The rapakivi granites (1.7 to 1.55 Ga) of southern Finland occur as epizonal batholiths (e.g., the Wiborg, Åland or Ahvenanmaa, Vehmaa, and Laitila batholiths) and stocks cutting the medium- to high-grade metamorphic Svecofennian (1.9 to 1.8 Ga) crust. Emplacement of the granites was associated with faulting and the intrusion of coeval sets of mainly west-northwest- (some north-northeast) trending diabase and quartz porphyry dikes, indicating an extensional continental tectonic regime.

The rapakivi granite batholiths and stocks are multiple intrusions, several of which also contain minor anorthositic and gabbroic bodies. Granites of the early intrusive phases commonly crystallized from water-deficient magmas and...