Compositional Characteristics of the Fire Clay Coal Bed in a Portion of Eastern Kentucky

HOWER, J. C., University of Kentucky, Lexington, KY, C. F. EBLE, Kentucky Geological Survey, Lexington, KY, W. M. ANDREWS, JR., and S. M. RIMMER, University of Kentucky, Lexington, KY

The Fire Clay (Hazard No. 4) coal bed (Middle Pennsylvanian Breathitt Formation) is one of the most extensively mined coals in eastern Kentucky. The coal is used for metallurgical and steam end uses and, with its low sulfur content, should continue to be a prime steam coal. This study focuses on the petrology, mineralogy, ash geochemistry, and palynology of the coal in an eight 7.5-min quadrangle area of Leslie, Perry, Knott, and Letcher counties.

At most sample locations in the study area, the Fire Clay coal bed contains a distinctive flint-clay parting generally thought to represent an ancient volcanic ash fall. The coal below the flint clay has a highly variable thickness, is composed of dull lithotypes, and is generally higher in ash, sulfur, and inertinite. Palynologically, this bench contains increased percentages of fern, calamite, and cordaite taxa. At the southeasternmost sites, a high K2O/Al2O3 parting underlies the very low K2O/Al2O3 flint clay.

The coal above the flint clay parting is more uniformly thick, and generally is lower in ash yield and sulfur content. "Bright" lithotypes in the upper bench of the Fire Clay coal contain abundant Lvcospora pellucida, L. granulata, and L. pusilla, indicating a Lepidophloios-Lepidodendron dominant flora. These lithotypes generally are high in vitrinite content. Intercalated "dull" coal lithotypes, in contrast, contain more fern and occasionally calamite taxa and inertinite.

A high-ash, low-vitrinite durain that contains a palynoflora dominated by ferns, calamites, and cordaites overlies the flint clay at several sites. The durain ash has a low K2O/Al2O3 ratio with a relatively high TiO2 content in the form of rutile. The overlying low-ash, high-vitrinite bright lithotypes are dominated by arboreous lycopsids, and are relatively rich in CaO, Ba, and Sr in the ash. The next lithotype in the succession, a low-vitrinite durain, differs from the lower durain in being low ash and fern dominant. This durain thins to the east and is not present at the easternmost site. The overlying lithotypes, although generally bright, exhibit a slight dulling-upward trend to the top of the coal bed. "Rider" coals associated with the Fire Clay tend to be thin and high in ash y eld and sulfur content. Their palynofloras are commonly dominated by Lvcospora micropapillata and L. orbicula, indicating that Anabathra, a small colonizing lycopsid, was a component of the swamp flora.

AAPG Search and Discovery Article #91005 © 1991 Eastern Section Meeting, Pittsburgh, Pennsylvania, September 8-10, 1991 (2009)