Radiative Thermal Diffusivity and Conductivity of the Upper Mantle

Olivine comprises >60% of the upper mantle, making it the dominant control on heat transport through the lithosphere. Accurate estimates of the thermal diffusivity and thermal conductivity are important to modeling geotherms, estimating lithospheric thickness, determining the depth range of melt generation, etc. Diffusivity and conductivity result from lattice vibration and radiative transport of thermal energy and depend upon temperature. New estimates of the radiative contribution to thermal diffusivity and thermal conductivity are made from the difference between previous experiments on olivine samples with Mg# ∼0.9. Thermal diffusivity can be expressed as