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Iron isotope evidence for very rapid accretion and differentiation of the proto-Earth.

ABSTRACT: Nucleosynthetic isotope variability among solar system objects provides insights into the accretion history of terrestrial planets. We report on the nucleosynthetic Fe isotope composition (?54Fe) of various meteorites and show that the only material matching the terrestrial composition is CI (Ivuna-type) carbonaceous chondrites, which represent the bulk solar system composition. All other meteorites, including carbonaceous, ordinary, and enstatite chondrites, record excesses in ?54Fe. This observation is inconsistent with protracted growth of Earth by stochastic collisional accretion, which predicts a ?54Fe value reflecting a mixture of the various meteorite parent bodies. Instead, our results suggest a rapid accretion and differentiation of Earth during the ~5-million year disk lifetime, when the volatile-rich CI-like material is accreted to the proto-Sun via the inner disk.

SUBMITTER: Schiller M

PROVIDER: S-EPMC7015677 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Iron isotope evidence for very rapid accretion and differentiation of the proto-Earth.

Schiller Martin M Bizzarro Martin M Siebert Julien J

Science advances 20200212 7

Nucleosynthetic isotope variability among solar system objects provides insights into the accretion history of terrestrial planets. We report on the nucleosynthetic Fe isotope composition (μ<sup>54</sup>Fe) of various meteorites and show that the only material matching the terrestrial composition is CI (Ivuna-type) carbonaceous chondrites, which represent the bulk solar system composition. All other meteorites, including carbonaceous, ordinary, and enstatite chondrites, record excesses in μ<sup> ...[more]

PMID: 32095530

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