Types of Metamorphism

Different criteria used to classify metamorphism are reviewed, and it is suggested three of these (plate tectonic setting, agents of metamorphism and geological setting) can be used to characterize most of the common types of terrestrial metamorphism. Accordingly, the nature of plate tectonic setting (convergent/divergent/transform/interior), thermal/baric gradients, geologic setting (igneous intrusion, meteorite impact, etc.) and agents (pressure variables, temperature and fluid-driven mass transfer) are used to classify the types of metamorphism. The classification uses vast amount of data collected over the last half-century, in conjunction with those available earlier, and improved understanding of metamorphic processes to characterize each type of metamorphism. Additionally, metamorphism in asteroidal bodies is considered.