PALEOENVIRONMENTAL AND SEQUENCE STRATIGRAPHIC INTERPRETATION OF A MARINE SHELLBED IN THE HINTON FORMATION, SOUTHERN WEST VIRGINIA

A regionally extensive, densely fossiliferous shellbed that is up to 2.5 meters thick occurs in the "Eads Mill" marine zone near the top of the Hinton Formation (Upper Mississippian/Chesterian). In this investigation the shellbed was studied at a single outcrop about 11 km north of Princeton, West Virginia. The shellbed is bounded above and below by sparsely fossiliferous claystone. The shellbed comprises three units: a 0.2-m-thick calcareous claystone, a 0.3-m-thick packstone, and a 2.0-m-thick shale (in ascending stratigraphic order). The claystone contains fragmented brachiopods and bivalves that appear in situ. The packstone is sharp based and contains heavily abraded and fragmented shell debris with identifiable pelmatazoan columnals and solitary rugose corals. The basal 0.25 m of the shale contains bioclastic material similar to that of the packstone. Brachiopods and bryozoans with scattered pelmatazoan columnals and solitary rugose corals dominate the fauna in the upper 1.75 m of the shale. Many of the brachiopods are articulated. Fossils within the upper 1.75 m of the shale are mainly concentrated in very thin to thin beds. Silt content increases upward in the shale. The shellbed appears to record a period of sediment starvation within a shallow marine environment. The packstone, which consists of transported shell material, may record wave or current reworking during minimal siliciclastic influx. In a sequence stratigraphic context, the shellbed is interpreted as a condensed section that was deposited during peak transgression; therefore, the shellbed may record a maximum flooding event.