Date of Award
Doctor of Philosophy (PhD)
In 1974 and 1975 about 2800 samples (of which 265 contained foram iniferids) of the Cannonball Formation were collected from 60 water test wells and two oil wells in Adams, Bowman, Burleigh, Divide, Dunn, Grant, Mercer, Morton, Oliver, Sioux, and Ward Counties in western North Dakota. Fifty species of benthonic foraminiferids and four species of planktonic foraminiferids were identified including eight textulariines, two milio lines and 44 rotaliines. Taxa reported for the first time from the Can nonball include: Reophax sp. (2 species), Am:mobaculites expansus Plummer, Spiroplectammina wilcoxensis Cushman and Ponton, Quinqueloculina plummerae Cushman and Todd, Dentalina eocenica Cushman, Lenticulina alabamensis (Cushman), L. ark.ansasana (Cushman and Todd), L. turbinata (Plummer), Lingulina sp., Spirobolivina emmendorferi (Jennings), Rosalina sp., Pararotalia perclara.(Loeblich and Tappan), Fursenkoina sp., Caucasina marylandica (Nogan), Nonion graniferum (Terquem), Pullenia quinqueloba (Reuss), and Anomalinoides umboniferus Schwager. A total of 93 species, including those I collected, has been reported from the Cannonball. The foraminiferid fauna occurs commonly in the mudstone lithofacies and rarely in the sandstone lithofacies in the lower to lower upper Cannon ball.
Two foraminiferid assemblages are recognized from R-mode cluster analysis, the Caucasina-Bulimina and Cibicidoides-Ceratobulimina assem blages. Little lateral and vertical continuity in the assemblages suggests strong environmental control and mixing during well drilling.
The presence of Globorotalia pseudobulloides and Globoconusa duabjergensis in my samples suggests that the Cannonball is Danian (earliest Paleocene).
The shallow-water affinities of the foraminiferid assemblages and small size and scarcity of planktonic foraminiferids suggest deposition in water depths of 100 m or less. The dominance of textulariines, including Ammobaculites, in western Adams and eastern Bowman Counties, indicates brackish-water environments in that area. A large, shallow, protected lagoon west of a north-trending barrier island chain is envisioned as a possible complex of depositional environments for the Cannonball. Brackish-water environments are thought to have occurred on the landward side of the lagoon with normal marine environments near the seaward side of the lagoon.
Fenner, William E., "Foraminiferids of the Cannonball Formation (Paleocene, Danian) in western North Dakota" (1976). Theses and Dissertations. 93.