Sedimentary Basin and Crustal Architecture on the Northern Canadian Polar Margin

Randell Stephenson¹, Dave Forsyth², and Ashton Embry^3
1 Vrije Universiteit, Amsterdam, Netherlands
² Geological Survey of Canada, Ottawa, ON
³ Geological Survey of Canada, Calgary, AB

Reconnaissance seismic wide-angle reflection/refraction surveys between 1985 and 1990, allowed mapping of the regional crustal and sedimentary basin architecture of part of the Canadian polar continental shelf - one of the least known continental margins on Earth. Major sedimentary basins that are at least 12 km thick are present and are interpreted to have formed coincident with the Early Cretaceous opening of the Amerasian part of the Arctic Ocean. They are separated from the Sverdrup Basin to the south by a basement high, the Sverdrup Rim, that is interpreted to be a primary regional structure related to two distinct phases of basin rifting. Complexities in the regional velocity models, in the area immediately north of Amund Ringnes Island, are suggestive of salt diapirs. Major basement highs or arches perpendicular to the continental margin appear to be the result of compressional deformation related to the Eurekan Orogeny (Paleocene-Eocene) that has strongly affected the adjacent Canadian Arctic Islands. A major unconformity, inferred from the velocity structure of the continental shelf, at depths up to 5 km, is interpreted to coincide with the culmination of Eurekan deformation in mid-Eocene. The Moho lies at 25-30 km and thins in the offshore direction, indicating that the inferred sedimentary basins overlie thinned continental crust. A major elliptical gravity high some 80 km to the north of Ellef Ringnes Island is probably related to a thick sedimentary succession prograded beyond the continent-ocean crustal boundary, analogous with similar gravity anomalies in the Beaufort Sea and elsewhere.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005