Heterogeneous distribution of 60Fe in the early solar nebula: Achondrite evidence

Abstract

60Fe-60Ni systematics in quenched angrites and two old eucrites were investigated by secondary ion mass spectrometry. The 60Ni/62Ni isotopic compositions were normal within 2 σ errors. The inferred initial 60Fe/56Fe ratios for quenched angrites was (6±9)–10-9, and similar upper limit values were also obtained from eucrites. Using the age difference of approximately 5 Ma between the quenched angrites and Ca-Al-rich inclusions, the initial 60Fe/56Fe ratio at the start of the solar system was calculated to be approximately (6±9)–10-8. This initial ratio is significantly smaller than previously published values obtained from chondritic materials, suggesting the heterogeneous distribution of 60Fe in the solar nebula. © 2006, The Seismological Society of Japan, Society of Geomagnetism and Earth, Planetary and Space Sciences, The Volcanological Society of Japan, The Geodetic Society of Japan, The Japanese Society for Planetary Sciences. All rights reserved.