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Primordial Earth mantle heterogeneity caused by the Moon-forming giant impact

Deng, H; Ballmer, MD; Reinhardt, C; Meier, MMM; Mayer, L; Stadel, J; Benitez, F; (2019) Primordial Earth mantle heterogeneity caused by the Moon-forming giant impact. The Astrophysical Journal , 887 , Article 211. 10.3847/1538-4357/ab50b9. Green open access

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Abstract

The giant impact hypothesis for Moon formation successfully explains the dynamic properties of the Earth–Moon system but remains challenged by the similarity of isotopic fingerprints of the terrestrial and lunar mantles. Moreover, recent geochemical evidence suggests that the Earth's mantle preserves ancient (or "primordial") heterogeneity that pre-dates the Moon-forming giant impact. Using a new hydrodynamical method, we here show that Moon-forming giant impacts lead to a stratified starting condition for the evolution of the terrestrial mantle. The upper layer of the Earth is compositionally similar to the disk, out of which the Moon evolves, whereas the lower layer preserves proto-Earth characteristics. As long as this predicted compositional stratification can at least partially be preserved over the subsequent billions of years of Earth mantle convection, a compositional similarity between the Moon and the accessible Earth's mantle is a natural outcome of realistic and high-probability Moon-forming impact scenarios. The preservation of primordial heterogeneity in the modern Earth not only reconciles geochemical constraints but is also consistent with recent geophysical observations. Furthermore, for significant preservation of a proto-Earth reservoir, the bulk major-element composition of the Earth–Moon system may be systematically shifted toward chondritic values.

Type: Article
Title: Primordial Earth mantle heterogeneity caused by the Moon-forming giant impact
Open access status: An open access version is available from UCL Discovery
DOI: 10.3847/1538-4357/ab50b9
Publisher version: https://doi.org/10.3847/1538-4357/ab50b9
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Giant impact, Moon, planets and satellites: formation
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10085235
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