LATE DEVONIAN (FRASNIAN-FAMENNIAN) δ13CORG PERTURBATIONS IN THE NORTHERN APPALACHIAN BASIN: AN INTEGRATED STUDY OF EXTINCTION THROUGH GEOCHEMICAL AND SEDIMENTOLOGICAL RECORDS

The Frasnian-Famennian (F-F) extinction consisted of two pulses, the Lower and Upper Kellwasser Events (LKW and UKW). In the Appalachian Foreland Basin, sedimentation rates in the Late Devonian were extremely high, resulting in temporally expanded stratigraphic sections. These expanded fossiliferous units provide new insight on the dynamics of environmental and biotic change through this critical interval for comparison with the well-studied and temporally condensed sections in Europe and Asia. Bush et al. (2015; Palaeogeography, Palaeoclimatology, Palaeoecology) argued that existing correlations between deeper-water sections in western New York and shallower-water sections to the east were incorrect for the LKW through UKW interval and proposed revised correlations based on biostratigraphic and lithostratigraphic evidence. Here, these revised correlations are integrated with newly generated δ¹³C_org data from multiple sections in New York and Pennsylvania that span the LKW and UKW events. A ~4‰ positive excursion coincides with the onset of deposition of the LKW approximate Pipe Creek Shale, an organic-rich unit deposited in an offshore setting. We also discuss the need for new stratigraphic terminology in the interval between the LKW and UKW in shallower-water settings in New York and Pennsylvania. For example, the “Hammond” Member is an informal unit that overlies the Pipe Creek in this region; it is laterally continuous throughout our study area and provides critical new insights into the role played by environmental and climatic change in the LKW extinction.