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Published March 1, 2009 | public
Journal Article

A search for nickel isotopic anomalies in iron meteorites and chondrites


We report Ni isotopic data, for ^(58,60–62)Ni, on (1) FeNi metal and sulfides in different groups of iron meteorites, (2) sulfides and a whole rock sample of the St. Séverin chondrite, and (3) chondrules from the Chainpur chondrite. We have developed improved, Multiple-Collector, Positive ion Thermal Ionization Mass Spectrometric (MC-PTIMS) techniques, with Ni+ ionization efficiency at 1‰, and chemical separation techniques for Ni which reduce mass interferences to the 1 ppm level, so that no mass interference corrections need be applied, except for ^(64)Ni (from ^(64)Zn, at the 0.1‰ level), for which we do not report results. We normalize the data to ^(62)Ni/^(58)Ni to correct for mass dependent isotope fractionation. No evidence was found for resolved radiogenic or general Ni isotope anomalies at the resolution levels of 0.2 and 0.5 εu (εu = 0.01%) for ^(60)Ni/^(58)Ni and ^(61)Ni/^(58)Ni, respectively. From the ^(56)Fe/^(58)Ni ratios and ε(^(60)Ni/^(58)Ni) values, we calculate upper limits for the initial value of (^(60)Fe/^(56)Fe)0 of (a) <2.7 × 10^−7 for Chainpur chondrules, (b) <10^−8 for the St. Séverin sulfide, and (c) <4 × 10^−9 for sulfides from iron meteorites. We measured some of the same meteorites measured by other workers, who reported isotopic anomalies in Ni, using Multiple-Collector, Inductively-Coupled Mass Spectrometry. Our results do not support the previous reports of Ni isotopic anomalies in sulfide samples from Mundrabilla by Cook et al. [Cook D. L., Clayton R. N., Wadhwa M., Janney P. E., and Davis A. M. (2008). Nickel isotopic anomalies in troilite from iron meteorites. Geophy. Res. Lett. 35, L01203] and in sulfides from Toluca and Odessa by Quitté et al. [Quitté G., Meier M., Latkoczy C., Halliday A. N., and Gunther D., (2006). Nickel isotopes in iron meteorites-nucleosynthetic anomalies in sulfides with no effects in metals and no trace of ^(60)Fe. Earth Planet. Sci. Lett. 242, 16–25]. Hence, we find no need for specialized physical–chemical planetary processes for the preservation of different Ni isotope compositions, between FeNi metal and sulfides in the same iron meteorites, as proposed by the above reports nor for complex astrophysical scenarios to provide the very peculiar Ni isotope anomalies reported by these workers for sulfides.

Additional Information

Copyright © 2008 Elsevier. Received 5 June 2008; accepted in revised form 24 November 2008; available online 11 December 2008. We thank D.L. Cook for a careful and fair review. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology and supported by NASA Cosmochemistry (RTOP 344-31-55-01). D.A. Papanastassiou was supported, in part by JPL RTD (Task R.03.019.006).

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October 18, 2023