Fracturing and frictional deformation have been found to contribute to strain energy dissipation across the entire lithosphere. Fractures play a fundamental role in strain localization deep into the ductile realm, and fracturing potentially contributes to the formation of shear bands in mylonitic shear zones. Pseudotachylites in lower-crustal rocks are evidence for frictional heating at great depth, and deep slow slip events in subduction zones likely involve some form of fracturing. Fractures are also thought to constitute first-order transient fluid migration pathways across the entire crust. Cyclical interplays between frictional and viscous deformation in the ductile realm have been described both in wet and dry crustal conditions, in intracontinental and in plate boundary settings, but the mechanisms responsible for these cyclical switches in deformation style are still highly debated.

Despite the evidence for their involvement, our picture of the mechanisms by which fractures form and function outside of the upper-crustal brittle domain is relatively unrefined. This session seeks to illuminate the role and mechanisms of fracture and frictional deformation outside of the shallow brittle domain and across a wide range of metamorphic conditions and scales. The aim is to draw a holistic picture of lithospheric strain energy dissipation, earthquakes in the ductile domain and synkinematic fluid-migration.

We invite contributions that cover field- and microstructural observations, experimental studies and numerical simulations on all scales, presenting observational, conceptual and modelling data.