Crystal?Plastic Deformation in Seismically Active Carbonate Fault Rocks

The spatial separation of macroscopic rheological behaviors has led to independent conceptual treatments frictional failure, often referred as brittle, and viscous deformation. Detailed microstructural investigations naturally deformed carbonate rocks indicate that both failure mechanisms might operate during seismic deformation carbonates. Here, we investigate the were active in two fault zones Greece by performing detailed slip-system analyses on data from automated crystal-orientation mapping transmission electron microscopy electron-backscatter diffraction. We combine with interpretations nanostructures predictions mechanism maps for calcite. nanometric grains at principal slip surface should deform diffusion creep but activation (0001)<20> system is evidence a contribution crystal plasticity. A similar crystallographic preferred orientation appears cataclastic parts despite exhibiting larger grain size different fractal dimension, compared surface. region exhibits microstructures consistent {104}<021> systems. Postdeformational, static recrystallization, annealing produce an equilibrium microstructure triple junctions equant size. propose repeated introduction plastic strain recrystallization reduces offers form cohesive nanogranular material. This formation leads grain-boundary strengthening effect resulting delocalization which observed over 6 orders magnitude (?m-m) expressed multiple faults planes, suggesting cyclic repetition annealing.