A systematic suite of constant strain rate experiments was performed on a vacuum-dried, high-purity, fine-grained clinopyroxenite using NaCl and NaF as confining media in a Griggs-type piston-cylinder apparatus. The experiments were carried out over a range of temperatures from 400o to 1100oC, strain rates from 10-3 to 10-7 s-1, and confining pressures from 170 to 1990 MPa. At T = 600oC and 8e = 1.1 X 10-5 s-1, 3 modes of deformation occur with increasing confining pressure. In experiments at P = 1500 MPa, 2 regimes of flow are clearly defined. The flow data within each regime can be satisfactorily fitted to thermally activated power laws. We believe that the parameters reflect flow dominated by the kinetics of dislocation glide associated with mechanical twinning and (100) <001> slip in the low temperature regime and creep by multiple slip accompanied by increased rates of diffusion and recovery in the high temperature regime. -after Authors
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Deformation of clinopyroxenite: evidence for a transition in flow mechanisms and semibrittle behavior.