Paleogene fungi from the Caribou Hills, Mackenzie Delta, northern Canada
Parsons, Marion Grace;Norris, Geoffrey
published: Aug 6, 1999
The extensive Tertiary strata in the Beaufort-Mackenzie Basin have been penetrated by many wells but are rarely exposed in outcrop. The most extensive outcrops are in the Caribou Hills along the east side of the Mackenzie Delta comprising delta plain sediments representing a diversity of Paleogene microenvironments. Rapid fluctuation between terrestrial and marine paleoenvironments occurs throughout much of the sequence reflected by the dominance of dinoflagellates and other marine algae, freshwater algae, pollen and spores of embryophyte plants, or fungal spores, hyphae, and fruiting bodies. The fungal propagules are numerous and diverse and four different assemblages, or ecostratigraphic-groups, are recognized (designated A -D). These are interpreted to be controlled largely by ecological factors, with some stratigraphic restrictions on the ranges of individual species. Seven interval zones are also recognized based on first appearance datums and last appearance datums. Assemblages A -D are recurrent groups which appear at different stratigraphic levels throughout the succession, and can be associated with several interval zones, and conversely, several assemblages can occur in a single interval zone.
Assemblage A occurs first in the section and is distinguished by the occurrence of Dicellaeporisporites poratus and Helicoonites goosii. Assemblage B is dominated by species of Exesisporites, Polyadosporites and Staphlosporonites and by Perisporiacites ? sp. A. Assemblage C contains a diversity of fungal palynomorph species belonging to the genera Anatolonites, Brachysporisporites, Ctenosporites, Foveodiporites, Fusiformisporites, Pesavis, Punctodiporites, and Striadiporites, among others. Assemblage D contains chiefly Diporisporites oblongatus, Lacrimasporonites permagnus sp.nov., Diporicellaesporites liaoningensis, and species of Polyadosporites and Staphlosporonites. In total, 92 species of fungal palynomorphs are described in full, 17 additional species are illustrated accompanied by brief descriptive notes, and 8 new species and one new genus (Ornatisporites) are formally designated. Additional fungi belonging to the genera Fractisporonites, Multicellaesporites, and Scolecosporites, and a diversity of fungal hyphae, are illustrated but not described. Correlation between the interval zones established for the Caribou Hills and the subsurface zonation in the Beaufort-Mackenzie Basin established by Norris (1997) for the Adgo F-28 well suggests that strata of late Paleocene to early to middle Eocene age are present in the pre-?Oligocene part of the Caribou Hills outcrop sections, and that, in part, both the Aklak and Taglu sequences are represented in the pre- ?Oligocene strata.