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    Extreme magnesium isotope fractionation at outcrop scale records the mechanism and rate at which reaction fronts advance

    Pogge von Strandmann, Philip A.E. and Dohmen, R. and Marschall, H.R. and Schumacher, J.C. and Elliott, T. (2015) Extreme magnesium isotope fractionation at outcrop scale records the mechanism and rate at which reaction fronts advance. Journal of Petrology 56 (1), pp. 33-58. ISSN 0022-3530.

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    Abstract

    Isotopic fractionation of cationic species during diffusive transport provides novel means of constraining the style and timing of metamorphic transformations. Here we document a major (~1‰) decrease in the Mg isotopic composition of the reaction front of an exhumed contact between rocks of subducted crust and serpentinite, in the Syros mélange zone. This isotopic perturbation extends over a notable length-scale (~1 m), implicating diffusion of Mg through an intergranular fluid network over a period of ~100 kyr. These novel observations confirm models of diffusion-controlled growth of reaction zones formed between rocks of contrasting compositions, such as found at the slab-mantle interface in subduction zones. The results also demonstrate that diffusive processes can result in exotic stable isotope compositions of major elements with implications for mantle xenoliths and complex intrusions.

    Metadata

    Item Type: Article
    Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication following peer review. The version of record is available online at the link above.
    Keyword(s) / Subject(s): diffusion, isotope, metasomatism, monomineralic
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences
    Depositing User: Philip Pogge von strandmann
    Date Deposited: 21 Oct 2015 16:41
    Last Modified: 28 Sep 2017 05:45
    URI: http://eprints.bbk.ac.uk/id/eprint/13142

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