Impact-induced melting during accretion of the Earth

Jellie de Vries, Francis Nimmo, H. Jay Melosh, Seth Andrew Jacobson, Alessandro Morbidelli, David C. Rubie*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Because of the high energies involved, giant impacts that occur during planetary accretion cause large degrees of melting. The depth of melting in the target body after each collision determines the pressure and temperature conditions of metal-silicate equilibration and thus geochemical fractionation that results from core-mantle differentiation. The accretional collisions involved in forming the terrestrial planets of the inner Solar System have been calculated by previous studies using N-body accretion simulations. Here we use the output from such simulations to determine the volumes of melt produced and thus the pressure and temperature conditions of metal-silicate equilibration, after each impact, as Earth-like planets accrete. For these calculations a parameterised melting model is used that takes impact velocity, impact angle and the respective masses of the impacting bodies into account. The evolution of metal-silicate equilibration pressures (as defined by evolving magma ocean depths) during Earth’s accretion depends strongly on the lifetime of impact-generated magma oceans compared to the time interval between large impacts. In addition, such results depend on starting parameters in the N-body simulations, such as the number and initial mass of embryos. Thus, there is the potential for combining the results, such as those presented here, with multistage core formation models to better constrain the accretional history of the Earth.

Original languageEnglish (US)
Article number7
JournalProgress in Earth and Planetary Science
Volume3
Issue number1
DOIs
StatePublished - Dec 1 2016

Keywords

  • Accretion
  • Core formation
  • Impacts
  • Melting
  • Metal-silicate equilibration

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

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