BRGM - Bureau de Recherches Géologiques et Minières (BRGM), ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327 : UMR7327, INSU - CNRS - Institut national des sciences de l'Univers, UO - Université d'Orléans : UMR7327
UO - Université d'Orléans : UMR7327 (Château de la Source - Avenue du Parc Floral - BP 6749 - 45067 Orléans cedex 2 - France)
3ISTerre - Institut des Sciences de la Terre (ISTerre, OSUG-C (Maison des Géosciences), 1381, rue de la Piscine, 38610 GIERES
ISTerre, Université Savoie Mont Blanc, Campus Scientifique, 73376 Le Bourget-du-Lac Cedex - France)
5GR - Géosciences Rennes (Bâtiment 15 - Université de Rennes 1 - Campus de Beaulieu -263 Av du général Leclerc- CS 74205 - 35042 Rennes Cedex - France - France)
Abstract : Water plays an important role in geological processes. Providing constraints on what may influence the distribution of aqueous fluids is thus crucial to understanding how water impacts Earth's geodynamics. Here we demonstrate that ductile flow exerts a dynamic control on water-rich fluid circulation in mantle shear zones. Based on amphibole distribution and using dislocation slip-systems as a proxy for syn-tectonic water content in olivine, we highlight fluid accumulation around fine-grained layers dominated by grain-size-sensitive creep. This fluid aggregation correlates with dislocation creep-accommodated strain that localizes in water-rich layers. We also give evidence of cracking induced by fluid pressure where the highest amount of water is expected. These results emphasize long-term fluid pumping attributed to creep cavitation and associated phase nucleation during grain size reduction. Considering the ubiquitous process of grain size reduction during strain localization, our findings shed light on multiple fluid reservoirs in the crust and mantle.
https://hal-insu.archives-ouvertes.fr/insu-01535741 Contributor : Nathalie PothierConnect in order to contact the contributor Submitted on : Friday, June 9, 2017 - 1:59:09 PM Last modification on : Wednesday, May 11, 2022 - 4:04:39 AM Long-term archiving on: : Sunday, September 10, 2017 - 1:35:35 PM