Surface textures of intrafault quartz grains as an indicator of fault movement

Quartz grains obtained from gouges which accompany faults are observed by means of a scanning electron microscope. It is assumed that quartz grains in the gouge are formed from the breakage of quartz in the parent rock due to fault movement, with corrosion by groundwater occuring on grain surfaces after the movement. Therefore, surface textures or morphology of the grains can become a good indicator in examining the mode of fracture at the time of faulting, or the length of time elapsed since the fault moved.