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Oxygen and magnesium isotopic compositions of amoeboid olivine aggregates from the Semarkona LL3.0 chondrite
Author(s) -
Itoh Shoichi,
Russell Sara S.,
Yurimoto Hisayoshi
Publication year - 2007
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/j.1945-5100.2007.tb00571.x
Subject(s) - chondrite , diopside , olivine , ordinary chondrite , anorthite , geology , meteorite , parent body , formation and evolution of the solar system , carbonaceous chondrite , chondrule , mineralogy , isotopes of oxygen , geochemistry , astrobiology , physics
Abstract— Amoeboid olivine aggregates (AOAs) in the LL3.0 Semarkona chondrite have been studied by secondary ion mass spectrometry. The AOAs mainly consist of aggregates of olivine grains with interstitial Al‐Ti‐rich diopside and anorthite. Oxygen‐isotopic compositions of all phases are consistently enriched in 16 O, with δ 17,18 O = ∼−50‰. The initial 26 Al/ 27 Al ratios are calculated to be 5.6 ± 0.9 (2σ) × 10 −5 . These values are equivalent to those of AOAs and fine‐grained calcium‐aluminum‐rich inclusions (FGIs) from pristine carbonaceous chondrites. This suggests that AOAs in ordinary chondrites formed in the same 16 O‐rich calcium‐aluminum‐rich inclusion (CAI)‐forming region of the solar nebula as AOAs and FGIs in carbonaceous chondrites, and subsequently moved to the accretion region of the ordinary chondrite parent body in the solar nebula.