The tectonic frame of the Variscan–Alleghanian orogen in Southern Europe and Northern Africa

Simancas, José Fernando; Tahiri, Abdelfatah; Azor, António; Lodeiro, Francisco González; Poyatos, D. Martínez; Hadi, Hassan El

doi:10.1016/j.tecto.2005.02.006

Cited by 165 publications

(93 citation statements)

References 57 publications

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“…2) played an important role in accommodating the oblique convergence between Laurussia and Gondwana (Ribeiro et al, 1990;Dias and Ribeiro, 1993;Shelley and Bossière, 2000;Simancas et al, 2005;Martínez Catalán et al, 2007;Ribeiro et al, 2007). Other authors, however, consider that these shear zones represent large strike-slip faults that crosscut the original boundaries between the Variscan geotectonic zones (Martínez Catalán, 2011;Ballèvre et al, 2014;Martínez Catalán et al, 2014;Gutiérrez-Alonso et al, 2015).…”

Section: Tectonic Frameworkmentioning

confidence: 99%

“…The closure of the Rheic Ocean and a series of orogenies were responsible for a mountain range hundreds of kilometres wide, which extended along much of the margins of northern Gondwana and southern Laurussia (e.g., Simancas et al, 2005;Martínez Catalán et al, 2007;Ribeiro et al, 2007). In Iberia, deformation associated with Pangea assembly was also responsible for the development of prominent orocline(s), which may have played an important role in the development of regional topographical relief following Pangea amalgamation, although the timing and mode of formation of these oroclines remains debated (see discussion in Weil et al, 2013;Pastor-Galán et al, 2015Dias et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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The transition from Pangea amalgamation to fragmentation: Constraints from detrital zircon geochronology on West Iberia paleogeography and sediment sources

Dinis

Fernandes

Jorge

et al. 2018

Sedimentary Geology

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Detrital zircon U-Pb geochronology data from late Carboniferous to Triassic clastic sedimentary rocks in SW Iberia were used to investigate the regional paleogeography during the transition from Pangea amalgamation to breakup. The major U-Pb zircon age peaks are middle Devonian to Carboniferous (~390-300 Ma), CambrianOrdovician (~530-440 Ma), Cryogenian-Ediacaran (~750-540 Ma), Stenian-Tonian (~1.2-0.9 Ga) and Paleoproterozoic (~2.3-1.8 Ga). Rapid exhumation of Variscan crystalline rocks at the contact between the South Portuguese zone and Ossa Morena Zone, explains the abundance of late Paleozoic ages in the upper Carboniferous-lower Permian continental successions. The U-Pb zircon data constrain the maximum depositional age of the Santa Susana Basin to c. 304 Ma and the Viar Basin to c. 297 Ma. The Triassic sequences, despite being c. 100 Ma younger than the Variscan tectonothermal events, contain low proportions of late Paleozoic zircon. The major peaks in all zircon spectra closely resemble those found in the adjacent basement rocks, indicating small source areas, mainly located near the rift shoulders. Longer travelled fluvial systems are postulated for the eastern portions of the Algarve Basin, which was closer to the westward advancing Tethys Ocean than the rift basins of West Iberia. Sequences that contain significant proportions of~1.2-0.9 Ga zircon are probably recycled from post-collisional Carboniferous-Permian continental deposits that were more extensive than those found today.

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Section: Tectonic Frameworkmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The transition from Pangea amalgamation to fragmentation: Constraints from detrital zircon geochronology on West Iberia paleogeography and sediment sources

Dinis

Fernandes

Jorge

et al. 2018

Sedimentary Geology

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“…1). We probe the southern part of the Iberian massif, which was formed by oblique compression between three tectonic blocks: the South Portuguese Zone (SPZ), the Ossa-Morena Zone (OMZ) and the Central Iberian Zone (CIZ) (for a review see Simancas et al 2005).…”

Section: Geological Setting and Previous Analysismentioning

confidence: 99%

Crustal thickness and images of the lithospheric discontinuities in the Gibraltar arc and surrounding areas

