Migmatite
Migmatite is a rock formed under high-grade metamorphism by partial melting (anatexis), producing a mixture of metamorphic and newly formed igneous material. It typically occurs in the deeper parts of the continental crust, commonly within Precambrian cratonic blocks, and represents a transitional stage between metamorphic and igneous rocks.
Migmatites form during prograde metamorphism when rocks reach temperatures and pressures sufficient for partial melting. The newly formed material, known as the neosome, commonly consists of light-coloured leucosome and darker melanosome, while remnants of the original rock form the paleosome; an intermediate mesosome may also be present.
Migmatites commonly display distinctive banding and folded structures, including ptygmatic folds, produced by melt migration and ductile deformation. They have long been regarded as linking regional metamorphism, crustal melting, and the origin of granitic rocks, and remain central to research on the evolution of the continental crust.
