Publicação
Non-coaxial progressive deformation vs. overlapping of different deformation phases : detailed geological-structural survey in the key area of Perais (southern edge of the CIZ)
| Resumo: | The main objective of this study was to identify and characterize the deformation events in the study area in Perais. The geological study of the Perais region, located 16 km southeast of Castelo Branco, examines the deformation events that have occurred over time. The area is in the Central Iberian Zone and is part of the Schist Graywacke Complex. Three orogenies affected the region: the Cadomian, the Variscan, and the Alpine, two of them successfully identified in the studied Perais area. The Cadomian Orogeny generated regional unconformities, while the Variscan Orogeny, with four compressive and two extensive phases, produced folds, faults, and shears. The Alpine Orogeny resulted in brittle deformation, uplift, erosion and crustal shortening due to the convergence between the African and Eurasian tectonic plates. Detailed structural geology mapping led to the recognition of three ductile deformation events affecting the detrital Malpica do Tejo Formation (pelites, greywackes and conglomerates) and different generations of quartz veins. The micro-tectonic study carried out by the careful observation of a number of oriented thin sections revealed different stages of ductile deformation, with evidence of heterogeneous deformation. This study concludes that the deformation observed in the Perais area is possibly related to the Variscan phases of deformation, specifically to the regional stages D1-M1 (ductile folding), D2- M2 (crenulation and shear deformation) and D3- M3 (upright heterogeneous folding), since there is not enough evidence to associate these with the Cadomian Orogeny by lacking clear crosscutting or overprint structural relationships. |
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| Autores principais: | Silva, Maria Inês Viegas Roque da |
| Assunto: | Geologia Estrutural microtéctonica deformação dúctil Orogeno Varisco Teses de mestrado - 2025 |
| Ano: | 2025 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | The main objective of this study was to identify and characterize the deformation events in the study area in Perais. The geological study of the Perais region, located 16 km southeast of Castelo Branco, examines the deformation events that have occurred over time. The area is in the Central Iberian Zone and is part of the Schist Graywacke Complex. Three orogenies affected the region: the Cadomian, the Variscan, and the Alpine, two of them successfully identified in the studied Perais area. The Cadomian Orogeny generated regional unconformities, while the Variscan Orogeny, with four compressive and two extensive phases, produced folds, faults, and shears. The Alpine Orogeny resulted in brittle deformation, uplift, erosion and crustal shortening due to the convergence between the African and Eurasian tectonic plates. Detailed structural geology mapping led to the recognition of three ductile deformation events affecting the detrital Malpica do Tejo Formation (pelites, greywackes and conglomerates) and different generations of quartz veins. The micro-tectonic study carried out by the careful observation of a number of oriented thin sections revealed different stages of ductile deformation, with evidence of heterogeneous deformation. This study concludes that the deformation observed in the Perais area is possibly related to the Variscan phases of deformation, specifically to the regional stages D1-M1 (ductile folding), D2- M2 (crenulation and shear deformation) and D3- M3 (upright heterogeneous folding), since there is not enough evidence to associate these with the Cadomian Orogeny by lacking clear crosscutting or overprint structural relationships. |
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