The high conductivity of iron and thermal evolution of the Earth's core

Hitoshi Gomi; Kenji Ohta; Kei Hirose; Stéphane Labrosse; Razvan Caracas; Matthieu J. Verstraete; John W. Hernlund

doi:10.1016/j.pepi.2013.07.010

The high conductivity of iron and thermal evolution of the Earth's core

Hitoshi Gomi^*, Kenji Ohta, Kei Hirose, Stéphane Labrosse, Razvan Caracas, Matthieu J. Verstraete, John W. Hernlund

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

We measured the electrical resistivity of iron and iron-silicon alloy to 100. GPa. The resistivity of iron was also calculated to core pressures. Combined with the first geophysical model accounting for saturation resistivity of core metal, the present results show that the thermal conductivity of the outermost core is greater than 90. W/m/K. These values are significantly higher than conventional estimates, implying rapid secular core cooling, an inner core younger than 1. Ga, and ubiquitous melting of the lowermost mantle during the early Earth. An enhanced conductivity with depth suppresses convection in the deep core, such that its center may have been stably stratified prior to the onset of inner core crystallization. A present heat flow in excess of 10. TW is likely required to explain the observed dynamo characteristics.

Original language	English
Pages (from-to)	88-103
Number of pages	16
Journal	Physics of the Earth and Planetary Interiors
Volume	224
DOIs	https://doi.org/10.1016/j.pepi.2013.07.010
Publication status	Published - Nov 2013
Externally published	Yes

Funding

We thank T. Komabayashi for discussions and Francis Nimmo and an anonymous reviewer for valuable comments. S.L. and R.C. are grateful to the LABEX Lyon Institute of Origins ( ANR-10-LABX-0066 ) of the Université de Lyon for its financial support within the program “Investissements d’Avenir” (ANR-11-IDEX-0007) of the French government operated par the National Research Agency (ANR). S.L. has been supported by the Agence Nationale de la Recherche under the grant ANR-08-JCJC-0084-01 . J.H. was supported by the National Science Foundation ( NSFEAR0855737 ).

Funders	Funder number
National Science Foundation	NSFEAR0855737, 1160917, 1161000
Institut des Origines de Lyon	ANR-10-LABX-0066
Agence Nationale de la Recherche	ANR-08-JCJC-0084-01
Japan Society for the Promotion of Science	24000005, 12J57032
Université de Lyon	ANR-11-IDEX-0007

Keywords

Core
Electrical resistivity
High pressure
Thermal conductivity
Thermal evolution

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10.1016/j.pepi.2013.07.010

Cite this

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title = "The high conductivity of iron and thermal evolution of the Earth's core",

abstract = "We measured the electrical resistivity of iron and iron-silicon alloy to 100. GPa. The resistivity of iron was also calculated to core pressures. Combined with the first geophysical model accounting for saturation resistivity of core metal, the present results show that the thermal conductivity of the outermost core is greater than 90. W/m/K. These values are significantly higher than conventional estimates, implying rapid secular core cooling, an inner core younger than 1. Ga, and ubiquitous melting of the lowermost mantle during the early Earth. An enhanced conductivity with depth suppresses convection in the deep core, such that its center may have been stably stratified prior to the onset of inner core crystallization. A present heat flow in excess of 10. TW is likely required to explain the observed dynamo characteristics.",

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T1 - The high conductivity of iron and thermal evolution of the Earth's core

AU - Gomi, Hitoshi

AU - Ohta, Kenji

AU - Hirose, Kei

AU - Labrosse, Stéphane

AU - Caracas, Razvan

AU - Verstraete, Matthieu J.

AU - Hernlund, John W.

PY - 2013/11

Y1 - 2013/11

N2 - We measured the electrical resistivity of iron and iron-silicon alloy to 100. GPa. The resistivity of iron was also calculated to core pressures. Combined with the first geophysical model accounting for saturation resistivity of core metal, the present results show that the thermal conductivity of the outermost core is greater than 90. W/m/K. These values are significantly higher than conventional estimates, implying rapid secular core cooling, an inner core younger than 1. Ga, and ubiquitous melting of the lowermost mantle during the early Earth. An enhanced conductivity with depth suppresses convection in the deep core, such that its center may have been stably stratified prior to the onset of inner core crystallization. A present heat flow in excess of 10. TW is likely required to explain the observed dynamo characteristics.

AB - We measured the electrical resistivity of iron and iron-silicon alloy to 100. GPa. The resistivity of iron was also calculated to core pressures. Combined with the first geophysical model accounting for saturation resistivity of core metal, the present results show that the thermal conductivity of the outermost core is greater than 90. W/m/K. These values are significantly higher than conventional estimates, implying rapid secular core cooling, an inner core younger than 1. Ga, and ubiquitous melting of the lowermost mantle during the early Earth. An enhanced conductivity with depth suppresses convection in the deep core, such that its center may have been stably stratified prior to the onset of inner core crystallization. A present heat flow in excess of 10. TW is likely required to explain the observed dynamo characteristics.

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KW - Electrical resistivity

KW - High pressure

KW - Thermal conductivity

KW - Thermal evolution

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JO - Physics of the Earth and Planetary Interiors

JF - Physics of the Earth and Planetary Interiors

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The high conductivity of iron and thermal evolution of the Earth's core

Abstract

Funding

Keywords

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