FIRST REPORT OF THE ARCHAEOCYATHID EXTINCTION AND THE REDLICHIID-OLENELLID EXTINCTION CARBON ISOTOPE EXCURSIONS (AECE AND ROECE) IN EASTERN LAURENTIA: IMPLICATIONS FOR PERTURBATIONS IN THE LATE EARLY CAMBRIAN CARBON CYCLE
Here we present carbon isotope stratigraphy constructed from the Early to Middle Cambrian Shady Dolomite Formation in southwestern Virginia. The carbonate carbon isotope (δ13Ccarb) data was generated from the drill core in the periplatform facies of the Shady that captures two negative δ13C excursions. Based on their stratigraphic positions and biostratigraphic data, the two negative CIEs likely represent the local appearance of the AECE and the ROECE. Locating the AECE and the ROECE in the Shady provides an eastern Laurentian record of these perturbations and strengthens the argument that they represent global changes in the late early Cambrian carbon cycle. This study also builds the foundation for employing other geochemical proxies for anoxia and volcanism such as Ca/I, Hg, and iron speciation to further understand the paleoenvironmental changes at the end of the early Cambrian and to bridge the gap between the two extinction events and their proposed driving mechanisms.