Under lithospheric temperature and pressure conditions, deformation occurs by mechanisms such as fracture, frictional glide, cataclastic, semi-brittle, and viscous flow - usually involving a number of processes such as pressure solution, dislocation creep, diffusion creep, and others. The 'end members', i.e., the predominantly pressure-dependent brittle deformation and the pre-dominantly temperature-dependent viscous deformation are reasonably well understood through numerous rock deformation and friction experiments. At the same time, the interaction of the 'end member' processes in the semi-brittle field is still only poorly understood.

Quartz is one of the most common minerals in the Earth’s crust, and our state of knowledge is greater than for many other crustal minerals. Its properties, from strength to solubility, play a key role in the rheological behaviour of rocks in the Earth’s crust. A wide range of brittle to plastic deformation mechanisms results in a richness of intra- and intercrystalline microstructures, storing a great deal of information concerning the ambient conditions present during their deformation history. Additionally, fluid-rock interaction resulting in dissolution-precipitation creep take place at the microscale and are expressed by cleavage development and quartz veins on a larger scale.

Here we invite contributions that are concerned with the deformation mechanisms and processes of aspects from brittle to viscous behaviour. We welcome observations and contributions from field-based, experimental and numerical research.

Invited Speakers: Jean Pierre Gratier and Z´eev Reches