Microscale stress heterogeneities: Mechanical, rheological, and mineralogical impact

The roots of lithospheric rheology lie at the grain scale, where mineral assemblages and microstructure respond to their environment. Phase shapes, distributions, and orientations transform macroscale loading into microscale stress and strain(-rate) fields, which in turn feed back to the macroscale response. Because of the heterogeneity induced by the inherent anisotropy of rock microstructure, these microscale fields can vary significantly from the bulk conditions. We present some examples of how microscale stresses influence microstructural evolution and rock rheology.