Abstract: The Earth is composed of a large set of structurally and compositionally complex minerals. Many important materials properties, such as thermal transport properties of lower mantle minerals, cannot yet be directly measured in laboratory at the relevant high pressure (P) and high temperature (T) conditions. Current database of these minerals properties are often estimated using long P-T extrapolation of lower P-T experimental measurements, resulting large uncertainties that might suggest very different geophysical implications. First-principles computational methods provide complimentary approaches to constrain estimations of these properties of Earth’s minerals. In this talk, I will present our recent work on thermal conductivity of lower mantle minerals. Anchoring on our latest first-principles calculations of lattice thermal conductivity of ferropericlase (Mg,Fe)O and Fe-bearing magnesium silicate perovskite (Mg,Fe)SiO3, and a re-evaluation of the radiative contribution to diffusive heat transfer, we present a new assessment of lower mantle thermal conductivity, and propose that the overall thermal conductivity is approximately constant at 3 W/m/K throughout the lower mantle. This significant downward adjustment of lower mantle thermal conductivity values implies that the mantle has a blanketing effect on heat flow coming out of the Earth’s core, thus slowing the Earth’s thermal evolution. Finally, I will discuss the opportunities of further developing thermal transport theory and computational methodologies based on recent experimental findings, in order to improve the robustness of theoretical models for the complex Earth minerals at the extreme high P-T conditions.

   

Date&Time: July 15, 2013 (Monday), 15:00 - 16:00
Location: 606 Conference Room