Reconstructing basin-scale drainage dynamics with regional subsurface mapping and channel-bar scaling, Aptian, Western Canada Foreland Basin

Abstract

An extensive subsurface dataset from the Lower Cretaceous McMurray Formation of northeastern Alberta, Canada, is leveraged to provide new insights into the Aptian drainage arrangement of the Western Canada Foreland Basin. Regional-scale stratigraphic mapping is supplemented with paleodrainage area estimates obtained using quantitative relationships between fluvial bankfull flow depth and drainage area in order to reconstruct paleocatchments, including those of a continental-scale river system and its tributaries. Using channel geometries delineated in high-resolution 3D seismic time slices, we test for evidence of a tidal prism within Aptian-aged drainage systems in order to assess the applicability of fluvial scaling relationships to the McMurray Formation.Refined paleogeographic reconstructions incorporate catchment estimates for the southerly-sourced trunk drainage system of the McMurray Formation, which corroborate the claim that the unit was associated with a continental-scale drainage network. Drainage area estimates for southwesterly-sourced tributary systems are, however, up to an order of magnitude smaller. These tributaries likely had headwaters in the North American Cordillera. This work demonstrates the applicability of combining regional mapping, sedimentological analysis, and fluvial scaling relationships to reconstruct sediment-routing systems from source-to-sink in the deep time record.