Variscan Orogeny: A Three Oceans Problem

Deformed Variscan rocks crop out across much of Europe and northwestern Africa and tell the story of the Paleozoic welding of Gondwana and Laurussia to form Earth’s last supercontinent, Pangaea. Although mainly preserved as continental products, this event was driven by the opening and closing of three oceans: first the Rheic Ocean’s Late Silurian subduction northward beneath Laurussia, then also southward beneath northeastern Gondwana in the Mid-Devonian. Devonian slab rollback along Laurussia’s southern margin then opened the Rhenohercynian Ocean while the Rheic Ocean continued subducting beneath Gondwana’s northeastern edge. Early Carboniferous retreat of that trench then rifted eastern Gondwana, opening the wedge-shaped Paleotethys Ocean. The Rheic and Rhenohercynian oceans then closed, melding the continents, contemporaneous with subduction along northern Paleotethys, widespread intracontinental magmatism, and then orogenic collapse.

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December 2025 --The Variscan Orogeny in Europe – Understanding Supercontinent Formation

The Variscan orogen formed between 380 and 300 million years ago through several accretionary and collisional cycles, culminating with the construction of the Pangea supercontinent. This process occurred via sequential opening and closure of oceanic basins, synchronous detachment of Gondwana derived continental ribbons, and their outboard amalgamation onto the Laurussia margin. The Variscan orogen is rather unique compared with other orogenic belts on Earth: its overthickened and dominantly magmatic crust in the central belt, surprisingly minor mantle involvement in the magmatic and geodynamic processes, coherent and pulsed magmatism along the collision suture, and its complex accretionary history. Because its final product, Pangea, is the youngest and best-understood supercontinent on Earth, the Variscan orogeny offers clues for understanding the mechanisms of supercontinent formation.