PHASE SHIFT INTERFERENCE MICROSCOPE STUDY OF DISSOLUTION-PRECIPITATION PROCESSES OF NONHYDROSTATICALLY STRESSED HALITE CRYSTALS IN SOLUTION

Abstract

Halite single crystals in saturated solution were used to study dissolution precipitation creep (DPC) at conditions where plastic deformation is negligible. Specifically, the free unloaded surfaces of these crystals were investigated by a novel Linnik-based phase shift interference microscope. The method allows observations of the crystal surface in-situ and with an axial resolution in the nanometer scale. Transport phenomena in open systems, temperature gradients, and gradients in strain energy density were found to cause morphological changes on the free crystal surface by dissolution/reprecipitation. We did not find evidence for DPC by applying a homogeneous stress field to the crystal as long as plastic deformation was avoided. These findings suggest that deformation of rocks by DPC in situations where dislocation creep is not activated, but is rather promoted by fluid transport through the rock or by episodic changes of extensive parameters affecting solubility than by homogeneous stress alone.