SILURIAN CONODONT BIOSTRATIGRAPHY OF THE APPALACHIAN BASIN: A REEXAMINATION OF C.T. HELFRICH’S COLLECTIONS

The conodont biozonation for the Silurian succession (Rose Hill, Mifflintown, Wills Creek, Tonoloway, Keyser, and New Creek formations) along the Wills Mountain Anticline in the central Appalachian Mountains was established by C.T. Helfrich nearly 40 years ago. At that time it was correlated with the European conodont zonation of Walliser (1964). The purpose of this work was to reexamine and update the taxonomy of the conodont fauna and consequent biozonation of the upper Rose Hill, Mifflintown, Wills Creek, and lower Tonoloway formations in the Appalachian Basin. Subsequent work will focus on refining the zonation for the conodont faunas of the middle and upper Tonoloway, Keyser, and New Creek formations in the region.

There have been extraordinary advances in conodont biostratigraphy and Silurian conodont biozonation since Helfrich’s original work in the Appalachian Basin. The form species he described can be synonymized to multielement species, and the conodont fauna recovered from the upper Rose Hill through lower Tonoloway formation can be divided into six zones that span the Llandovery (late Telychian Stage) through Ludlow series. The ozarkodinid species in Helfrich’s collections display interesting morphologies (forms with both nonfused and fused denticulation) which co-occur unexpectedly. These intriguing features merit further investigation, especially in relation to global biogeochemical events.