9629279 Gurnis The PIs propose a collaborative project integrating seismological and geodynamic tools and concepts to elucidate the dynamics and fine structure of the lower mantle and "D" region. Seismic data will be used to determine details of apparent down- and up-welling, and contamination from shallow earth structures will be elucidated by the interplay between direct seismic modeling and prediction made from dynamic models. Dynamic models will be used to construct 2D and 3D velocity models which in turn will be used to construct synthetics, and their predictions will be compared with appropriate data sets for verification and feed-back to produce improved models. Recent tomographic models will be used to construct 2D cross-sections and corresponding synthetics in year one, and fully dynamic models will be used to study thermochemical boundaries in hot regions where partial melting or entrainment of core material could play a role in a year or two. ***
