THE INFLUENCE OF CHANGING SEA LEVEL ON MID-OCEAN RIDGE MAGMATISM: CORRELATING HYDROTHERMAL ACTIVITY WITH OXYGEN ISOTOPE RECORDS ALONG THE EAST PACIFIC RISE

The retreat of glaciers may have caused enhanced volcanism in high latitude areas during the last deglaciation (Maclennan et al., 2002; Licciardi et al., 2007; Huybers and Langmuir, 2009). Additionally, melting glaciers may have indirectly affected submarine volcanism via changes in sea level (Lund and Asimow, 2008; Huybers and Langmuir, 2009). If there is clear evidence for coherent changes in hydrothermal activity with oxygen isotope records along mid-ocean ridges, it would increase the possibility that sea level-driven changes in magmatism play an important role in glacial-interglacial CO₂ cycles, driving climate change. Arsenic is scavenged from seawater by Fe oxyhydroxides and Mn oxides that precipitate out of hydrothermal plumes near hydrothermal vent systems (Dymond, 1981). Changing concentrations of these metals through time along the East Pacific Rise (EPR) should reflect changes in the frequency and magnitude of plume events. By correlating the oxygen isotope record to changes in metal concentrations, a time stamp can be placed on hydrothermal activity, which is predicted to lag changing sea level by thousands of years (Lund and Asimow, 2011). Sediment cores were sampled at three locations along the EPR in order to build stratigraphically and chronologically accurate records using oxygen isotopes and metal concentrations. Initial results show a marked increase in Fe, Mn, and As concentrations following deglacial periods. These results follow a consistent pattern observed with other core sites further north along the EPR (Lund et al., 2015). By correlating the oxygen isotopes and the hydrothermal activity, glacial-interglacial variations in sea level can be modeled and related to mid-ocean ridge magmatism.