To provide constraints on the rheological properties of garnet, we have experimentally investigated the creep behavior of garnet at high pressures and temperatures using a deformation-DIA. Samples were cold-pressed from a garnet powder and deformed at constant displacement rates ranging from 1.1×10-5 to 2.6×10-5 s-1 at high temperatures (1 273-1 473 K) and high pressures (2.4-4.1 GPa). Differential stress and pressure were measured using X-ray diffraction techniques based on the elastic strain of various lattice planes as a function of orientation with respect to the applied stress field. The plastic strain of a deforming sample was monitored in-situ through a series of radiographs. Our results provide a measure of the dependence of creep rate of garnet on the temperature with an activation energy of ~280 kJ/mol and on pressure with an activation volume of ~10×10-6 m3/mol. The flow behavior of garnet quantified by this study provides the basis for modeling geodynamic processes occurring within subducted lithosphere.
- high pressure