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Chromium isotopic systematics of the Sutter's Mill carbonaceous chondrite: Implications for isotopic heterogeneities of the early solar system
Author(s) -
Yamakawa Akane,
Yin QingZhu
Publication year - 2014
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/maps.12346
Subject(s) - murchison meteorite , carbonaceous chondrite , chondrite , meteorite , silicate , geology , pyroxene , geochemistry , formation and evolution of the solar system , mineralogy , analytical chemistry (journal) , chemistry , astrobiology , olivine , physics , environmental chemistry , organic chemistry
Recent studies have shown that major meteorite groups possess their own characteristic 54 Cr values, demonstrating the utility of Cr isotopes for identifying genetic relationships between the planetary materials in conjunction with other classical tools, such as oxygen isotopes. In this study, we performed Cr isotope analyses for whole rocks and chemically separated phases of the new CM 2 chondrite, Sutter's Mill ( SM 43 and 51). The two whole rocks of Sutter's Mill show essentially identical ε 54 Cr excesses ( SM 43 = +0.95 ± 0.09ε, SM 51 = +0.88 ± 0.07ε), relative to the Earth. These values are the same within error with that of the CM 2‐type Murchison (+0.89 ± 0.08ε), suggesting that parent bodies of Sutter's Mill and Murchison were formed from the same precursor materials in the solar nebula. Large ε 54 Cr excess of up to 29.40ε is observed in the silicate phase of Sutter's Mill, while that of Murchison shows 15.74ε. Importantly, the leachate fractions of both Sutter's Mill and Murchison form a steep linear anticorrelation between ε 54 Cr and ε 53 Cr, cross‐cutting the positive correlation previously observed in carbonaceous chondrites. The fact that L4 acid leachate fraction contains higher 54 Cr excesses than that of L5 step designed to dissolve refractory minerals suggests that spinel is not a major 54 Cr carrier. We also note that L5 contains 53 Cr anomalies lower than the solar initial value, suggesting it carries a component of nucleosynthetic anomaly unrelated to the 53 Mn decay. We have identified five endmember components of nucleosynthetic origin among the early solar system materials.