Geophysical Investigation of the Triangle Zone Structure in the Jumpingpound-Wildcat Area, Southern Alberta Foothills

Robin Tage Slotboom

ABSTRACT

Balanced vertical geological cross-sections, constrained by abundant seismic, well, and surface data from the Jumpingpound-Wildcat Hills area, show the triangle zone to be a NW-SE trending antiformal stack of duplexes involving Cretaceous rocks that have been forced eastward into foreland strata between two bedding-parallel detachments. The lower of these detachments carries carbonate rocks of Mississippian age in its hanging wall. It rises from a flat near the base of the Banff Formation, and flattens out beneath the Edmonton Group, near the top of the Belly River Formation. The upper detachment rides within the Edmonton Group, and the two detachments are not observed to merge at a simple branch point near the triangle zone. Gravity data acquired in the area have a subtle, but identifiable response to the carbonate rocks that have been thrusted into the clastic sedimentary section.