Unraveling the stratigraphic architecture of the Jurassic-Cretaceous Nikanassin Group, northwestern Alberta, Canada

Upper Jurassic-earliest Cretaceous strata of northwestern Alberta are represented by deposits of the Nikanassin Group. This clastic sedimentary package is interpreted to record deposition in a foreland basin setting, which developed in response to uplift in the Cordillera. The Nikanassin Group contains three formations from oldest to youngest, the Monteith, Beattie Peaks and Monach. The transition from deltaic to coastal plain and fluvial depositional systems through the Monteith, Beattie Peaks and Monach formations appears to record a genetically related conformable succession of facies associations attributable to overall progradation. Lateral and vertical variability in facies is associated with a complex depositional history influenced by basin physiography and evolution, climate and tectonics. Regional thickness trends suggest increased accommodation to the southwest, providing supporting evidence that the foreland basin had initiated prior to Nikanassin Group deposition.