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Low-pressure, water-assisted anatexis of basic dykes in a contact metamorphic aureole, Fuerteventura (Canary Islands): oxygen isotope evidence for a meteoric fluid origin

Holloway, M. ; Bussy, F. ; Vennemann, T.

In: Contributions to Mineralogy and Petrology, 2008, vol. 155, no. 1, p. 111-121

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    Titre
    • Low-pressure, water-assisted anatexis of basic dykes in a contact metamorphic aureole, Fuerteventura (Canary Islands): oxygen isotope evidence for a meteoric fluid origin
    Auteur
    • Holloway, M.. Institute of Mineralogy and Geochemistry, Anthropole, University of Lausanne, 1015, Lausanne, Switzerland
    • Bussy, F.. Institute of Mineralogy and Geochemistry, Anthropole, University of Lausanne, 1015, Lausanne, Switzerland
    • Vennemann, T.. Institute of Mineralogy and Geochemistry, Anthropole, University of Lausanne, 1015, Lausanne, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Contributions to Mineralogy and Petrology, 2008, vol. 155, no. 1, p. 111-121. Springer-Verlag
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:321473
    Summary
    Migmatites produced by low-pressure anatexis of basic dykes are found in a contact metamorphic aureole around a pyroxenite-gabbro intrusion (PX2), on Fuerteventura. Dykes outside and inside the aureole record interaction with meteoric water, with low or negative δ18O whole-rock values (+0.2 to −3.4‰), decreasing towards the contact. Recrystallised plagioclase, diopside, biotite and oxides, from within the aureole, show a similar evolution with lowest δ18O values (−2.8, −4.2, −4.4 and −7.6‰, respectively) in the migmatite zone, close to the intrusion. Relict clinopyroxene phenocrysts preserved in all dykes, retain typically magmatic δ18O values up to the anatectic zone, where the values are lower and more heterogeneous. Low δ18O values, decreasing towards the intrusion, can be ascribed to the advection of meteoric water during magma emplacement, with increasing fluid/rock ratios (higher dyke intensities towards the intrusion acting as fluid-pathways) and higher temperatures promoting increasing exchange during recrystallisation