Deformation of Diopside Single Crystal at Mantle Pressure, 1: Mechanical data

Elodie Amiguet , Paul Raterron , Patrick Cordier , Hélène Couvy , Jiuhua Chen

Steady state deformation experiments were carried out in a Deformation-DIA high-pressure apparatus (D-DIA) on oriented diopsideB single crystals, at pressure () ranging from 3.8 to 8.8GPa, temperature () from 1100° to 1400°C, and differential stress () between 0.2 and 1.7GPa. Three compression directions were chosen in order to test the activity of diopside dislocation slip systems, i.e., ½<110>{} systems activated together, both [100](010) and [010](100) systems together, or [001] dislocation slip activated in (100), (010) and {110} planes. Constant applied stress and specimen strain rates () were monitored using time-resolved synchrotron X-ray diffraction and radiography, respectively. Transmission electron microscopy (TEM) investigation of the run products revealed that dislocation creep was responsible for sample deformation. Comparison of the present high- data with those obtained at room- by Raterron and Jaoul (1991) - on similar crystals deformed at comparable conditions - allows quantifying the effect of on 1/2<110>{} activity. This translates into the activation volume = 17 ± 6cmP/mol in the corresponding creep power law. Our data also show that both 1/2<110> dislocation slips and [001] have comparable slip activities at mantle and , while [100](010) and [010](100) slip systems remain marginal. These results show that has a significant effect on high- dislocation creep in diopside, the higher the pressure the harder the crystal, and that this effect is stronger on 1/2<110> slip than on [001] slip.

Mots clés: upper mantle; clinopyroxenes; diopside; high pressure; dislocation creep; slip systems; rheological law; activation volume

Elodie Amiguet, Paul Raterron, Patrick Cordier, Hélène Couvy, Jiuhua Chen. Deformation of Diopside Single Crystal at Mantle Pressure, 1: Mechanical data. Physics of the Earth and Planetary Interiors, 2009, 177 (3-4), pp.122. ⟨10.1016/j.pepi.2009.08.010⟩. ⟨hal-00592586⟩