Research ArticleSPACE SCIENCES

Early scattering of the solar protoplanetary disk recorded in meteoritic chondrules

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Science Advances  01 Jul 2016:
Vol. 2, no. 7, e1601001
DOI: 10.1126/sciadv.1601001
  • Fig. 1 Petrographic survey of magnetite-bearing Vigarano-like carbonaceous (CV) chondrules.

    (A) Backscattered electron image of a porphyritic olivine-pyroxene (POP) chondrule in Kaba (CV3) revealing the preferential distribution of sulfides (FeS) and magnetites (Fe3O4) in the outer zone mainly composed of low-Ca pyroxenes. (B) Ameboidal Fe3O4 in contact with olivine, low-Ca pyroxene, and mesostasis (meso) within a chondrule of Vigarano. (C) Ameboidal Fe3O4 surrounded by mesostasis in Kaba. (D) Ameboidal Fe3O4 in contact with olivine, low-Ca pyroxene, and mesostasis within a chondrule of Vigarano. (E) Liquid-shaped Fe3O4 entrapped between olivine in a POP chondrule of Vigarano. A rounded opaque assemblage (OA) is also observed in direct contact with the magnetite. (F) Large sulfide-magnetite pool partially entrapping olivine and low-Ca pyroxenes within a chondrule of Vigarano.

  • Fig. 2 Oxygen isotopic variations of SAMs and coexisting olivines within chondrules of the Kaba and Vigarano CV3 chondrites.

    The orange field corresponds to the O-isotopic composition of the impact plume with which the chondrules equilibrated, as modeled (see text) to reproduce the O-isotopic composition of SAMs. There is no meteorite parent body known, either primitive (pink field) or differentiated (blue field), that corresponds to this composition. However, outer-belt icy planetesimals (enriched in 17,18O) would have oxygen isotopic composition corresponding to the impact plume. The inset shows the typical range of oxygen isotopic compositions established for the Sun, CAIs, and chondrules and ice present in meteorites. CCAM, carbonaceous chondrite anhydrous mineral.

  • Fig. 3 Conditions of formation of magnetite in CV chondrules.

    Oxygen fugacity as a function of temperature for a gas of solar composition (C/O = 0.5), the IW buffer, Allende inclusions, and chondrules (as determined from the iron content of olivines in type I chondrules). The fO2 required for forming and stabilizing FeSO melts (SAMs; red circles) lies ≈3 log units higher than the chondrule olivine field. This fO2 is in good agreement with that determined for impact-induced silicate melt–vapor plumes (green field).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/7/e1601001/DC1

    Oxygen mass balance calculation

    fig. S1. Compiled EDX maps of Si, Mg, and S of magnetite-bearing chondrules.

    fig. S2. Chemical composition of magnetite.

    fig. S3. Sulfur isotopic composition of troilite grains associated to magnetite.

    fig. S4. Influence of the amount of oxygen dissolved in FeS melts on silicate mineral/Fe-S-O matte dihedral angles.

    fig. S5. Three-oxygen isotope diagram showing previous results of oxygen composition of magnetite in CV chondrules.

    fig. S6. Fe-S-O phase diagram.

    table S1. Chemical composition of magnetite grains.

    table S2. Oxygen isotopic composition of magnetite grains.

    table S3. Sulfur isotopic composition of sulfides associated to magnetite grains.

    References (4346)

  • Supplementary Materials

    This PDF file includes:

    • Oxygen mass balance calculation
    • fig. S1. Compiled EDX maps of Si, Mg, and S of magnetite-bearing chondrules.
    • fig. S2. Chemical composition of magnetite.
    • fig. S3. Sulfur isotopic composition of troilite grains associated to magnetite.
    • fig. S4. Influence of the amount of oxygen dissolved in FeS melts on silicate mineral/Fe-S-O matte dihedral angles.
    • fig. S5. Three-oxygen isotope diagram showing previous results of oxygen composition of magnetite in CV chondrules.
    • fig. S6. Fe-S-O phase diagram.
    • table S1. Chemical composition of magnetite grains.
    • table S2. Oxygen isotopic composition of magnetite grains.
    • table S3. Sulfur isotopic composition of sulfides associated to magnetite grains.
    • References (4346)

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