ABSTRACT: Proterozoic Control of Laramide Faults in the Colville Hills and the Northern Plains of Northwest Territories, Canada

MACLEAN, B. C., and D. G. COOK, Geological Survey of Canada, Calgary, Alberta, Canada

Regional analysis of some 5000 km of reflection seismic data in the Colville Hills and western plains of the Northwest Territories reveals a thick Proterozoic sedimentary section deformed on crustal scale intracratonic faults that have undergone several periods of reactivation. Northeast-directed Laramide compressional stresses, imposed on the pre-Cambrian structures, preferentially reactivated a NNW-SSE fault trend in a right-lateral sense. The result is a close correspondence between Laramide and Proterozoic structures under the Colville Hills. Under Anderson and Horton plains, where the pre-Cambrian structural grain is northeast-southwest, a close Laramide/Proterozoic structural relationship was not developed. Monoclines, developed during a possibly pre-Cretaceous Phanerozoic exten ional phase, influenced a least one Laramide structure. There is evidence of syn-Laramide and possible post-Laramide extension.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)