Date of Completion


Embargo Period



Penny Vlahos, Robert Mason

Field of Study



Master of Science

Open Access

Open Access


Melting glaciers may have indirectly affected submarine volcanism via changes in sea level. As sea level quickly drops, the rate of pressure change increases, resulting in decompression melting in the upper mantle, increasing magmatic flux. Given that hydrothermal activity at mid-ocean ridges is driven by near-axis magmatic heat, the concentration of hydrothermal proxies in ridge crest sediments (Fe, Mn, and As) can be used to infer long-term changes in hydrothermal plume activity. Using a series of well-dated sediment cores from the East Pacific Rise (EPR), we find glacial-interglacial variations in the concentrations of Fe, Mn, and As at multiple locations, with peak concentrations occurring during glacial terminations. These results are similar to those from sites further north along the EPR, suggesting widespread changes in hydrothermal activity along the EPR. A basaltic ash layer in Core OC170-026-159 aligns with Glacial Termination II, suggesting a volatile, submarine eruption. Diagenetic overprinting, sediment focusing, and dilution with non-hydrothermal components are unlikely complicating factors for the interpretation of hydrothermal proxies. The release of carbon and geothermal heat during increased hydrothermal activity would promote deglaciations, but the exact mechanism remains unclear.

Major Advisor

David Lund