%0 Book Section %T Pegmatite mylonites: origin and significance %+ Géosciences Rennes (GR) %A Gapais, Denis %A Brem Moundi, Awa Louan, A. %B Rock Deformation from Field, Experiments and Theory: A Volume in Honour of Ernie Rutter %E G. F. ZELLMER, M. EDMONDS and S. M. STRAUB (Eds.) %S geological society special publication %V 409 %N 1 %P 167-173 %8 2015 %D 2015 %R 10.1144/SP409.7 %Z Sciences of the Universe [physics]/Earth SciencesBook sections %X Pegmatites generally behave as resistant objects compared to their host rocks during solid-state deformation. They usually show folding or boudinage within their host rocks, features observed from low-grade to high-grade deformations, up to upper-amphibolite metamorphic conditions. Here we describe mylonitic pegmatite veins emplaced within S-C fabric-bearing two-mica granites. Pegmatites consist mainly of feldspar and quartz ribbons, with remnants of coarse-grained Kfs phenocrysts. Quartz ribbons are made of large grains elongated in the shearing direction, with evidence of dynamic recrystallization involving grain boundary migration. Ribbons show very strong lattice-preferred orientations of c-axes at low angles to the stretching lineation. From these, we propose that quartz ribbons are formed by oriented growth during syn-shearing crystallization of the pegmatite. Subsequent syn-shearing solid-state deformation involved grain size reduction accompanied by prism slip. The occurrence of pegmatite mylonites within granitoid intrusions should be considered as a univocal argument for synkinematic emplacement. %G English %L insu-01121077 %U https://insu.hal.science/insu-01121077 %~ INSU %~ UNIV-RENNES1 %~ UR2-HB %~ CNRS %~ GR %~ OSUR %~ UR1-HAL %~ UR1-SDLM %~ UR1-SDLMJONCH %~ GR-3T %~ UNIV-RENNES2 %~ TEST-UNIV-RENNES %~ TEST-UR-CSS %~ UNIV-RENNES %~ INRAE %~ UR1-ENV