Geodynamic evolution of the SW Europe Variscides

• Main Author: Ribeiro, António
• Publication Date: 2007
• Other Authors: Munhá, José, Dias, Rui, Mateus, António, Pereira, Eurico, Ribeiro, Luísa, Fonseca, Paulo, Araújo, António Alexandre, Oliveira, Tomás, Romão, José, Chaminé, Helder, Coke, Carlos, Pedro, Jorge
• Format: Article
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://hdl.handle.net/10174/2215
• topic: Rheic; Suture; Iberia; Obduction; Subduction; Collision; Variscan; Finisterra

Abstract The early evolution of SW Europe Variscides started by opening of the Rheic ocean at 500 Ma, splitting Avalonia from Armorica/Iberia. Subduction on the SE side of Rheic generated the Paleotethys back-arc basin (430–390 Ma, splitting Armorica from Iberia), with development of Porto-Tomar-Ferreira do Alentejo (PTFA) dextral transform defining the boundary between continental Armorica and Finisterra microplate to the W. Obduction of Paleotethys was followed by Armorica/Iberia collision and emplacement of NW Iberian Allochthonous Units at 390–370 Ma, whereas toward the west of PTFA, there was antithetic ophiolite obduction (Beja-Acebuches and Rheic ophiolites plus Finisterra continental slices) on top of Ossa-Morena Zone, with simultaneous development of eclogites and orogenic magmatism under a flake–double wedge tectonic regime. Continued convergence (<370 Ma) proceeded by intracontinental deformation, with progressive tightening of the Ibero-Armorican Arc through dextral transpression on the Cantabrian Indentor, from Iberia to Armorica. The proposed model is discussed at the light of the driving mechanism of ‘‘soft plate tectonics.’’