Late formation of a comet Wild 2 crystalline silicate particle, Pyxie, inferred from Al–Mg chronology of plagioclase
書誌事項
- 公開日
- 2015-01
- 権利情報
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- https://www.elsevier.com/tdm/userlicense/1.0/
- DOI
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- 10.1016/j.epsl.2014.11.020
- 公開者
- Elsevier BV
この論文をさがす
説明
We examined the Al–Mg isotope systematics of plagioclase in a FeO-poor ferromagnesian Wild 2 particle (C2092,7,81,1,0; named Pyxie) using a ∼2 μm spot. Three analyses show average 27Al/24Mg ratio of ∼65 and excess δ26Mg⁎ value of +0.1±4.5‰+0.1±4.5‰ (2σ), indicating no resolvable 26Mg excess in the particle. The inferred initial (26Al/27Al)0 ratio of plagioclase in Pyxie is estimated as (−0.6±4.5)×10−6(−0.6±4.5)×10−6 with an upper limit of 4×10−64×10−6. The result is very similar to that of the FeO-rich ferromagnesian particle “Iris” (Ogliore et al., 2012). Assuming homogeneous distribution of 26Al in the early solar system, Pyxie formed at least 2.6 Ma after the oldest Ca–Al-rich inclusions. This minimum formation age is marginally younger than formation ages of most chondrules in type ∼3.0 chondrites but comparable with those of Mg# < 98 chondrules in CR3 chondrites. Considered in conjunction with similar oxygen isotope ratios between Pyxie (and Iris) and Mg# < 98 chondrules in CR3 chondrites, it is inferred that the ferromagnesian Wild 2 particles and Mg# < 98 chondrules in CR3 chondrites formed late in local disk environments that had similar oxygen isotope ratios and redox states.
収録刊行物
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- Earth and Planetary Science Letters
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Earth and Planetary Science Letters 410 54-61, 2015-01
Elsevier BV
