Thermal Contact Metamorphism
Thermal contact metamorphism is metamorphism under high-temperature conditions. There are two main types: (1) thermal contact metamorphism, which is caused by a magmatic intrusion, the heat energy of which changes the minerals and geologic texture of the surrounding rock in the contact zone but with no change in chemical composition; and (2) contact metasomatic metamorphism, during which magmatic hydrothermal metasomatism in the late stage changes the chemical composition, mineral composition and structure of the surrounding rock at the contact zone. In the former, no chemical or metasomatic changes occur, and thermal contact metamorphic rocks, such as chert and spotted slate, can form. The latter is characterized by changes in chemical composition and lithology, and contact metasomatic metamorphic rocks, such as skarn rocks, can form.