EXAMINATION OF INFERRED LATE FRASNIAN AND EARLY FAMENNIAN FAUNA AT ELKINS, WEST VIRGINIA

The Late Devonian Frasnian-Famennian extinction is considered one of the five largest extinction events of the Phanerozoic Era, causing the loss of about 30% of existing genera. While this event has been extensively studied, many questions have yet to be resolved. The exact timing of the extinction, and whether or not it was a single event or a series of events, as well as the cause or causes of the extinction are still debated. A new exposure of the Foreknobs Formation near Elkins, WV, has allowed for a detailed study of this extinction through at least several hundred thousand years of late Frasnian strata and a similar duration of subsequent early Famennian beds. This exposure contains abundant brachiopods, bivalves, and crinoids stems. These beds were sampled and the contained fauna identified. Based on a previous correlation of an outcrop gamma ray log to established subsurface stratigraphy, the Frasnian-Famennian boundary has been inferred to occur at about 240 meters above the base of the section. While Frasnian index fossils are absent above this point, no definitive Famennian index fossils were identified. Brachiopods, by far, dominated all of the samples below 200 meters in the stratigraphic section. Above 200 meters, bivalves are much more prominent, reaching a maximum of 47% of identified individuals at the inferred Frasnian-Famennian boundary, as well as 12-25% of individuals in several younger collections. This may indicate that the bivalves were being opportunists and taking over the brachiopods' ecological niche at this locality late in the Frasnian and early in the Famennian. Cluster analysis revealed distinct faunal assemblages, but has shown no distinct temporal patterns.