%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
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