Date of Award
Master of Science (MS)
Jurassic rocks in the southern two-thirds of North Dakota consist mainly of limestone, shale, anhydrite, and salt of the Piper Formation; shaly limestone, calcareous and non-calcareous shales of the Rierden Formation; shale and sandstone of the Swift Formation; and, at the top, non-marine shale and local sandstones of the Morrison Formation.
The units generally are conformable in the deep part of the Williston Basin, and are unconformable near the edge of the basin in eastern North Dakota. The Poe Member of the Piper Formation, however, unconformably overlies the Spearfish Formation in the western part of North Dakota where Dunham salt is absent; where the Dunham is present, the sequence is conformable. Also, the Morrison Formation is unconformably overlain by the Cretaceous Dakota Group except in local areas where the boundary may be gradational.
Mechanical-log characteristics or the Jurassic formations, upon which the study was based, are such that units may be correlated with assurance in the subsurface in the western half of the study area. Facies changes and the progressive thinning of the units make correlation more difficult toward the edge of the basin to the east.
Piper limestones and Swift sandstones appear to be the most promising for petroleum potential, although to date no oil has been discovered in the Jurassic rocks within the study area. The Poe Member may contain gypsum at the eastern edge of the basin. The Dunham beds are a potential source of salt in western North Dakota.
Salisbury, Richard A., "Jurassic stratigraphy of the southern two-thirds of North Dakota" (1966). Theses and Dissertations. 258.