[S-IT21] Interaction and Coevolution of the Core and Mantle in the Earth and Planets

[SIT21-P09] Lattice thermal conductivity of CaSiO₃ perovskite at high pressures and high temperatures

*Kotaro Onga¹, Kenji Ohta¹, Akira Hasegawa^1,2, Takashi Yagi², Kei Hirose^3,4, Yasuo Ohishi⁵ (1.Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2.National Institute of Advanced Industrial Science and Technology, 3.Earth-Life Science Institute, Tokyo Institute of Technology, 4.Department of Earth and Planetary Science, The University of Tokyo, 5.Japan Synchrotron Radiation Research Institute)

Keywords:CaPv, thermal conductivity, lower mantle

Laboratory measurements of thermal conductivity of deep Earth materials provide important information on the dynamics and thermal evolution of the mantle and the core. CaSiO₃ perovskite (CaPv) is a constituent of pyrolitic lower mantle and of the subducting oceanic crust at depth greater than 560 km. In recent years, there are many reports of the laboratory-based lower mantle thermal conductivity profiles, but the thermal conductivity of CaPv has never been measured and included in the models [1,2,3,4,5] . CaPv is an unquenchable high-pressure phase at ambient conditions, and temperature-induced structure change from tetragonal to cubic occurs at around 500 K [6]. Therefore, in-situ high pressure and temperature X-ray diffraction (XRD) and thermal conductivity measurements are required to determine the thermal conductivity of CaPv in the Earth’s deep interior.
In this study, we determined the thermal conductivity of CaPv at about 50 GPa and high temperature to 1950 K by a combination of synchrotron XRD measurements and the pulsed light heating thermoreflectance technique. Based on our experimental results, we consider the effect of the presence of CaPv on the thermal conductivity of the pyrolitic lower mantle and the subducting oceanic crust.



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