Aqueous alteration of opaque assemblages in the Ningqiang carbonaceous chondrite

Evidence from oxygen isotopes

Weibiao Hsu, Yunbin Guan, Xin Hua, Ying Wang, L. A. Leshin, Thomas Sharp

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Chondrules and matrix of the Ningqiang carbonaceous chondrite contain numerous opaque assemblages (OAs). These OAs are mainly composed of Ni-rich metal, magnetite, sulfides, phosphates with minor amounts of silicates and trace amounts of Pt-metal grains. Their mineral assemblage is very similar to that of OAs found in Allende refractory inclusions. In this study, we performed in situ analyses of O-isotopic compositions of magnetite and whitlockite in OAs and of olivine adjacent to OAs from Ningqiang. O-isotopic compositions of magnetite vary by 16‰ in δ18O and fall on a regression line with a slope of 0.51 and a mean Δ17O of -2.9 ± 0.3 (1σ)‰ in the three-O-isotope diagram. Magnetite grains have consistently higher Δ17O values than their adjacent olivine grains. The mineral chemistry and O-isotopic compositions of OAs in Ningqiang chondrules and matrix are most consistent with the formation of magnetites and whitlockite by aqueous alteration of preexisting metal alloys within a planetary body. Formation of magnetites and phosphates in OAs thus do not constrain processes in the early solar nebula, but rather provide information on metamorphism in a planetary environment.

Original languageEnglish (US)
Pages (from-to)107-114
Number of pages8
JournalEarth and Planetary Science Letters
Volume243
Issue number1-2
DOIs
StatePublished - Mar 15 2006

Fingerprint

Oxygen Isotopes
Ferrosoferric Oxide
carbonaceous chondrites
carbonaceous chondrite
oxygen isotopes
magnetite
oxygen isotope
chondrule
isotopic composition
Metals
olivine
Minerals
metal
phosphates
planetary environments
Chemical analysis
Phosphates
minerals
phosphate
metals

Keywords

  • Aqueous alteration
  • Ion microprobe
  • Ningqiang carbonaceous chondrite
  • Opaque assemblages
  • Oxygen isotopes

ASJC Scopus subject areas

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

Cite this

Aqueous alteration of opaque assemblages in the Ningqiang carbonaceous chondrite : Evidence from oxygen isotopes. / Hsu, Weibiao; Guan, Yunbin; Hua, Xin; Wang, Ying; Leshin, L. A.; Sharp, Thomas.

In: Earth and Planetary Science Letters, Vol. 243, No. 1-2, 15.03.2006, p. 107-114.

Research output: Contribution to journalArticle

Hsu, Weibiao ; Guan, Yunbin ; Hua, Xin ; Wang, Ying ; Leshin, L. A. ; Sharp, Thomas. / Aqueous alteration of opaque assemblages in the Ningqiang carbonaceous chondrite : Evidence from oxygen isotopes. In: Earth and Planetary Science Letters. 2006 ; Vol. 243, No. 1-2. pp. 107-114.
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