Weidner 9418689 The project's goal is to increase the understanding of the earth's upper mantle and transitin zone through an integrated, quantitative analysis of seismological and mineralogical data. The seismic data sets will include the frequency-dependent travel times of direct and multiply reflected shear waves, surface waves, and higher modes on vertical, radial, and transverse seismograms, as well as mantle reflectivity profiles obtained from horizontally polarized ScS reverberations. The latter will allow tight constraints to be placed on the existance, location, and impedance contrasts across upper-mantle discontinuities. The seismological data from each corridor will be inverted for a path-averaged, anisotropic earth model subject to different sets of mineralogical constraints. These constraints will be generated by self-consistent mineralogical modeling of upper-mantle structure assuming hypothetical compositions and phase relations, and then tested for consistency with the seismic data. Among the hypotheses to be examined are competing compositional models (e.g., pyrolite vs. piclogite), the hypothesis of chemical homogeneity, and mechanisms for polarization anisotropy. ****
