Zinc isotope anomalies in primitive meteorites identify the outer solar system as an important source of Earth's volatile inventory

Paul S. Savage (1) , Frédéric Moynier (1) , Maud Boyet (2)

1 IPGP (UMR_7154) - Institut de Physique du Globe de Paris
2 OPGC - Observatoire de Physique du Globe de Clermont-Ferrand

The source of and timing of delivery of the volatile elements to Earth is a question that is fundamental to understanding how our planet evolved. Here, we show that primitive meteorites have resolved mass-independent Zn isotope anomalies from the terrestrial reservoir. Carbonaceous chondrites (CC), likely originating from the outer Solar System are distinct from non-CC, and Earth is intermediate between these two components. Modelling based on these data indicates that around 30% of Earth's budget of Zn and other moderately volatile material derives from the participation of 6% of CC-like materials during Earth's accretion, with the remaining coming from NC meteorites. This implies that, despite the relatively minor mass of Earth thought to derive from CC-like material, the CC component of Earth was relatively and significantly volatile-enriched; this is in line with the observation that the terrestrial elemental abundance pattern of moderately volatile elements could be explained by a carbonaceous source, and with the carbonaceous chondrite-like isotopic budget of more volatile-rich material accreted later in Earth's accretion history (e.g. Hg, Se, N, noble gases).

Keywords: Meteorites; Cosmochemistry; Origin; solar system; Accretion

Domains: Sciences of the Universe [physics]

Paul S. Savage, Frédéric Moynier, Maud Boyet. Zinc isotope anomalies in primitive meteorites identify the outer solar system as an important source of Earth's volatile inventory. Icarus, 2022, 386, ⟨10.1016/j.icarus.2022.115172⟩. ⟨insu-03748507⟩