Journal
GEOCHIMICA ET COSMOCHIMICA ACTA
Volume 77, Issue -, Pages 252-265Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.gca.2011.11.002
Keywords
-
Categories
Funding
- NASA [NNX07AI80G, NNX11AK82G]
- Harvard University Origins of Life Initiative
- Canadian Institute for Advanced Research (CIFAR)
- Faculty of Environmental Sciences [42900/1312/3166]
- NASA [NNX11AK82G, 143351] Funding Source: Federal RePORTER
Ask authors/readers for more resources
Refractory inclusions in primitive meteorites are the oldest objects formed in the Solar System. They exhibit large mass-dependent isotopic effects in many elements, including Si, Mg and Ca, indicative of their complex origin. We report data for both mass-dependent (delta) and mass-independent (epsilon) Ca isotopic effects, and rare earth element (REE) abundances in six refractory inclusions from the Allende CV3 meteorite. Our data reveal large mass-dependent Ca isotopic effects in these refractory inclusions, with delta Ca-44/40 ranging from -5.60 to +0.35 (relative to NIST SRM 915a), which are significantly lower than that of the bulk silicate Earth (delta Ca-44/40 = 1.05 +/- 0.04). Importantly, delta Ca-44/40 is correlated with REE patterns: refractory inclusions with Group II REE patterns have lighter Ca isotope compositions compared to those with Group I REE patterns. Specifically, the studied refractory inclusions form negative Ca-44/Ca-40-Tm/Er and Ca-44/Ca-40-Nd/Er trends, implying segregation of up to 3% of an ultrarefractory evaporation residue from a chondritic reservoir prior to the formation of refractory inclusions. This residue would have to be characterized by high Ca-44/Ca-40 and low Tm/Er and Nd/Er. At 2 sigma levels of +/- 0.5 and +/- 1.5 for epsilon Ca-40/44 and epsilon Ca-43/44, respectively, the six refractory inclusions studied show no detectable Ca-40 or Ca-43 anomalies relative to the terrestrial standards. However, five out of the six refractory inclusions do show a Ca-48 excess of several epsilon-units, clearly resolvable from the terrestrial standards. (C) 2011 Elsevier Ltd. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available