The Variscan orogeny or Hercynian orogeny was a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica (Laurussia) and Gondwana to form the supercontinent of Pangaea.
Introduced date unknownLast edited Oct 15, 2026, 3:14 PM
The chain originated from the convergence and collision of three continental masses: the microcontinentArmorica and the supercontinentsProtogondwana and (a union of and from the ). This convergence contributed to the formation of the supercontinent .
This page is based on “Variscan orogeny” from English Wikipedia, (r1374515202) CC BY-SA 4.0 used under the license. The original authors are listed in its page history.
Today, the chain is heavily eroded, with most geological evidence consisting of metamorphic rocks and granites, which once formed the deep roots of the massif.
Nomenclature
The name Variscan comes from the Medieval Latin name for the district Variscia, the home of a Germanic tribe, the Varisci; Eduard Suess, professor of geology at the University of Vienna, coined the term in 1880. (Variscite, a rare green mineral first discovered in the Vogtland district of Saxony in Germany, which is in the Variscan belt, has the same etymology.)
Hercynian, on the other hand, derives from the Hercynian Forest. Both words were descriptive terms of strike directions observed by geologists in the field, variscan for southwest to northeast, hercynian for northwest to southeast.1 The variscan direction reflected the direction of ancient fold belts cropping out throughout Germany and adjacent countries and the meaning shifted from direction to the fold belt proper.
One of the pioneers in research on the Variscan fold belt was the German geologist Franz Kossmat, establishing a still valid division of the European Variscides in 1927.2
The other direction, Hercynian, for the direction of the Harz Mountains in Germany, saw a similar shift in meaning. Today, Hercynian is often used as a synonym for Variscan but is somewhat less used than the latter in the English speaking world.34 In the United States, it is used only for European orogenies; the contemporaneous and genetically linked mountain-building phases in the Appalachian Mountains have different names.56 "Variscan" is preferred for the orogenic cycle, and "Hercynian" for the resulting massifs, though both describe related geological entities.7
The regional term Variscan underwent a further meaning shift since the 1960s. Geologists generally began to use it to characterize late Paleozoic fold-belts and orogenic phases having an age of approximately 380 to 280 Ma.
Some publications use the term Variscan for fold belts of even younger age,8 deviating from the meaning as a term for the North American and European orogeny related to the Gondwana-Laurasia collision.
The Variscan Belt reappears in Sardinia in Italy and in Germany where the Rhine Massif (Ardennes, Eifel, Hunsrück, Taunus and other regions on both sides of Middle Rhine Valley), the Black Forest, the Odenwald and Harz Mountains remain as testimony. In southern Iberia it is marked by a classic strike-slip suture zone between very distinct suspect terranes, and clear evidence can be seen of ductile shearing between high-grade metamorphic rocks and lower grade sedimentary rocks in a wide belt north of the Algarve and extending into the northernmost part the autonomous region of Andalusia and southern Extremadura.910
In the Czech Republic and southwestern Poland the Bohemian Massif is the eastern end of the unmodified Variscan belt of crustal deformation in Europe. Further Variscan developments to the southeast are partly hidden and overprinted by the Alpine orogeny. In the Alps a Variscan core is built by Mercantour, Pelvoux, Belledonne, Montblanc and Aar Massif. Dinaric, Greek and Turkish mountain chains are the southeastern termination of the Variscan proper.11
The Variscan chain, stretching 5,000 kilometres (3,100 mi) long, 700 kilometres (430 mi) wide, and initially reaching 6,000 metres (20,000 ft) in elevation, is evident across Europe and beyond.1516 Key regions include:
The Variscan orogeny partly overlapped with the Acadian orogeny, which shaped the Appalachians. Its northwest-southeast (Armorican) and northeast-southwest (Variscan) branches form a characteristic "Hercynian V" pattern.17 European Hercynian massifs primarily consist of Carboniferousgranites, metamorphic rocks (gneiss, micaschist), and locally quartzite and Carboniferous coal deposits.
