Source depletion and extent of melting in the Tongan sub-arc mantle

J. T. Caulfield*, S. P. Turner, A. Dosseto, N. J. Pearson, C. Beier

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    37 Citations (Scopus)

    Abstract

    The fluid immobile High Field Strength Elements (HFSE) Nb and Ta can be used to distinguish between the effects of variable extents of melting and prior source depletion of the Tongan sub-arc mantle. Melting of spinel Iherzolite beneath the Lau Basin back-arc spreading centres has the ability to fractionate Nb from Ta due to the greater compatibility of the latter in clinopyroxene. The identified spatial variation in plate velocities and separation of melt extraction zones, combined with extremely depleted lavas make Tonga an ideal setting in which to test models for arc melt generation and the role of back-arc magmatism. We present new data acquired by laser ablation-ICPMS of fused sample glasses produced without the use of a melt fluxing agent. The results show an arc trend towards strongly sub-chondritic Nb/Ta (

    Original languageEnglish
    Pages (from-to)279-288
    Number of pages10
    JournalEarth and planetary science letters
    Volume273
    Issue number3-4
    DOIs
    Publication statusPublished - 15 Sep 2008

    Keywords

    • HFSE
    • depletion
    • sub-arc
    • back-arc
    • hydrous
    • melting
    • HIGH-FIELD STRENGTH
    • ISLAND-ARC
    • LAU BASIN
    • SUBDUCTION ZONES
    • GEOLOGICAL-MATERIALS
    • ELEMENT COMPOSITION
    • VOLCANIC-ROCKS
    • HIGH-PRESSURE
    • FLOW BENEATH
    • 1.5 GPA

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