Tectonic evolution of the Amerasia Basin, Arctic Ocean

Abstract

The tectonic evolution of the Arctic Ocean remains debated. We present a new interpretation of selected seismic profiles for the Amerasia Basin. We extend and correlate the seismic stratigraphy for the area from the Alpha-Mendeleev Rise to the Canada Basin. The seismic stratigraphy is tied to isotope ages of volcanic rocks. It shows that the Canada Basin postdates formation of the Alpha-Mendeleev Rise. We distinguish the following stages in the formation of the Amerasia Basin: Stage 1. Jurassic-Neocomian formation of continental rifts. Stage 2. Barremian (Aptian)-Albian (125–100 Ma) large-scale extensional tectonics and magmatism in the Alpha-Mendeleev Rise and adjacent basins, formation of SDR-type complexes and failed passive volcanic continental margins. Continental rifting occurs with local formation of SDR-type complexes in the future Canada Basin. Stage 3. Late Cretaceous (100–70 Ma) back-arc opening of the Canada Basin with rotation of Alaska toward the Pacific Ocean. Transitional crust and highly stretched (hyper-extended) continental crust formed first, followed by oceanic crust. Sea-floor spreading propagated toward the Nautilus Basin and the Alpha-Mendeleev Rise. Large submarine volcanoes formed during late stages of the opening. Stage 4. ca. 70–56 Ma formation of graben systems in the 78˚N Basin, Stefansson Basin, north and east of the Chukchi Borderland. Stage 5. Cenozoic general subsidence of the basin and formation of normal faults north of the Chukchi Borderland. Amerasia Basin formation began just after the end of the Verkhoyansk-Chukotka collision orogeny and South Anyui Ocean closure, simultaneously with orogenic collapse.