Seminar date: Tuesday, May 13th 2025 at 9am Beijing; 10am Tokyo; 11am Australian Eastern
May 12th at 6pm Pacific and 9pm Eastern (North America)
Speaker: Prof. David B. Kemp (he/him), China University of Geosciences (Wuhan)
The early Toarcian oceanic anoxic event (T-OAE or 'Jenkyns Event', ~183 Ma) in the Early Jurassic was one of the biggest hyperthermals of the Phanerozoic. Warming has been linked primarily to carbon release from the Ferrar large igneous province, and perhaps from other surficial reservoirs. Two key impacts of large-scale warming during the T-OAE were widespread seawater deoxygenation and a marked acceleration in hydrological cycling. In particular, global-scale deoxygenation across the T-OAE has been inferred from metal isotope data, as well as from evidence for global redox-sensitive trace element drawdown. Similarly, warming-driven increases in global weathering, runoff and storminess have been inferred from both geochemical and sedimentological data. Understanding the links between carbon release and these changes in the Earth system demands high-resolution and temporally well-constrained data, but such data are often lacking. I will present and discuss some new work on the timing and pattern of redox and hydrological changes through the T-OAE. The data come from the well-studied Yorkshire section in the UK, and demonstrate a complex millennial-scale pattern of changing redox conditions in response to inferred carbon release. Similarly rapid changes in terrestrial fluxes, likely controlled by changing runoff, accompanied these redox changes. Together, the data highlight the geologically rapid rate at which basin-scale redox and hydrological conditions can change in response to abrupt warming.