In the eo-Variscan phase, from the late Ordovician to Silurian (450–400 Ma), extension gave way to plate convergence, leading to the collision of Gondwana in the south with the Euro-American continent (Laurentia-Baltica) in the north, involving intermediate plates like Avalonia and Armorica. Subduction of the African plate margin beneath the Euro-American plate closed the Rheic Ocean and Centralian Ocean, producing arc magmatism and high-pressure, high-temperature metamorphism as continental and oceanic lithosphere was buried beyond 100 km.19 Basic magmatic rocks transformed into eclogites, and acidic rocks into granulites.19
During the meso-Variscan phase, from the early to mid-Devonian (380–340 Ma), continental collision between Laurussia and Gondwana caused obduction of oceanic material onto continental crust. This phase featured high-pressure, medium-temperature metamorphism and significant deformation, including thrusting and nappe tectonics.20
In the neo-Variscan phase, from the late Devonian to late Carboniferous (380–290 Ma), nappe tectonics stacked metamorphic units, creating relief comparable to the modern Alps. The thickened crust—nearly double its normal thickness—caused thermal perturbations,21 leading to partial melting (anatexis) and widespread plutonism (granite formation), alongside medium-pressure, medium-temperature metamorphism.20 The unstable, thickened crust underwent isostatic thinning, driven by gravitational collapse or changes in plate kinematics. This late-orogenic extension, lasting into the Permian, involved tangential tectonics, intense erosion exposing lower crustal rocks, and the formation of sedimentary basins filled with material from bordering faults, volcanic flows, and calderas.22
von Raumer, J.; Stampfli, G.M.; Bussy, F. (2003). "Gondwana-derived microcontinents - the constituents of the Variscan and Alpine collisional orogens". Tectonophysics. 365 (1–4): 7–22. Bibcode:2003Tectp.365....7V. doi:10.1016/S0040-1951(03)00015-5.
Stampfli, GM; Borel, GD (2004). "The TRANSMED Transects in Space and Time: Constraints on the Paleotectonic Evolution of the Mediterranean Domain". In Cavazza W; Roure F; Spakman W; Stampfli GM; Ziegler P (eds.). The TRANSMED Atlas: the Mediterranean Region from Crust to Mantle. Springer Verlag. ISBN 978-3-540-22181-4.
Kossmat, F. (1927). "Gliederung des varistischen Gebirgsbaus". Abh. Sächs. Geol. L.-A. 1. Leipzig: 1–39. ↩
Google search on December 29, 2007: approximately 44,500 for Variscan orogeny, approximately 15,000 Hercynian orogeny. In German: 1,170 for "variszische Orogenese", 154 for "herzynische Orogenese". ↩
Crespo-Blanc, Ana; Orozco, Miguel (1991-10-01). "The boundary between the Ossa-Morena and Southportuguese Zones (Southern Iberian Massif): Major suture in the European Hercynian Chain". Geologische Rundschau. 80 (3): 691–702. Bibcode:1991GeoRu..80..691C. doi:10.1007/BF01803695. ISSN1432-1149. S2CID128688878. ↩
Renard, Maurice; Lagabrielle, Yves; Martin, Erwan; Saint Sauveur, Marc de Rafelis (2015). Éléments de géologie [Elements of geology] (in French). Dunod. p. 458. ISBN 978-2-10-072066-8. ↩↩2
The abundance of radioactive elements (uranium, thorium) in crustal material generated significant heat, increasing the geothermal gradient and causing post-thickening thermal relaxation. ↩
Today, the chain is heavily eroded, with most geological evidence consisting of metamorphic rocks and granites, which once formed the deep roots of the massif.
Nomenclature
The name Variscan comes from the Medieval Latin name for the district Variscia, the home of a Germanic tribe, the Varisci; Eduard Suess, professor of geology at the University of Vienna, coined the term in 1880. (Variscite, a rare green mineral first discovered in the Vogtland district of Saxony in Germany, which is in the Variscan belt, has the same etymology.)
Hercynian, on the other hand, derives from the Hercynian Forest. Both words were descriptive terms of strike directions observed by geologists in the field, variscan for southwest to northeast, hercynian for northwest to southeast.1 The variscan direction reflected the direction of ancient fold belts cropping out throughout Germany and adjacent countries and the meaning shifted from direction to the fold belt proper.
One of the pioneers in research on the Variscan fold belt was the German geologist Franz Kossmat, establishing a still valid division of the European Variscides in 1927.2
The other direction, Hercynian, for the direction of the Harz Mountains in Germany, saw a similar shift in meaning. Today, Hercynian is often used as a synonym for Variscan but is somewhat less used than the latter in the English speaking world.34 In the United States, it is used only for European orogenies; the contemporaneous and genetically linked mountain-building phases in the Appalachian Mountains have different names.56 "Variscan" is preferred for the orogenic cycle, and "Hercynian" for the resulting massifs, though both describe related geological entities.7
The regional term Variscan underwent a further meaning shift since the 1960s. Geologists generally began to use it to characterize late Paleozoic fold-belts and orogenic phases having an age of approximately 380 to 280 Ma.
Some publications use the term Variscan for fold belts of even younger age,8 deviating from the meaning as a term for the North American and European orogeny related to the Gondwana-Laurasia collision.
