Geological materials such as ice and olivine are often modelled as viscous fluids at the large scale. However, they have complex, evolving microstructures which are not present in normal fluids, and these can have a significant impact on large-scale flow behaviour. These different materials have many commonalities in how the evolving microstructure influences the large scale flow, yet research is often siloed into individual disciplines.

With this session, we aim to bring together researchers from a range of disciplines, studying a variety of anisotropic materials, and working on different aspects of complex viscous flow such as: viscous anisotropy related to CPO or extrinsic microstructures; crystallographic preferred orientation (CPO) or fabric evolution; other controls on rheology such as grain size, dynamic recrystallisation and deformation mechanisms; and impact of rheology on complex flow, e.g. in the transition through a shear margin.

We encourage submissions investigating this topic through numerical modelling, laboratory experiments and observational studies. We are aiming to convene an inclusive and collaborative session, and invite contributions from all disciplines. We particularly encourage early career researchers to participate.