Paleoproterozoic supercontinent: Origin and evolution of accretionary and collisional orogens exemplified in Northern cratons

Abstract

The evolution of the North American, East European, and Siberian cratons is considered. The Paleoproterozoic juvenile associations concentrate largely within mobile belts of two types: (1) volcanic-sedimentary and volcanic-plutonic belts composed of low-grade metamorphic rocks of greenschist to low-temperature amphibolite facies and (2) granulite-gneiss belts with a predominance of high-grade metamorphic rocks of high-temperature amphibolite to ultrahigh-temperature granulite facies. The first kind of mobile belt includes paleosutures made up of not only oceanic and island-arc rock associations formed in the process of evolution of relatively short-lived oceans of the Red Sea type but also peripheral accretionary orogens consisting of oceanic, island-arc, and backarc terranes accreted to continental margins. The formation of the second kind of mobile belt was related to the activity of plumes expressed in vigorous heating of the continental crust; intraplate magmatism; formation of rift depressions filled with sediments, juvenile lavas, and deposits of pyroclastic flows; and metamorphism of lower and middle crustal complexes under conditions of granulite and high-temperature amphibolite facies that, in addition, spreads over the fill of rift depressions. The evolution of mobile belts pertaining to both types ended with thrusting in a collisional setting. Five periods are recognized in Paleoproterozoic history: (1) origin and development of a superplume in the mantle that underlay the Neoarchean supercontinent; this process resulted in separation and displacement of the Fennoscandian fragment of the supercontinent (2.51–2.44 Ga); (2) a period of relatively quiet intraplate evolution complicated by locally developed plume-and plate-tectonic processes (2.44–2.0 (2.11) Ga); (3) the origin of a new superplume in the subcontinental mantle (2.0–1.95 Ga); (4) the complex combination of intense global plume-and plate-tectonic processes that led to the partial breakup of the supercontinent, its subsequent renascence and the accompanying formation of collisional orogens in the inner domains of the renewed Paleoproterozoic supercontinent, and the emergence of accretionary orogens along some of its margins (1.95–1.75 (1.71) Ga); and (5) postorogenic and anorogenic magmatism and metamorphism (<1.75 Ga).