Lower Paleozoic extensional tectonics in the limit between the West Asturian-Leonese and Central Iberian Zones of the Variscan Fold-Belt in NW Spain

Catalán, José R. Martı́nez; Rodríguez, Manuel Pozo; Alonso, P. Villar; Pérez-Estaún, Andrés; Lodeiro, Francisco González

doi:10.1007/bf01828614

Cited by 59 publications

(25 citation statements)

References 14 publications

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“…The Sardic phase has been proposed, marking a stratigraphic discontinuity close to the Middle-Upper Ordovician boundary interval in some areas of the Central Iberian Zone (e.g. Buçaco and Truchas Syncline ;Martínez Catalán et al, 1992;Días da Silva et al, 2016) and the Morais allochthonous complex of the Galicia-Trás-os-Montes Zone (Días da Silva, 2014; Días da Silva et al, , 2016. In the Truchas Syncline, the significance of the discontinuity (or discontinuities) was questioned by a biostratigraphic study of conodonts and the re-interpretation of some of these scouring surfaces as the result of Hirnantian glaciogenic incisions (Sarmiento et al, 1999).…”

Section: Iberian Massifmentioning

confidence: 99%

Comparative geochemical study on Furongian–earliest Ordovician (Toledanian) and Ordovician (Sardic) felsic magmatic events in south-western Europe: underplating of hot mafic magmas linked to the opening of the Rheic Ocean

et al. 2020

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Abstract. A geochemical comparison of early Palaeozoic felsic magmatic episodes throughout the south-western European margin of Gondwana is made and includes (i) Furongian–Early Ordovician (Toledanian) activities recorded in the Central Iberian and Galicia–Trás-os-Montes zones of the Iberian Massif, and (ii) Early–Late Ordovician (Sardic) activities in the Eastern Pyrenees, Occitan Domain (Albigeois, Montagne Noire and Mouthoumet massifs) and Sardinia. Both phases are related to uplift and denudation of an inherited palaeorelief, and stratigraphically preserved as distinct angular discordances and paraconformities involving gaps of up to 22 million years. The geochemical features of the predominantly felsic Toledanian and Sardic activities point to a predominance of magmatic byproducts derived from the melting of metasedimentary rocks, rich in SiO2 and K2O and with a peraluminous character. Zr ∕ TiO2, Zr ∕ Nb, Nb ∕ Y and Zr vs. Ga ∕ Al ratios, and rare-earth element (REE) and εNd(t) values suggest the contemporaneity, for both phases, of two geochemical scenarios characterized by arc and extensional features evolving to distinct extensional and rifting conditions associated with the final outpouring of mafic tholeiite-dominant lava flows. The Toledanian and Sardic magmatic phases are linked to neither metamorphism nor penetrative deformation; on the contrary, their unconformities are associated with foliation-free open folds subsequently affected by the Variscan deformation. The geochemical and structural framework precludes subduction-generated melts reaching the crust in a magmatic arc-to-back-arc setting and favours partial melting of sediments and/or granitoids in the lower continental crust triggered by the underplating of hot mafic magmas related to the opening of the Rheic Ocean.

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Section: Iberian Massifmentioning

confidence: 99%

Comparative geochemical study on Furongian–earliest Ordovician (Toledanian) and Ordovician (Sardic) felsic magmatic events in south-western Europe: underplating of hot mafic magmas linked to the opening of the Rheic Ocean

et al. 2020

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“…1A). The former represents the reactivated remains of an ophiolitebearing Cadomian suture (N-MORB amphibolites and dismembered serpentinite slices; Ábalos, 1990;Quesada & Dallmeyer, 1994;Arenas et al, 2018;Díez Fernández et al, 2019), and the latter a major normal Cambrian fault that episodically separated platform and basinal settings (another example is the Vivero Fault separating the Ollo de Sapo Anticline and the Lugo Dome), and played a key role during the Variscan Orogeny as major reactivated thrust systems (Martínez Catalán et al, 1992;Russo & Bechstädt, 1994;Álvaro et al, 2010).…”

