Geologic concepts of the Arctic Ocean basin are that it is (1) a permanent or old feature of the earth's crust, dating from at least the early Paleozoic and probably from the Proterozoic, or (2) a relatively young feature, Mesozoic and/or Cenozoic, formed by subsidence of continental crust or by continental drift, through a process of rifting and/or sea-floor spreading. If the Arctic basin is considered as a whole, the great differences between parts of the basin indicate that its overall tectonic history has been far too complicated to be explained by either hypothesis.

Oceanographic and geophysical studies indicate that the Arctic Ocean basin is not a uniformly deep basin isolated from the world ocean system, but that it is divided into separate basins by submarine mountain ranges. The Eurasian basin, separated from the Canada basin by the Lomonosov Ridge, is connected to the northern Atlantic by a deep trough. The Gakkel Ridge, which crosses the Eurasian basin as an extension of the Mid-Atlantic Ridge, has volcanic and seismic activity that can be related to sea-floor spreading.

The shape of the Lomonosov Ridge shows a good fit with the continental margin of Eurasia, and the ridge appears to be a narrow fragment of Eurasia that has drifted passively into the center of the Arctic Ocean as the Eurasian basin spread.

The Canada basin, on the other side of the Lomonosov Ridge, contains the Alpha Cordillera, which is probably a dormant midocean ridge from an older period of seafloor spreading. The opposite margins of the Canada basin do not have a good geometric fit.

Undeformed Cenozoic and, in places, Mesozoic deposits rimming both the Eurasian and the Canada basins indicate that no major movement has occurred between the floor of the Arctic Ocean basin and its continental margins since at least Early Cretaceous time.

Paleozoic rocks around the edges of the Arctic Ocean are generally much more deformed than Mesozoic and Cenozoic rocks. The Canada basin is rimmed on the south by a discontinuously exposed system of Paleozoic fold belts, elements of which seem to extend into both ends of the Lomonosov Ridge. The early development of geosynclines along the margins of the modern Canada basin--followed by deformation, metamorphism, granite intrusion, and major uplift and clastic-wedge sedimentation--indicates that a proto-Canada basin with continental margin tectonics existed in the early Paleozoic.

The Eurasian basin appears to be a feature much younger than the Canada basin. No Paleozoic fold belts parallel its edges; instead, the Eurasian basin appears to truncate the Ural, Cherskiy, and Verkhoyansk fold belts.

The close similarity in the geology of Alaska and Siberia indicates that North America and Asia have been connected since the Paleozoic, and probably since the Precambrian, and that a proto-Canada basin, structurally separate from the Pacific and the Atlantic, can be identified as a center of Paleozoic marine sedimentation that served as an avenue for polar migration of faunas. Stratigraphic, structural, and petrologic features suggest that the boundary between the Paleozoic Cherskiy fold belt and the Mesozoic Verkhoyansk fold belt marks the suture of the Eurasian and North American continental plates that collided in Early Cretaceous time, perhaps as a consequence of opening of the Atlantic.

The available data are best explained by considering a series of stages in the development of the Arctic, beginning with development of a proto-Canada basin (Cambrian-Middle Devonian), which probably closed in Late Devonian-Early Mississippian time, followed by formation of successor basins (Mississippian-Triassic), opening of the modern Canada basin (Late Jurassic or Early Cretaceous), development of the deep Canada basin (Late Cretaceous), and opening of the Eurasian basin in connection with sea-floor spreading from Gakkel Ridge (Cenozoic).