A search for nickel isotopic anomalies in iron meteorites and chondrites

• Published in: Geochimica et cosmochimica acta 2009-03, Vol.73 (5), p.1461-1471
• Main Authors: Chen, J.H., Papanastassiou, D.A., Wasserburg, G.J.
• Format: Article
• Language: English
• ISSN: 0016-7037; 1872-9533
• DOI: 10.1016/j.gca.2008.11.040

We report Ni isotopic data, for 58,60–62Ni, 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 64Ni (from 64Zn, at the 0.1‰ level), for which we do not report results. We normalize the data to 62Ni/ 58Ni 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 60Ni/ 58Ni and 61Ni/ 58Ni, respectively. From the 56Fe/ 58Ni ratios and ε( 60Ni/ 58Ni) values, we calculate upper limits for the initial value of ( 60Fe/ 56Fe) 0 of (a)