Wetting facilitates late-stage segregation of precious metal-enriched sulfosalt melt in magmatic sulfide systems

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    The wetting behavior of As-rich sulfosalt melts against monosulfide solid solution (MSS) is investigated using experiments to elucidate late-stage fractionation processes in magmatic sulfide systems, which may control the distribution of platinum group elements. A range of As-rich melt compositions is found to wet MSS, including those that contain significant proportions (1%–45%) of precious metals (Pt, Pd, and Au). However, extremely Au rich or Pt rich sulfosalt melts (>∼40% Au; >∼50% Pt + 5% Au) do not wet MSS. These results imply that if magma contamination and/or fractionation processes were able to produce a late-stage As-rich melt (sulfosalt melts crystallize cooler than MSS) that exceeds ∼0.2% of the rock volume, then an interconnected melt drainage network would be able to form along MSS crystal triple junctions. The dense sulfosalt melt could thereby drain downward, progressively sequestering incompatible Bi, Sb, Te, Pt, Pd, and Au to form sulfosalt melt accumulations that continue to fractionate to form the platinum group minerals. This late-stage fractionation model is consistent with the observed mineral distribution in numerous magmatic sulfide deposits.
    Original languageEnglish
    Pages (from-to)951 - 954
    Number of pages4
    JournalGeology
    Volume38
    Issue number10
    DOIs
    Publication statusPublished - 2010

    Cite this

    @article{049c0b6055d949168afc62b27bd7c0cb,
    title = "Wetting facilitates late-stage segregation of precious metal-enriched sulfosalt melt in magmatic sulfide systems",
    abstract = "The wetting behavior of As-rich sulfosalt melts against monosulfide solid solution (MSS) is investigated using experiments to elucidate late-stage fractionation processes in magmatic sulfide systems, which may control the distribution of platinum group elements. A range of As-rich melt compositions is found to wet MSS, including those that contain significant proportions (1{\%}–45{\%}) of precious metals (Pt, Pd, and Au). However, extremely Au rich or Pt rich sulfosalt melts (>∼40{\%} Au; >∼50{\%} Pt + 5{\%} Au) do not wet MSS. These results imply that if magma contamination and/or fractionation processes were able to produce a late-stage As-rich melt (sulfosalt melts crystallize cooler than MSS) that exceeds ∼0.2{\%} of the rock volume, then an interconnected melt drainage network would be able to form along MSS crystal triple junctions. The dense sulfosalt melt could thereby drain downward, progressively sequestering incompatible Bi, Sb, Te, Pt, Pd, and Au to form sulfosalt melt accumulations that continue to fractionate to form the platinum group minerals. This late-stage fractionation model is consistent with the observed mineral distribution in numerous magmatic sulfide deposits.",
    author = "Tomkins, {Andrew George}",
    year = "2010",
    doi = "10.1130/G31263.1",
    language = "English",
    volume = "38",
    pages = "951 -- 954",
    journal = "Geology",
    issn = "0091-7613",
    publisher = "Geological Society of America",
    number = "10",

    }

    Wetting facilitates late-stage segregation of precious metal-enriched sulfosalt melt in magmatic sulfide systems. / Tomkins, Andrew George.

    In: Geology, Vol. 38, No. 10, 2010, p. 951 - 954.

    Research output: Contribution to journalArticleResearchpeer-review

    TY - JOUR

    T1 - Wetting facilitates late-stage segregation of precious metal-enriched sulfosalt melt in magmatic sulfide systems

    AU - Tomkins, Andrew George

    PY - 2010

    Y1 - 2010

    N2 - The wetting behavior of As-rich sulfosalt melts against monosulfide solid solution (MSS) is investigated using experiments to elucidate late-stage fractionation processes in magmatic sulfide systems, which may control the distribution of platinum group elements. A range of As-rich melt compositions is found to wet MSS, including those that contain significant proportions (1%–45%) of precious metals (Pt, Pd, and Au). However, extremely Au rich or Pt rich sulfosalt melts (>∼40% Au; >∼50% Pt + 5% Au) do not wet MSS. These results imply that if magma contamination and/or fractionation processes were able to produce a late-stage As-rich melt (sulfosalt melts crystallize cooler than MSS) that exceeds ∼0.2% of the rock volume, then an interconnected melt drainage network would be able to form along MSS crystal triple junctions. The dense sulfosalt melt could thereby drain downward, progressively sequestering incompatible Bi, Sb, Te, Pt, Pd, and Au to form sulfosalt melt accumulations that continue to fractionate to form the platinum group minerals. This late-stage fractionation model is consistent with the observed mineral distribution in numerous magmatic sulfide deposits.

    AB - The wetting behavior of As-rich sulfosalt melts against monosulfide solid solution (MSS) is investigated using experiments to elucidate late-stage fractionation processes in magmatic sulfide systems, which may control the distribution of platinum group elements. A range of As-rich melt compositions is found to wet MSS, including those that contain significant proportions (1%–45%) of precious metals (Pt, Pd, and Au). However, extremely Au rich or Pt rich sulfosalt melts (>∼40% Au; >∼50% Pt + 5% Au) do not wet MSS. These results imply that if magma contamination and/or fractionation processes were able to produce a late-stage As-rich melt (sulfosalt melts crystallize cooler than MSS) that exceeds ∼0.2% of the rock volume, then an interconnected melt drainage network would be able to form along MSS crystal triple junctions. The dense sulfosalt melt could thereby drain downward, progressively sequestering incompatible Bi, Sb, Te, Pt, Pd, and Au to form sulfosalt melt accumulations that continue to fractionate to form the platinum group minerals. This late-stage fractionation model is consistent with the observed mineral distribution in numerous magmatic sulfide deposits.

    UR - http://geology.geoscienceworld.org/cgi/reprint/38/10/951.pdf

    U2 - 10.1130/G31263.1

    DO - 10.1130/G31263.1

    M3 - Article

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