9301602 Poreda This proposal is a collaborative research effort between the University of Rochester and the University of Rhode Island to use multiple isotopic tracers to investigate the dynamics of outgassing when thermally buoyant mantle plumes interact with the depleted asthenosphere along the Mid-Atlantic Ridge (79 N -6 S). This proposal will focus on the isotopic analyses of the noble gases (He, Ne, Ar, Xe) and on the elemental parent/daughter concentrations (Rb/Sr, Sm/Nd, U/Pb, Th/Pb and Cl). On hand-picked MORB glass, a complete multi-isotope and concentration data set will be established for elements of varying volatilities, ranging from Sr, Nd,Pb to He,Ne, Ar, Xe and Cl. By combining both volatile and lithophile isotope measurements with geophysical data, this research will attempt to constrain the outgassing behavior of mantle plumes, the nature, scale length and mixing characteristics of mantle heterogeneities and the dynamics of plume-asthenosphere mixing. The four provinces of investigation are: the Equatorial Atlantic, the Jan Mayen-Mohns-Knipovich Ridge, the Iceland-Reykjanes-Kolbeinsey Ridge and the Azores-Mid Atlantic Ridge . Each region has unique geochemical and tectonic characteristics that will provide insights into mantle evolution and plume dynamics.
