GEOMETRY OF THE THRUST FRONT NEAR PINCHER CREEK, ALBERTA

Near Pincher Creek, Alberta, the leading edge of the Canadian Cordille ra approximates a triangle zone geometry with both wedge and duplex ch aracteristics. Shortening across the wedge area is estimated at approx imately 35%, most of the displacement having occurred across low-angle thrust ramps and flats that offset Jurassic to Upper Cretaceous-age s trata. A detachment extends eastward from the wedge tip for a minimum of 14 kilometres under the foreland, across which several kilometres o f shortening may have been accommodated by backthrust and duplex mecha nisms within the hanging wall of the upper detachment. Folded Tertiary -age strata indicate that triangle zone development continued through Paleocene time. Other wedge geometries have been identified west of th e leading edge, suggesting that triangle zone development occurred thr oughout the Laramide Orogeny. Locally, no commercial hydrocarbon produ ction occurs from the triangle zone; however, both source and elastic reservoir rocks are carried in the wedge, with potential trapping geom etries.