Variscan orogeny: a three ocean problem

Variscan orogenic evolution was dominated by closure of the Rheic Ocean and its two successors, the Rhenohercynian and Paleotethys oceans. The Rheic subduction started in late Silurian – early Devonian at the margin of Laurussia but also along two Gondwana derived continental ribbons. Rapid mid-Devonian roll-back of peri-Laurentian subduction led to growth of the Rhenohercynian Ocean and migration of remaining subduction systems towards the margin of Gondwana. In the east, late Devonian subduction of the Rheic beneath Gondwana resulted in opening of Paleotethys Ocean and separation of a wide continental ribbon. Spreading of Paleotethys resulted in outboard early Carboniferous collision of three continental ribbons and welding of an elongated continental mass that finally collided with Laurussia in the north. Finally, Gondwana collided with the whole system in the west while ongoing subduction of Paleotethys in the east resulted in massive extension and melting of the Variscan crust.