Towards the definition of the GSSP of the Norian Stage (Upper Triassic): Integrated stratigraphy and correlation of the two candidate sections Black Bear Ridge (BC, Canada) and Pizzo Mondello (Italy)

The Norian Stage is one of the two stages of the Upper Triassic Series that remains undefined. Considerable research has been undertaken in the last 10 years in order to identify the best candidate sections and more recently this research has focused on the Black Bear Ridge section on Williston Lake (British Columbia, Canada) and the Pizzo Mondello section in Sicily (Italy). Both sections are characterized by good exposure, rather uniform facies, and good paleontologic records and are thus suitable as GSSP sections for the Carnian-Norian Boundary (CNB). In recent years the two sections have been studied in great detail in regards to conodont, pelagic bivalve, ammonoid, and radiolarian biostratigraphies as well as by facies analysis, magnetostratigraphy, and stable isotopic variations. Both sections show a rich conodont and pelagic bivalve record that is calibrated by less commonly occurring ammonoids. Pizzo Mondello has also yielded radiolarians and a very good magnetostratigraphic record. Black Bear Ridge is exceptional in preserving an unrivalled record of conodont evolution through the boundary interval, with demonstrable faunal turnover and appearance of key conodont indices that coincide with the FAD of the bivalve Halobia austriaca, which has been proposed as a primary marker for the GSSP. The conodont record of Black Bear Ridge is also calibrated with ammonoid and radiolarian faunas from nearby sections. The correlatability of the CNB datum is under evaluation.