REVISIONS TO THE CHRONOSTRATIGRAPHIC CORRELATION OF WENLOCK—PRIDOLI (SILURIAN) STRATA OF THE SOUTH-CENTRAL AND WESTERN MARGINS OF THE APPALACHIAN BASIN

The south-central and western margins of the Appalachian Basin contain extensive outcrops of Silurian strata that have been well studied for over a century. These studies provided a general means of chronostratigraphic correlation to global series and stage boundaries, however, a rarity of zonally diagnostic fauna inhibited precise global chronostratigraphic correlation of these units. Here, we present additional bio- and chemostratigraphic data for the Wenlock through Pridoli interval, complementing our previous findings from Virginia, West Virginia, and Ohio that demonstrate the need for significant revision to the global chronostratigraphic correlation of several units within the south-central Appalachian Basin by more than a series in some cases.

These new data include high-resolution (≤ 25 cm) δ¹³C_carb analyses and conodont biostratigraphy from Crabbottom, Virginia, which provide a nearly continuous chemostratigraphic record for upper Llandovery through Pridoli strata of the south-central Appalachian Basin. Additionally, we contribute new conodont biostratigraphic data to complement the collections of C. T. Helfrich. At present, diagnostic elements of Distomodus staurognathoides, Pterospathodus amorphognathoides amorphognathoides, Kockelella walliseri, Ozarkodina sagitta rhenana, Oz. bohemica longa, K. ortus absidata ?, Oz. snajdri, Coryssognathus dubius, and Oz. crispa are observed within the new collection; providing further refinement to series, stage, and zonal boundaries. Assignments within the Ludlow—Pridoli interval remain tentative due to a highly variable δ¹³C_carb record, absence of a high amplitude Lau Excursion, and lack of diagnostic Ludlow conodont fauna.