Geodynamic evolution of the SW Europe Variscides

• Author(s): Ribeiro, António ; 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
• Date: 2007
• Persistent ID: http://hdl.handle.net/10174/2215
• Origin: Repositório Científico da Universidade de Évora
• Subject(s): Rheic; Suture; Iberia; Obduction; Subduction; Collision; Variscan; Finisterra
• Document Type: Article
• Language: English
• Editor(s): American Geophysical Union

Description

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.’’