Melt distribution in mantle rocks deformed in shear

Shear experiments on olivine-basalt aggregates provide compelling evidence that the dynamic distribution of melt is controlled by the magnitude and or ientation of the differential stress. Our results suggest that deformed, pa rtially molten upper mantle rocks will have highly anisotropic physical pro perties including seismic wave velocities and melt permeability. In additio n, our results provide a basis for interpreting geophysical observations, s uch as shear-wave splitting and for modeling melt migration processes benea th mid-ocean ridges, specifically focused flow of melt toward the ridge axi s.