The Proterozoic Fort Simpson structural trend in northwestern Canada

The Fort Simpson structural trend is a series of north-northwest - striking Middle Proterozoic anticlinal culminations buried beneath Paleozoic and Mesozoic cover in northwestern Canada. Interpretations of seismic reflection profiles coupled with drilling data and outcrop and potential-field observations show that the culminations are cored by equivalent to 1.85 Ga crystalline rocks and include overlying sedimentary rocks of the equivalent to 1.7-1.3 Ga Hornby Bay and Dismal Lakes Groups. Formation of the structures probably occurred along west-dipping thrust faults following deposition of the Dismal Lakes Group strata and prior to deposition of the equivalent to 0.8-0.7 Ga Mackenzie Mountains Supergroup strata that unconformably overlie the Dismal Lakes rocks. This time interval coincides with major east-southeast - directed thrusting in the same rocks beneath the Anderson Plains to the north.