Core merging and stratification following giant impact - Université Claude Bernard Lyon 1 Accéder directement au contenu
Article Dans Une Revue Nature Geoscience Année : 2016

Core merging and stratification following giant impact

Maylis Landeau
Peter Olson
  • Fonction : Auteur
Benjamin H. Hirsh
  • Fonction : Auteur

Résumé

A stratified layer below the core-mantle boundary has long been suspected on the basis of geomagnetic and seismic observations(1-3). It has been suggested that the outermost core has a stratified layer about 100 km thick(3-6) that could be due to the diffusion of light elements(7,8). Recent seismological evidence, however, supports a layer exceeding 300 km in thickness of enigmatic origin(9-11). Here we show from turbulent mixing experiments that merging between projectile and planetary core following a giant impact can lead to a stratified layer at the top of the core. Scaling relationships between post-impact core structure and projectile properties suggest that merging between Earth's protocore and a projectile core that is enriched in light elements and 20 times less massive can produce the thick stratification inferred from seismic data. Our experiments favour Moon-forming impact scenarios involving a projectile smaller than the proto-Earth(12,13) and suggest that entrainment of mantle silicates into the protocore led to metal-silicate equilibration under extreme pressure-temperature conditions. We conclude that the thick stratified layer detected at the top of Earth's core(9,10) can be explained as a vestige of the Moon-forming giant impact during the late stages of planetary accretion.
Fichier non déposé

Dates et versions

hal-02331994 , version 1 (24-10-2019)

Identifiants

Citer

Maylis Landeau, Peter Olson, Renaud Deguen, Benjamin H. Hirsh. Core merging and stratification following giant impact. Nature Geoscience, 2016, 9 (10), pp.786+. ⟨10.1038/NGEO2808⟩. ⟨hal-02331994⟩
40 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More