Satakunta dyke swarms

The Häme dyke swarm formed due to the upwelling of mantle, possibly related to the Gothian orogeny.

The swarms were triggered by extensional plate tectonics and convection of hot upper mantle.

Tholeiitic magmas, formed under the continental lithosphere, were probably encouraged by elevated mantle temperature underneath the Columbia supercontinent.

[2] The dyke swarm has been considered to be a result of a failed rift in the Bothnian Sea that developed as part of an extensional tectonic setting within the supercontinent of Columbia.

Viewed in a map the dyke swarm has the form of a 90-degrees fan radiating open to the east from a point in the Bothnian Sea.