change in the tectonic regime during tectonic evolution of Chukotka Mesozoides from collision to extension. These events might be related to the opening of the Amerasian Basin, which had begun in the Jurassic, and to the formation (in the Aptian–Albian time) of the Makarov and Podvodnikov oceanic basins, as well as the Anakhurgen, Nutesyn, and Kameshkov basins in the continental framework of the Eastern Arctic. The synchronicity of the tectonic extension and spreading events in the Canada Basin, on the one hand, and collisional events, deformations, and reorganization of structural style and sedimentary environment in the South Anyui suture, on the other hand, is noted. This may be regarded as confirmation of the rotation hypothesis of formation of the Amerasian Basin.