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

• Published in: Physics of the earth and planetary interiors Vol. 224; pp. 88 - 103
• Main Authors: Gomi, Hitoshi, Ohta, Kenji, Hirose, Kei, Labrosse, Stéphane, Caracas, Razvan, Verstraete, Matthieu J., Hernlund, John W.
• Format: Journal Article Web Resource
• Language: English
• Published: Elsevier B.V 01.11.2013; Elsevier
• Subjects: Core; Earth; Earth core; Earth sciences & physical geography; Electrical resistivity; Gallium base alloys; Geophysics; Heat transfer; High pressure; Iron; Physical, chemical, mathematical & earth Sciences; Physique, chimie, mathématiques & sciences de la terre; Sciences de la terre & géographie physique; Thermal conductivity; Thermal evolution; Thermal conductivity; Electrical resistivity; Thermal evolution; Core; High pressure
• ISSN: 0031-9201; 1872-7395
• DOI: 10.1016/j.pepi.2013.07.010

•The thermal conductivity of the Earth’s core is greater than 90W/m/K.•Such high conductivity is a consequence of electrical resistivity saturation.•Present-day CMB heat flow is higher than 10TW.•Rapid secular cooling supports the young inner core and a basal magma ocean.•The center of the core may have been stratified before the birth of inner core. We measured the electrical resistivity of iron and iron-silicon alloy to 100GPa. 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 90W/m/K. These values are significantly higher than conventional estimates, implying rapid secular core cooling, an inner core younger than 1Ga, 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 10TW is likely required to explain the observed dynamo characteristics.