CALCIUM ISOTOPE COMPOSITION OF METEORITES, EARTH, AND MARS

Journal Article · Tue Sep 01 04:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/702/1/707; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21333785

Simon, Justin I; DePaolo, Donald J ^[1]; Moynier, Frederic ^[2]

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1. Center for Isotope Geochemistry, Earth and Planetary Science, University of California, Berkeley, CA 94720 (United States)
2. Earth and Planetary Sciences and McDonnell Center for Space Sciences, Washington University in St Louis, MO 63130 (United States)

The relative abundances of calcium isotopes in the mass range 40-44 were measured in primitive and differentiated meteorites and igneous rocks from Earth and Mars in search of non-mass-dependent variations that could provide clues about early solar system processes. Most bulk samples of planetary materials have calcium isotopic compositions identical with Earth's within the current resolution of about 0.01% in {sup 40}Ca/{sup 44}Ca. Possible exceptions include carbonaceous chondrites, some ordinary chondrites, and two samples of calcium-aluminum-rich inclusions, which have small excesses of {sup 40}Ca. The samples with {sup 40}Ca excesses are also known to have {sup 50}Ti and {sup 135}Ba excesses and {sup 142}Nd and {sup 144}Sm deficits. Collectively these data from refractory elements suggest that the planetary embryos represented by chondrites preserve isotopic heterogeneity that reflects different nucleosynthetic sources. No late admixture from a single nucleosynthetic source can explain all observations. The results are most compatible with variable proportions of material derived from Type II supernovae. The initial calcium isotope compositions of Earth and Mars are indistinguishable and similar to the {sup 40}Ca abundance found in some chondrites and all differentiated meteorites studied. It appears that isotopic heterogeneity in calcium was still present at the completion of disk formation but was homogenized during planetary accretion.

• OSTI ID: 21333785
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 702; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
ALUMINIUM
ASTEROIDS
BARIUM 135
CALCIUM
CALCIUM 40
CALCIUM 44
CHONDRITES
IGNEOUS ROCKS
ISOTOPE RATIO
MARS PLANET
NEODYMIUM 142
PROTOPLANETS
SAMARIUM 144
SOLAR SYSTEM
SUPERNOVAE
TITANIUM 50