Palaeozoic Basement of the Pyrenees Josep Maria Casas, J
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Palaeozoic Basement of the Pyrenees Josep Maria Casas, J. Álvaro, S. Clausen, Maxime Padel, C. Puddu, J. Sanz-López, T. Sánchez-García, M. Navidad, P. Castiñeiras, M. Liesa To cite this version: Josep Maria Casas, J. Álvaro, S. Clausen, Maxime Padel, C. Puddu, et al.. Palaeozoic Basement of the Pyrenees. Palaeozoic Basement of the Pyrenees, Springer, Cham, pp 229-259, 2019, Part of the Regional Geology Reviews book series (RGR), Print ISBN 978-3-030-10518-1 / Online ISBN 978-3- 030-10519-8. 10.1007/978-3-030-10519-8_8. hal-02309572 HAL Id: hal-02309572 https://hal-brgm.archives-ouvertes.fr/hal-02309572 Submitted on 9 Oct 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Palaeozoic Basement of the Pyrenees 8 J. M. Casas, J. J. Álvaro, S. Clausen, M. Padel, C. Puddu, J. Sanz-López, T. Sánchez-García, M. Navidad, P. Castiñeiras, and M. Liesa Abstract 8.1 Introduction In the Pyrenees, the Cambrian-Lower Ordovician strata represent a quiescent time span with no remarkable J. M. Casas, J. J. Álvaro tectonic activity, followed by a late Early-Mid Ordovician episode of uplift and erosion that led to the formation of In the Pyrenees, the aftermath of the late Ediacaran-early the Sardic unconformity. Silurian sedimentation was Terreneuvian magmatism, related to the Cadomian subduc- widespread and transgressive followed by a Devonian tion, records the transition to passive-margin conditions. succession characterized by a complex mosaic of sedi- Cambrian-Lower Ordovician strata represent a quiescent time mentary facies. Carboniferous pre-Variscan sediments span with no remarkable tectonic activity, followed by a late (Tournaisian-Viséan cherts and limestones) precede the Early-Mid Ordovician episode of uplift and erosion that led to arrival of the synorogenic siliciclastic supplies of the the formation of the Sardic unconformity. Uplift was accom- Culm flysch at the Late Serpukhovian. All this succession panied by magmatic activity that pursuit until the Late was subsequently affected by the Serpukhovian- Ordovician, the latter coinciding with an extensional pulse that Bashkirian (Variscan) collision, as a result of which, the developed normal faults and controlled the record of Palaeozoic rocks were incorporated into the northeastern post-Sardic sediments infilling palaeorelief depressions (the branch of the Ibero-Armorican Arc. significance of this magmatism and tectonic activity is still Coordinators: J. M. Casas, J. J. Álvaro. J. Sanz-López J. M. Casas (&) Dpto. de Geologia, Universidad de Oviedo, Jesus Arias de Departamento de Dinàmica de la Terra i de l’Oceà-Institut Velasco s/n, 33005 Oviedo, Spain de Recerca Geomodels, Universitat de Barcelona, Martí e-mail: [email protected] è Franqu s s/n, 08028 Barcelona, Spain T. Sánchez-García e-mail: [email protected] Departamento Investigación Recursos Geológicos, Área Recursos J. J. Álvaro Minerales y Geoquímica, Instituto Geológico y Minero de España, Instituto de Geociencias (CSIC-UCM), Dr. Severo Ochoa 7, Ríos Rosas 23, 28003 Madrid, Spain 28040 Madrid, Spain e-mail: [email protected] e-mail: [email protected] M. Navidad Á P. Castiñeiras S. Clausen Departamento de Petrología y Geoquímica, Universidad UMR 8198 EEP CNRS, Université de Lille 1, Bâtiment SN5, Complutense de Madrid, Novais 12, 28040 Madrid, Spain Avenue Paul Langevin, 59655 Villeneuve d’Ascq Cedex, France e-mail: [email protected] e-mail: [email protected] P. Castiñeiras M. Padel e-mail: [email protected] é BRGM, 3 Avenue Claude Guillemin, 45100 Orl ans, France M. Liesa e-mail: [email protected] Departament de Mineralogia, Petrologia i Geologia aplicada, C. Puddu Universitat de Barcelona, Martí Franquès s/n, 08028 Barcelona, Departamento de Ciencias de la Tierra, Universidad de Zaragoza, Spain Pedro Cerbuna 12, 50009 Zaragoza, Spain e-mail: [email protected] e-mail: [email protected] © Springer Nature Switzerland AG 2019 229 C. Quesada and J. T. Oliveira (eds.), The Geology of Iberia: A Geodynamic Approach, Regional Geology Reviews, https://doi.org/10.1007/978-3-030-10519-8_8 [email protected] 230 J. M. Casas et al. under debate; see Sect. 8.3). Silurian sedimentation was French Central) massifs to the north, and Sardinia to the east. widespread and transgressive, sealing the Sardic uplift Palaeozoic rocks are involved in three main Alpine thrust palaeorelief and Late Ordovician rifting pulsation, followed sheets, the so-called Lower Structural Units (Muñoz 1992) by a Devonian succession characterized