Rapid timescales for magma ocean crystallization on the howardite-eucrite-diogenite parent body

TY - JOUR

T1 - Rapid timescales for magma ocean crystallization on the howardite-eucrite-diogenite parent body

AU - Schiller, Martin

AU - Baker, Joel

AU - Creech, John

AU - Paton, Chad

AU - Millet, Marc-Alban

AU - Irving, Anthony

AU - Bizzarro, Martin

PY - 2011/10/10

Y1 - 2011/10/10

N2 - 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 1/2 730,000yr). 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 + 0.5Myr 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 2-3Myr. Thermal models predict that such rapid cooling and magma ocean crystallization could only occur on small asteroids (<100km), implying that 4 Vesta is not the source of the HED meteorites.

AB - 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 1/2 730,000yr). 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 + 0.5Myr 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 2-3Myr. Thermal models predict that such rapid cooling and magma ocean crystallization could only occur on small asteroids (<100km), implying that 4 Vesta is not the source of the HED meteorites.

UR - http://www.scopus.com/inward/record.url?scp=80053540389&partnerID=8YFLogxK

U2 - 10.1088/2041-8205/740/1/L22

DO - 10.1088/2041-8205/740/1/L22

M3 - Letter

AN - SCOPUS:80053540389

SN - 2041-8205

VL - 740

JO - The Astrophysical Journal Letters

JF - The Astrophysical Journal Letters

IS - 1

M1 - L22

ER -