Kattsund-Koster dyke swarm

The Kattsund-Koster dyke swarm is a dyke swarm of Mesoproterozoic age in southeastern Norway and the West Coast of Sweden.

The most prominent outcrops are in the Koster Islands in Sweden and Kattsund in Norway, hence the name.

Some dykes are deformed and metamorphosed into amphibolite.

Radiometric dating has shown that the dyke swarm is about 1421 million years old.

Geologists have suggested that the dyke swarm is related to extensional tectonics.

View of the diabase and gabbro dykes in the Koster Islands , Sweden.