Variscan Cycle

Simancas, José Fernando

doi:10.1007/978-3-030-10519-8_1

Cited by 14 publications

(13 citation statements)

References 271 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The crust‐mantle boundary is essentially flat in the Iberian Massif except when there are remnants of Variscan imbrications or it is affected by the Alpine contraction (Ayarza et al., 2021; Martínez Poyatos et al., 2012; Simancas et al., 2013). A generally flat subhorizontal Moho is identified at depths of 31–33 km (Ehsan et al., 2014; Palomeras et al., 2009; Palomeras, Ehsan, et al., 2021) in the southern CIZ, Ossa‐Morena zone, and South Portuguese zone.…”

Section: Discussionmentioning

confidence: 99%

“…The Variscan orogeny led to crustal thickening during the early Carboniferous, before its late‐Variscan thermal weakening and gravitational collapse (Barbero & Villaseca, 2000; Rubio Pascual et al., 2013, 2016). In some places of the CIZ, the lower crust was significantly thinned by pervasive extension and widespread melting processes (Alcock et al., 2015; Ayarza et al., 2021; Díez Fernández & Pereira, 2016; Escuder Viruete et al., 1998; Martínez Catalán et al., 2014), also evidenced by the intrusion of late‐Variscan granitoids (e.g., Bea et al., 2003; Orejana et al., 2012; Simancas et al., 2013). The generalized gravitational collapse of this orogen and crustal thinning was driven by broad ductile shear zones that formed under a regional N‐S to NW‐SE direction of extension (e.g., Dias da Silva et al., 2021; Doblas, 1991; Doblas, López‐Ruiz, et al., 1994; Escuder Viruete et al., 1998).…”

Section: Discussionmentioning

confidence: 99%

“…Ordovician to Silurian slates and quartzite conformably overlie the previous successions (Diez‐Montes et al., 2010) and the Devonian and Carboniferous sedimentary sequences crop out scarcely (Gutiérrez‐Marco et al., 2019). All of these sequences are intruded by huge volumes of late Carboniferous‐early Permian granitoids, which allowed for a magmatic classification from north to south into: Zone I, with negligible volume of granitoids; Zone II, with a vast volume of granitoids; and Zone III, where granitoids are less abundant (Simancas et al., 2013; Figure 2). The granitoids in the Spanish part of the SPCS correspond to the Ávila or Central System batholith, one of the largest batholiths in the European Variscan orogen (e.g., Villaseca et al., 2012).…”

Section: Settingmentioning

confidence: 99%

“…The SPCS is an Alpine mountain range that crosses the Iberian Massif, the westernmost outcrop of the Variscan orogen in Europe (e.g., Díaz Alvarado et al, 2013;Martínez Catalán et al, 2014). The Iberian Massif is classically divided in six zones (Pérez-Estaún and Simancas, 2019) that from north to south are: Cantabrian, West Asturian-Leonese, Galicia-Trás-os-Montes, Central Iberian, Ossa-Morena, and South Portuguese zones (Figure 1a). Regarding their paleogeographic affinity, the Cantabrian, West Asturian-Leonese, and Central Iberian zones represent the Paleozoic margin of Gondwana (Martínez Catalán et al, 1997;Pérez-Estaún et al, 1988) whereas the Galicia-Trás-os-Montes zone is completely allochthonous over the Central Iberian zone (CIZ; Arenas et al, 2014;Martínez Catalán et al, 1997).…”

Section: Geology Of the Study Areamentioning

confidence: 99%

“…The S1–S4 labels along with the receivers' positions indicate the acquisition geometry for each shot. Dashed black lines separate zones I, II, and III according to the presence of granitoids (Simancas et al., 2013). MPF, Messejana‐Plasencia fault; SGT, South Gredos thrust; TiT, Tiétar thrust; ToT, Toledo thrust.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Crustal Imbrication in an Alpine Intraplate Mountain Range: A Wide‐Angle Cross‐Section Across the Spanish‐Portuguese Central System

et al. 2022

View full text Add to dashboard Cite

Intraplate ranges are topographic features that can occur far from plate boundaries, the expected position of orogens as described in the plate tectonics theory. To understand the lithospheric structure of intraplate ranges, we focused on the Spanish‐Portuguese Central System (SPCS), the most outstanding topographic feature in the central Iberian Peninsula. The SPCS is an Alpine range that exhumes Precambrian‐Paleozoic rocks and is located at >200 km from the northern border of the Iberian microplate. Here, we provide a P‐wave velocity model based on wide‐angle seismic reflection/refraction data of the central SPCS (Gredos sector). Our results show: (a) a layered lithosphere characterized by three major interfaces: Conrad, Mohorovicic, and Hales discontinuities, (b) an asymmetry of the crust‐mantle boundary under the SPCS, (c) the extent of the Variscan batholith forming the main outcrops of Gredos, and (d) the thinning of the lower crust toward the south. This model suggests that the exhumation of the SPCS basement was driven by a south‐vergent thick‐skinned thrust system, developed in the southern part of the SPCS and that promoted crustal imbrication and a Mohorovicic discontinuity's offset under the SPCS. Thus, the deformation mechanisms of the crust seem to be controlled by the presence of the late‐ to post‐Variscan granitoids that assimilated the Variscan mid‐crustal detachment creating a new rheological boundary. This tectonic structure allowed the formation of Alpine crustal‐scale thrust systems that eased coupled deformation of the upper and lower crust, leading to limited underthrusting of both crustal layers.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Settingmentioning

