Fig. 11

Deformation mechanism maps for quartz under approximate conditions of deformation of the protomylonite–mylonite (a; temperature = 400 °C, confining pressure = 390 MPa) and ultramylonite (b; temperature = 300 °C, confining pressure = 286 MPa). The exterior mylonite likely deformed at a higher temperature than the other samples—indicated by a 10−15 s−1 strain rate contour at 500 °C (dotted line). The piezometer of Cross et al. (2017) is indicated by the dashed line. Dashed lines in (b) represent strain rate contours for Nabarro–Herring diffusion creep. The calculated differential stresses for ultramylonite-I are indicated by the black outline in (b)