Date of Award

1981

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Geology

First Advisor

F.R. Karner

Abstract

To date, most environmental reconstructions of lignite bearing formations in western North Dakota have been done on a formational scale. The objective of this study was to investigate one of the non-lignite intervals, the Kinneman Creek Interval, directly above the strati graphically lowest lignite in the Paleocene Sentinel Butte Formation. The Kinneman Creek Interval has been recognized in the Sentinel Butte Formation throughout most of western North Dakota.

The field area is located in west-central North Dakota in Mercer, Oliver, and McLean Counties and is bi sected by the Missouri River. Excellent exposures are provided in the highwalls of Baukol-Noonan, North American, and Consolidation Coal Companies surface lignite mines and numerous logs are available from test holes drilled by coal companies and the North Dakota Geological Survey.

The Kinneman Creek Interval is a laterally continuous, poorly indurated light bluish gray to yellowish brown gray, silt and fine sand unit with associated clay beds. The interval dips gently to the west and varies in thickness from six to thirty-eight metres. The dominant bed forms in the study area are: climbing ripples and rhythmites, most commonly found in highwall exposures at Glen harold and center; homogeneous sands, found most frequently at Falkirk; and trough shaped ripples and draped bedforms found commonly at all three mines. Measurements of paleo current direction taken from primary sedimentary structures suggest the sediment source for the interval was west and northwest of the study area.

Laboratory analyses were conducted on eleven samples from two vertical sections of the Kinneman Creek Interval ( one from the Glenharold Mine and one from the Falkirk Mine). The analyses included determination of sand-silt-clay ratios, approximate bulk chemistry using scanning electron microprobe techniques, and bulk mineralogy using x-ray diffraction techniques. The samples suggest grain size is coarsest at the Falkirk Mine. Bulk chemical analyses did not reveal any major differences in samples. Relative amounts of clay minerals, kaolinite, chlorite, and micas were greatest in Glenharold Mine samples. The proportion of feldspars was greatest in Falkirk Mine samples.

The interval in the study area has many features attributable to a range of environments including fluvial, lacustrine and fluvial deltaic. The character of sediments and structures at the Falkirk Mine as indicated by test holes and highwall exposures, is somewhat different. than that of Center and Glenharold Mines. The Kinneman Creek Interval in the Falkirk area may have been deposited in a fluvial system while the interval in the Center and Glen harold areas suggest a quiet water or lacustrine depositional environment.

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