Characterization of the glide planes of the [001] screw dislocations in olivine using electron tomography |
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Authors: | Alexandre Mussi Patrick Cordier Sylvie Demouchy Claude Vanmansart |
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Affiliation: | 1. Unité Matériaux et Transformations, UMR 8207 CNRS, Université Lille1, 59655, Villeneuve d’Ascq, France 2. Géoscience Montpellier, UMR 5342 CNRS, Université Montpellier 2, 34095, Montpellier, France
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Abstract: | A San Carlos olivine polycrystal has been deformed under uppermost mantle conditions, by compression at 900 °C, at a strain rate of 1.1 × 10?5 s?1, under a confining pressure of 300 MPa, using the Paterson press. Transmission electron tomography of dislocations has been performed by scanning transmission electron microscopy, by conventional transmission electron microscopy using the weak-beam dark-field technique, associated with precession or not, in order to determine the glide planes of [001] screw dislocations. This recent technique is the most suitable one since most [001] dislocations exhibit straight screw segments due to the high lattice friction on this character at low temperature. We find that [001] dislocations glide in (100), (010) and {110} as already reported, but also more unexpectedly in {120} and {130}. We show that at 900 °C, [001] {110} glide is dominant in polycrystals. We have, however, noted and characterized numerous cross-slip events in the specimen. |
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