Dynamic recrystallization of feldspar: A mechanism for ductile shear zone formation

Feldspar aggregates experimentally deformed in the dislocation creep regime undergo dynamic recrystallization because recovery is difficult due to the limited climb of dislocations. Recrystallizing aggregates have a lower strength because of the cyclic production of small, strain-free grains, and they develop a strong preferred orientation, consistent with that observed in mylonites. Thus, recrystallization-accommodated dislocation creep may be responsible for the grain-size reduction and strain softening that lead to the formation of many mylonites and ductile shear zones.