Schiller, Martin, Baker, Joel, Creech, John, Paton, Chad, Millet, Marc-Alban ![]() |
Abstract
Asteroid 4 Vesta has long been postulated as the source for the howardite-eucrite-diogenite (HED) achondrite meteorites. Here we show that Al-free diogenite meteorites record variability in the mass-independent abundance of 26Mg (26Mg*) that is correlated with their mineral chemistry. This suggests that these meteorites captured the Mg-isotopic evolution of a large-scale differentiating magma body with increasing 27Al/24Mg during the lifespan of the short-lived 26Al nuclide (t 1/2 ~ 730,000 yr). Thus, diogenites and eucrites represent crystallization products of a large-scale magma ocean associated with the differentiation and magmatic evolution of the HED parent body. The 26Mg* composition of the most primitive diogenites requires onset of the magma ocean crystallization within 0.6–0.4 + 0.5 Myr of solar system formation. Moreover, 26Mg* variations among diogenites and eucrites imply that near complete solidification of the HED parent body occurred within the following 2-3 Myr. Thermal models predict that such rapid cooling and magma ocean crystallization could only occur on small asteroids (<100 km), implying that 4 Vesta is not the source of the HED meteorites.
Item Type: | Article |
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Date Type: | Publication |
Status: | Published |
Schools: | Earth and Environmental Sciences |
Subjects: | Q Science > QE Geology |
Uncontrolled Keywords: | astrochemistry; meteorites, meteors, meteoroids; minor planets, asteroids: general; protoplanetary disks |
Publisher: | Institute of Physics |
ISSN: | 2041-8205 |
Date of Acceptance: | 2 September 2011 |
Last Modified: | 01 Nov 2022 10:56 |
URI: | https://orca.cardiff.ac.uk/id/eprint/93305 |
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