Mancilla

Stich

Morales

et al. 2015

Geophysical Journal International

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S U M M A R YThe Gibraltar arc and surrounding areas are a complex tectonic region and its tectonic evolution since Miocene is still under debate. Knowledge of its lithospheric structure will help to understand the mechanisms that produced extension and westward motion of the Alboran domain, simultaneously with NW-SE compression driven by Africa-Europe plates convergence. We perform a P-wave receiver function analysis in which we analyse new data recorded at 83 permanent and temporary seismic broad-band stations located in the South of the Iberian peninsula. These data are stacked and combined with data from a previous study in northern Morocco to build maps of thickness and average v P /v S ratio for the crust, and cross-sections to image the lithospheric discontinuities beneath the Gibraltar arc, the Betic and Rif Ranges and their Iberian and Moroccan forelands. Crustal thickness values show strong lateral variations in the southern Iberia peninsula, ranging from ∼19 to ∼46 km. The Variscan foreland is characterized by a relatively flat Moho at ∼31 km depth, and an average v P /v S ratio of ∼1.72, similar to other Variscan terranes, which may indicate that part of the lower crustal orogenic root was lost. The thickest crust is found at the contact between the Alboran domain and the External Zones of the Betic Range, while crustal thinning is observed southeastern Iberia (down to 19 km) and in the Guadalquivir basin where the thinning at the Iberian paleomargin could be still preserved. In the cross-sections, we see a strong change between the eastern Betics, where the Iberian crust underthrusts and couples to the Alboran crust, and the western Betics, where the underthrusting Iberian crust becomes partially delaminated and enters into the mantle. The structures largely mirror those on the Moroccan side where a similar detachment was observed in northern Morocco. We attribute a relatively shallow strong negativepolarity discontinuity to the lithosphere-asthenosphere boundary. This means relatively thin lithosphere ranging from ∼50 km thickness in southeastern Iberia and northeastern Morocco to ∼90-100 km beneath the western Betics and the Rif, with abrupt changes of ∼30 km under the central Betics and northern Morocco. Our observations support a geodynamic scenario where in western Betics oceanic subduction has developed into ongoing continental subduction/delamination while in eastern Betics this process is inactive.

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“…1 and 2). This suture is rootless and problems exist for a clear correlation with the other suture zones described in the belt, although it is generally accepted that all of them correspond to a unique, more or less complex, oceanic domain, the Rheic Ocean (Simancas et al, 2005;Martínez Catalán et al, 2009). The allochthonous complexes show a late Variscan synformal structure and they are considered to be large klippens composed of several terranes, stacked in a huge and structurally intricated nappe pile (Fig.…”

Section: Geological Contextmentioning

confidence: 99%

The eclogite facies gneisses of the Cabo Ortegal Complex (NW Iberian Massif): Tectonothermal evolution and exhumation model

Albert

Arenas

Martı́nez

et al. 2013

Journal of Iberian Geology

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The tectonothermal evolution of the eclogite facies gneisses of the Cabo Ortegal Complex has been investigated using new field and petrologic studies. This gneissic unit is included in the high-pressure and high-temperature (HP-HT) upper units of the allochthonous complexes of NW Iberia, a Cambrian arc-derived peri-Gondwanan terrane emplaced above ophiolitic units considered to represent the Rheic Ocean suture. Two detailed cross-sections performed in excellent exposures on the Cantabrian coast allows a clear understanding of the lithological constitution and deformations affecting the unit. The eclogitic gneiss unit is constituted by metasedimentary gneisses with abundant mafic inclusions, felsic rocks and rare ultramafic inclusions. The felsic rocks range from centimetric leucosomes to metric bodies and most of them were generated during extensive partial melting affecting the unit. The first tectonic fabric detected in the unit is a rarely preserved S1 foliation developed during subduction (ca. 400-390 Ma; 22 kbar). A drastic and fast exhumation (ca. 390 Ma; 12-10 kbar) generated a regional mylonitic foliation which represents the most prominent structural feature in the HP-HT upper units. The consecutive generation of extensional detachments, recumbent folds and a basal thrust occurred during the change from continental-type subduction to the underthrusting of ophiolitic units. These consecutive structures are probably related and the consequence of a long and pronounced exhumation of the subducted complex. The tectonothermal evolution of the eclogite facies gneisses of the Cabo Ortegal Complex represents an illustrative example of the intricate history of these deeply subducted units, which are relatively frequent in the suture zone of the Variscan Belt. It is important to remark that the structural, metamorphic and geochronological patterns in the evolution of this gneissic unit follows almost perfectly the ISSN (print): 1698-6180. ISSN (online): 1886-7995

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The tectonic frame of the Variscan–Alleghanian orogen in Southern Europe and Northern Africa

Cited by 165 publications

References 57 publications

The transition from Pangea amalgamation to fragmentation: Constraints from detrital zircon geochronology on West Iberia paleogeography and sediment sources

The transition from Pangea amalgamation to fragmentation: Constraints from detrital zircon geochronology on West Iberia paleogeography and sediment sources

Crustal thickness and images of the lithospheric discontinuities in the Gibraltar arc and surrounding areas

The eclogite facies gneisses of the Cabo Ortegal Complex (NW Iberian Massif): Tectonothermal evolution and exhumation model

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