Dynamic pressure variations in the lower crust caused by localized fluid-induced weakening

Abstract Metamorphism of dry, lower crust within orogens is often localized in shear zones composed mechanically weaker rocks 1–4 . Several field-based studies suggest zone development preceded by brittle faults which provide the fluid pathways required for metamorphism and weakening 4–12 However, a unifying model couples long-term geological deformation to migration metamorphic reactions does not exist. Here, we present visco-elasto-plastic where most pertinent features observed transformed emerge from basic mechanical principles during coherent rock volume with associated introduction. These include strikingly dynamic heterogeneous pressure distribution reacting deforming volumes. Lower crustal variations may reach 1 GPa at same depth. This will have first order effects on pattern crust, explain apparent discrepancies between relevant tectonic settings petrologically-inferred burial depths.