Early Mesozoic Plate Reorganization
The initial phase of the post-Hercynian break-up of the Pangea Supercontinent spanned Late Permian to Middle Jurassic times and culminated in the development of a new divergent/ transform plate boundary between Gondwana and Laurasia.
In the Arctic-North Atlantic and Tethys domains, this plate reorganization is reflected by the Triassic to Middle Jurassic development of multidirectional rift systems that transected the Variscan fold belt and its European foreland (Plates 9-12). The evolution of these rift systems was governed, on the one hand, by the rapid southward propagation of the Norwegian-Greenland Sea Rift and, on the other hand, by the development and rapid westward propagation of the Tethys Rift system. In the Central and North Atlantic areas, these two megarift systems met and interfered with each other.
As long as crustal separation was not yet achieved in these rift systems wide areas around the future plate margins were subjected to tensional stresses. This is particularly evident in Western and Central Europe where the localization of Mesozoic grabens was to a large extent governed by the reactivation of Permo-Carboniferous fracture systems.
In the Tethys domain, the Late Permian to Early Triassic development of the Neo-Tethys sea floor spreading axis and its gradual westward propagations culminated during the Middle Jurassic in crustal separation between Laurasia and Africa and the opening of new oceanic basins in the Central and Western Mediterranean areas as well as in the Central Atlantic. This fundamental plate reorganization in the Atlantic-Tethys domain, which governed the first break-up phase of Pangea