Structure and Variscan evolution of Malpica–Lamego ductile shear zone (NW of Iberian Peninsula)

Pamplona, J.; Rodrigues, Benedito C.; Llana‐Fúnez, Sergio; Simões, P. P.; Ferreira, Narciso; Coke, Carlos; Pereira, Eurico; Castro, Paulo Ferreira; Rodrigues, José Feliciano

doi:10.1002/9781118844953.ch13

Cited by 3 publications

(1 citation statement)

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“…The Tamames shear zone, and more important, the Malpica-Lamego shear zone (Figs. 1 and 2), which are several hundreds of kilometers long (Coke and Ribeiro, 2000;Llana-Fúnez and Marcos, 2001), are related to the development of D 3 upright folds (Díez Fernández and Martínez Catalán, 2012;Pamplona et al, 2015) and in some instances were exploited by the intrusion of deep-sourced magmas (e.g., Gallastegui, 1993), thus indicating their crustal-scale nature. Sinistral shear zones located nearby are interpreted to represent subsidiary shear zones equivalent to bookselftype structures (Iglesias Ponce de Leon and Choukroune, 1980;Shelley and Bossière, 2000).…”

Section: Kinematic Analysismentioning

confidence: 99%

Strike-slip shear zones of the Iberian Massif: Are they coeval?

Fernández

Pereira

2017

Lithosphere

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Strike-slip shear zones of the Variscan orogen are used to derive the evolution of paleostrain and discuss the kinematics of the waning stages of the Gondwana-Laurussia collision during the amalgamation of Pangea. In the Iberian Massif, the recognition of three late Carboniferous deformation events related to strike-slip tectonics (D 3 , D 4 , D 5) in the Trancoso-Pinhel region (Portugal) reveals that late orogenic transcurrent deformation was episodic and occurred in a short period of time (<15 m.y.). Early stages of strike-slip deformation included dextral and sinistral shear zones and orogen-parallel upright folds (D 3 ; ca. 311 Ma). These structures followed the development of extensional shear zones (D 2) during the tectonothermal reequilibration of the orogen. D 3 structures were deflected and folded by the sinistral D 4 Juzbado-Penalva do Castelo shear zone, dated as ca. 309-305 Ma by SHRIMP (sensitive high-resolution ion microprobe) U-Pb zircon dating of synkinematic granitoids. D 3 and D 4 structures were folded under east-west compression (D 5) influenced by the strike-slip movement of the dextral Porto-Tomar shear zone. Variscan movement along the Porto-Tomar shear zone started ca. 304 Ma (onset of the Buçaco basin and syn-D 5 granites), but ceased before ca. 295 Ma (age of the final closure of the Ibero-Armorican arc and crosscutting granites). The contrasting geometry, kinematics, and timing of these strike-slip shear zones are explained by deformation partitioning upon a rheologically inhomogeneous crust with structural and tectonothermal anisotropies generated during previous deformation. The convergence vector between Gondwana and Laurussia during D 3-D 5 remained the same, and was equivalent to the vector that explains the previous tectonic record (D 2) in central and northwestern Iberia.

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