Japan Geoscience Union Meeting 2016

Presentation information

International Session (Oral)

Symbol S (Solid Earth Sciences) » S-IT Science of the Earth's Interior & Techtonophysics

[S-IT06] Interaction and Coevolution of the Core and Mantle

Mon. May 23, 2016 10:45 AM - 12:15 PM 304 (3F)

Convener:*Satoru Tanaka(Department of Deep Earth Structure and Dynamics Research Japan Agency for Marine-Earth Science and Technology), Taku Tsuchiya(Geodynamics Research Center, Ehime University), Chair:Kenji Ohta(Department of Earth and Planetary Sciences, Tokyo Institute of Technology), Takashi Yoshino(Institute for Study of the Earth's Interior, Okayama University)

11:30 AM - 11:45 AM

[SIT06-10] Lattice thermal conductivity of lower mantle minerals

*Kenji Ohta1, Yoshiyuki Okuda1, Takashi Yagi2, Kei Hirose3, Ryosuke Sinmyo3 (1.Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2.National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, 3.Earth-Life Science Institute, Tokyo Institue of Technology)

Keywords:lower mantle , thermal conductivity, bridgmanite, ferropericlase

Heat in the Earth’s interior is transported dominantly by convection in the mantle and core, and by conduction at thermal boundary layers. The thermal conductivity of the bottom thermal boundary layer of the mantle determines the magnitude of heat flux from the core, and is intimately related to the formation of mantle plumes, the long-term thermal evolution of both mantle and core, and the driving force for generation of the geomagnetic field (Lay et al. 2008). Recent technical progress both in the experiment and the theoretical calculation enables us to reveal high-pressure and high-temperature behavior of lattice thermal conductivity of lower mantle minerals, MgSiO3 perovskite (birdgmanite) and MgO periclase. However, the effect of iron incorporation into these minerals on the lattice thermal conductivity is still controversial.
We measured the lattice component of thermal conductivities both of (Mg,Fe)(Si,Al)O3 bridgmanite and (Mg,Fe)O ferropericlase at the Earth’s lower mantle pressures and 300 K using a pulsed light heating thermoreflectance technique in a diamond anvil cell. We found that iron incorporation into bridgmanite shows minor effect on the thermal conductivity. On the other hand, the obtained conductivity of ferropericlase was considerably lower than that of MgO periclase. The estimated lattice thermal conductivity of bridgmanite-dominant lowermost mantle is comparable to conventionally assumed value of 10 W/m/K (Stacey, 1992). However, our results imply that local existence of (Mg,Fe)O ferropericlase in the lower mantle induce strong heterogeneity of thermal conductivity.

Lay, T. et al.: Nature Geosci. 1, 25-32 (2008).
Stacey, F.: Physics of the Earth, 3rd ed. (1992).