Wed 6th May, 12 – 1 pm, Rm 312.222

Abstract

The ~66 Ma Cretaceous–Paleogene (KPg) boundary marks one of the most significant biological turnovers in Earth history, leaving an evolutionary imprint still visible in the modern biota. Two major geologic events, the Chicxulub bolide impact and the eruptions of the Deccan Traps continental flood basalts that cover a surface area of ≈500 000 km2 in western India, occurred near the KPg boundary, and both have been identified as possible triggers for the extinction. Establishing causal relationships remains difficult, however, as recent high-precision geochronology demonstrates that the main phase of the Deccan eruptions began ≈250 000 years prior to the KPg boundary and the associated impact, and ended ≈750 000 years later. In order to address this issue, we measured sulfur abundance and isotope composition at two exceptionally well-preserved terrestrial KPg boundary sections in Alberta, Canada in order to trace atmospheric sulfur injections from these two events. Our results suggest that, in the immediate vicinity of the KPg boundary, the onset of a Deccan volcanic episode coincided with the impact. This episode lasted for ~5 times longer than any direct geochemical evidence for the impact and was followed by a second distinct volcanic episode, thousands of years later. This chronology of events may help explain the delayed recovery of terrestrial and marine ecosystems into the brave new Paleocene world.

Biography

Boz Wing is an Associate Professor and Dawson Chair in Geology in the Department of Earth and Planetary Sciences at McGill University. He is currently seated at UWA in the Centre for Exploration Targeting where he holds a Geldden Fellowship to work with Marco Fiorentini. He received his PhD in Metamorphic Geology from Johns Hopkins University, where he worked on monazite petrology and inverse theory for crustal fluid flow with John Ferry.  He moved to the University of Maryland for a post-doc, building a stable isotope laboratory and thinking about Precambrian atmospheric chemistry with James Farquhar. Almost a decade ago he moved to McGill where he oversees the Stable Isotope Laboratory with his colleague Galen Halverson, and tries to keep up with the awesome students and post-docs who actually run the lab.  His research program is roughly split between projects that focus on the peculiar mineralizing environments of the Precambrian, and those that try to maximize the gain on geochemical signals of early biological evolution, neither of which he will talk about in his presentation.