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Relative timing of transcurrent displacements in northern Gondwana: U-Pb laser ...
Pereira, M. Francisco; Silva, J. Brandao; Drost, Kerstin; Chichorro, Martim; Apraiz, ArturoThe Variscan belt of Western and Central Europe was formed by the oblique subduction of the Rheic Ocean and the collision of Laurussia with Gondwana during the Late Palaeozoic. We present field relationships and new U–Pb LA-ICP-MS zircon and monazite ages for Variscan gneisses and granites from a key section of the western Iberian Massif. The Martinchel section records the interplay of two kilometre-scale Varis...
Exhumation of high-pressure rocks in northern Gondwana during the Early
Pereira, M. Francisco; Apraiz, Arturo; Chichorro, Martim; Silva, Jose B.; Armstrong, R.A.The Coimbra–Córdoba shear zone (CCSZ) represents a major intra-continental shear zone of the European Variscan orogen. The shear criteria found in metamorphic rocks of the CCSZ are consistent with sinistral transcurrent movements. Isoclinal and open folds with axes parallel to the stretching lineation are responsible for dip variations in the mylonitic foliation, but are related to the same kinematics. In selec...
Tectonothermal analysis of high-temperature mylonitization in the
Pereira, M. Francisco; Apraiz, Arturo; Silva, Jose B.; Chichorro, MartimMylonites in pelitic and quartzofeldsphatic gneisses from the Ouguela tectonic unit (Coimbra–Córdoba shear zone, SW Iberian Massif) have been studied as an example of high-temperature ductile deformation associated with transcurrent tectonics. Detailed microstructural and P–T analysis indicates that ductile deformation evolved from a metamorphic peak at approximately 650–750 °C and 7.5–9.5 kbar (quartzofeldspha...
Crustal growth and deformational processes in the northern
Pereira, M. Francisco; Silva, Jose B.; Chichorro, Martim; Moita, Patricia; Santos, J. Francisco; Apraiz, Arturo; Ribeiro, CristinaThe aim of this article is to present a compilation of available information on the Évora Massif based on structural mapping, whole-rock geochemistry, recognition of metamorphic mineral assemblages, and geothermobarometry. In our view, transcurrent movements responsible for strong orogen-parallel stretching were dominant and had a major role in the geodynamic evolution of this part of Ossa-Morena zone (southwes...
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