Influence of Penecontemporaneous Tectonism on Development of Breathitt Formation Coals, Eastern Kentucky

James C. Hower, Eric J. Trinkle, James D. Pollock

The Middle Pennsylvanian Breathitt Formation coal beds in the central portion of the Eastern Kentucky coalfield exhibit changes in lithology, petrology, and chemistry that can be attributed to temporal continuity in the depositional systems. The study interval within northern Perry and Knott Counties includes coals from the Taylor coal bed at the base of the Magoffin marine member upward through the Hazard No. 8 (Francis) coal bed.

The Taylor to Francis lithologic interval thickens and becomes increasingly dominated by sandstone eastward from Perry County to Knott County. Compositional trends are also noted. The upper branch of the Taylor coal bed changes from a high-vitrinite, moderate-ash and moderate-sulfur bright coal in the west to a durain with less than 30% vitrinite and up to 44% ash and 8.3% sulfur in Knott County. The Hazard coal bed splits into a number of benches to the east. Sulfur content in the east is about 4.7% compared to less than 1% sulfur in the west. The Hazard No. 7 coal is a 2-m thick, low-sulfur coal in Perry County. To the east, the coal thins and splits and the sulfur increases to 5.1%. The overlying rocks change from plant-fossil-bearing gray shale in the west to black shale in centra Knott County. Similar to these lower three coals, the Francis coal also thins, splits, and increases in sulfur content to the east. The apparent similarities in the characteristics of the four coals suggest a temporal continuity of the depositional systems throughout the region. In particular, the increased presence of marine beds, high-sulfur coals, and split coals in central Knott County suggests that the latter area may have been part of a continuously subsiding trough that maintained the area at a slightly lower elevation than the adjacent area to the west, which is characterized by the thicker low-sulfur coals.

AAPG Search and Discovery Article #91031©1988 AAPG Eastern Section, Charleston, West Virginia, 13-16 September 1988.