ABSTRACT: Coal-Bottomed Channels in the Breathitt Fm. (Pennsylvanian), Eastern Kentucky

GREB, STEPHEN F., CORTLAND EBLE, and DONALD R. CHESNUT, JR., Kentucky Geological Survey, Lexington, KY

Channel-bottom coal beds occur at many stratigraphic levels within the Breathitt Formation. Channels are between 2.5 and 5 m in depth, 10 to 100 m in width, and are draped by thin coals that are rooted along the basal scour. Coals are lycopsid dominant (80 to 90%) with rare ferns, pteridosperms, and calamites. Sulfur contents vary from 1.1 to 9.0 %, and ash contents vary between 5.5 and 54.3%.

Coals comprise less than one-tenth of the channel fill at 18 sites

studied, with the remainder often comprised of rhythmically bedded sandstones and siltstones with multimodal wave, current, and combined flow ripples, fossil plant debris, Asterosoma, Conostichus, Phycodes, Monocraterion, Olivellites, Planolites, Rhizocarallium, Rosselia, and Teichichnus trace fossils, as well as rare productoid and spiriferid brachiopods. Channels are usually overlain by dark, carbonaceous shales that may contain siderite nodules, rare Conostichus, Zoophycos, Planolites, and Scalarituba trace fossils, and lingulid and orbiculoid brachiopods. These shales also fill parts of the coal-bottomed channels. Siderite nodules and sideritic layers are common.

The coals are interpreted as peats that filled abandoned coastal channels. Low sulfur and ash values for many of the coals may indicate fresh-water origin. Overlying units exhibit faunal and sedimentological evidence of tidal, brackish- to marine-water origin. However, in many cases, inundation by tidal sedimentation did not cause increased ash and sulfur in the underlying peats.

AAPG Search and Discovery Article #91013©1992 AAPG Eastern Section Meeting, Champaign, Illinois, September 20-22, 1992 (2009)