Biostratigraphy of Cretaceous and Paleogene Strata from Northern Yukon Territory and District of Mackenzie, Northwest Territories
Date
2018-04-27
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Abstract
The biostratigraphic utility of the angiosperm pollen genus Pulcheripollenites is improved through the development of new biozones. Species of Pulcheripollenites, including one new species, P. sweetii, aid interpretations and correlations within three northern Canadian basins, in combination with additional new palynostratigraphic data and previously published biozonation schemes. Palynological assemblages recovered from the Bonnet Plume, Eagle Plain and Brackett basins determine relative ages and establish correlations with existing biozones that constrain intra- and interbasinal correlations for Upper Cretaceous and Paleogene strata. Strata from the upper Bonnet Plume Formation of the Bonnet Plume Basin range in age from the late Campanian to late Paleocene/early Eocene. The diverse assemblages recovered from the Bonnet Plume Basin contribute to paleogeographic and phytogeographic determinations and point to issues of diachroneity. Assemblages recovered from the Eagle Plain Basin were very impoverished compared to the Bonnet Plume and Brackett basins and contained reworked palynomorphs, making age determinations and biostratigraphic correlations problematic. New biostratigraphic data, including marine macrofauna, foraminifera, and palynomorphs provide significant constraints on the age of the Eagle Plain Group. Strata from the Cody Creek Formation, the youngest unit of the Eagle Plain Group, contained assemblages of six distinct ages including: Late Albian to Cenomanian (or younger), Turonian (or younger), mid-Coniacian (or younger), Santonian to possibly early Campanian, mid- to late Campanian and late Maastrichtian. Distribution of biostratigraphic ages confirms deposition of the Eagle Plain Group as a prograding succession and that Cody Creek strata are time transgressive from south to north. Strata from the East Fork and Little Bear formations of the Brackett Basin range from Turonian (or younger) to mid-Maastrichtian. A marine age equivalent of the Summit Creek Formation is recognized within the East Fork Formation based on palynological analysis. Recycled palynomorphs are common in strata of the Little Bear and East Fork formations and the age of recycled populations are stratigraphically inverted providing evidence for progressive unroofing of the orogenic wedge during Cordilleran orogenesis. This research provides a foundation for regional geologic mapping, basin evolution studies and resource assessment in these northern Canadian basins.
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Keywords
Palynology, biostratigraphy, Cretaceous, Paleogene, Canadian northern basins, Pulcheripollenites
Citation
Bell, K. M. (2018). Biostratigraphy of Cretaceous and Paleogene Strata from Northern Yukon Territory and District of Mackenzie, Northwest Territories (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/31864