Abstract

Three large basins were formed in Arctic Canada subsequent to the mid-Paleozoic Ellesmerian Orogeny: the Sverdrup, Beaufort-Mackenzie and Northern Baffin Basins. The Sverdrup, a successor basin to the Franklinian Geosyncline, subsided into three depocentres, the Sabine, Ellef-Edinburgh and Norwegian, which are separated by transverse arches. The Beaufort-Mackenzie Basin is located in a rift zone between the Canadian Shield and the Brooks Orogen. The intersection of the northeast-trending Kaltag fault system and northwest-trending Brookian structural front localized Upper Mesozoic and Tertiary depocentres in the Mackenzie Delta and Beaufort Sea. A Jurassic to Upper Cretaceous marine transgression was followed by Tertiary regressions and prograding shelf deposits. Submerged deltaic depocentres developed with composite thicknesses of sedimentary units being over 15 000 m. Depocentres shifted progressively northward in Upper Cretaceous, Lower Tertiary and Oligo-Miocene sedimentary cycles. A deep shale trough formed in Cretaceous and Early Tertiary time west of Richards Island in the rift zone and was deformed by lutokinetic diapirs having reliefs of thousands of metres. Baffin Bay is a Cretaceous-Tertiary rift of the Canada-Greenland Shield. Depocentres developed in Northern Baffin Bay, Lancaster Sound and Home Bay.

Over 250 000 km of reflection seismic surveys have been acquired by industry in the past decade north of the Arctic Circle. Structure and isochronous maps were made from this data base to define post-Ellesmerian depocentres. Seismogeological units were mapped to estimate sedimentary volumes, thicknesses and rates of sedimentation. Petroleum exploration factors described are the structure of the Franklinian floor, Upper Paleozoic carbonate buildups on intra-basinal arches in the Sverdrup Basin, the distribution of delta front reservoirs in the Upper Cretaceous and Tertiary of the Beaufort-Mackenzie Basin, and the occurrence of Paleozoic and Mesozoic reservoirs in the crests of faulted blocks in Baffin Bay-Lancaster Sound.