Determining controls on shear instabilities in dehydrating gypsum

The interaction between dehydration reactions and deformation in metamorphic environments is important in tectonics. While experiments have been run to understand how dehydration reactions and deformation interact, there is still a gap in our understanding because previous work could not simultaneously resolve the temporal and spatial evolution of grain-scale processes. Here we propose to use operando 4D microtomography (4DµCT) to directly document dehydration in shearing rocks on the grain scale, allowing us to unequivocally determine conditions where dehydration can lead to shear instabilities.We will react and shear gypsum fault gouge and pre-cut gypsum rocks at a range of conditions and collect discrete 4DµCT data while monitoring sample strength and permeability. The resulting data will link grain-scale processes to the macro-scale evolution of the samples allowing the formulation of models for the coupling between processes in dehydrating deforming rocks.