Dilatational anelasticity in partial melts: Viscosity, attenuation, and velocity dispersion

摘要: Thermodynamic constraints on the geometry of melt/solid interfaces require that a texturally equilibrated partial melt respond to changes in mean normal stress through adjustment sizes melt-bearing triple-grain junctions. This dilatational response is well-modeled as standard anelastic solid provided rate limited by solid-state deformation processes attending dilatation rather than flow itself. Using this model, we have analyzed flexural creep data obtained for fine-grained comprising MgSiO3 polycrystalline phase equilibrium with sodium aluminosilicate melt. The (or “bulk”) viscosity two-phase material nearly an order magnitude less its shear viscosity, latter being determined diffusional creep. corresponding modulus controls extent several orders smaller elastic bulk aggregate. Applied case harmonic loading, model predicts substantial band-limited dissipation spectrum (Qk−1) tnat would be absent but presence creates large and strong P wave absorption (Qp−1) band enstatite material, accompanied velocity dispersion. Through enhanced attenuation, suppresses P-to-S ratios produces equivalent Q values two modes.