metamorphism

Concepts of metamorphism, metamorphic reaction, prograde and retro – metamorphisms.

It has a prismatic and splintery texture and is abundant in regionally metamorphosed (see metamorphism) rocks such as schists.

Thus, the boron-bearing rock system and the magnesian rocks are the foundation of the borate deposits, whereas regional metamorphism and migmatitization and tectonism are the necessary conditions.

Xiaertai rock group,a set of metamorphic rock system in Xiaertai area,has experienced strong ductilebrittle deformation and then thermal contact metamorphism and dynamometamorphism in the late stage.

No.39 coal is one of high-metamorphism anthracite with black color and near-metallic luster in which semibright coal and semidull coal are dominant lithetype and there is a little dull coal.

The former three stages reflect the major process of eclogite facies metamorphism and the latest stages the light overprinting of greenschist facies retrometamorphism at the shallow level of crust.