Geology of Norway

About 1400 million years ago in the Mesoproterozoic tectonic extension and continental magmatism led to the formation of Kattsund-Koster dyke swarm in southeastern Norway.

The depositional environment changes from fluvial in the parautochthon to deepwater marine in the lowermost allochthon consistent with a paleogeography of an originally westward deepening basin.

Devonian age continental sediments are exposed in three main areas in and around mainland Norway; the Solund, Kvamshesten, Håsteinen and Hornelen basins along the west coast between Sognefjord and Nordfjord, on the islands of Smøla, Hitra and the western end of the Fosen Peninsula in Trøndelag and at Røragen near Røros close to the Swedish border.

Movement on these detachments led to deposition of thick sequences of continental clastic sediments in their hanging walls and was in part responsible for the exhumation of late Caledonian ultra high-pressure metamorphic rocks, including eclogites, in their footwalls.

The only Triassic rocks preserved onshore are found on Svalbard but strata of this age are also widely known from the results of exploration drilling along the entire continental shelf.

Rocks of Jurassic age are exposed onshore at one locality on Andøya and have been discovered nearshore and beneath the Beitstadfjorden, northeast of Trondheim.