EUROPE/East European Craton 45 At about 1.64–1.62 Ga, and again at 1.57 Ga, around 1.5 Ga, and 0.93 Ga, numerous large intrusions of rapakivi granites and associated charnockitic, mangeritic, and anorthositic rocks penetrated the Fennoscandian crustal segment Extensive swarms of mafic dykes and sheets were formed throughout the Proterozoic, with maxima at 2.45–2.1 Ga, 1.6– 1.5 Ga, and 1.3–1.2 Ga and 0.97–0.95 Ga Some of these may be the results of superplume events in the Earth’s mantle In addition there are plugs and plutons of alkaline and carbonatitic rocks (see Igneous Rocks: Carbonatites), some of which are Precambrian and others Phanerozoic in age Alkaline magmatism was particularly voluminous in the Kola Peninsula and along rifts such as the Permian Oslo Graben in Norway Other intrusions formed isolated minor plugs Sarmatia The Sarmatian segment is built up of several Archaean crustal provinces with ages ranging between 3.7 Ga and 2.7 Ga (Figure 11) Belts of Palaeoproterozoic crust intervene between some of these, but accretion and welding appear to have commenced in the Archaean The oldest crustal units are the Palaeo- to Mesoarchaean Podolian Block in the extreme southwest and the Oskol (Kursk-)–Azov Block in the east Ages of 3.65–3.60 Ga have been obtained from ultramafic and tonalitic rocks, while major TTG intrusions are 3.4–3.3 Ga old Both the Podolian Block and the Oskol–Azov Block represent one-time lower crust but have evolved through several events of high-grade granulitic metamorphism and multiphase magmatism in the Archaean and Palaeoproterozoic The Sumy–Dniepr gneiss–granite–greenstone terrane is generally somewhat younger It was formed mainly between 3.2 Ga and 3.1 Ga and is characterized by numerous belts of principally mafic metavolcanic and sedimentary rocks These contain basal sequences of komatiites, komatiitic basalts, and tholeiites, reaching thicknesses of 4–5 km Atop the mafic volcanics rest calc-alkaline felsic volcanic rocks, tuffites, immature sandy metasediments, and banded iron formations with quartzites These belts were metamorphosed and deformed concomitantly with the development of domal structures containing juvenile TTG-type granitoids and felsic gneisses with granulites The alteration processes were related either to rifting and the opening of a Mesoarchaean ocean or to the evolution of a preexisting oceanic basin of Palaeo- to Mesoarchaean age In the Palaeoproterozoic, between about 2.6 Ga and 2.3 Ga, major belts of supracrustal rocks containing numerous banded iron formations were formed Some of these outline the margins of Archaean terranes, while others appear to be controlled by rifts in the interior parts of the Oskol–Azov Block The latter are the cause of the strong Kursk magnetic Figure 11 The processes that shaped the internal structure of Sarmatia were the docking of the older Archaean Oskol Azov and the younger Archaean Sumy Dniepr crustal blocks and, during the Proterozoic, the accretion of the Podolian Block to the evolving main mass of the Sarmatian crustal segment The latter process was coeval with the generation of mantle derived juvenile Proterozoic crust elsewhere in Sarmatia Directly related to the assembly of the East European Craton were the formation of the East Voronezh belts along the developing boundary between Sarmatia and Volgo Uralia about 2.1 2.0 Ga ago and the formation of the continental margin Osnitsk Mikashevichi Igneous Belt and the outboard Central Belarus Belt at around 2.0 Ga These two belts faced the ocean basin that was consumed during the collision of united Volgo Uralia and Sarmatia (i.e ‘Volgo Sarmatia’) with Fennoscandia ß Svetlana Bogdanova