We present major and trace element data for eighteen 1.71–1.66 Ga granitoid samples, and Sm–Nd whole‐rock isotope data for eleven ofthese samples, in a transect across the border between the Transscandinavian Igneous Belt (TIB) and the Eastern Segment in central southernSweden. The geochemistry of the granitoids varies from alkalic to alkali‐calcic and peraluminous in the east to predominantly calc‐alkalineand metaluminous in the west. Rocks in the west also have lower SiO2 contents. Trace element signatures favour formation in an activecontinental margin setting. Nd isotope data are completely overlapping along the transect and initial εNd values are mildly depleted in therange +0.3 to +2.6. The combined data suggest that the magmas were derived mainly from juvenile, pre‐existing crust, increasingly mafic andless alkaline towards the west.