ABSTRACT: Lower Breathitt Formation (Lower Pennsylvanian) Coal Geology, Eastern Kentucky
GREB, STEPHEN F., DONALD R. CHESNUT, JR., and CORTLAND EBLE, Kentucky Geological Survey, Lexington, KY
Along the western outcrop margin of Pennsylvanian rocks in the Central Appalachian basin, the lower Breathitt Formation occurs as tongues beneath the Corbin and Rockcastle Sandstone Members of the Lee Formation. More than 350 thickness measurements, and 280 measured sections were used to analyze 12 named coal beds in this interval. Seventy-three percent of the coals measured were overlain by dark shales, many of which contain marine- to brackish-water fauna, and can be mapped along the outcrop margin into the subsurface. Coals are commonly underlain by laminated siltstones and sandstones that may also contain brackish- to marine-water fauna and tidal structures. These factors suggest that eustasy was a primary control on coal burial and preservation. Although lower Breathitt coals are often overlain by strata of brackish- to marine-water origin, total sulfur values are variable. Values between 0.60 and 1.2% are common.
The Early Pennsylvanian unconformity acted as a topographic control on the distribution and thickness of parts of the Contrary coal zone and Livingston coals which occur in paleovalleys. Paleotopographic highs and depressions also cause abrupt changes in coal thickness and elevation in the Stearns No. 1, Stearns No. 1.5, Beattyville, Tattlers, Halsey Rough, and various unnamed coal beds. Lee sandstone position and thickness is another control on lower Breathitt coal-bed distribution; the widespread Barren Fork coal is underlain across much of its occurrence by stable substrates of the Rockcastle Sandstone Member of the Lee Formation. The Beaver Creek and Grayhawk coals are locally truncated by overlying Lee sandstones.
AAPG Search and Discovery Article #91013©1992 AAPG Eastern Section Meeting, Champaign, Illinois, September 20-22, 1992 (2009)