Overview of the Tectonic Evolution of Canada’s Beaufort –Mackenzie Region

By

L.S. Lane (Geological Survey of Canada)

The Canadian Beaufort Sea continental margin is well known, based on interpretation of multiple datasets defining the deep crustal architecture, regional structural trends and temporal-spatial tectonic evolution. Of 53 hyrdocarbon discoveries, most are trapped in structures formed during either Jurassic-Cretaceous rifting or Tertiary orogenesis. Normal faults, active from Late Jurassic to mid-Cretaceous time, accommodated northwestward extension and continent margin formation in post-Albian time. The most prominent of these structures is the Eskimo Lakes Fault Zone, beneath the Mackenzie Delta and Tuktoyaktuk Peninsula. This zone marks the cratonward limit of thick Jurassic to Tertiary syn-rift and post-rift successions, and traps significant oil and gas accumulations including the Parsons Lake gas field. From latest Cretaceous to Late Miocene time, five pulses of orogenic deformation are documented. The two most significant pulses are Paleocene to middle Eocene, and Late Miocene in age. The earlier event produced an arcuate array of structures onshore in northwestern Yukon, and offshore in the basin. These structures did not develop exclusively by Cordilleran orogenesis because they include an important component of east-west shortening which probably was a response to North Atlantic tectonics of latest Cretaceous and early Tertiary age. The Late Miocene pulse represents the final deformation event for much of the region (Holocene deformation occurs locally). Miocene structures form linear folds in the distal part of the Beaufort-Mackenzie basin. Folds and secondary faults related to Tertiary deformation trap oil and gas beneath the Mackenzie Delta, in the central Beaufort and at Amauligak in the eastern Beaufort.

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.