Postcollisional granitoids and aptian-albian extension in tectonic evolution of Chukotka mesozoides, Northeast Russia

Abstract

New U–Pb SIMS zircon datings from granitoid plutons and dikes of Western Chukotka together with earlier obtained data confirm that postcollisional granitoid magmatism and dike intrusion occurred in Aptian–Albian (117–105 m.y.) and fix change of tectonic regime from collision to extension in tectonic evolution of Chukotka Mesozoides. These events may be related to continuing expansion of Amerasian basin since Jurassic and forma- tion in Aptian—Albian time of both oceanic Makarov, Podvodnikov basins and Anakhurgen, Nutesyn and Kameshkov basins in continental framework of Eastern Arctic. Synchronism of tectonic events of extension and spreading in the Canada Basin and collisional events, deformations and reorganization of structural style and sedimentary environment in the South-Anyui suture is noted. This may be regarded as confirmation of rotation hypothesis of Amerasian Basin formation.