Crustal structure beneath the Western Canada Sedimentary Basin: constraints from gravity and magnetic modelling
Regional gravity and magnetic anomalies that originate from crystalline basement rocks extend over many parts of the Western Canada Sedimentary Basin. Although these potential-field anomalies provide a basis for tectonic subdivisions of the basement crust, most previous interpretations of these features have been largely qualitative in nature. This study focuses on numerical simulation and quantitative interpretation of five regional potential-field anomalies in Alberta, Canada, for which independent constraints on crustal structure are available from Lithoprobe seismic and electromagnetic studies. The Kimiwan High (~55°N, 116°W) is a roughly 250 km long linear magnetic high. Seismic profiles across this anomaly provide evidence for a crustal-scale extensional fault system that offsets the Winagami reflection sequence, a series of mid-crustal sills. We find that the magnetic anomaly can be modelled as either a 1540 km wide zone of moderate positive susceptibility (4.5 × 103 SI units) in the hanging wall...