Integrated ichnology and sedimentology of mixed river- and wave-influenced delta complexes, Upper Cretaceous basal Belly River Formation, central Alberta, Canada

Marine-generated bounding discontinuities subdivide the basal Belly River cycles into 3 allomembers (D, E, and G). Detailed sedimentological and ichnological analysis of allomembers D and E of the Upper Cretaceous basal Belly River Formation (central Alberta) reveals 13 discrete facies. Sedimentary facies are grouped into 6 mappable facies associations. Depositional environments are interpreted to record a variety of marginal-marine, paralic, and coastal environments, including: river-dominated, storm-influenced deltas (FA1); storm-dominated, mixed river- and wave-influenced deltas (FA2); fluvial channels (FA3); fluvio-estuarine distributary channels (FA4); marine-influenced, lower delta plains (FA5); and delta/coastal plains (FA6).Based on the integration of data from cored intervals, multiple dip- and strike oriented cross-sections, and net-sand isopach maps; no lateral variations in facies distribution, consistent with the asymmetric delta model, are identified. Correlations indicate that the deposits of Allomember D are exclusively linked to FA1 successions, whereas the deposits of Allomember E are exclusively linked to FA2 successions.