Precambrian metallogeny related to tectonics in the eastern part of the Baltic Shield

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Abstract The bulk of the eastern Baltic Shield is underlain by Archaean continental crust composed of three segments with varying tectonic settings. • - The Kola Peninsula Province consists of granulite-gneiss terrain with Fe, NiCu deposits; greenstone belts with NiCu, BIF and REE deposits; a highly deformed volcanic-sedimentary basin with kyanite deposits and Late Archaean gabbroanorthosite intrusions hosting FeTiV ores. • - The Karelian Province is a typical granite-greenstone belt terrain. The greenstone belts were formed during the Lopian orogeny (2.9-2.6 Ga) in tectonic environments resembling rifts and island arcs. They contain NiCu and massive pyrite deposits with Cu mineralizations, and BIF deposits. Late orogenic granites host Mo, CuMo deposits of the porphyry type. • - The Belomorian Province is a region of granulite-gneiss and granite-greenstone belt terrains reworked tectonically and metamorphically during the Lopian and Svecofennian orogenies (2.0–1.75 Ga) which involved continent-continent collision. Here, muscovite and rare metals-muscovite pegmatite deposits are related to Svecofennian igneous and metamorphic processes. In the Early Proterozoic the main metallogenic events were associated with intracontinental rift structures of the Karelian stage (2.5-2.0 Ga) in the Kuolajarvi-Vetrenny Poyas zone and the Monchegorsk-Fedorova-Pana Toundri zone and of the Svecofennian stage (2.0–1.8 Ga) in the Pechenga-Imandra-Varzuga zone. The above mentioned zones contain major NiCu, PGE and Ti deposits hosted by layered intrusions (2.45-2.35 Ga) and gabbro-wehrlites (2.0–1.9 Ga), and Cu and Au mineralizations hosted by metavolcanic rocks. Epicontinental sediments of the Jatulian Group (2.2-2.0 Ga) in a slightly deformed within-plate basin contain Cu, CuCo and schungite deposits. The Early Proterozoic Svecofennian Province is represented by the Ladoga belt only. Metamorphic zoning, thrusts, deformation and granite-gneiss domes developed, and some Cu, CuZn, FeTi, W and graphite mineralizations formed there. The tectonic setting of the Ladoga belt is interpreted as that of a deformed shelf deposit on a rifted and passive continental margin. In addition to this an abortive continental-rift belt with rapakivi granite intrusions (1.65-1.55 Ga) developed along the southern boundary of the Baltic Shield. Sn and SnCuZnFe deposits and fluorite and rare-metal mineralizations are associated with these granites.