Late formation of a comet Wild 2 crystalline silicate particle, Pyxie, inferred from Al-Mg chronology of plagioclase

Daisuke Nakashima, Takayuki Ushikubo, Noriko T. Kita, Michael K. Weisberg, Michael E. Zolensky, Denton S. Ebel

Research output: Contribution to journalArticle

19 Citations (Scopus)

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 ~2 μm spot. Three analyses show average 27Al/24Mg ratio of ~65 and excess δ26Mg* value of +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 with an upper limit of 4×10-6. 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.

Original languageEnglish
Pages (from-to)54-61
Number of pages8
JournalEarth and Planetary Science Letters
Volume410
DOIs
Publication statusPublished - 2015 Jan 5

Keywords

  • Al-Mg isotope systematics
  • Comet 81P/Wild 2
  • Crystalline silicate
  • Solar system formation
  • Stardust

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'Late formation of a comet Wild 2 crystalline silicate particle, Pyxie, inferred from Al-Mg chronology of plagioclase'. Together they form a unique fingerprint.

  • Cite this