Stratigraphy of the Silurian-Devonian Upper Helderberg group in northeastern West Virginia (United States)

The Silurian-Devonian Helderberg Group in northeastern West Virginia is composed of the following formation: Keyser Limestone, New Creek Limestone, Corriganville Limestone, Mandata Shale, and Shriver Chert. The upper Helderberg Group is interpreted as a transgressive-regressive sequence of shallow marine and tidal flat deposits on a carbonate ramp. Gas is produced from the New Creek Limestone, the Corriganville Limestone, and the Shriver Chert. The gas reservoirs are located on anticlines. The Middle Devonian Needmore Shale is the gas source rock, and the Mandata Shale and the Shriver Chert are the seal rocks. Biostratigraphic (conodont) and chemostratigraphic (delta 13C carbon isotopes) analyses are presented to create a high-resolution chronostratigraphic framework. The conodont Icriodus woschmidti and the delta13C carbon isotope values indicate that most the upper Helderberg Group is within the Lockhovian Stage. The Silurian-Devonian boundary is within the upper Keyser Formation, either 3 m to 25 m below of the top of the formation.