Tectonometamorphism

Tectonometamorphism is metamorphism driven primarily by tectonic forces associated with crustal deformation. It occurs during orogenic activity at convergent, divergent, and transform plate boundaries where rocks experience large differential stresses as the crust thickens, shortens, or is sheared. In these settings temperature and pressure evolve along specific P–T–paths, and fluids released during dehydration reactions promote mineral reactions and recrystallization. The result is both metamorphic mineralogical changes and deformation features such as foliations, lineations, and shear zones.

Geological settings include regional metamorphism in mountain belts, dynamic metamorphism in fault zones, and high-pressure/low-temperature metamorphism in subduction zones (blueschist and eclogite facies). Exhumation processes bring these rocks back to shallower levels. Mineral assemblages record pressure and temperature histories, with low-grade materials giving slate and phyllite and higher-grade rocks forming schist, gneiss, and migmatite.

Distinction from contact metamorphism: while contact metamorphism is dominated by heat from intruding magma with limited deformation, tectonometamorphism is controlled by tectonic stress and crustal evolution and typically involves significant deformation and the development of structural fabrics.

Implications: understanding tectonometamorphism helps reconstruct orogenesis, crustal recycling, and the thermal and mechanical evolution of plate tectonics. Geothermobarometry and metamorphic petrology are used to infer pressure–temperature conditions, duration, and timing of tectonic events.