ORGANIC CARBON ISOTOPE AND CONODONT BIO-CHEMOSTRATIGRAPHY OF THE BASE TELYCHIAN (SILURIAN) GLOBAL BOUNDARY STRATOTYPE SECTION AND POINT (GSSP), CEFN CERIG, WALES

The International Subcommission on Silurian Stratigraphy (ISSS) is currently evaluating potential new locations for placement of the Global Boundary Stratotype Section and Point (GSSP) for the base of the Telychian Stage (Llandovery Series). The current GSSP, located at Cefn Cerig, Wales, contains few biostratigraphically useful fossils, has never been studied for carbon isotope chemostratigraphy, and is overlain by a basin-wide synsedimentary slide complex that truncates most of the Telychian in the surrounding area. The GSSP is currently thought to lie in the upper Stimulograptus sedgwickii Zone (upper Aeronian) whereas the base of the Telychian is traditionally correlated at the base of the overlying Spirograptus guerichi Zone. Here, we provide new conodont biostratigraphic and organic carbon isotope (δ¹³C_org) chemostratigraphic information from Cefn Cerig to facilitate correlation with any future GSSP selected by the ISSS. Data from other sections demonstrate that the late Aeronian carbon isotope excursion is complete prior to the first occurrence of Sp. guerichi and that it will be difficult to project the current GSSP position precisely into any future section chosen as a replacement.