ABSTRACT

One section of the Lower Cretaceous McMurray Formation and basal Clearwater Formation from the subsurface of northeast Alberta has been examined for its microfloral content. The recovered microfloral assemblage consists of 58 genera and 94 species of spores and pollen grains; one species of megaspore perispore; and 5 genera and 7 species of dinoflagellates. One species of Tsugae pollenites radiostriatus pollen is proposed as new.

The presence of Appendicisporites unicus, Plicatella trichacanthus var. dissectus, Cicatricosisporites perforatus, Contignisporites perplexus and Januasporites spiniferus indicate an Early to early Middle Albian age for the McMurray Formation in the type well.

The studied section has been subdivided into two zones: a lower zone containing only pollen and spores and an upper zone containing microplankton as well. The distribution of microplankton indicates a continental origin for most of the McMurray Formation except for the uppermost 21 ft (above 117 ft in the core) in which abundant microplankton make their appearance.

The distribution of palynomorphs within the core indicates a progressive decrease in species content upwards. This is interpreted as being the result of climatic changes brought about by the advancing Boreal Sea (Clearwater Formation deposits).