Naturally deformed quartz-rich rocks
Figure caption
undeformed / semibrittle & bulging recrystallization / subgrain rotation recrystallization / grain boundary migration recrystallization
19
Mica-poor Heavitree quartzite deformed at greenschist conditions with subgrain rotation recrystallization.
In mica-poor quartzites of sheet 2, deformed at same conditions as sample shown in photo #18, there is little or no solution-precipitation. Original detrital quartz grains are flattened and stretched and show severe undulose extinction due to the development of subgrains by lattice rotation. The large grains are surrounded by a mantle of recrystallized grains, ~50 mm in size, which formed by subgrain rotation in dislocation creep regime 2. The recrystallized grains are larger than in the sample illustrated in photo 18 because the grain boundaries were not pinned by micas. (703 A)