Abstract: Coal Resources of Colorado and Wyoming

E. R. Landis

The coals in Colorado and Wyoming that have resource potential are in rocks of Early Cretaceous through Eocene age and were deposited in environments ranging from coastal lagoons to flood-plain swamps. Within regional and subregional zones that persist for many tens of miles in one or more directions, individual beds are commonly lenticular and nonpersistent. However, some exceptional beds persist as entities for more than 50 mi (80 km) in one direction. Individual beds having only a few small partings exceed thicknesses of 100 ft (30 m) in a few areas, but the average thickness of beds in the two states is much less. The coals range in rank from anthracite to lignite. The higher rank coals are in areas of greater thermal and metamorphic activity, although the general relation of higher rank to increasing age and greater depth of burial is also true. Ash contents of most beds currently mined range from about 5 to 10% and sulfur contents are usually less than 1%. Analyses of major, minor, and trace-element constituents of the coal generally indicate the absence of potentially valuable or deleterious constituents. The combined estimated remaining resources of Colorado and Wyoming to a depth of 6,000 ft (1,800 m) total about 1,233 billion MT (35% of the U.S. total), of which about 239 billion MT are categorized as identified resources to a depth of 3,000 ft or 900 m (15% of the U.S. total).

AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC