The Variscan belts of North-West Africa: An African legacy to the Wilson Cycle concept

Michard, André; Driouch, Youssef; Kuiper, Yvette D.; Caby, Renaud; Farah, Aboubaker; Ouanaimi, Hassan; Soulaimani, Abderrahmane; Chabou, Moulley Charaf; Saddiqi, Omar

doi:10.1016/j.jafrearsci.2023.105042

Cited by 7 publications

(2 citation statements)

References 162 publications

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“…The geological framework of the studied region is characterized by a folded Variscan belt primarily consisting of Paleozoic basement formations. These basement rocks have undergone metamorphism, ranging from greenschist to amphibolite facies, and have been intruded by syn-to late-orogenic magmatic intrusions during the Variscan orogeny [31][32][33]. These formations are exposed below an undeformed cover of Mesozoic to Cenozoic strata.…”

Section: Geological Settingmentioning

confidence: 99%

Geological and Geochemical Characterization of Variscan Pegmatites in the Sidi Bou Othmane District, Central Jebilet Province, Morocco

Wafik,

El Aouad,

Daafi

et al. 2024

Geosciences

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The Sidi Bou Othmane (SBO) pegmatite district is situated in the Central Jebilet massif, Western Meseta domain, Morocco. The SBO district is hosted essentially in a volcano-sedimentary series composed of Late-Devonian Sarhlef shales. Pegmatite bodies crop out as dykes, which are oriented from N-S to E-W and are generally variably deformed with ductile and/or brittle structures with ante, syn- or post-kinematic criteria. Petrographic observations of pegmatite dykes show that feldspars (i.e., albite, microcline) are the most abundant mineral phases, followed by quartz and micas, with tourmaline and accessory minerals such as garnet, and zircon also featuring heavily, as well as secondary minerals such as clinochlore, sericite, and illite. The geochemical study of the SBO pegmatites indicates that they have mainly S-type granitic compositions, which are peraluminous granites with calc-alkalic affinities. The study of trace elements indicates that SBO pegmatites were formed in post-orogenic syn-collision context during the Variscan orogeny by the partial melting of argilliferous sediment. They can be ascribed to the muscovite-bearing pegmatite; moreover, they have good potential regarding ceramics. They also contain minerals, such as feldspar, which have been recently assessed as critical raw materials by the European Union.

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Section: Geological Settingmentioning

confidence: 99%

Geological and Geochemical Characterization of Variscan Pegmatites in the Sidi Bou Othmane District, Central Jebilet Province, Morocco

Wafik,

El Aouad,

Daafi

et al. 2024

Geosciences

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“…As discussed in Luo et al (2022), the timing of this subduction event is not well constrained; it could have been during the Late Devonian Neoacadian orogeny, which does not have a clear record in southern New England (Kuiper et al, 2017;van Staal et al, 2009), or during the Carboniferous-Permian Alleghanian closure of the Rheic Ocean, whose subduction polarity is controversial (Domeier & Torsvik, 2014;Hermes & Murray, 1988;Michard et al, 2010Michard et al, , 2023Nance & Linnemann, 2008;Nance et al, 2012). The observation that the shear zone, which lies only ∼15 km deeper than the continental Moho, smoothly undercuts the prominent Moho depth offset between CS03 and CS04 (Figure 7) may suggest that the formation of the shear zone, and thus the subduction event, postdated the formation of the Moho depth offset.…”

Section: Mantle Anisotropymentioning

confidence: 99%

Insights From Layered Anisotropy Beneath Southern New England: From Ancient Tectonism to Present‐Day Mantle Flow

Luo,

Long,

Link

et al. 2023

Geochem Geophys Geosyst

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Seismic anisotropy beneath eastern North America, as expressed in shear wave splitting observations, has been attributed to plate motion‐parallel shear in the asthenosphere, resulting in fast axes aligned with the plate motion. However, deviations of fast axes from plate motion directions are observed near major tectonic boundaries of the Appalachians, indicating contributions from lithospheric anisotropy associated with past tectonic processes. In this study, we conduct anisotropic receiver function (RF) analysis using data from a dense seismic array traversing the New England Appalachians in Connecticut to examine anisotropic layers in the crust and upper mantle and correlate them with past tectonic processes as well as present‐day mantle flow. We use the harmonic decomposition method to separate directionally‐dependent variations of RFs and focus on features with the same harmonic signals observed across multiple stations. Within the crust, there are multiple features that may be correlated with stratification in the Hartford Basin, faults in the Taconic thrust belt, shear zones formed during Salinic/Acadian terrane accretion events, and orogen‐parallel crustal flow in the Acadian orogenic plateau. We apply a Bayesian inversion method to obtain quantitative constraints on the direction and strength of intra‐crustal anisotropy beneath the Hartford Basin. In the upper mantle, we identify a fossil shear zone possibly formed during oblique subduction of Rheic Ocean lithosphere. We also find evidence for a plate motion‐parallel flow zone in the asthenosphere that is likely disturbed by mantle upwelling near the southern margin of the Northern Appalachian Anomaly in the eastern part of the study area.

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Tectonic pattern and relative age of Ba-rich veins in front of a poly-deformed Precambrian inlier (Saghro, Morocco)

Nait-Bba,

Aabi,

Samaoui

et al. 2024

J Iber Geol

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The Variscan belts of North-West Africa: An African legacy to the Wilson Cycle concept

Cited by 7 publications

References 162 publications

Geological and Geochemical Characterization of Variscan Pegmatites in the Sidi Bou Othmane District, Central Jebilet Province, Morocco

Geological and Geochemical Characterization of Variscan Pegmatites in the Sidi Bou Othmane District, Central Jebilet Province, Morocco

Insights From Layered Anisotropy Beneath Southern New England: From Ancient Tectonism to Present‐Day Mantle Flow

Tectonic pattern and relative age of Ba-rich veins in front of a poly-deformed Precambrian inlier (Saghro, Morocco)

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