Earth formation in the lab: metal-silicate equilibration and core stratification after planetary impacts. | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Earth formation in the lab: metal-silicate equilibration and core stratification after planetary impacts.

Mardi 27 Février 2018
Séminaires Dynamique des fluides géologiques
Maylis Landeau
(DAMTP)
Extrait: 

Earth formed by successive collisions between planetary embryos, most of
them formed of a metallic core and a silicate mantle. I will present
laboratory experiments on the fluid dynamics of these collisions. Our
experiments replicate the cratering process observed in impact
simulations and inferred at the surface of terrestrial planets. Unlike
simulations, experiments produce small-scales and turbulent mixing.

We obtain scaling laws for mixing as a function of the velocity, size
and density of the impactor. Applied to Earth formation, these scalings
predict full chemical equilibration between the impactor core and the
mantle silicates for impactors much smaller than the Earth. In contrast,
we predict partial equilibration for giant impacts. Our results also
indicate that the stratification inferred from seismic data at the top
of Earth's core could be a vestige of the giant impact that formed the
Moon.