GEOLOGIC FRAMEWORK FOR THE COAL-BEARING ROCKS OF THE CENTRAL APPALACHIAN BASIN

Coal production has been an important economic factor in the Central A ppalachian Basin. However, regional stratigraphic and structural relat ionships of the coal-bearing rocks of the basin have been poorly under stood due to numerous separate nomenclatural schemes employed by vario us states. In order to estimate coal resources and understand mechanis ms controlling the distribution of coal within the basin, a reliable g eologic framework is necessary. Seven detailed cross sections across t he Central Appalachian Basin were constructed in order to examine the stratigraphic and structural framework of the coal-bearing rocks in th e basin. The cross sections were based on more than 1000 oil and gas w ell logs, measured sections, and borehole information from Kentucky, O hio, Tennessee, Virginia and West Virginia. The cross sections reveale d three main points discussed here: southeast thickening of the Pennsy lvanian strata, unconformable northwestward onlapping relationship of Lower Pennsylvanian strata over underlying Lower Pennsylvanian and Mis sissippian strata and regional continuity of beds. The cross sections, geologic mapping, coal-resource studies, extensive new highway exposu res and the occurrence of tonstein beds indicate that many coal beds a nd marine strata are laterally extensive, albeit locally variable acro ss the basin. Certain quartzose sandstone bodies are also extensive ov er large areas of the basin. Existing stratigraphic nomenclature schem es obscured the geologic framework of the basin, so a new unified nome nclature scheme was devised to better describe stratigraphic features of the basin. The new stratigraphic nomenclature, now only formalized for Kentucky, was based on key stratigraphic units that proved to be e xtensive across the basin. Lower and Middle Pennsylvanian rocks are no w recognized as the Breathitt Group (the Breathitt Formation was eleva ted to group rank). The Breathitt Group was subdivided into eight coal -bearing formations by relatively thick marine strata, and, in the low er part of the Breathitt Group, by quartzose sandstone formations.