Explanation

Rock formed by metamorphism. It is formed by magmatic rocks or sedimentary rock formed first in the crust, under the influence of environmental conditions, mineral composition, chemical composition, structure and structure change. Its lithological characteristics are not only controlled by the original rock and have a certain degree of inheritance, but also have neogenesis in mineral composition and structural structure due to different metamorphic processes (such as containing metamorphic minerals and directional structures). Generally, metamorphic rock formed by metamorphism of magmatic rocks is called "orthometamorphic rock", and metamorphic rock formed by metamorphism of sedimentary rock is called "paranenenebe metamorphic rock". According to the metamorphic formation conditions, it can be divided into thermal contact metamorphic rock, regional metamorphic rock and dynamic metamorphic rock. metamorphic rock are widely distributed in China and all over the world. Precambrian strata are mostly composed of metamorphic rock; After the Paleozoic era, metamorphic rock were distributed in crustal active zones (such as geosyncline areas) in various geological periods, around some intrusions and in fracture zones.

Classification