EUSTATIC AND TECTONIC CONTROL OF SEDIMENTATION IN THE PENNSYLVANIAN STRATA OF THE CENTRAL APPALACHIAN BASIN, U.S.A. D. R. CHESNUT Jr. Kentucky Geological Survey, 228 Mining and Mineral Resources Building, University of Kentucky, Lexington, KY 40506-0107, U.S.A. Analysis of the Breathitt Group (Lower and Middle Pennsylvanian) of the Central Appalachian Basin reveals three orders of depositional cycles or trends. The Breathittn coarsening-upward trend (20 million years (MA)) represents increasing intensity of the Alleghenian Orogeny. The major marine transgression (MMT) cycle (2.5 Ma) was controlled by an unknown eustatic or tectonical mechanism. The major coal beds and intervening strata make up the coal-clastic cycle (CC cycle) (=Appalachian cyclothem) which has a 0.43 Ma periodicity. This periodicity supports eustatic control of sedimentation modulated by an orbital periodicity. Extensive coastal peats deposited at lowstand (CC cycle) were preserved as coals, whereas highstand peats were eroded during the subsequent drop in sea level. Autocyclic processes such as delta switching and avulsion occurred within CC cycles. An Early Pennsylvanian unconformity represents uplift and erosion of mid-Carboniferous foreland basin deposits. The uplift may have been caused by crustal relaxation or collisional braking. Distribution of post-unconformity strata shows that the Early Pennsylvanian foreland basin was underfilled (i.e., the forebulge had not been crested). Alluvial deposits (Breathitt Group) derived from the highlands were transported to the northwest toward the forebulge. During lowstand (MMT cycle), the only outlet available to further sediment transport (Lee Formation) was toward the southwest (Ouachita Trough), along the Black Warrior-Appalachian foreland basins. This transport was periodically interrupted by northeastward transgression (MMT cycle), from the trough through the foreland basins. The Middle Pennsylvanian marks a period of intermittent overfilling of the foreland basin and cresting of the forebulge. Marine transgressions (CC cycle) entered through the foreland basins and across saddles in the forebulge. After the Ouachita Trough was destroyed during the late Middle Pennsylvanian, marine transgressions migrated only across saddles in the forebulge. In the late Pennsylvanian, marine waters entered the basin only across the diminished forebulge north of the Jessamine Dome.