Water-poor quartz, which contained 100ppm H/Si in the form of hydrogarnet defects, was deformed in compression under a confining pressure of about 1GPa, and differential stresses of 2 to 3GPa, at temperatures ranging from 500 to 900C. Transmission electron microscopic observations showed that little or no precipitation occurred during deformation, and that plastic deformation was achieved by dislocation glide alone. That is, dislocation climb was inhibited. The activated (water-weakened) glide systems were a basal and c+a prismatic in {10•0}. Both glide systems exhibited perfect dislocations, and dislocations which were widely dissociated into partials with identical Burgers vectors. The results suggested that the glide motion of basal a and prismatic c±a dislocations was made easier when the dislocations were dissociated and (4H)Si point defects were available in the crystal.

P.Cordier, J.C.Doukhan: Philosophical Magazine A, 1995, 72[2], 497-514