Geologic Structure and Tectonic Evolution of the Canada Basin, Arctic Ocean

By

A. Grantz (Stanford University), L.C. Kovacs (Naval Research Laboratory), D.C. McAdoo (NOAA Geoscience Lab), and P.E. Hart (U.S. Geological Survey)

Geophysical and geologic data indicate that Canada Basin is underlain by oceanic crust of normal thickness (7 +/- 1 km) formed in two stages of sea-floor spreading that followed Sinemurian to early Neocomian pre-breakup extension. The earlier stage of spreading separated Northwind Ridge from the Arctic Islands, and rotated it 35 degrees clockwise, during the Berriasian (?) and Valanginian. The younger stage, well expressed in low-amplitude magnetic anomalies that radiate northward from a pole in the lower Mackenzie Valley, is Hauterivian to earliest Aptian. The axis of these anomalies coincides with a narrow linear negative gravity anomaly that is typical of extinct spreading centers, and a graben recorded in seismic reflection data.

Sediment from the Mackenzie River deposited a clastic wedge (oceanic layer 1) in the Canada Basin that is 14 km thick at the Mackenzie Delta and thins to 5 to 7 km beneath the western part of the basin. Underlying layer 1 are well-bedded strata of erratic thickness ranging up to 1 km that contain strong seismic reflectors and intrusive bodies. We interpret this unit, which contains numerous normal faults older than layer 1, to be oceanic layer 2A.

Northwind Escarpment, which bounds Canada Basin on the west, is a sediment-starved, non-volcanic margin containing grabens and a belt of transitional crust as much as 100 km wide that stands 1 to 3 km higher than oceanic crust in the central Canada Basin. In these and other respects it resembles the classic sediment-starved nonvolcanic passive continental margin off western Iberia.

AAPG Search and Discovery Article #90008©2002 AAPG Pacific Section/SPE Western Region Joint Conference of Geoscientists and Petroleum Engineers, Anchorage, Alaska, May 18–23, 2002.