Low thermal conductivity of iron-silicon alloys at Earth’s core conditions with implications for the geodynamo

Author:

Hsieh Wen-PinORCID,Goncharov Alexander F.ORCID,Labrosse StéphaneORCID,Holtgrewe Nicholas,Lobanov Sergey S.ORCID,Chuvashova Irina,Deschamps Frédéric,Lin Jung-FuORCID

Abstract

AbstractEarth’s core is composed of iron (Fe) alloyed with light elements, e.g., silicon (Si). Its thermal conductivity critically affects Earth’s thermal structure, evolution, and dynamics, as it controls the magnitude of thermal and compositional sources required to sustain a geodynamo over Earth’s history. Here we directly measured thermal conductivities of solid Fe and Fe–Si alloys up to 144 GPa and 3300 K. 15 at% Si alloyed in Fe substantially reduces its conductivity by about 2 folds at 132 GPa and 3000 K. An outer core with 15 at% Si would have a conductivity of about 20 W m−1 K−1, lower than pure Fe at similar pressure–temperature conditions. This suggests a lower minimum heat flow, around 3 TW, across the core–mantle boundary than previously expected, and thus less thermal energy needed to operate the geodynamo. Our results provide key constraints on inner core age that could be older than two billion-years.

Funder

Academia Sinica

Ministry of Science and Technology, Taiwan

Publisher

Springer Science and Business Media LLC

Subject

General Physics and Astronomy,General Biochemistry, Genetics and Molecular Biology,General Chemistry

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