The distribution of fluids in natural rock salt to understand deformation mechanisms

This contribution presents a microstucutral study of samples from the Qum-Kuh salt glacier (central Iran) and a salt mine of Neuhof (Germany) representing the extruded part and the source layer of the salt diapiric system, respectively. The main objectives are to identify the active deformation mechanisms and to track the in-situ distribution of fluids, which is the key point to understand the interplay between deformation mechanisms. Intense deformation of the Neuhof rock salt was accommodate by coupled activity of Solution-Precipitation (SP), Grain Boundary (GB) sliding and microcracking of halite grains pointing to the enhancement of continuous SP creep by microcracking. For the salt fountain, GB microstructures and deformation experiments point both to effective GB healing indicating a paradox with microstructural studies of similar rock salts, with evidence for both active dislocation creep and SP creep during the deformation of salt fountains.