Geochronological history of metamorphism of rocks of Preriphean formations, the western slope of the Southern Urals

The Early Precambrian age is most authentically established for the polymetamorphic complexes of the paleocontinental zone of the Southern Urals. They are composed of Archean (up to 3.5 Ga) and Paleozoic rocks. The lowest limit of the early granulite metamorphism affecting the Archean formations is ca. 2.8 Ga. The gneiss-migmatite complexes were formed by successive manifestations of granulite metamorphism (2.8 Ga) which was replaced by the amphibolite facies metamorphism and accompanying granitization (2.0–1.8 Ga).