The He-Ne-Ar-H2O-CO2 Isotope and Abundance Systematics of the Central Indian Ridge: Constraints on Plume-Ridge Interaction and the Degassing History of the Reunion Hotspot

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ABSTRACT (Hilton)OCE-0726573Intellectual Merit: This research involves a detailed study of the isotope and abundance characteristics of magmatic volatiles in lavas from the Central Indian Ridge and its associated seamounts and fracture zones. The volatile characteristics of seafloor lavas provide key constraints on the structure and evolution of the Earth's mantle. The goal of the research is to use volatiles to decipher the evolution and degassing history of the Reunion hotspot as it impinges and interacts with the Central Indian spreading ridge to learn more about the mixing of magmas and plume-ridge interactions. The light rare gases (He, Ne and Ar) will be analyzed to determine volatile origins and mantle fluxes. Major gases (carbon dioxide and water) will provide controls on melting characteristics and degassing behavior. A detailed geophysical survey and dredging for volcanic glasses will be carried out in the Indian Ocean at four places on the Central Indian Ridge and its associated fracture zones and ridges. The geochemical sample suite will be supplemented by other samples from the region collected previously by two international groups (UK and France). These collaborators will also contribute expertise and analytical effort to the project. Noble gas-major volatile systematics of all samples will be carried out at Scripps Institution of Oceanography using a combination of crushing, stepped melting and laser probing. Major and trace element chemistry plus Sr-Nd-Pb-Hf-Th isotope work will be carried out by the international collaborators at no cost. Data will be used to improve out understanding of hotspot-ridge interactions and the dynamics of magma melting and movement at a locality where the hotspot is located oblique the ridge axis in contrast to Iceland where the hotspot is located on the ridge axis. Broader Impacts: Broader impacts of the work support the integration of research and education at every academic level from K-12 to post graduate work, including professional development for science educators in the informal, formal and community college settings. Activities that will be carried out include a staff professional development series at the Birch Aquarium at Scripps, professional development for high school Earth Sciences teachers, and presentations at community colleges. The work will support a female graduate student who will also act as the Chief Scientist on the cruise. There is also a strong international collaboration component with UK and French scientists.