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Meteoric fluid‐rock interaction in Variscan shear zones
Author(s) -
Dusséaux Camille,
Gébelin Aude,
Boulvais Philippe,
Gardien Véronique,
Grimes Stephen,
Mulch Andreas
Publication year - 2019
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1111/ter.12392
Subject(s) - geology , massif , leucogranite , meteoric water , shear (geology) , muscovite , shear zone , geochemistry , hydrogen isotope , isotope , petrology , geomorphology , mineralogy , metamorphic rock , geotechnical engineering , seismology , paleontology , groundwater , quartz , gneiss , physics , quantum mechanics , tectonics
Variscan shear zones in the Armorican Massif represent sites of strong fluid‐rock interaction. The hydrogen isotope composition of muscovite (δ D M s ) 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 (δD water ) present within the shear zones during high‐temperature deformation. A ~40‰ difference in δD water 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.