The development of microtextures and dislocation substructures in naturally deformed olivines from various geological environments

High voltage electron microscopy and petrofabric analysis techniques are used to distinguish dislocation substructures and preferred orientation patterns of the mineral olivine in naturally deformed peridotites. In order to obtain information over a wide field in which different types of deformation occur, samples were studied from various geological environments. Olivines from Iherzolite nodules in basalts (Dreiser Weiher, Germany; Auvergne, France), alpine-type orogenic peridotites (Finero, Alpe Arami, Switzerland; Kittelfjäll, Sweden), and peridotite nodules in kimberlites (Lesotho) show crystal plasticity as an important mechanism allowing deformation. Depending on the intensity and conditions of deformation (P, T, \u03b5), various glide systems and dislocation substructures are developed. Increasing deformation produced dislocation substructures in which complete sequences are recognized from strain hardening regimes via (dynamic) recovery up to different types of recrystallization. Depending on the deformation conditions, dislocation glide systems {0k1} [100] were produced during high temperature and/or low strain rate creep, while at lower temperatures and/or higher strain rates, dislocations with Burgers vector b=[001] predominate. This makes it possible to distinguish between mono- and poly-phase deformation influences in the dislocation substructures in some orogenic peridotites and kimberlite nodules. Literature results of experimental deformation on olivine, and detailed information about the structural-petrological history of the studied rocks are indispensable and therefore extensively discussed.