The results of shear strength on rough fracture indicate that elevated temperatures effect to granite behavior.
The effect of temperatures insignificant below 373 kelvin suggesting that this temperatures ranges is in the brittle regime.
Above 373 kelvin the temperatures effect is greater (Ohnaka 1995.)
The increasing temperatures and the cause of shear displacement increasing and shear strength decreasing.
This may be related to Development of localized plastic deformation in shear failure zone