文摘
The Palaeoproterozoic sedimentary cover of the Archaean basement complex in the Fennoscandian Shield is intruded by several stages of mantle-derived magmas. The 2.1 Ga Fe-tholeiitic magmatism, which is characterized by hypabyssal intrusions, dykes and volcanic flows intersecting the cover, also forms a widespread dyke swarm within the basement in North Karelia, eastern Finland. There are certain differences between these age-related sets of dykes, suggesting lithospheric thinning resulting from extensional tectonics during 2.1 Ga events.