Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6428452 | Earth and Planetary Science Letters | 2015 | 8 Pages |
Abstract
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 â¼2 μm spot. Three analyses show average 27Al/24Mg ratio of â¼65 and excess δ26Mgâ value of +0.1±4.5â° (2Ï), indicating no resolvable 26Mg excess in the particle. The inferred initial (26Al/27Al)0 ratio of plagioclase in Pyxie is estimated as (â0.6±4.5)Ã10â6 with an upper limit of 4Ã10â6. 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 â¼3.0 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.
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Physical Sciences and Engineering
Earth and Planetary Sciences
Earth and Planetary Sciences (General)
Authors
Daisuke Nakashima, Takayuki Ushikubo, Noriko T. Kita, Michael K. Weisberg, Michael E. Zolensky, Denton S. Ebel,