Thermal diffusivity of olivine under upper mantle conditions

Thermal diffusivity of olivine with (Mg0.89Fe0.11)2SiO4 composition is measured at pressures up to 9 GPa and temperatures up to 1700 K using the Ångström method in a cylindrical geometry. The experimental results demonstrate that lattice thermal diffusivity increases with increasing pressure at a small rate: 46 per cent increase over 10 GPa. The experimental data also suggest that radiative thermal diffusivity may decrease with increasing pressure. Thermal diffusivity in the upper mantle has almost constant values of 7–8 × 10−7 m2 s−1.