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Rhéologie d'agrégats olivine-orthopyroxène sous haute pression

Abstract : This thesis presents our work on the rheology of two of the main minerals of the upper mantle : olivine and orthopyroxene. First, fined-grained polycrystalline aggregates (with grain sizes between 100 nm and 5 µm) of olivine and pyroxene were synthesized by Spark Plasma Sintering (SPS) and vacuum sintering. The samples were then deformed at pressures between 2 and 6 GPa in D-DIA presses installed on synchrotrons X-ray beamlines at NSLS and ESRF so that measurements of the differential stress and strain could be obtained in situ. The influence of pressure on low-temperature plasticity of olivine was studied at room temperature (ID06 beamline, ESRF synchrotron, Grenoble). High-temperature deformation mechanisms of olivine and orthopyroxene were also studied between 900 and 1200°C (X17B2 beamline, NSLS synchrotron, New York). Mechanical results and microstructural analysis by EBSD suggest a deformation by diffusion creep. Rheological laws including the effect of pressure, temperature, differential stress and grain size were determined for each mineral. Under these conditions, orthopyroxene appears less viscous than olivine. Finally, two-phase aggregates (Ol/Px volume ration of 80/20 and 70/30) were also deformed. Differential stress, estimated in each phase, indicates the contribution of a second deformation mechanism, in agreement with microstructural observations.
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Contributor : Williams Exbrayat <>
Submitted on : Tuesday, October 25, 2016 - 10:05:34 AM
Last modification on : Wednesday, October 14, 2020 - 10:20:35 AM


  • HAL Id : tel-01320921, version 2


Arnaud Proietti. Rhéologie d'agrégats olivine-orthopyroxène sous haute pression. Planétologie. Universite Toulouse III Paul Sabatier, 2016. Français. ⟨tel-01320921v2⟩