Late Campanian and Maastrichtian Pulcheripollenites: Taxonomy, Phylogeny and Biostratigraphic Utility, northwestern North America (TALK) 

Kimberley M. Ball¹ and Arthur R. Sweet²

¹University of Calgary, Calgary, Alberta, T2N 1N4, Canada

²Geological Survey of Canada, Calgary, Alberta, T2L 2A7, Canada

Email: kmball@ucalgary.ca

Srivastava (1969) described the genus Pulcheripollenites and three species, P. inrasus, P. krempii and P. narcissus, from the lower part of the Horseshoe Canyon (formally Edmonton) Formation of central Alberta. Triatriopollenites pseudomagnificus Stanley 1965 from the middle part of the Hell Creek Formation of northwestern South Dakota is herein considered a fourth species of Pulcheripollenites. Additionally one new species was identified in this study. Populations of Pulcheripollenites from the Campanian and Maastrichtian are illustrated and described from west-central Alberta, east-central Yukon Territory and west-central Northwest Territories.

The first appearance datum (FAD) of Pulcheripollenites in the Alberta Basin occurs immediately above the Nomad Member of the Wapiabi Formation in the central Alberta Foothills and just above the correlative Pakowki Formation in the Alberta Plains at ca. 79.5 Ma. In the Bonnet Plume Basin, Yukon Territory and the Brackett Basin, Northwest Territories the FAD of Pulcheripollenites is at ca. 76 Ma years, as inferred from its association with the FADs of Cranwellia and associated taxa. In the Alberta Basin the latter taxa have FADs at ca. 76.5 Ma (Braman and Sweet, in press). This may indicate either a prolonged (up to 4 m.y.) unconformity below the FAD of Pulcheripollenites in northern basins or an earlier origin in Alberta. The last occurrence datum (LAD) of Pulcheripollenites in both the Alberta Basin and northern basins is in the early Late Maastrichtian.

Morphologic variation within Pulcheripollenites during the Late Campanian and up into the Late Maastrichtian include changes: (1) in the polar outline from triangular, to rounded-triangular, to sub-circular; (2) in the equatorial outline from rhombic to sub-circular; (3) in the apertures from brevicolpate to elongate, then circular pores; (4) in the compound ectexinal sculpture from dominantly striate with prominent lirae and reduced inter-lirae muri to a fine and even reticulum; (5) from a tectate margo bordering the colpi to an entirely intectate ectexine and (6) from a foot layer of more or less uniform thickness to one aspidate bordering the aperture and then extended into poral protrusions. Consequently, the study of Pulcheripollenites over extended stratigraphic intervals allows phylogenetic trends to be recognized and enhances its’ biostratigraphic utility.

References

Braman, D.R. and Sweet, A.R. (in press). Biostratigraphically useful Late Cretaceous-Paleocene terrestrial palynomorphs from the Canadian Western Interior Sedimentary Basin. Palynology, Special Volume.

Srivastava, S.K. (1969). Some angiosperm pollen from the Edmonton Formation (Maestrichtian), Alberta, Canada. J. Sen Memorial Volume, Botanical Society of Bengal, 47- 67.

Stanley. E. A. (1965). Upper Cretaceous and Paleocene plant microfossils and Paleocene dinoflagellates and hystrichospaerids from northwestern South Dakota. Bulletin of American Paleontology, 49, 177-384.