No interconnection of ferro-periclase in post-spinel phase inferred from conductivity measurement

Electrical conductivities of post-spinel, which are thought to be a dominant assembly in the lower mantle, were investigated at the conditions of the uppermost lower mantle (25 GPa and temperatures ranging from 300 to 2000K) in a Kawai-type multi-anvil apparatus. Post-spinel phases with a bulk composition of ((Mg,Fe)₂SiO₄: X_Fe = 0.09) were measured to constrain the bulk conductivity of the lower mantle. To investigate interconnectivity of ferro-periclase in silicate perovskite matrix, a single phase composed of magnesium silicate perovskite ((Mg,Fe)SiO₃: X _Fe = 0.1) and ferro-periclase ((Mg,Fe)O: X_Fe = 0.13) were also measured. The conductivity values of the silicate perovskite are distinctly lower than those for the, coexisting ferro-pericalse. Both absolute values and change in activation enthalpy for the conductivity of the post-spinel phases are similar to those for the silicate perovskite. These observations suggest that ferro-periclase in post-spinel are isolated in silicate perovskite matrix.