confidence: 99%

Section: Geology Of the Study Areamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Crustal Imbrication in an Alpine Intraplate Mountain Range: A Wide‐Angle Cross‐Section Across the Spanish‐Portuguese Central System

et al. 2022

View full text Add to dashboard Cite

show abstract

The Variscan basement in the western shoulder of the Lusitanian Basin (West Iberian Margin): insights from detrital-zircon geochronology of Jurassic strata

et al. 2021

View full text Add to dashboard Cite

There is no consensus about the geological nature of the westernmost portion 15 of the Iberian Massif. In the present research, the detrital zircon U-Pb signatures of 16 Jurassic strata of the Lusitanian Basin, known to be west-sourced, are combined with 17 published U-Pb data for the Precambrian-Palaeozoic basement and the Lusitanian Basin 18 units to better understand this poorly exposed portion of the Iberian Massif. Cryogenian to 19Ediacaran ages prevail in a northern Upper Jurassic unit, while Lower and Upper Jurassic 20 rocks in southern locations yield mostly Carboniferous to upper Permian zircons. These 21 age results, coupled with their respective U/Th ratios, suggest that the basin covers two 22 distinct terranes of the Iberian Massif. Another noteworthy feature of west-derived 23 deposits is the abundance of <310 Ma ages. It is proposed that a combination of crustal 24 thinning in the West Iberian Margin with regional eastward basement tilt, favoured the 25 enrichment of relatively young zircon in the western shoulder of the basin relative to its 26 eastern margin. The detrital zircon age signatures also reveal a middle to late Permian 27 thermal event in restricted areas, which is probably associated with the oldest stages of 28 Alpine extension in West Iberia.

show abstract

Heterogeneous deformation in fold and thrust belts induced by anisotropies in the ocean topography; the South Portuguese Variscan Zone example (SW Portugal)

Bolacha,

Dias,

Fonseca

2024

J Iber Geol

View full text Add to dashboard Cite

The Variscan fold and thrust belt related with the South Portuguese Zone presents a SW forward propagation and the coeval development of synthetic folds and thrusts pervasive at all scales. Although several models have been proposed for their formation, the estimated strain pattern is more compatible with a push from the rear induced by the north-eastern subduction zone. Although there is a strong consistence concerning the kinematics of these Variscan structures, there is an important contrast of their geometries between the inner and the external sectors, where the very low dips prevails. Although, there are some previous models suggesting that the behaviour of the more external domains could be related with the interference between the undeformed sedimentary sequence of the upper plate with the active margin of the fold and thrust belt, independent evidence of this process is lacking. The realization of scaled analogue experiments concerning the Carboniferous evolution of SW Iberia Variscides, not only show that they could induced the flat lying major thrust of the external domains, but also emphasize their important role in the structural evolution of much of the fold and thrust belt.Resumen El cinturón Varisco de pliegues y cabalgamientos relacionado con la Zona Sur Portuguesa presenta propagación hacia el SW y el desarrollo coetáneo de pliegues y cabalgamientos sintéticos generalizados a todas las escalas. Aunque se han propuesto varios modelos para su formación, el más compatible con el patrón de deformación estimado es el de un empuje desde atrás inducido por la subducción hacia el NE. Aunque existe una gran consistencia en cuanto a la cinemática de estas estructuras variscas, hay un importante contraste de sus geometrías entre los sectores interno y externo, donde predominan los buzamientos muy bajos. Aunque existen algunos modelos previos que sugieren que el comportamiento de los dominios más externos podría estar relacionado con la interferencia entre la secuencia sedimentaria no deformada de la placa superior con el margen activo del cinturón de pliegues y cabalgamientos, faltan evidencias independientes de este proceso. La realización de experimentos análogos a escala sobre la evolución Carbonífera de los Varíscides del SO de Iberia, no sólo muestran que podrían inducir el cabalgamiento principal sub-horizontal de los dominios externos, sino que también enfatizan su importante papel en la evolución estructural de gran parte del cinturón de pliegues y cabalgamientos.

show abstract

Variscan Cycle

Cited by 14 publications

References 271 publications

Crustal Imbrication in an Alpine Intraplate Mountain Range: A Wide‐Angle Cross‐Section Across the Spanish‐Portuguese Central System

Crustal Imbrication in an Alpine Intraplate Mountain Range: A Wide‐Angle Cross‐Section Across the Spanish‐Portuguese Central System

The Variscan basement in the western shoulder of the Lusitanian Basin (West Iberian Margin): insights from detrital-zircon geochronology of Jurassic strata

Heterogeneous deformation in fold and thrust belts induced by anisotropies in the ocean topography; the South Portuguese Variscan Zone example (SW Portugal)

Contact Info

Product

Resources

About