From the Early Paleozoic Platforms of Baltica and Laurentia to the Caledonide Orogen of Scandinavia and Greenland

The Caledonide Orogen in the Nordic countries is exposed in Norway, western Sweden, westernmost Finland, on Svalbard and in northeast Greenland. In the mountains of western Scandinavia, the structure is dominated by E-vergent thrusts with allochthons derived from the Baltoscandian platform and margin, from outboard oceanic (Iapetus) terranes and with the highest thrust sheets having Laurentian affinities. The other side of this bivergent orogen is well exposed in northeastern Greenland, where W-vergent thrust sheets emplace Laurentian continental margin assemblages onto the platform. Svalbard's Caledonides are disrupted by late Caledonian faults, but have close affinity with the Laurentian margin in Northeast Greenland. Only Svalbard's Southwestern terrane is foreign to this margin, showing affinity to the Pearya terrane of northern Ellesmere Island in arctic Canada. Between the margins of western Scandinavia and eastern Greenland, the wide continental shelves, now covered by late Paleozoic and younger successions, are inferred to be underlain by the Caledonide hinterland, probably incorporating substantial Grenville-age basement. In northernmost Norway, the NE-trending Caledonian thrust front truncates the NW-trending Neoproterozoic Timanide orogen of northwest Russia. Much of the central and eastern parts of the Barents Shelf are thought to be underlain by Caledonian-deformed Timanide basement. Caledonian orogeny in Norden resulted from the closure of the Iapetus Ocean and Scandian collision of continent Baltica with Laurentia. Partial subduction of the Baltoscandian margin beneath Laurentia in the midlate Silurian was followed by rapid exhumation of the highly metamorphosed hinterland in the early Devonian, and deposition of Old Red Sandstones in intramontane basins. Late Scandian collapse of the orogen occurred on major extensional detachments, with deformation persisting into the late Devonian.