Table of Deformation Mechanisms and Processes
by Mark Jessell & Paul Bons at the Department of Earth Sciences, Monash University
(interactive version at:
Fracturing (M) Breaking of inter-atomic bonds Gouge, breccias, boudinaged grains +ve or -ve -ve   Any, more at high stress & low T
Frictional Sliding (M) Frictional sliding on surfaces Gouges, breccias, pseudotachylites, domino grains +ve or -ve -ve Any, more at high stress & low T
Lattice Diffusion (M) Diffusional movement of vacancies and interstitials New crystal void of pre-existing impurities (hard to prove in nature) +ve ? (Nabarro-Herring) or  (Coble creep) Any, more at low stress & high T
Dislocation Glide (M) Re-arrangement of inter-atomic bonds Deformation lamellae, deformation bands, undulose extinction +ve ++ve also a hardening with finer grain size (Hall-Petch Law) Any, more at low stress & high T
Twinning (M) Re-arrangement of inter-atomic bonds and re-orientation of lattice site  Twins (sharp nosed, narrow, parallel to rational twin planes) +ve ++ve   Calcite especially at low T and low strain, plagioclase, quartz (but not visible), amphiboles
Kinking (M) Dislocation glide on single slip system Kink bands +ve +ve   Micas, low T quartz, kyanite
Grain Boundary Migration (P or M) Local diffusion and reorientation of atoms or atomic clusters Irregular grain boundaries, pinning microstructures, orientation families, Lattice preferred orientations with strong point maxima, non-120°-triple junctions +ve or -ve +ve Produces low dislocation density material Q softer Any, more at high T, especially quartz, olivine, fsp
Rotation Recrystallisation (P) Progressive addition of dislocations of same sign to sub-grain wall Mortar texture or core and mantle texture, bi-modal grain size -ve -ve Change in grain size can strengthen or weaken material Any, more at low stress & high T, especially quartz, fsp, olivine
Recovery (P) Climb, mutual annihilation of dislocations of opposite signs, formation of subgrain walls Polygonisation, foam textures, 120°-triple junctions -ve +ve or -ve Produces low dislocation density material Q softer Any, more at high T
Climb (M) Diffusional addition or removal of atoms at dislocation line   +ve 0   Any, more at high T
Lattice Rotation (P) Dislocation glide and/or bulk rotation of grains Lattice preferred orientations 0 +ve Well developed fabrics may be stronger or weaker than random fabrics Any, more at low stress & high T
Bulk Rotation (M or P) Physical rotation of whole or part of mineral grains Helical inclusion trails, bending of crystals, delta & sigma porphyroclasts +ve +ve or -ve   Any
Grain Boundary Sliding (M) Dislocation movement on "clean" grain boundaries, shearing on "dirty" ones   0 0   Any
Diffusive Mass Transfer (M or P) "Long range" diffusion of atoms Veins, pressure shadows, porhyroblasts +ve or -ve ?   Any, especially quartz and calcite
Phase Change (M or P) Changed crystal structure without change in bulk chemistry of mins Phase boundaries in minerals ? ? Often associated with volume change Quartz, calcite-aragonite, olivine