Oxygen and magnesium isotopic compositions of amoeboid olivine aggregates from the Semarkona LL3.0 chondrite
Oxygen and magnesium isotopic compositions of amoeboid olivine aggregates from the Semarkona LL3.0 chondrite
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DOI：
10.1111/j.1945-5100.2007.tb00571.x
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发表时间：
2004-11
影响因子：
2.2
通讯作者：
S. Itoh;S. Russell;H. Yurimoto
中科院分区：
文献类型：
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作者：
S. Itoh;S. Russell;H. Yurimoto
摘要采用二次离子质谱法研究了Semarkona球粒陨石LL3.0中变形虫橄榄石聚集体（AOAs）。AOAs主要由橄榄石颗粒集合体和间隙富含Al - Ti的透辉石和钙长石组成。各相氧同位素组成均富集于16O， δ17,18O = ~−50‰。初始26Al/27Al比值为5.6±0.9 （2σ） × 10−5。这些值与原始碳质球粒陨石中AOAs和细粒富钙铝包裹体（fgi）的值相当。这表明，普通球粒陨石中的AOAs与碳质球粒陨石中的AOAs和fgi一样，形成于太阳星云中富含16O的富钙铝包裹体（CAI）形成区，并随后移动到太阳星云中普通球粒陨石母体的吸积区。
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 16O, with δ17,18O = ∼−50‰. The initial 26Al/27Al 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 16O‐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.