NEUTRON-POOR NICKEL ISOTOPE ANOMALIES IN METEORITES

We present new, mass-independent, Ni isotope data for a range of bulk chondritic meteorites. The data are reported as [epsilon[sup 60]]Ni[sub 58/61], [epsilon[sup 62]]Ni[sub 58/61], and [epsilon[sup 64]]Ni[sub 58/61], or the parts per ten thousand deviations from a terrestrial reference, the NIST SRM 986 standard, of the [sup 58]Ni/[sup 61]Ni internally normalized [sup 60]Ni/[sup 61]Ni, [sup 62]Ni/[sup 61]Ni, and [sup 64]Ni/[sup 61]Ni ratios. We also determined to high precision the mass-dependent fractionation of two meteorite samples which span the range of [epsilon[sup 62]]Ni[sub 58/61] and [epsilon[sup 64]]Ni[sub 58/61]. We have examined different nucleosynthetic environments to determine the possible source of the anomalous material responsible for the isotopic variations observed in Ni and other transition elements within bulk samples. Correlations of Ni isotope anomalies with O, Cr, and Ti isotope ratios and Pb/Yb in bulk meteorites suggest that the heterogeneous distribution of isotopic anomalies in the early solar system likely resulted from nebular sorting of chemically or physically different materials bearing different amounts of isotopes synthesized proximally to the collapse of the protosolar nebula.