Proterozoic thick-skinned intracratonic deformation, Colville Hills region, Northwest Territories, Canada

Abstract

Thick-skinned intracratonic structures reminiscent of those in the Rocky Mountain foreland of the United States are recorded in petroleum industry seismic data in the Colville Hills region, Northwest Territories, Canada. This record differs fundamentally from previous seismic interpretations that invoked Proterozoic thin-skinned stratigraphic repetitions and large horizontal transport on flat, bedding-parallel thrust faults. Regionally continuous reflections document more than 1100 m.y. of stability punctuated by intracratonic uplifts, warps, and sags representing at least six tectonic phases, five compressional and one extensional. No continental collisional event is directly recorded, although the most important phase, during which large basement blocks were uplifted more than 5 km, may represent adjustments related to the pre-1270 Ma collisional Racklan orogeny documented in the northern Cordillera.