The Variscan Belt reappears in Sardinia in Italy and in Germany where the Rhine Massif (Ardennes, Eifel, Hunsrück, Taunus and other regions on both sides of Middle Rhine Valley), the Black Forest, the Odenwald and Harz Mountains remain as testimony. In southern Iberia it is marked by a classic strike-slip suture zone between very distinct suspect terranes, and clear evidence can be seen of ductile shearing between high-grade metamorphic rocks and lower grade sedimentary rocks in a wide belt north of the Algarve and extending into the northernmost part the autonomous region of Andalusia and southern Extremadura.910
In the Czech Republic and southwestern Poland the Bohemian Massif is the eastern end of the unmodified Variscan belt of crustal deformation in Europe. Further Variscan developments to the southeast are partly hidden and overprinted by the Alpine orogeny. In the Alps a Variscan core is built by Mercantour, Pelvoux, Belledonne, Montblanc and Aar Massif. Dinaric, Greek and Turkish mountain chains are the southeastern termination of the Variscan proper.11
The Variscan chain, stretching 5,000 kilometres (3,100 mi) long, 700 kilometres (430 mi) wide, and initially reaching 6,000 metres (20,000 ft) in elevation, is evident across Europe and beyond.1516 Key regions include:
The Variscan orogeny partly overlapped with the Acadian orogeny, which shaped the Appalachians. Its northwest-southeast (Armorican) and northeast-southwest (Variscan) branches form a characteristic "Hercynian V" pattern.17 European Hercynian massifs primarily consist of Carboniferousgranites, metamorphic rocks (gneiss, micaschist), and locally quartzite and Carboniferous coal deposits.
In the eo-Variscan phase, from the late Ordovician to Silurian (450–400 Ma), extension gave way to plate convergence, leading to the collision of Gondwana in the south with the Euro-American continent (Laurentia-Baltica) in the north, involving intermediate plates like Avalonia and Armorica. Subduction of the African plate margin beneath the Euro-American plate closed the Rheic Ocean and Centralian Ocean, producing arc magmatism and high-pressure, high-temperature metamorphism as continental and oceanic lithosphere was buried beyond 100 km.19 Basic magmatic rocks transformed into eclogites, and acidic rocks into granulites.19
During the meso-Variscan phase, from the early to mid-Devonian (380–340 Ma), continental collision between Laurussia and Gondwana caused obduction of oceanic material onto continental crust. This phase featured high-pressure, medium-temperature metamorphism and significant deformation, including thrusting and nappe tectonics.20
In the neo-Variscan phase, from the late Devonian to late Carboniferous (380–290 Ma), nappe tectonics stacked metamorphic units, creating relief comparable to the modern Alps. The thickened crust—nearly double its normal thickness—caused thermal perturbations,21 leading to partial melting (anatexis) and widespread plutonism (granite formation), alongside medium-pressure, medium-temperature metamorphism.20 The unstable, thickened crust underwent isostatic thinning, driven by gravitational collapse or changes in plate kinematics. This late-orogenic extension, lasting into the Permian, involved tangential tectonics, intense erosion exposing lower crustal rocks, and the formation of sedimentary basins filled with material from bordering faults, volcanic flows, and calderas.22
von Raumer, J.; Stampfli, G.M.; Bussy, F. (2003). "Gondwana-derived microcontinents - the constituents of the Variscan and Alpine collisional orogens". Tectonophysics. 365 (1–4): 7–22. Bibcode:2003Tectp.365....7V. doi:10.1016/S0040-1951(03)00015-5.
Stampfli, GM; Borel, GD (2004). "The TRANSMED Transects in Space and Time: Constraints on the Paleotectonic Evolution of the Mediterranean Domain". In Cavazza W; Roure F; Spakman W; Stampfli GM; Ziegler P (eds.). The TRANSMED Atlas: the Mediterranean Region from Crust to Mantle. Springer Verlag. ISBN 978-3-540-22181-4.
Kossmat, F. (1927). "Gliederung des varistischen Gebirgsbaus". Abh. Sächs. Geol. L.-A. 1. Leipzig: 1–39. ↩
Google search on December 29, 2007: approximately 44,500 for Variscan orogeny, approximately 15,000 Hercynian orogeny. In German: 1,170 for "variszische Orogenese", 154 for "herzynische Orogenese". ↩
Crespo-Blanc, Ana; Orozco, Miguel (1991-10-01). "The boundary between the Ossa-Morena and Southportuguese Zones (Southern Iberian Massif): Major suture in the European Hercynian Chain". Geologische Rundschau. 80 (3): 691–702. Bibcode:1991GeoRu..80..691C. doi:10.1007/BF01803695. ISSN1432-1149. S2CID128688878. ↩
Renard, Maurice; Lagabrielle, Yves; Martin, Erwan; Saint Sauveur, Marc de Rafelis (2015). Éléments de géologie [Elements of geology] (in French). Dunod. p. 458. ISBN 978-2-10-072066-8. ↩↩2
The abundance of radioactive elements (uranium, thorium) in crustal material generated significant heat, increasing the geothermal gradient and causing post-thickening thermal relaxation. ↩