Development of the Verkhoyansk-Kolyma orogenic system as a result of interaction of adjacent continental and oceanic plates

The Mid-Cretaceous Verkhoyansk-Chukchi Tectonic Domain is characterized by fanlike diverging systems of tectonic sheets and imbricate thrusts verging to the two framing continents. The Verkhoyansk and New Siberian-Chukchi-Brooks Fold-Thrust systems of the deformed margins of the Siberian and Hyperborean-North American continents, respectively, adjoin the inner Verkhoyansk-Kolyma Collision System. The above fold-thrust systems include the Verkhoyansk and Colville foredeeps coeval with thrusting. The Verkhoyansk-Kolyma Fold-Nappe System is composed of Cambrian to Upper Jurassic oceanic, marginal-sea, and island-arc complexes and bounded by a collision suture consisting of the Kolyma Loop abutted on the South Anyui segment along a left-lateral strike-slip fault. The inner root zone and the outer zone of nappes overthrusting the adjacent continents are distinguished in the suture. Several levels of structural unconformities, olistostrome-molasse sequences, and zones of amphibolite-greenschist metamorphism coeval with thrusting correspond to particular stages in the evolution of the Verkhoyansk-Kolyma System. The Neoproterozoic and Early Paleozoic oceans closed during the Baikalian and Caledonian orogenies. The Alazeya-South Anyui-Angayucham ocean that evolved from the Devonian to the Late Jurassic was subject to gradual closure against the background of trilateral compression during convergence of the Siberian and Hyperborean-North American cratons and accretion and collision along the Pacific margin. The fold-nappe structure of the Verkhoyansk-Kolyma Orogen and the boundary collision suture were disturbed by left-lateral strike-slip faults during Mid-Cretaceous compression, and the South Anyui segment of the suture was displaced to the northwest along the strike-slip fault. The Mid-Cretaceous Orogeny at the Pacific margin gave rise to meridional compression of its back zone and latitudinal squashing of the Verkhoyansk-Kolyma Orogen with formation of the Kolyma and Kobuk looplike limitations.