Abstract: Fort Union Coals of the Northern Rockies and Great Plains: A Linchpin Toward a New Approach to National Coal Resource Assessment

Romeo M. Flores, Gary D. Stricker

The U.S. Geological Survey recently initiated a 5-year program to assess the Nation's coal resources, which emphasizes a new approach relating coal quantity and quality. One assessment region includes the northern Rocky Mountains and Great Plains of Wyoming, Montana, and North Dakota, which contains a vast expanse of Paleocene Fort Union coal-bearing rocks that yielded about 30% (>299 million short tons) of the total coal produced (1.03 billion short tons) in the U.S. for 1994.

Production is from 14 coal beds/zones (Wyodak-Anderson, Anderson-Dietz, Rosebud, Beulah-Zap, Hagel, Harmon, Ferris Nos. 23, 24, 25, 31, 38, 39, Hanna No. 80, and Deadman seams) mined in the Hanna, Green River, Powder River, and Williston Basins. About 254 million short tons produced from 25 mines are from the Wyodak-Anderson, Anderson-Dietz, and Rosebud coal beds/zones in the Powder River Basin (PRB). These coals are considered as clean and low contaminant compliance coals containing less sulfur and ash (arithmetic mean for sulfur is 0.58% and ash is 7%, as-received basis) than coals produced from other regions in the coterminous U.S. Preliminary elemental analysis of coal samples from the PRB for those hazardous air pollutants (HAPs) named in the Amendments to the 1990 Clean Air Act (including Sb, As, Be, Cd, Cr, Co, Pb, Mn, Hg, Ni, Se, and U), indicates that PRB coals are lower in HAPs contents than other coals from within the region and also other regions in the U.S. Arithmetic means of HAPs contents of these coals are: Sb=0.35, As=3.4, Be=0.6, Cd=0.08, Cr=6.1, Co=1.6, Pb=3.6, Mn=23.5, Hg=0.09, Ni=4.6, Se=0.9, and U=1.1 (in ppm, as-received, and on a whole-coal basis).

These coal-quality parameters will be used to delineate coal quantity of the 14 Fort Union coal beds/zones defined in the resource assessment for expanded utilization of coals into the next several decades as controlled by present and future environmental constraints.

AAPG Search and Discovery Article #90952©1996 AAPG Rocky Mountain Section Meeting, Billings, Montana