1.8 Ga Svecofennian bimodal complexes in Russian Karelia comprise an eastern branch of 600 km long belt extending from Åland Islands to the NW Ladoga region. The rocks range from ultramafic, calc-alkaline, apatite-rich potassium lamprophyres to HiBaSr granites, and form a shoshonitic series with K₂O + Na₂O > 5%, K₂O/Na₂O > 0.5, Al₂O₃ > 9% over a wide spectrum of SiO₂ (32-70%). The rock types in the series are related by fractional crystallization. Apatite-saturated initial melts are considered to having been generated from an enriched lithospheric mantle metasomatized by CO₂-, F- and H₂O-rich fluids. Although strongly enriched in all rocks, P₂O₅, LREE, Ba and Sr define a decreasing trend with increasing SiO₂.