Unlocking the zinc isotope systematics of iron meteorites
MetadataShow full item record
Zinc isotope compositions (δ66Zn) and concentrations were determined for metal samples of 15 iron meteorites across groups IAB, IIAB, and IIIAB. Also analyzed were troilite and other inclusions from the IAB iron Toluca. Furthermore, the first Zn isotope data are presented for metal–silicate partitioning experiments that were conducted at 1.5 GPa and 1650 K. Three partitioning experiments with run durations of between 10 and 60 min provide consistent Zn metal–silicate partition coefficients of ∼0.7 and indicate that Zn isotope fractionation between molten metal and silicate is either small (at less than about ±0.2‰±0.2‰) or absent. Metals from the different iron meteorite groups display distinct ranges in Zn contents, with concentrations of 0.08–0.24 μg/g for IIABs, 0.8–2.5 μg/g for IIIABs, and 12–40 μg/g for IABs. In contrast, all three groups show a similar range of δ66Zn values (reported relative to ‘JMC Lyon Zn’) from +0.5‰+0.5‰ to +3.0‰+3.0‰, with no clear systematic differences between groups. However, distinct linear trends are defined by samples from each group in plots of δ66Zn vs. 1/Zn, and these correlations are supported by literature data. Based on the high Zn concentration and δ66Zn ≈ 0 determined for a chromite-rich inclusion of Toluca, modeling is employed to demonstrate that the Zn trends are best explained by segregation of chromite from the metal phase. This process can account for the observed Zn–δ 66Zn–Cr systematics of iron meteorite metals, if Zn is highly compatible in chromite and Zn partitioning is accompanied by isotope fractionation with Δ66Znchr-met≈−1.5‰≈−1.5‰. Based on these findings, it is likely that the parent bodies of the IAB complex, IIAB and IIIAB iron meteorites featured δ 66Zn values of about −1.0 to +0.5‰+0.5‰, similar to the Zn isotope composition inferred for the bulk silicate Earth and results obtained for chondritic meteorites. Together, this implies that most solar system bodies formed with similar bulk Zn isotope compositions despite large differences in Zn contents.
This article is published under the Open Access publishing model and distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0/ Please refer to the licence to obtain terms for any further reuse or distribution of this work.
Copyright © 2014 Published by Elsevier B.V. Open Access funded by Science and Technology Facilities Council, UK http://www.stfc.ac.uk/home.aspx
Showing items related by title, author, creator and subject.
Oxygen isotope variation in primitive achondrites: The influence of primordial, asteroidal, and terrestrial processessGreenwood, R.; Franchi, I.; Gibson, J.; Benedix, Gretchen (2012)A detailed oxygen isotope study of the acapulcoites, lodranites, winonaites, brachinites and various related achondrites has been undertaken to investigate the nature of their precursor materials. High levels of terrestrial ...
Van Roosbroek, N.; Debaille, V.; Pittarello, L.; Goderis, S.; Humayun, M.; Hecht, L.; Jourdan, Fred; Spicuzza, M.; Vanhaecke, F.; Claeys, P. (2015)A 435kg piece of the Mont Dieu iron meteorite (MD) contains cm-sized silicate inclusions. Based on the concentration of Ni, Ga, Ge, and Ir (8.59±0.32 wt%, 25.4±0.9ppm, 61±2ppm, 7.1±0.4ppm, respectively) in the metal host, ...
Reclassifcation of Villalbeto de la Pena—Occurrence of a winonaite-related fragment in a hydrothermally metamorphosed polymict L-chondritic brecciaBischoff, A.; Dyl, Kathryn; Horstmann, M.; Ziegler, K.; Wimmer, K.; Young, E. (2013)The Villalbeto de la Peña meteorite that fell in 2004 in Spain was originally classified as a moderately shocked L6 ordinary chondrite. The recognition of fragments within the Villalbeto de la Peña meteorite clearly bears ...