A colossal impact enriched Mars' mantle with noble metals

R. Brasser, S. Mojzsis

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Once the terrestrial planets had mostly completed their assembly, bombardment continued by planetesimals left over from accretion. Highly siderophile element (HSE) abundances in Mars' mantle imply that its late accretion supplement was 0.8 wt %; Earth and the Moon obtained an additional 0.7 wt % and 0.02 wt %, respectively. The disproportionately high Earth/Moon accretion ratio is explicable by stochastic addition of a few remaining Ceres-sized bodies that preferentially targeted Earth. Here we show that Mars' late accretion budget also requires a colossal impact, a plausible visible remnant of which is the emispheric dichotomy. The addition of sufficient HSEs to the Martian mantle entails an impactor of at least 1200 km in diameter to have struck Mars before ~4430 Ma, by which time crust formation was well underway. Thus, the dichotomy could be one of the oldest geophysical features of the Martian crust. Ejected debris could be the source material for its satellites.

Original languageEnglish
Pages (from-to)5978-5985
Number of pages8
JournalGeophysical Research Letters
Volume44
Issue number12
DOIs
Publication statusPublished - Jun 28 2017

Fingerprint

noble metals
mars
Mars
Earth mantle
accretion
mantle
dichotomies
metal
moon
Moon
crusts
siderophile elements
crust
siderophile element
impactors
terrestrial planets
protoplanets
planetesimal
supplements
debris

Keywords

  • dynamics
  • geochemistry
  • highly siderophile elements
  • impacts
  • late veneer
  • Mars

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

Cite this

A colossal impact enriched Mars' mantle with noble metals. / Brasser, R.; Mojzsis, S.

In: Geophysical Research Letters, Vol. 44, No. 12, 28.06.2017, p. 5978-5985.

Research output: Contribution to journalArticle

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