Semibrittle deformation and partial melting of perthitic K-feldspar: An experimental study

To investigate the relationships between deformation, cracking, and partial melting in the lower continental crust, axial compression and hydrostatic experiments were performed on K‐feldspar single crystals at temperatures of 700° and 900°C and confining pressures between 0.75 and 1.5 GPa. Sample deformation was carried out at a constant strain rate of ~ 10 −6 s −1 . The samples deformed at 700°C show typical brittle behavior with formation of conjugate fractures and peak stresses that increase with confining pressure. Samples deformed at 900°C show formation of shear fractures, peak stresses below the Goetze criterion, and inverse confining pressure dependence of peak stress, indicating that along the fractures deformation was not dominantly friction controlled. Microstructural and chemical analyses reveal the presence of melt (