Deformation Experiments
Deformation experiments with high resolution of stress and strain rate are typically conducted with Paterson Gas-Medium apparatuses at pressures of 300 MPa. This relatively low pressure necessitates careful control of the sample chemistry to suppress melting at temperatures above ~1150°C. The samples in our experiments are therefore made by a solution-gelation method. Comparison of the strength of genuinely melt-free sol-gel samples (dots) with nominally melt-free San Carlos olivine-derived samples indicates that melt contents up to 1% increase the the strain rates for a given stress by two orders of magnitude (from Faul and Jackson, 2007).
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Comparison of the strength of nominally melt-free olivine with sol-gel. olivine. |
FESEM orientation contrast image of a sol-gel sample deformed at 1300°C. A rare subgrain boundary is visible in the grain near the top-left. |