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The available geological, petrological, and isotopic data on Archean rocks of the Baltic shield are used to analyze the formation of the crust of the ancient Vodlozero domain. This made it possible to reveal the succession of endogenic processes in different parts of the domain and correlate them between each other. Several stages of magmatic processes reflecting changes in magma-generation environments are definable in the crust formation. The earliest stages of magmatism (3.24 and 3.13-3.15 Ga) are mostly represented by rocks of the tonalite-trondhjemite-granodiorite association. The next stage of endogenic activity (3020-2900 Ma) was marked by the formation of volcanics of the komatiite-basalt and andesite-dacite associations constituting greenstone belts in marginal parts of the Vodlozero domain and basic dikes accompanied by layered pyroxenite-norite-diorite intrusion in its central part. These basic bodies crossing earlier tonalities were formed in extension settings related to the formation of the mantle plume, which is confirmed by the rock composition. This stage culminated in the formation of trondhjemites at margins of greenstone structure. The next stage of endogenic activity commenced at 2890-2840 Ma by the emplacement of high-magnesian gabbro and diorite dikes in the western margin of the domain, where they cross rocks of the tonalitetrondhjemite association. This stage was marked by the formation of intermediate-acid subvolcanic bodies and dikes as well as basite intrusions including the layered and differentiated Semch intrusion, the largest one in the Vodlozero domain. The stage culminated at approximately 2850 Ma in the emplacement of tonalities of the limited distribution being represented by the Shilos massif in the north of the domain and Shal'skii massif on the eastern shore of Lake Onega. The important stage in the geological history of the Vodlozero domain is the formation of the intracratonic Matkalakhta greenstone belt at approximately 2.8 Ga, which includes arenite quartzite and graywackes and polymictic conglomerates developed in the Lake Oster area in addition to volcanics. These rocks indicate a stable tectonic regime, which resulted in deep erosion of the crust. The emplacement of sanukitoids (2.73-2.74 Ga) as well as subsequent two-feldspar granites (2.68-2.70 Ga) and basite dikes (2.61-2.65 Ga) may be considered as resulting from the plume influence on the relatively stabilized sialic crust of the Baltic shield. [ABSTRACT FROM AUTHOR]

The article discusses a study published in the journal "Doklady Akademii Nauk" in 2013 to investigate new data on the age of archean rocks from the Vodlozero domain of the Karelian Craton area. It informs that the Vodlozero domain is a fragment of the Baltic Shield with Mesoarchean crust. The intrusive origin of tonalities is evident from the presence of xenoliths.

The late Archaean Panozero pluton in Central Karelia (Baltic Shield) is a multi-phase high-Mg, high-K intrusion with sanukitoid affinities, emplaced at 2·74 Ga. The magmatic history of the intrusion may be subdivided into three cycles and includes monzonitic and lamprophyric magmas. Compositional variations are most extreme in the monzonite series and these are interpreted as the result of fractional crystallization. Estimates of the composition of the parental magmas to the monzonites and lamprophyres show that they are enriched in light rare earth elements, Sr, Ba, Cr, Ni and P but have low contents of high field strength elements. Radiogenic isotope data indicate a low U/Pb, high Th/U, high Rb/Sr, low Sm/Nd source. The magmatic rocks of the Panozero intrusion are also enriched in H2O and CO2; carbon isotope data are consistent with mantle values, indicating a fluid-enriched mantle source. The similarity in trace element character of all the Panozero parental magmas indicates that all the magmas were derived from a similar mantle source. The pattern of trace element enrichment is consistent with a mantle source enriched by fluids released from a subducting slab. Nd-isotope data suggest that this enrichment took place at c. 2·8 Ga, during the main episode of greenstone belt and tonalite–trondhjemite–granodiorite formation in Central Karelia. Sixty million years later, at 2·74 Ga, the subcontinental mantle melted to form the Panozero magmas. Experimental studies suggest that the monzonitic magmas originated by the melting of pargasite–phlogopite lherzolite in the subcontinental mantle lithosphere at 1–1·5 GPa. The precise cause of the melting event at 2·74 Ga is not known, although a model involving upwelling of asthenospheric mantle following slab break-off is consistent with the geochemical evidence for the enrichment of the Karelian subcontinental mantle lithosphere by subduction fluids. [ABSTRACT FROM AUTHOR]