Journal articles
An early geodynamo driven by exsolution of mantle components from Earth’s core
Abstract : Terrestrial core formation occurred in the early molten Earth by gravitational segregation of immiscible metal and silicate melts, stripping iron-loving elements from the silicate mantle to the metallic core1-3, and leaving rock-loving components behind. Here we performed experiments showing that at high enough temperature, Earth's major rock-loving component, magnesium oxide, can also dissolve in core-forming metallic melts. Our data clearly point to a dissolution reaction, and are in agreement with recent DFT calculations. Using core formation models5, we further show that a high-temperature event during Earth's accretion (such as the Moon-forming giant impact) can contribute significant amounts of magnesium to the early core. As it subsequently cools, the ensuing exsolution of buoyant magnesium oxide generates a substantial amount of gravitational energy. This energy is comparable to if not significantly higher than that produced by inner core solidification - the primary driver of the Earth's current magnetic field1. Since the inner core is too young to explain the existence of an ancient field prior to ~1 billion years, our results solve the conundrum posed by the recent paleomagnetic observation of an ancient field at least 3.45 Gyr old.
Cited literature [41 references]
https://hal-insu.archives-ouvertes.fr/insu-02135813
Contributor : Eva Fareau <>
Submitted on : Tuesday, May 21, 2019 - 3:38:12 PM
Last modification on : Friday, March 27, 2020 - 2:10:00 AM
Contributor : Eva Fareau <>
Submitted on : Tuesday, May 21, 2019 - 3:38:12 PM
Last modification on : Friday, March 27, 2020 - 2:10:00 AM
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emss-68569.pdf
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