V.P. CHEKULAEV, N.A. ARESTOVA, JU.S. EGOROVA (IPGG RAS)

Neoarchaean granite of the Karelian Province: geological setting, geochemistry, origin

Geology and chemical composition of the Neoarchaean granites from the Karelian Province, the Baltic Shield, have been studied. It is shown that the granites is widespread over the area of the province and formed during a short time interval of 2.68–2.72 Ga. Variations in chemical composition are mainly caused by variations in rare and RE element grades controlled by the restite mineral composition, which depends on the pressure and melting temperature in the source. The Nd isotope composition in the granites within the Vodlozero domain indicate on an old crust source, such as old rocks of the TTG association. In the most granites of other domains, it indicates on the separation of the source from the protolyte shortly before the initial melt formation. Variety of geological forms and chemical composition of the granites are not caused by variations in the geodynamic setting.
Keywords: Baltic Shield, Karelia, Neoarchaean, granites, geology, geochemistry, origin.