CSEDI Collaborative Research: Multidisciplinary Studies of the Core-Mantle Boundary Region

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9905733 Williams The investigators propose to couple seismic interrogations of the structure of the core-mantle boundary with statistical analyses, mineral physics experiments (on melt/solid coexistence at ultra-high pressure), and simulations of rates of heat advection and conduction away from the CMB in order to explore the chemical, structural and thermal properties of the recently discovered ultra-low velocity zone (ULVZ) at the base of Earth's mantle. This zone likely contains partial melt, is structurally complex and may be chemically distinct from the overlying mantle. Upwellings from this zone also probably produce hot spots at Earth's surface. The investigators plan to (1) utilize broad band seismic data and waveform modeling of diffracted waves at the CMB to characterize the thicknesses and locations of ULVZ's; (2) statistically analyze available seismic observations to characterize the spatial variability of the ULVZ; (3) constrain likely advective and conductive components of heat flow across both the ULVZ and non-ULVZ-containing regions using fluid dynamic simulations; and (4) determine the compositions of liquidus phases in natural peridotitic assemblages at ultra-high pressures.