Rocks under stress: How dramatic the effect of stress on metamorphic reactions really is?

Recent decades have been connected with an impressively accelerating pace in the development and availability of new analytical techniques to earth scientists. Interestingly, the smaller the scale considered, the more heterogeneous an apparently uniform rock sample is. This heterogeneity is not only characterized by variation in chemical composition but also in mechanical properties. The mechanical effects may influence element transport and mineral assemblage in rocks which can, in turn, significantly control the mechanical-chemical coupling rates and mechanisms of various processes in the Earth’s interior.

Considering the interplay of metamorphic reaction and mechanical properties in our quantification approaches is critical for correct interpretation of observations in metamorphic rocks. In my contribution, I will show major applications of the new quantification approaches, the accompanying obstacles and the consequences for our petrological interpretations. New findings from coupled experimental and numerical studies emphasize the necessity of quantifying the stress/pressure distribution before any complex thermodynamic interpretations. In fact, any thermodynamic interpretation of a stressed system must take into account the locally-resolved state of stress during sample deformation.