The terrestrial late veneer from core disruption of a lunar-sized impactor

H. Genda, R. Brasser, S. Mojzsis

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18 Citations (Scopus)

Abstract

Overabundances in highly siderophile elements (HSEs) of Earth's mantle can be explained by conveyance from a singular, immense (D∼3000 km) “Late Veneer” impactor of chondritic composition, subsequent to lunar formation and terrestrial core-closure. Such rocky objects of approximately lunar mass (∼0.01 M) ought to be differentiated, such that nearly all of their HSE payload is sequestered into iron cores. Here, we analyze the mechanical and chemical fate of the core of such a Late Veneer impactor, and trace how its HSEs are suspended – and thus pollute – the mantle. For the statistically most-likely oblique collision (∼45°), the impactor's core elongates and thereafter disintegrates into a metallic hail of small particles (∼10 m). Some strike the orbiting Moon as sesquinary impactors, but most re-accrete to Earth as secondaries with further fragmentation. We show that a single oblique impactor provides an adequate amount of HSEs to the primordial terrestrial silicate reservoirs via oxidation of (<m-sized) metal particles with a hydrous, pre-impact, early Hadean Earth.

Original languageEnglish
Pages (from-to)25-32
Number of pages8
JournalEarth and Planetary Science Letters
Volume480
DOIs
Publication statusPublished - Dec 5 2017

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Keywords

  • Hadean Earth
  • highly-siderophile elements
  • Late Veneer
  • mantle
  • SPH models

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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