Integrated Ichnology, sedimentology and stratigraphy of the Lower Falher member, Spirit River formation, northeastern British Columbia and central Alberta

The lower Falher Member comprises facies successions of wave- and storm-dominated delta complexes and strandplain settings. Both are characterized by interbedded, moderately burrowed mudstones and sandstones, passing into heterolithic intervals dominated by sporadically burrowed, stacked sandy tempestites. These pass upwards into current ripples and trough cross-stratification, capped by low-angle planar-stratified sandstones, pebbly sandstones and conglomerates. Prodeltaic intervals contain syneresis cracks, organic-rich mudstone drapes of fluid-mud origin, current and combined flow ripples, soft-sediment deformation, and carbonaceous detritus. Trace fossil suites are typified by reduced diversities and abundances of ichnogenera, lowered bioturbation intensities (BI 0-2), and a paucity of suspension-feeding structures in the tempestites. Offshore deposits contain rare fluid-mud drapes, and greater bioturbation intensities (BI 0-5), increased ichnogenera diversities, and the presence of suspension-feeding structures in sandy tempestites. These facies characteristics may be useful in identifying other deposits in the Western Interior Seaway, which have been interpreted as wave- and storm-dominated shorelines.