The Mid-Variscan Allochthon: Keys from correlation, partial retrodeformation and plate-tectonic reconstruction to unlock the geometry of a non-cylindrical belt

Catalán, José R. Martı́nez; Schulmann, Karel; Ghienne, Jean‐François

doi:10.1016/j.earscirev.2021.103700

Cited by 84 publications

(49 citation statements)

References 487 publications

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“…329-327 Ma; leucosomes) that are characterized by a typical arc calc-alkaline signature associated with a source of andesitic composition [18]. This finding supports the recycling of intermediate-mafic plutonic rocks, representing former stages of growth of the root of a magmatic arc at the time of the coeval subduction of the Paleotethys oceanic lithosphere [77].…”

Section: Visean-serpukhovian: Main Stage Of Arc-magmatismsupporting

confidence: 71%

Changing Carboniferous Arc Magmatism in the Ossa-Morena Zone (Southwest Iberia): Implications for the Variscan Belt

et al. 2022

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Carboniferous magmatism in southwestern Iberia was continuously active for more than 60 m.y. during the development of the Appalachian-Variscan belt of North America, North Africa and Western-Central Europe. This collisional orogen that records the closure of the Rheic Ocean is essential to understanding the late Paleozoic amalgamation of the Pangea supercontinent. However, the oblique convergence between Laurussia and Gondwana that lasted from the Devonian to the Carboniferous was likely more complex. Recently, a new tectonic model has regarded the Iberia Variscan belt as the site of coeval collisional and accretionary orogenic processes. Early Carboniferous plutonic rocks of southwest Iberia indicate arc magmatism in Gondwana. The Ossa-Morena Zone (OMZ) acted as the upper plate in relation to the geometry of the Paleotethys subduction. This active accretionary-extensional margin was progressively involved in a collisional phase during the Late Carboniferous. Together, the Évora Massif and the Beja Igneous Complex include three successive stages of bimodal magmatism, with a chemical composition indicative of a long-lived subduction process lasting from the Tournaisian to the Moscovian in the OMZ. The earliest stage of arc magmatism includes the Tournaisian Beja and Torrão gabbro-dioritic rocks of the Layered Gabbroic Sequence. We present new geochemical and Nd isotopic and U-Pb geochronological data for magmatic rocks from the Main (Visean-Serpukhovian) and Latest (Bashkirian-Moscovian) stages of arc magmatism. Visean Toca da Moura trachyandesite and rhyolites and Bashkirian Baleizão porphyries and Alcáçovas quartz diorite share enriched, continental-crust like characteristics, as indicated by major and trace elements, mainly suggesting the addition of calc-alkaline magma extracted from various mantle sources in a subduction-related setting (i.e., Paleotethys subduction). New U-Pb zircon geochronology data have allowed us to establish a crystallization age of 317 ± 3 Ma (Bashkirian) for Alcáçovas quartz diorite that confirms a temporal link with Baleizão porphyry. Positive εNd(t) values for the Carboniferous igneous rocks of the Beja Igneous Complex and the Évora gneiss dome indicate production of new juvenile crust, whereas negative εNd(t) values also suggest different grades of magma evolution involving crustal contamination. The production and evolution of Carboniferous continental crust in the OMZ was most likely associated with the development of an active continental margin during the convergence of the Paleotethys Ocean with Gondwana, involving juvenile materials and different grades of crustal contamination.

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Section: Visean-serpukhovian: Main Stage Of Arc-magmatismsupporting

confidence: 71%

Changing Carboniferous Arc Magmatism in the Ossa-Morena Zone (Southwest Iberia): Implications for the Variscan Belt

et al. 2022

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“…The crustal structure domains have been plotted alongside the extensional domains and the geology of onshore Iberia (Figure 3) in an attempt to understand how the onshore Variscan domains correlate with the basement interpreted to underlie the WIM. A major impediment to the correlation is posed by the presence of the Porto‐Tomar Shear Zone (PTSZ; Martínez Catalán et al, 2021, Figure 3), a major Variscan structure separating the outcrop of the Variscan massif in the east from Mesozoic basin infill to the west. Despite this, it is known that some continuity across this shear zone exists, as Lower Permian low‐grade metamorphic rocks, similar to those typically found in SPZ, were drilled in the Vila Franca de Xira and Bemfeito wells and dredged offshore to the south of Berlengas crustal block (Ribeiro et al, 2007; Valverde‐Vaquero et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…Ocean Drilling Program (ODP) drill holes (green circles): ODP Leg 103 (Boillot et al, 1987), Leg 149 (Sawyer et al, 1994), Leg 173 (Whitmarsh et al, 1998; Boillot et al, 1989) and Site 398 (DSDP Leg 47B of the IPOD Project, Boillot et al, 1979). The onshore Variscan zonation is from Martinez Catalan, 2011; Martínez Catalán et al, 2021). BCSZ, Badajoz‐Córdoba Shear Zone; COB, Continental Oceanic Boundary; CIZ, Central Iberian Zone; CZ, Cantabrian Zone; GTMZ, Galicia Trás‐os‐Montes Zone; OCC: Outermost Continental Crust; OMZ, Ossa‐Morena Zone; PTSZ, Porto‐Tomar Shear Zone; SPZ, South Portuguese Zone; SISZ, Southern Iberian Shear Zone; WALZ, West Asturian‐Leonese Zone.…”

Section: Geological Settingmentioning

confidence: 99%

“…The Variscan Orogen is well preserved on the onshore of western Iberia where it is zonated, forming outcrop belts with a roughly NW–SE trend. Three of these zones extend into the offshore and are, from north to south, the Central Iberian Zone (CIZ), the Ossa‐Morena Zone (OMZ) and the South Portuguese Zone (SPZ) (Martínez Catalán et al, 2021). The CIZ and OMZ are composed mainly of metamorphic rocks, derived from the Gondwana margin, and intrusives (Table 1).…”

Section: Geological Settingmentioning

confidence: 99%

“…A fourth unit, present in western Iberia but not clearly extending offshore is the Galicia‐Trás‐os‐Montes Zone (GTMZ), a nappe stack of peri‐Gondwanan units thrust over the Central Iberian Zone (Martínez Catalán et al, 2021) (Figure 1).…”

Section: Geological Settingmentioning

confidence: 99%

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On the influence of Variscan inheritance on rifting of the Western Iberian margin

et al. 2022

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The passive margin of Western Iberia (WIM) developed during the Mesozoic over the pre-existing Variscan Orogen. In the present study we use integrated interpretation and modelling to understand the distribution of Variscan basement provinces in the offshore of Iberia. The NW-SE trending fabric of the Variscan Orogen can be recognized in the WIM, and different Variscan basement provinces behaved differently during extension. Furthermore, major Variscan structures reactivated in extension, compartmentalizing rifting and having a major impact on the final architecture of the WIM.

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DENÈLE,

BERGER

2023

The Variscan Belt of Western Europe 2

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The Mid-Variscan Allochthon: Keys from correlation, partial retrodeformation and plate-tectonic reconstruction to unlock the geometry of a non-cylindrical belt

Cited by 84 publications

References 487 publications

Changing Carboniferous Arc Magmatism in the Ossa-Morena Zone (Southwest Iberia): Implications for the Variscan Belt

Changing Carboniferous Arc Magmatism in the Ossa-Morena Zone (Southwest Iberia): Implications for the Variscan Belt

On the influence of Variscan inheritance on rifting of the Western Iberian margin

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