Evolution of H2O content in deforming quartz aggregates: An experimental study

• Published in: Journal of Structural Geology
• Main Authors: Stünitz, H, Raimbourg, Hugues, Nègre, L, Précigout, J, Jollands, M, Pongrac, P, Jeřabek, P, Gies, N, Lüder, M
• Other Authors: Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), University of Tromsø (UiT), Magma & Déformation, Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Gemological Institute of America, Institute of Petrology and Structural Geology, Univerzita Karlova Praha, Česká republika = Charles University Prague, Czech Republic (UK), Institute of Geological Sciences Bern, Universität Bern = University of Bern = Université de Berne (UNIBE), ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), ANR-11-EQPX-0036,PLANEX,Planète Expérimentation: simulation et analyse in-situ en conditions extrêmes(2011)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2024
• Subjects: [SDU]Sciences of the Universe [physics]; Norway; Northern Norway
• Online Access: https://insu.hal.science/insu-04357852; https://insu.hal.science/insu-04357852/document; https://insu.hal.science/insu-04357852/file/1-s2.0-S0191814123002468-main.pdf; https://doi.org/10.1016/j.jsg.2023.105029

International audience Deformation experiments were carried out on pure quartzite samples (>99% quartz) with a grain size of ~200 μm from Tana, Northern Norway. Deformation conditions were 900 • C, 0.1 wt% H 2 O added, strain rate ~1 × 10-6 s-1 at variable confining pressures from 600 to 2000 MPa. Detailed FTIR measurements of H 2 O indicate that the H 2 O content in the grain boundary region is higher than that inside quartz grains. Hydrostatic treatment and deformation at the chosen temperature and pressure conditions lead to further H 2 O loss from grain interiors and H 2 O increase in the grain boundary region. Varying the confining pressure does not have an observable effect on the H 2 O transfer from grains to the grain boundary region. The 3585 cm-1 absorption band increases systematically with increasing confining pressure. As this band is associated with OH in dislocations, the increase may indicate an increased dislocation density with increasing pressure. The triplet of 3317, 3375 and 3438 cm-1 associated with Al-content in quartz increases in the grain boundary region indicating an exchange of H + together with Al 3+ for Si 4+. The Al and H exchange suggest dissolution-precipitation processes in the grain boundary region facilitating the movement of the quartz grain boundaries (grain boundary migration). The H 2 O in the grain boundary region will be important for enhancing grain boundary migration and thus recrystallization processes during deformation.