Reflection Seismic Evidence for Structural Style, Northeastern British Columbia Foothills: ABSTRACT

Upper Paleozoic and Mesozoic rocks of the Rocky Mountain Foothills, northward from the Alberta - British Columbia border (approximately 120{degrees}W) are characterized by systems of upright to asymmetric, fault-propagation box folds, broken locally by moderately to steeply dipping reverse faults. The regional seismic grid shows that there are several levels of detachment: within thick successions of Devonian, Carboniferous, Triassic, Jurassic and Cretaceous shales. Prospective carbonate and terrigenous clastic gas reservoirs lying between detachments have structural geometries that are semi-independent of geometries in underlying and overlying structural compartments. Regional shortening across this structural domain is less than 20 percent. This style contrasts with the much-publicized Alberta Foothills, where regional shortening may be 100 percent, and where eastward-verging, imbricate thrust slices and associated, structurally stacked, fault-bend folds are the principal hydrocarbon traps. In the B.C. Foothills domain the structural relief, complexity, and degree of disharmony of individual structures increase westward. Fractured rocks in moderately to steeply dipping asymmetric fold limbs in the central and western part of the domain are prospects for on-going exploration.