Lithofacies of the Silurian Keefer Sandstone, east-central Appalachian basin, USA

Fourteen lithofacies of the Keefer Sandstone in the area of northeastern West Virginia and western Maryland were identified. Depositional environments of the lithofacies include storm-dominated marine shelf/basin, barrier island, and backbarrier tidal flat and lagoon. Coastal lithofacies document a dominant basinward progradation, with some sea-level rise, which placed backbarrier lithofacies above barrier island lithofacies. Shelf lithofacies, as stacked coarsening-upward sequences, document as many as four fluctuations within the major progradation. Coarsening-upward sequences are typically capped by transgressive sands which represent material eroded from relatively landward environments and transported basinward during coastal retreat. Deposition of cycles within the Keefer occurred under conditions of tectonic quiescence, dominant steady or falling sea level followed by rise in sea level, and in a climate which was warm and humid.