Sina Marti, Postdoctoral fellow at the University of Edinburgh, School of Geosciences, will present her work on: "The brittle viscous transition in mafic rocks - interplay between fracturing, reaction and viscous deformation".
The talk will be about the brittle viscous transition in mafic rocks as observed from rock deformation experiments. The transition thereby takes place by a switch from brittle fracturing and cataclastic flow to viscous dissolution-precipitation creep and grain boundary sliding. Mineral reactions and resulting grain size refinement by nucleation are observed to be critical processes for the switch to viscous deformation, i.e., grain size sensitive creep. In the transitional regime, the mechanical response of the sample is a mixed-mode between brittle and viscous rheology and microstructures associated with both brittle and viscous deformation are observed. As grain size reduction by reaction and nucleation is a time dependent process, the brittle-viscous transition is not only a function of T but to a large extent also of microstructural evolution.