Collaborative research: Dynamics and origins of explosive silicic volcanism at 2300 mbsl on a mid-ocean ridge spreading center

Brown University, Providence RI

Investigators

Abstract

Very little is known about explosive silicic volcanic eruptions in deep sea environments because so few have been discovered and documented. On land these types of eruptions pose significant hazards for populations living near the volcano and/or along the path of any ash cloud dispersal zone. This research analyzes samples from a 2012 Monterrey Bay Aquarium Research Institute (MBARI) cruise to the Alarcon Rise in the Gulf of California that discovered a unique silicic (rhyolite, dacitic, andesitic) eruption center lying 2,300 to 2,400 meters below the sea surface. Goals of the research are to fill a major gap in our understanding of deep marine explosive volcanic events. Work includes collection of a comprehensive geochemical, petrological, and volcanological dataset of the volatile and degassing history of the eruptive center. It will involve merging topographic/feature information obtained from high resolution (1 meter) bathymetric maps of the area and analyses of 6 volcaniclastic scoop bags and 24 push cores that contain samples of pumice and fluidal silicic material. Data will be used to determine the mechanism of magmatic differentiation and volatile enrichment, as well as volcaniclastic transport processes, pyroclast dispersal extent, and fragmentation mechanisms. It will also determine how much magmatic volatiles influence magma viscosity and eruption style in deep sea explosive eruptions by measuring the volatile (H2O, CO2, S, etc.) contents in the eruptive glasses. Additionally, U-Th and U-Th/He and Ar age dating will take place to determine if the deposits represent more than one eruption and, if there is more than one, when they took place. Both stable isotopes (O and H) and radiogenic isotopes (Sr, Nd, Pb, Hf) of the collected lavas and glasses will be analyzed to examine impacts of potential continental and oceanic crustal assimilation in the origination of the eruption(s). Broader impacts of the research are strong and multifaceted. They include the creation of a website and virtual reality displays of the study area and its volcano and volcanic deposits for educators and the distribution of this visual over YouTube and at the Monterrey Bay Aquarium Research Institute Open House. There is also significant international collaboration with scientists from Mexico and Australia; and there will be an increase in the infrastructure for science by developing new geochemical analytical procedures and capabilities at the University of California, Santa Cruz. Additional impacts are that the project supports two early career PIs, one of whom is at an institution in an EPSCoR state (Rhode Island).