Meteoric fluid‐rock interaction in Variscan shear zones

Variscan shear zones in the Armorican Massif represent sites of strong fluid‐rock interaction. The hydrogen isotope composition of muscovite (δDMs) from syntectonic leucogranite allows to determine the source of fluids that infiltrated the footwall of three detachment zones and the South Armorican S...

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Bibliographic Details
Published in:Terra nova (Oxford, England) England), 2019-08, Vol.31 (4), p.366-372
Main Authors: Dusséaux, Camille, Gébelin, Aude, Boulvais, Philippe, Gardien, Véronique, Grimes, Stephen, Mulch, Andreas
Format: Article
Language:English
Subjects:
Deformation
Earth Sciences
Fluids
Geochemistry
Hydrogen
Hydrogen isotopes
Isotopes
Magma
Muscovite
Ratios
Rocks
Sciences of the Universe
Shear zone
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Summary:Variscan shear zones in the Armorican Massif represent sites of strong fluid‐rock interaction. The hydrogen isotope composition of muscovite (δDMs) from syntectonic leucogranite allows to determine the source of fluids that infiltrated the footwall of three detachment zones and the South Armorican Shear Zone. Using temperatures of hydrogen isotope exchange estimated from microstructural data, we calculate the hydrogen isotope ratios of water (δDwater) present within the shear zones during high‐temperature deformation. A ~40‰ difference in δDwater values from deep to shallow crustal level reveals a mixing relationship between deep crustal fluids with higher δD values that range from −34 to −33‰, and meteoric fluids with δD values as low as −74‰ in the upper part of detachment footwalls.
ISSN:0954-4879
1365-3121
DOI:10.1111/ter.12392