Transformation- and reaction-enhanced ductility in rocks

Abstract
Enhanced ductility is expected if deformation occurs during phase changes in minerals or during metamorphic reactions. Transformation-enhanced ductility largely arises from stresses generated by the transformation and may be an important consideration during mantle deformation. Reaction-enhanced ductility is a more complex process reflecting softening due to fluid release, increased diffusivities and the formation of small, strain-free grains. It is suggested that deformation should preferentially occur during the development of new minerals and may be inhibited by subsequent grain growth.