Constraints on the Depth, Thickness, and Strength of the G Discontinuity in the Central Pacific From S Receiver Functions

The relative motion of the lithosphere with respect to asthenosphere implies existence a boundary zone that accommodates shear between rigid plates and flowing mantle. This is typically referred as lithosphere-asthenosphere (LAB). width this mechanisms accommodating across it have important implications for coupling mantle convection surface plate motion. Seismic observations provided evidence several physical might help enable motion, but how these each contribute overall accommodation remains unclear. Here we present receiver function constraints on discontinuity structure oceanic upper at NoMelt site in central Pacific, where local velocity, anisotropy, conductivity, attenuation down ?300 km depth provide comprehensive picture structure. We image seismic Vsv decrease 4.5% or more over 0–20 thick gradient layer centered ?65 km. associate feature Gutenberg (G), interpret our observation G resulting from strain localization dehydration based good agreement dry solidus. Transitions Vsv, azimuthal observed roughly similar depths suggest represents region localized within broader asthenosphere.