Low-pressure,water-assisted anatexis of basic dykes in a contact metamorphic aureole,Fuerteventura (Canary Islands): oxygen isotope evidence for a meteoric fluid origin |
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| Authors: | M I Holloway F Bussy T W Vennemann |
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| Institution: | (1) Institute of Mineralogy and Geochemistry, Anthropole, University of Lausanne, 1015 Lausanne, Switzerland |
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| Abstract: | 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.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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| Keywords: | Basic dykes Contact aureole Meteoric water Oxygen isotopes Partial melting |
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