%0 Journal Article %T Syn-kinematic hydration reactions, grain size reduction, and dissolution-precipitation creep in experimentally deformed plagioclase-pyroxene mixtures %+ Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO) %+ University of Tromsø (UiT) %+ Géodynamique - UMR7327 %A Marti, Sina %A Stünitz, Holger %A Heilbronner, Renée %A Plümper, Oliver %A Kilian, Rüdiger %< avec comité de lecture %@ 1869-9510 %J Solid Earth %I European Geosciences Union %V 9 %P 985-1009 %8 2018 %D 2018 %Z 2018SolE....9..985M %R 10.5194/se-9-985-2018 %Z Sciences of the Universe [physics]Journal articles %X It is widely observed that mafic rocks are able to accommodate high strains by viscous flow. Yet, a number of questions concerning the exact nature of the involved deformation mechanisms continue to be debated. In this contribution, rock deformation experiments on four different water-added plagioclase-pyroxene mixtures are presented: (i) plagioclase(An60-70)-clinopyroxene-orthopyroxene, (ii) plagioclase(An60)-diopside, (iii) plagioclase(An60)-enstatite, and (iv) plagioclase(An01)-enstatite. Samples were deformed in general shear at strain rates of 3×10-5 to 3×10-6 s-1, 800 °C, and confining pressure of 1.0 or 1.5 GPa. Results indicate that dissolution-precipitation creep (DPC) and grain boundary sliding (GBS) are the dominant deformation mechanisms and operate simultaneously. Coinciding with sample deformation, syn-kinematic mineral reactions yield abundant nucleation of new grains; the resulting intense grain size reduction is considered crucial for the activity of DPC and GBS. In high strain zones dominated by plagioclase, a weak, nonrandom, and geometrically consistent crystallographic preferred orientation (CPO) is observed. Usually, a CPO is considered a consequence of dislocation creep, but the experiments presented here demonstrate that a CPO can develop during DPC and GBS. This study provides new evidence for the importance of DPC and GBS in mid-crustal shear zones within mafic rocks, which has important implications for understanding and modeling mid-crustal rheology and flow. %G English %2 https://insu.hal.science/insu-03595903/document %2 https://insu.hal.science/insu-03595903/file/se-9-985-2018.pdf %L insu-03595903 %U https://insu.hal.science/insu-03595903 %~ OBSPM %~ INSU %~ BRGM %~ CNRS %~ UNIV-ORLEANS %~ ISTO %~ OSUC %~ PSL %~ OBSPM-PSL