RAPID TIMESCALES FOR MAGMA OCEAN CRYSTALLIZATION ON THE HOWARDITE-EUCRITE-DIOGENITE PARENT BODY

Journal Article · Mon Oct 10 00:00:00 EDT 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/740/1/L22· OSTI ID:21565390

Schiller, Martin; Paton, Chad; Bizzarro, Martin ^[1]; Baker, Joel; Creech, John; Millet, Marc-Alban ^[2]; Irving, Anthony ^[3]

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1. Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Copenhagen DK-1350 (Denmark)
2. School of Geography, Environment and Earth Sciences, Victoria University of Wellington, Wellington (New Zealand)
3. Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195 (United States)

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 {sup 26}Mg ({sup 26}Mg*) 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 {sup 27}Al/{sup 24}Mg during the lifespan of the short-lived {sup 26}Al nuclide (t {sub 1/2} {approx} 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 {sup 26}Mg* composition of the most primitive diogenites requires onset of the magma ocean crystallization within 0.6{sup -0.4} {sub +0.5} Myr of solar system formation. Moreover, {sup 26}Mg* 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.

• OSTI ID: 21565390
• Journal Information: Astrophysical Journal Letters, Vol. 740, Issue 1; Other Information: DOI: 10.1088/2041-8205/740/1/L22; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ACHONDRITES
ALUMINIUM 26
ALUMINIUM 27
ASTEROIDS
CRYSTALLIZATION
ELEMENT ABUNDANCE
EVOLUTION
MAGMA
MAGNESIUM 24
MAGNESIUM 26
SEAS
SOLAR SYSTEM
SOLIDIFICATION
VARIATIONS
ABUNDANCE
ALKALINE EARTH ISOTOPES
ALUMINIUM ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
EVEN-EVEN NUCLEI
ISOTOPES
LIGHT NUCLEI
MAGNESIUM ISOTOPES
METEORITES
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
PHASE TRANSFORMATIONS
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
STABLE ISOTOPES
STONE METEORITES
SURFACE WATERS
YEARS LIVING RADIOISOTOPES