Fe-carbide and Fe-sulfide liquid immiscibility in IAB meteorite, Campo del Cielo: implications for iron meteorite chemistry and planetesimal core compositions

Andrew George Tomkins, Eleanor Rose Mare, Massimo Raveggi

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    The majority of iron meteorites evolved in a relatively low-sulfur environment whereas chondritic meteorites tend to be comparatively sulfur-rich. Since liquid iron should incorporate sulfide minerals as it migrates from its chondritic source, this represents something of a conundrum in our understanding of iron meteorite formation, and by association, of asteroid core formation. Here, we investigate a series of samples of the Campo del Cielo suite of silicate-bearing (nonmagmatic) iron meteorites, which come from a single fall event. These likely formed in an impact-related process by rapid accumulation of liquid metal and incorporation of silicate clasts. We model the competing processes of rapid crystallisation of metal and flotational separation of the silicate clasts to provide a basis for understanding the fractionation of the Fe-Ni-S-C-P-(Cr-O) liquid. A combination of textural analysis of complex metal-graphite and sulfide veins and networks, laser ablation analysis of metal and sulfides, and published phase relations, are used to show that fractionation promoted evolution to a system with immiscible Fe-carbide and Fe-sulfide liquids. We suggest that this development of immiscibility allowed the silicate clasts to become enriched in S, C and P as they underwent flotational separation. This process left a large accumulation of light element-depleted FeNi metal, represented by the bulk of the Campo del Cielo meteorites.
    Original languageEnglish
    Pages (from-to)80 - 98
    Number of pages19
    JournalGeochimica et Cosmochimica Acta
    Volume117
    DOIs
    Publication statusPublished - 2013

    Cite this

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    title = "Fe-carbide and Fe-sulfide liquid immiscibility in IAB meteorite, Campo del Cielo: implications for iron meteorite chemistry and planetesimal core compositions",
    abstract = "The majority of iron meteorites evolved in a relatively low-sulfur environment whereas chondritic meteorites tend to be comparatively sulfur-rich. Since liquid iron should incorporate sulfide minerals as it migrates from its chondritic source, this represents something of a conundrum in our understanding of iron meteorite formation, and by association, of asteroid core formation. Here, we investigate a series of samples of the Campo del Cielo suite of silicate-bearing (nonmagmatic) iron meteorites, which come from a single fall event. These likely formed in an impact-related process by rapid accumulation of liquid metal and incorporation of silicate clasts. We model the competing processes of rapid crystallisation of metal and flotational separation of the silicate clasts to provide a basis for understanding the fractionation of the Fe-Ni-S-C-P-(Cr-O) liquid. A combination of textural analysis of complex metal-graphite and sulfide veins and networks, laser ablation analysis of metal and sulfides, and published phase relations, are used to show that fractionation promoted evolution to a system with immiscible Fe-carbide and Fe-sulfide liquids. We suggest that this development of immiscibility allowed the silicate clasts to become enriched in S, C and P as they underwent flotational separation. This process left a large accumulation of light element-depleted FeNi metal, represented by the bulk of the Campo del Cielo meteorites.",
    author = "Tomkins, {Andrew George} and Mare, {Eleanor Rose} and Massimo Raveggi",
    year = "2013",
    doi = "10.1016/j.gca.2013.04.024",
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    pages = "80 -- 98",
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    }

    Fe-carbide and Fe-sulfide liquid immiscibility in IAB meteorite, Campo del Cielo: implications for iron meteorite chemistry and planetesimal core compositions. / Tomkins, Andrew George; Mare, Eleanor Rose; Raveggi, Massimo.

    In: Geochimica et Cosmochimica Acta, Vol. 117, 2013, p. 80 - 98.

    Research output: Contribution to journalArticleResearchpeer-review

    TY - JOUR

    T1 - Fe-carbide and Fe-sulfide liquid immiscibility in IAB meteorite, Campo del Cielo: implications for iron meteorite chemistry and planetesimal core compositions

    AU - Tomkins, Andrew George

    AU - Mare, Eleanor Rose

    AU - Raveggi, Massimo

    PY - 2013

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    N2 - The majority of iron meteorites evolved in a relatively low-sulfur environment whereas chondritic meteorites tend to be comparatively sulfur-rich. Since liquid iron should incorporate sulfide minerals as it migrates from its chondritic source, this represents something of a conundrum in our understanding of iron meteorite formation, and by association, of asteroid core formation. Here, we investigate a series of samples of the Campo del Cielo suite of silicate-bearing (nonmagmatic) iron meteorites, which come from a single fall event. These likely formed in an impact-related process by rapid accumulation of liquid metal and incorporation of silicate clasts. We model the competing processes of rapid crystallisation of metal and flotational separation of the silicate clasts to provide a basis for understanding the fractionation of the Fe-Ni-S-C-P-(Cr-O) liquid. A combination of textural analysis of complex metal-graphite and sulfide veins and networks, laser ablation analysis of metal and sulfides, and published phase relations, are used to show that fractionation promoted evolution to a system with immiscible Fe-carbide and Fe-sulfide liquids. We suggest that this development of immiscibility allowed the silicate clasts to become enriched in S, C and P as they underwent flotational separation. This process left a large accumulation of light element-depleted FeNi metal, represented by the bulk of the Campo del Cielo meteorites.

    AB - The majority of iron meteorites evolved in a relatively low-sulfur environment whereas chondritic meteorites tend to be comparatively sulfur-rich. Since liquid iron should incorporate sulfide minerals as it migrates from its chondritic source, this represents something of a conundrum in our understanding of iron meteorite formation, and by association, of asteroid core formation. Here, we investigate a series of samples of the Campo del Cielo suite of silicate-bearing (nonmagmatic) iron meteorites, which come from a single fall event. These likely formed in an impact-related process by rapid accumulation of liquid metal and incorporation of silicate clasts. We model the competing processes of rapid crystallisation of metal and flotational separation of the silicate clasts to provide a basis for understanding the fractionation of the Fe-Ni-S-C-P-(Cr-O) liquid. A combination of textural analysis of complex metal-graphite and sulfide veins and networks, laser ablation analysis of metal and sulfides, and published phase relations, are used to show that fractionation promoted evolution to a system with immiscible Fe-carbide and Fe-sulfide liquids. We suggest that this development of immiscibility allowed the silicate clasts to become enriched in S, C and P as they underwent flotational separation. This process left a large accumulation of light element-depleted FeNi metal, represented by the bulk of the Campo del Cielo meteorites.

    U2 - 10.1016/j.gca.2013.04.024

    DO - 10.1016/j.gca.2013.04.024

    M3 - Article

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    JO - Geochimica et Cosmochimica Acta

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