Kattsund-Koster dyke swarm

Large geological structure in Norway and Sweden

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

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. The dykes are made up of tholeiitic diabase and some dykes of intermediate composition. 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.^[1]

References

^ Hageskov, Bjørn; Pedersen, Svend (1988). "Rb-Sr age determination of the Kattsund-Koster dyke swarm in the Østfold-Marstrand belt of the Sveconorwegian Province, W Sweden - SE Norway". Bulletin of the Geological Society of Denmark. 37: 51–61.

Geology of Fennoscandia

Paleosurfaces

Sedimentary cover

Moraines	Billingen terminal moraine Pulju moraine Rogen moraine Salpausselkä Sevetti moraine Skövde terminal moraine Trollgarden Veiki moraine
Sedimentary rock	Alum Shale Formation Hedmark Group Jotnian sedimentary rock Reusch's Moraine Visingsö Group

Structures

Faults and shear zones	Burträsk Fault Iapetus Suture Lainio Fault Nordfjord-Sogn Detachment Pärvie Fault Protogine Zone Röjnoret Fault Sorgenfrei-Tornquist Zone South Finland Shear Zone
Large impact craters	Dellen Gardnos crater Granby crater Hummeln structure Lappajärvi Lockne crater Lumparn Mien Ritland crater Siljan Ring Sääksjärvi Söderfjärden Suvasvesi Tvären
Morphostrucures	Central Swedish lowland Gulf of Bothnia rift Lake Inari graben Lake Ladoga graben Lofoten horst Muhos Graben Norrland terrain Omberg horst Oslo Graben Scandinavian Mountains Scanian horsts South Swedish Dome Vättern graben White Sea Rift System