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Anatexis (loss of texture) is partial melting of rock under extreme conditions of temperature and pressure.

Anatexis more often results from tectonism (regional metamorphism) than from magmatism (contact metamorphism) because magmas typically carry too little excess heat to melt significant quantities of surrounding rock while themselves continuing to remain molten.

Anatexis provides a common form of magmatic mixing in areas of active magmatism, wherby adjacent magma bodies can develop transient subsurface communications before their eruption or final subsurface emplacement. Anatexis-related magmatic mixing involves the secondary melting of mid- to lower crustal rocks upon contact with much hotter, rising mafic melts of mantle origin, and produces felsic (feldspar- and quartz-rich) magmas in arc and continental rift settings. Such melts may reach high crustal levels carrying both mantle heat and mantle material.

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