Application of reaction front propagation modelling to amphibolite-facies plagioclase hydration: an example from the Bergen arcs, Norway

Fluid inflitration along brittle presursors is commonly with associated with hydration and deformation of the host rock. In many cases the relative timing of fracturing, fluid infiltration, reaction, and deformation is unclear, making it difficult to disentangle the relative importance of processes that facilitate advancement of the hydration front. Here we present the transition from an anhydrous and relatively undeformed precursor rock into a highly deformed and hydrated plagioclase-rich rock. The studied outcrop preserves both (1) the interface between the anhydrous granulite-facies parent lithology and a statically hydrated amphibolite-facies rock, and (2) a transition from statically hydrated amphibolite to the sheared amphibolite-facies lithologies. Detailed petrography, quantitative mineral chemistry and bulk rock analyses have been applied to investigate compositional variations and assemblage microstructure across both interfaces. Here, we produce hydro-chemical numerical models based on local equilibrium thermodynamics in an attempt to reproduce the characteristics of the hydration and deformation interfaces. Here, we present a comparison between the observed characteristics of the hydration front and those produced by modelling of the reaction front propagation.