| It is generally believed that the high temperature (plastic) flow of rocks under upper lithospheric conditions is relatively insensitive to hydrostatic pressure. For that reason, pressure is normally not taken into account when extrapolating laboratory creep data to natural conditions prevalent in the crust. However, this might be unjustified in case of materials like calcite and rocksalt. The mechanical behaviour of these materials at intermediate temperatures and stresses is likely to be controlled by dislocation cross slip mechanisms. These type of mechanisms are expected to be strongly pressure dependent. Aim: To determine the pressure dependence of high temper temperature creep of calcite materials and rocksalt. To assess the significance of hydrostatic pressure in extrapolation of flow laws from laboratory to crustal conditions. Methods: Experimental deformation of poly- as well as single crystals using the 1 GPa gas apparatus. Present topics: Deformation mechanisms in marble deformed at high temperature and high pressure. The effect of pressure on the plastic deformation of rock salt. The role of pressure in the mechanism based description of the plastic deformation of rock salt. |
