“…This differential stress and associated tectonic pressure is the result of the mechanically heterogeneous precollisional continental lithosphere, due to weak and strong ellipses, which is motivated by field studies in the Western Alps (Petri et al, 2019). Several studies suggest such deviations from the lithostatic pressure in the order of a few hundreds of MPa, based on the metamorphic rock record in the Monte Rosa unit (Luisier et al, 2019(Luisier et al, , 2021Vaughan-Hammon et al, 2021a, 2021b. Furthermore, some studies propose that deviations from lithostatic pressure can also be caused by differential volumetric deformation, for example, due to dehydration reactions (Luisier et al, 2019(Luisier et al, , 2021Schmalholz et al, 2020;Vaughan-Hammon et al, 2021a).…”