Constraints from material properties on the dynamics and evolution of Earth's core

TitleConstraints from material properties on the dynamics and evolution of Earth's core
Publication TypeJournal Article
Year of Publication2015
AuthorsDavies C, Pozzo M, Gubbins D, Alfe D
JournalNature Geoscience
Volume8
Pagination678-+
Date Published2015/09
Type of ArticleReview
ISBN Number1752-0894
Accession NumberWOS:000360392000010
Keywordsab-initio calculations; compositional; electrical-conductivity; geomagnetic secular variation; heat-flux; inner-core; liquid-iron; mantle boundary; outer-core; stratification; thermal-conductivity
Abstract

The Earth's magnetic field is powered by energy supplied by the slow cooling and freezing of the liquid iron core. Efforts to determine the thermal and chemical history of the core have been hindered by poor knowledge of the properties of liquid iron alloys at the extreme pressures and temperatures that exist in the core. This obstacle is now being overcome by high-pressure experiments and advanced mineral physics computations. Using these approaches, updated transport properties for Fe-Si-O mixtures have been determined at core conditions, including electrical and thermal conductivities that are higher than previous estimates by a factor of two to three. Models of core evolution with these high conductivities suggest that the core is cooling much faster than previously thought. This implies that the solid inner core formed relatively recently (around half a billion years ago), and that early core temperatures were high enough to cause partial melting of the lowermost mantle. Estimates of core-mantle boundary heat flow suggest that the uppermost core is thermally stratified at the present day.

DOI10.1038/ngeo2492
Short TitleNat. Geosci.
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