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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 66 (1982)

Issue: 5. (May)

First Page: 605

Last Page: 605

Title: Application of Computer Graphics to Coal Geology and Coal-Resource-Assessment Studies, Canyon Coal Bed, Birney 1° Sheet, Montana: ABSTRACT

Author(s): Antoinette L. Medlin, Mary A. Carey, Laura N. Robinson, William C. Culbertson

Article Type: Meeting abstract

Abstract:

The National Coal Resources Data System (NCRDS) of the U.S. Geological Survey has the capability through spatial data bases and computer software to depict coal geology and calculate coal resources by computer. The Birney 1:100,000 map in southeastern Montana and the Canyon coal bed were selected to demonstrate this capability. The Birney quadrangle includes parts of Big Horn, Rosebud, and Powder River Counties. Other political entities are the Northern Cheyenne Indian Reservation and the Custer National Forest. The Canyon coal bed locally splits into an upper and lower unit, whose thicknesses range from 1/3 to 33 ft (0.1 to 10 m).

The desired data subset retrieved from the stratigraphic (USTRAT) data base consists of more than 300 drill-hole and 100 outcrop locations and their respective Canyon coal stratigraphic sections. Required digitized information included: X-Y locations (lat. and long.) for each point, township-range intersections, county, and national forest boundaries from the base map, the Indian reservation boundary, the Canyon bed outcrop, and the 200, 400, and 1,000 ft (61, 122, and 305 m) overburden isolines as drafted by the geologist.

GARNET, a NCRDS interactive graphics program, produces isopachs and structure maps, does trend analysis, and allows the user to edit data points, expand areas of interest, and calculate coal-resource areas and tonnages for any defined area. The USGS methodology for calculating and reporting coal resources requires that computations be delimited by criteria of coal thickness, overburden thickness, rank, and distance from points of observation as related to land classification and political subdivisions. GARNET allows interactive graphic combination of digitized and computer-derived lines to produce boundaries of these categories.

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Copyright 1997 American Association of Petroleum Geologists