Chemical analyses of coal and coal-associated shale samples from the lower part of the Fort Union Formation, Little Snake River coal field, Sweetwater and Carbon counties, Wyoming

As part of a continuing program by the U.S. Geological Survey to collect and analyze representative samples of U.S. coals, 26 coal and 5 coal-associated shale samples were collected from 13 core and rotary-drill holes in the lower part of the Paleocene Fort Union Formation in the Little Snake River coal field, Sweetwater and Carbon Counties, Wyoming (fig. 1). The samples are briefly described in table 1. Twenty-six of the samples were collected from eight core holes that were drilled in connection with the Red Rim EMRIA (Energy Mineral Rehabilitation Inventory and Analyses) study (U.S. Department of the Interior, 1976). The locations of these eight holes and five other drill holes are shown in figure 2.

Detailed geologic mapping of part of the sample collection area was done by Sanders (1974) in his work on the Riner quadrangle. Seven of the core holes (index map locations 1-7) are located in this quadrangle. In his discussion, Sanders (1974) describes the coal beds in the lower part of the Fort Union Formation as being thin, discontinuous, and generally lenticular. Few beds attain a thickness of more than five feet. In the Riner quadrangle coal beds in the lower part of the Fort Union Formation dip 12° to 24° northwestward.