Alpine, Variscan, eo-Variscan belts: comparison between hot and cold orogens from the examples of French segments

The Cenozoic Alpine, and Paleozoic Variscan eo-Variscan collisional belts are compared in the framework of Wilson cycle considering differences between cold hot orogens. W. Alps result opening closure Liguro-Piemonte ocean, whereas Eo-variscan orogenies document multiple ocean openings collisions space a polyorogenic history time. Jurassic or Early Ordovician break-up Pangea Pannotia megacontinents led to formation passive continental margins, Liguro-Piemonte, Rheic, Tepla-Le Conquet, Medio-European oceans, respectively. In Mesozoic, microcontinents such as Apulia Sesia Armorica Saxo-Thuringia were individualized. oceanic convergence stage was associated with development arcs back-arc basins belt but magmatic missing Alps, inferred one. Though nappe stack is mainly developed subducted European Gondwana crust western cases, Moldanubian nappes formed upper plate case. Alpine metamorphic evolutions occurred under ca. 8 °C/km 30 gradients, During late- post-orogenic stages, all experienced “unthickening” accommodated by extensional tectonics, retrogression, intramontane basin opening. importance crustal melting, represented migmatites, granites, hydrothermal circulations Eo-Variscan major difference presence, absence, previous Cadomian basement might have also influenced rheological behavior crust.