Date of Award

1974

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

A.M. Cvancara

Abstract

Two hundred-forty samples (of which fifty-five contained micro fossils) were collected from six measured sections in the Cannonball Formation (Paleocene, Danian) in Grant, Morton and Oliver Counties, North Dakota. Twenty-six species of benthonic foraminiferids were identified from these samples: 6 textulariines, 2 miliolines and 18 rotaliines. No planktonic foraminiferids were found. The fauna is characterized by a predominance of individuals of textulariines, especially the lituolids. Although the Cannonball Formation is characterized by an alternating sequence of sandstones and mudstones> the foraminiferid fauna was restricted to the mudstone facies in the upper and upper-middle part of the formation. Two characteristic assemblages based on dominant families and genera are recognized, the lituolid (dominantly arenaceous) and nodosari.id (dominantly calcareous) assemblage. R-mode cluster analysis shows three distinct clusters of species: one corresponds to the lituolid assemblages, another corresponds to the nodosariid assemblage, and the third is composed of species that are represented only rarely in the fora miniferid fauna. The. Q-mode cluster analysis shows a high level of correlation between two lithologic units in two widely separated stratigraphic sections; other foraminiferid correlations were not possible because of the sparse occurrence of foraminiferids in other stratigraphic sections.

The two assemblage, the dominance of arenaceous forms, the absence of planktonic forms and the occurrence of the mic:rofauna in the mudstone facies suggests nearshora, shallow (less than 100 m), possibly cooler, protected environments such as shallow bays behind barrier islands. The dominance of textulariines in the sediments is indicative of lower than normal marine salinity.

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