Kevin Geyer Harrison 

This research outlines a sequence of events that may help explain the observed state change in Deccan volcanism about 66 million years ago. Two mantle plumes may have created a reservoir of melt in the mantle that erupted to form the Deccan continental flood basalts (Glisovic and Forte, 2017). Interestingly, these plumes and the melt reservoir they produced were very buoyant. (Glisovic and Forte, 2017). My research explores the possibility that exsolved supercritical fluids helped make the plumes and the melt reservoir highly buoyant. The exsolved supercritical fluids may have been volatiles, such as carbon dioxide and water. Manga and Brodsky (2006) found that the exsolution of volatiles may increase the buoyancy of a melt and Richards et al. (2015) concluded that carbon dioxide and water may exsolve as supercritical fluids at high temperatures and pressures. Supercritical fluids typically have densities that are less than liquids (Clifford, 1999). Richards et al. (2015) and Renne et al. (2015) found that the Chicxulub impact may have caused a state change in Deccan volcanism, although the mechanism that caused this change is unknown. This research will outline how a change in tectonics may have stopped Deccan volcanism and caused a build-up of magma in the mantle. It will show how seismic waves generated by the Chicxulub impact re-started volcanic eruptions by exploring the role of supercritical volatiles in volcanic systems. This research suggests that the exsolution of volatiles as gases, liquids, and supercritical fluids in the Earth’s interior plays a pivotal role in volcanic eruptions. For example, exsolved volatiles increase the permeability of the crust to volcanic eruptions. This research also explores how the density, dynamic viscosity, and thermal conductivity of carbon dioxide and water change with depth in the Earth’s interior.