Melt inclusions from the deep Slave lithosphere

Implications for the origin and evolution of mantle-derived carbonatite and kimberlite

Esmé van Achterbergh*, William L. Griffin, Chris G. Ryan, Suzanne Y. O'Reilly, Norman J. Pearson, Kevin Kivi, Buddy J. Doyle

*Corresponding author for this work

    Research output: Contribution to journalArticle

    44 Citations (Scopus)

    Abstract

    Melt inclusions in clinopyroxenes from lherzolitic xenoliths from the deep lithospheric mantle beneath the Slave Craton (Lac de Gras area, Canada) reveal multiple origins for carbonatitic melts. One type of inclusions consists of a series of silicate-carbonate-silicate concentric layers, interpreted to have unmixed under disequilibrium conditions during rapid ascent to the surface. Bulk major- and trace-element compositions are typical of Group 1 kimberlites and quantitative nuclear microprobe imaging of the globules reveals fractionation of related elements (e.g. F-Br, Nb-Ta) between the silicate and carbonate components. The globules probably formed by partial melting of carbonated peridotite, consistent with results of melting experiments and some models for the generation of kimberlite magmas. They provide evidence for a genetic relationship between some carbonate-rich magmas and ultramafic silicate magmas, and for the possibility of unmixing processes of these melts during their evolution. The second inclusion type comprises carbonate-rich globules interpreted as samples of Mg-carbonatite melt that quenched on ascent to the surface. Bulk major- and trace-element compositions indicate that the melts were derived from a carbonate-rich source and oxygen, carbon, and strontium isotope data are consistent with the involvement of recycled crustal material and suggest that some mantle-derived carbonatites are unrelated to kimberlites.

    Original languageEnglish
    Pages (from-to)461-474
    Number of pages14
    JournalLithos
    Volume76
    Issue number1-4 SPEC. ISS.
    DOIs
    Publication statusPublished - Sep 2004

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