--> ABSTRACT: Stratigraphic Framework of the Powder River Basin, Wyoming and Montana, Utilizing Computer-Generated Isopach and Structure Contour Maps and Cross Sections, by Bonnie L. Crysdale; #91002 (1990).

Datapages, Inc.Print this page

ABSTRACT: Stratigraphic Framework of the Powder River Basin, Wyoming and Montana, Utilizing Computer-Generated Isopach and Structure Contour Maps and Cross Sections

Bonnie L. Crysdale

A series of U.S. Geological Survey (USGS) Miscellaneous Field Investigations maps show regional structure, thickness, and areal extent of selected Precambrian through Tertiary formations in the Powder River basin, Wyoming and Montana. These maps were prepared for the Evolution of Sedimentary Basins Program from a computerized database that contains depths to the tops of stratigraphic units (including major bentonite and coal beds) from more than 8500 boreholes in the Powder River basin. These tops were determined from electric logs by USGS scientists. Mapping and statistical and graphic applications have been accomplished using commercially available software on a VAX 11/780 computer.

The maps were generated to aid in the description and interpretation of basin evolution and tectonic history, and the characterization of hydrocarbon reservoirs within producing fields. All of the units mapped in the Powder River basin exhibit structural characteristics typical of Laramide-style basins: deep, asymmetric structural depressions adjacent to major basin-hounding thrust faults and thick sequences of Upper Cretaceous and Tertiary strata. The maximum thickness of sedimentary rocks in the basin is more than 16,500 ft, including 14,000 ft of Cretaceous and Tertiary rocks. Uplift of the Belle Fourche arch in the northeast part of the basin during the Laramide orogeny (which affected the pattern of hydrocarbon migrations and accumulations) is indicated on north-south cross secti ns that show the deformation and erosion of Cretaceous and older beds across the arch.

AAPG Search and Discovery Article #91002©1990 AAPG Rocky Mountain Section Meeting, Denver, Colorado, September 16-19, 1990