Evidence for an Early Permian Oceanic Rift in the Northern North Atlantic

Abstract

The Greenland-Svalbard and Proto-Bay of Biscay fault zones are small circles to a common pole, and it can be shown that transform motion on these faults opens the Rockall Trough and the eastern Norwegian Sea. Arthaud and Matte calculate a dextral movement along the Proto-Bay of Biscay fault of more than 100 km. This movement took place between the emplacement of the Variscan granites and the beginning of the Triassic, and we argue here that this was one of the results of ocean floor spreading in Rockall Trough and the eastern Norwegian Sea. Widespread intrusions of dolerite in Sweden, Norway, England and Scotland c. 290 Ma imply that the lithosphere had reached its limit of strength in relative tension and it is surmised that this is the time that the lithosphere began to separate between Greenland and Northwest Europe. Magmatism continued in the Early Permian as evidenced by the Oslo extrusives and fluorite deposits of magmatic derivation in England. Rosemary Bank is an extinct volcano in the northern Rockall Trough, and judging from the remanent magnetic vector, this seamount was probably active during the Permian.