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The AAPG/Datapages Combined Publications Database

North Dakota Geological Society

Abstract

NDGS-AAPG

Symposium on the Geology of Rocky Mountain Coal, October 2-4, 1984

Pages 28 - 40

DISTRIBUTION, ABUNDANCE, AND MACERAL CONTENT OF THE LITHOTYPES IN THE BEULAH-ZAP BED OF NORTH DAKOTA

D.R. Kleesattel, University of North Dakota Energy Research Center, Box 8213, University Station, Grand Forks, North Dakota 58202

ABSTRACT

Relationships between the maceral contents of the megascopically observable components (lithotypes) of the Beulah-Zap lignite bed follow patterns similar to those of bituminous coals. The lignite seam was divided into 10 lithologic units (lithobodies) on the basis of petrographic features within the units. These lithobodies range in size from 5 to 85 cm. Lithotypes within the lithobodies were physically separated for various analyses and their relative abundances estimated. Three distinct lithotypes have been identified in the Beulah-Zap lignite: vitrain (35%), fusain (5%), and attritus (60%), by volume.

Maceral identification was made using reflected light microscopy. Distribution of the maceral groups within the lithotypes of the Beulah-Zap lignite was found to resemble the distribution patterns in bituminous coals. The lithotype fusain was found to be rich in the intertinite macerals such as fusinite, semifusinite, and macrinite. The attritus is composed of all three maceral groups of variable percentages, huminite (41%-82%), inertinite (10%-65%), and liptinite (4%- 13%). The identified liptinite macerals include sporinite, resinite, cutinite, and subrinite. The huminite maceral group, consisting mainly of ulminite, was found to be the major constituent of the vitrain lithotype.

Elemental compositions were determined by proximate/ultimate analysis and scanning electron microprobe. Microprobe analyses show slight compositional variation of individual macerals included in the vitrain and fusain lithotypes. Macerals in the attritus lithotype were observed to have a varied calcium concentration compared to the other lithotypes.

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