23 July 2024 - New publication in The Annual Review of Earth and Planetary Sciences

The deformation of minerals is a consequence of the microscopic displacement of crystal defects. The two most commonly invoked mechanisms are dislocation creep and diffusion creep. In the former, deformation is produced by shear resulting from the movement of dislocations. In contrast, in the latter, point defects produce strain through the transport of matter. However, an alternative mechanism, dislocation climb, has been proposed whereby dislocations gain degrees of freedom by absorbing or emitting point defects. Dislocation climb is traditionally regarded as a recovery mechanism that enables creep to maintain a steady state, whereas only dislocation glide produces strain. However, in 1967, Nabarro demonstrated that, under specific conditions, deformation could occur exclusively as a result of the climb of dislocations: pure climb creep. This mechanism is likely to be the main deformation mechanism in planetary interiors. Another, hitherto little considered mechanism, has been identified recently: the mixed climb of dislocations. In this mode of deformation, dislocations move by both glide and climb, with comparable contributions to the strain produced. Experimental evidence of this mechanism have been found in the natural deformation of quartz and olivine in nature.

To learn more:

P. Carrez, A. Mussi & P. Cordier (2024) On dislocation climb as an important deformation mechanism for planetary interiors. Annual Review of Earth and Planetary Sciences, 52, 409-441. https://doi.org/10.1146/annurev-earth-031621-063108