Simulating coseismic deformation of quartz in the middle crust and fabric evolution during postseismic stress relaxation — An experimental study

摘要: Abstract Non-steady state deformation and annealing experiments on vein quartz are designed to simulate earthquake-driven episodic in the middle crust. Three types of were carried out using a modified Griggs-type solid medium apparatus. All three start with high stress at temperature 400 °C constant strain rate 10− 4 s− 1 (type A), some followed by stability field α-quartz for 14–15 h zero nominal differential temperatures 800–1000 °C A + B), or 15 h 900 °C residual A + C). The samples reveal very strength > 2 GPa few percent permanent strain. microstructures after short-term A) record localized brittle plastic deformation. Statisc A + B) results recrystallisation restricted highly damaged zones. new grains aligned strings without crystallographic preferred orientation, indicate nucleation growth. Annealing non-hydrostatic conditions A + C) shear zones that also develop from bands cracks formed during preceding In this case, however, recrystallised zone is several grain diameters wide, elongate, marked orientation indicates flow dislocation creep dynamic recrystallisation. Quartz identical those produced type A + B observed cores recovered Long Valley Exploratory Well Quaternary Caldera, California, considerable seismic activity. demonstrate behaviour coseismic loading subsequent static decaying experimentally microfabrics allow identify similar processes exhumed rocks.