부산대학교 도서관

The coupled Iberian oroclines of the western European Variscan orogen accommodated >1100 km of post-Variscan orogen-parallel shortening at translation rates in excess of 5 cm·yr-1 Palinspastic restoration of the Iberian coupled oroclines reveals a north-south-trending 2300-km-long Variscan ribbon bound by ophiolite-bearing allochthons. The requirements for orocline formation, including continuing subduction and the consumption of vast tracks of oceanic lithosphere, cannot be reconciled within traditional models that view the Variscan as a record of the closure of a single (Rheic) ocean resulting in terminal Gondwana-Laurussia collision and a stable Pangea supercontinent. Paleomagnetic data from the Gondwana-derived Variscan autochthon indicate its mid-Paleozoic separation (as the Armorican microplate) and the growth of a second mid-Paleozoic (Paleotethys) ocean. The Gondwanan stratigraphic and faunal character of the Variscan autochthon can be reconciled by a model within which counterclockwise separation results in an Armorican ribbon continent that remains close or connected to Gondwana to the south and extends north toward Laurasia between an older (Rheic) ocean to the west and a newly opened (Paleotethys) ocean to the east. Geologic and paleomagnetic data further indicate that, despite translating steadily northward, Gondwana remained separated from Armorica throughout the various stages of Variscan orogenesis. We explain Pangean amalgamation as being coincident with buckling of a linear Armorican ribbon continent caught between Laurussia to the north and the northward-migrating Gondwana to the south. In this model, Variscan orogenesis is explained in terms of individual accretionary events generated through continuous, west-dipping subduction along the margins of the Armorican ribbon continent.