by a complex mosaic named Nogueres, Orri and Rialp thrust sheets. These units of sedimentary facies. Tournaisian-Viséan cherts and lime- form an antiformal stack with their basal thrusts stones represent the Carboniferous pre-Variscan sediments, north-dipping or subvertical in the northern side of the chain, preceding the arrival of the synorogenic siliciclastic supplies subhorizontal in the central part, and south-dipping in the of the Culm flysch at the Late Serpukhovian. All this southern contact with the Mesozoic-Cenozoic cover. In the succession was subsequently affected by the Serpukhovian- description that follows, we will focus on the Palaeozoic Bashkirian (Variscan) collision, as a result of which, the rocks of the Nogueres and Orri units, which constitute a Palaeozoic rocks were incorporated into the northeastern complete pre-Variscan succession, ranging in age from branch of the Ibero-Armorican Arc. In this chapter, we update Cambrian to Carboniferous. Exposures of the Rialp unit only data and interpretations from these Palaeozoic rocks of the occur in a small tectonic window of the central Pyrenees. Pyrenees, with a new proposal for the lower Transverse (N-S-trending) displacement related to the Cambrian-Ordovician stratigraphy and an update of the Upper Alpine deformation is about 150–160 km (Muñoz 1992), so Ordovician, Silurian, Devonian and pre-Variscan Carbonif- the original Palaeozoic basin should be located northward erous stratigraphy. Exposed data emphasize the affinity of the from present-day arrangement. Moreover, the Alpine Pyrenean basement rocks with that of the neighbouring deformation gave rise to important horizontal axes rotation Sardinia, Mouthoumet and Montagne Noire-French Central related to antiformal stack development. In contrast, Alpine Massif domains, as well as its differences with the Palaeozoic metamorphism is absent and internal deformation is mod- evolution of the Iberian Massif. erated. As a result, the original characteristics of the In the Pyrenees, the pre-Variscan Palaeozoic rocks con- Palaeozoic rocks may be confidently reconstructed in the stitute a 3–4 km-thick succession that crops out in the Pyrenees. As discussed below, other pre-Alpine movements backbone of the cordillera (Fig. 8.1). These rocks form an may be also envisaged in order to obtain a reliable original elongated strip unconformably overlain by Mesozoic and Early Palaeozoic palaeoposition of the Pyrenenan domain Cenozoic rocks, which lie geographically disconnected from and to establish its geodynamic relationship with the neighbouring outcrops of the Catalan Coastal Range to the neighbouring Variscan Sardinia, Mouthoumet and Montagne south, the Mouthoumet and Montagne Noire (southern Noire-French Central Massif domains. Fig. 8.1 Simplified geological map of the Pyrenees with the location of the massifs mentioned in the text [email protected] 8 Palaeozoic Basement of the Pyrenees 231 8.2 Cambro-Ordovician (pre-Sardic) plano-convex exposures and microbial framebuilding textures Stratigraphy: Jujols Group (e.g., Gorges de la Fou in the Vallespir-Roc de Frausa area, and isolated bioherms close to Valcebollère village; Fig. 8.3 J. J. Álvaro, J. M. Casas, S. Clausen, M. Padel a–d) characteristic of reefal complexes. In the Aspres area, the Courbis Limestone of the Valcebollère Formation has yielded The Jujols Group (Fig. 8.2) was firstly described by Cavet the acritarch Archaeodiscina cf. umbonulata Volkova, 1968. (1957) as the Jujols Schists, comprising a monotonous A. umbonulata is a cosmopolitan species ranging approxi- succession of alternating shale and sandstone overlying the mately from Cambrian Age 3 to early Cambrian Age 4 Canaveilles Series in the northern Canigó massif. Cavet (Laumonier et al. 2015; T. Palacios, pers.com. 2016). Asso- (1957) attributed an Ordovician age to the Jujols Schists, ciated with the Courbis Limestone, some centimetric layers of which then included what is now considered as Upper grainy phosphorites have been identified, for the first time, Ordovician conglomerates and volcanic deposits. These are marking the topmost part of the Valcebollère Formation. underlain by a significant erosive unconformity and angular The Serdinya Formation consists of a roughly 1500 m discordance representative of the Sardic Phase, and therefore thick rhythmic alternation of shale and sandstone beds. excluded from the Jujols Group (Laumonier 1988). Layers are 1 mm to several cm thick, change in colour from According to Cavet (1957), the base of the Jujols Schists grey to characteristic