Geophysical and Geochemical Contraints on Submarine Volcanic Processes

Meghan Jones, Ph.D., 2019
S. Adam Soule, Advisor

This thesis investigates submarine volcanic processes using observations and samples from the 2011 Axial Seamount eruption, the 2012 Havre Volcano eruption, and the Mid-Atlantic Ridge near 14°N. I first develop best practices for quantifying vesicle textures and reconstructing total CO2 concentrations in mid-ocean ridge basalts (MORB). I next demonstrate that ascent rates during the 2011 Axial Seamount eruption were highly variable, likely due to lateral dike propagation and evolving reservoir overpressures, and show that ascent rates influence flow morphology. In the following chapter, I show that bubble accumulation produces highly vesicular MORB that pop upon recovery from the seafloor and suggest that mantle carbon concentrations are lower than previously proposed. Finally, I evaluate models for the submarine dispersal of giant pumice clasts using observations from the 2012 Havre Volcano eruption. I show that the seafloor distribution of giant pumice is controlled by conductive cooling, the advective displacement of steam by water through highly permeable pathways, and clast breakup during transport and deposition. Together, these chapters provide critical constraints on the flux of volatiles at mid-ocean ridges and the processes governing the emplacement of volcanic products on the seafloor.