Seismic Interpretation of the Triangle Zone at Jumping Pound, Alberta

We interpret the structure at Jumping Pound, Alberta to be a NW-SE-trending antiformal stack of thrust sheets involving Cretaceous rocks that have been wedged into the foreland between two detachments. The lower of these detachments carries carbonate rocks of Mississippian age in its hanging wall. It rises from a flat in the Mississippian Banff Formation and flattens out near the top of the Upper Cretaceous Belly River Formation. An upper detachment rides within the Upper Cretaceous Edmonton Group. Apparently there is no simple branch point connecting the two faults directly in front of the main culmination. Tectonic wedging probably extends a considerable distance to the foreland, where the two faults likely merge. Three major thrust sheets involving Lower to Upper Cretaceous strata have been stacked to form the main culmination of the wedge, The structure is tightly folded at Jumping Pound and broadens northwest along strike. Shortening at the level of the mid-Cretaceous Cardium Formation is greater than that at the level of the Paleozoic section, indicating that much of the shallow section shortening was fed from Paleozoic-involved culminations further to the west (e.g., Jumping Pound West culmination) along a detachment within the Jurassic Fernie Formation.