Thermal conductivity of deep Earth materials with implications for the mantle and core dynamics

Abstract:

Thermal conductivity of Earth materials under relevant pressure-temperature conditions is crucial to determine the temperature profile in Earth’s interior, which in turn influences its thermo-chemical structures and geodynamics. However, precise measurements of the thermal conductivity of deep Earth materials under extreme conditions have been challenging due to the difficulty and limitation of experimental techniques. Recently we have successfully combined an ultrafast optical pump-probe method with high-pressure diamond cells to precisely measure the thermal conductivity of a series of deep Earth materials, from the upper mantle all the way down to the core, under extreme conditions, i.e., an anatomy of deep Earth thermal conductivity. In this talk, I will present some of our recent representative results on the effects of hydration, iron, aluminum, and silicon on the thermal conductivity of mantle and core materials along with their impacts on the thermo-chemical features and geodynamics in different regions in the deep Earth interior. Commonly, these “impurities” all reduce the thermal conductivity of pure material and thus hinder the heat transfer. Some future directions that are critical to further understand the thermal state and dynamics of the deep Earth will also be discussed.