Correlation of Lithospheric Velocity and Electrical Conductivity for Southern Africa

Southern Africa is the world’s premier location for studying the Sub-Continental Lithospheric Mantle (SCLM) given the abundance of geophysical and geochemical data that now exist for it. In particular, the Southern African Seismic Experiment (SASE) and the Southern African Magnetotelluric Experiment (SAMTEX) have added a wealth of seismological and electrical data that can be explored for physical property information and compared and contrasted both qualitatively and quantitatively. Qualitatively there is significant spatial correlation between low velocity and low resistivity regions and between high velocity and high resistivity regions. Adopting a quadratic relationship between shear-wave velocity and resistivity, based on mineral physics arguments, and predicting the velocity from the observed resistivity shows that the two are compatible except for two distinct regions. This relationship requires that resistivity be controlled by bulk property effects, particularly temperature variation, and not by minor conductive phases.