ABSTRACT
Reliable modeling of the deformation of rocksalt under the very low strain rates characterizing long term engineering conditions or natural halokinesis requires extrapolation of experimentally-derived flow laws to rates much lower than those attainable in the laboratory. This extrapolation must be based on an understanding of the microscale deformation mechanisms operating under these conditions, from studies of natural laboratories. The engineering creep laws generally used in the salt mining industry are based on dislocation creep processes quantified in laboratory experiments of necessarily limited duration. However, a large body of evidence clearly demonstrates that under conditions of long-term deformation, grain boundary dissolution-precipitation processes, such as solution-precipitation creep (or “pressure solution”) and dynamic recrystallization, play a significant role. In this contribution, we briefly review the microphysics of grain boundary water related, solution-precipitation processes in halite, together with the flow behaviour associated with these processes, and we discuss the contribution of these mechanisms to the strain rate during long-term creep.
