HercynianVariscan

The Hercynian Variscan orogeny is a late Paleozoic mountain-building event that created a broad belt of folded and metamorphosed rocks across Euramerica and related regions. The terms "Hercynian" and "Variscan" are used for the same tectonic episode in different regions and historical literature, with Variscan often preferred for central European geology and Hercynian for western areas.

Timing and processes: Deformation began in the late Devonian and continued through the Carboniferous into the early Permian, roughly 383 to 290 million years ago, with peak crustal thickening around 360 to 300 Ma. The orogeny results from the collision of Gondwana with Laurussia (Baltica and Laurentia) and the closure of the Rheic Ocean, producing nappe stacking and regional metamorphism.

Geographic expression: In Europe the orogeny produced the Variscan belt, including the Bohemian Massif, Massif Central, Armorican Massif, Central Iberian Zone, and adjoining units such as the Rhenohercynian, Saxo-Thuringian, and Moravo-Silesian zones. The belt is marked by granitoid intrusions, metavolcanic rocks, and Carboniferous coal measures. Broader palaeogeographic reconstructions extend the orogenic framework into parts of western Africa and eastern North America as remnants of the same late Paleozoic convergence.

Significance: The Hercynian/Variscan orogeny helped assemble the supercontinent Pangaea and shaped European crustal architecture, tectonostratigraphic units, and metallogeny. In current usage, "Variscan" is often preferred for European studies, while "Hercynian" remains in regional vocabularies and older literature.