Section: Structural Style Of the Central Iberian Zonementioning

confidence: 99%

Updated stratigraphic framework and biota of the Ediacaran and Terreneuvian in the Alcudia-Toledo Mountains of the Central Iberian Zone, Spain

et al. 2019

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Se presenta en este trabajo una revisión actualizada de la estratigrafía del Ediacárico-Terranóvico del valle de Alcudia y los montes de Toledo, Zona Centroibérica. Se subdivide el Supergrupo infrayacente ediacárico del Alcudiense Inferior-Domo Extremeño en los Grupos del Guadiana (Formaciones de La Coronada y Sta. Ma de Zújar) y de Campanario (Formaciones de Botija, Monroy y Orellana). El supergrupo contiene varios acritarcos sin utilidad bioestratigráfica, así como dubiofósiles, pero su edad se ha establecido claramente a partir de zircones detríticos. Este litosoma siliciclástico aparece recubierto mediante contacto disconforme con el Grupo mixto de Ibor (Formaciones de Castañar, Villarta y Arrocampo) o la Formación siliciclástica del Cíjara. El contenido fósil del Grupo de Ibor incluye sabellidítidos, vendoténidos, macrofitas, bioacumulaciones y arrecifes con Cloudina, Sinotubulites, Protolagena y estromatolitos y trombolitos, así como una amplia variedad de icnofósiles; la Formación del Cíjara ha librado microfósiles bacterianos como Bavlinella y Palaeogomphosphaeria, y pistas fósiles simples (Gordia, Helminthoidichnites y treptícnidos). El límite Ediacárico-Cámbrico, a partir de icnofósiles, se sitúa en la parte basal de la Formación de Arrocampo y en la parte terminal de la del Cíjara. El valle del Alcudia ofrece algunas peculiaridades, lo que se refleja por el mantenimiento de una subdivisión litoestratigráfica propia: el Grupo de Ibor se divide en las Formaciones de Tamujar, Hinojosas (caracterizada por su contenido en icnofósiles, que incluye treptícnidos, Monomorphichnus, Psammichnites y Taphrelminthopsis) y Cabezarrubias (con Bergaueria y Planolites). Otra discontinuidad mayor se reconoce a techo del Grupo de Ibor y de la Formación del Cíjara, recubiertos respectivamente por la Formación de San Lorenzo y unas capas de megabrechas muy características. Las megabrechas, interpretadas como depósitos de talud y conocidas como las capas de Fuentes, Membrillar y Navalpino, se sitúan a base de la Formación del Pusa, de composición heterolítica y de edad Terranóvico a Serie cámbrica 2. Se subdivide el Pusa en tres miembros, destacando el intermedio por el registro de yacimientos de interés económico de fosfato (Capa de Fontanarejo). La Formación del Pusa contiene el fósil de cuerpo blando Beltanelliformis así como numerosos icnofósiles (Monomorphicnus y Treptichnus; miembro inferior), espículas de esponja asociadas con trombolitos (miembro intermedio) y Scenella, trilobites, arqueociatos e icnofósiles (Dactyloidites, Psammichnites, Rusophycus y Teichichnus; miembro superior). En ausencia de megabrechas, el Grupo de Ibor aparece directamente recubierto por las Formaciones de San Lorenzo y Fuentepizarra, esta última caracterizada por su contenido en calizas fosfáticas ricas en microfósiles, como Anabarella, que caracterizan la transición Fortuniense-Piso Cámbrico 2.

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“…The autochthon consists of Neoproterozoic to Lower Devonian stratigraphic sequences, within which are two major unconformities that record global Lower Palaeozoic extensional events related to the formation of a passive margin along the northern margin of Gondwana and the opening of the Rheic Ocean (Gutierrez Martínez Catalán et al, 1992;Dias da Silva et al, 2011;2014b). The WALZ and CZ preserve more proximal facies than the CIZ (Marcos et al, 2004).…”

Section: Geological Setting Of the Iberian Massifmentioning

confidence: 99%

A first estimation of the contraction related to vertical axis rotation: the case of the Ibero-Armorican Arc formation

Casas

Guimerà

Álvarez-Marrón

et al. 2020

Preprint

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Abstract. Different models have been proposed to explain the formation of the Ibero-Armorican Arc, which require significant vertical axis rotations, at the end of the Variscan orogeny. Estimates of the amount of contraction (horizontal shortening) needed for these rotations range from 54 % to 91 % perpendicularly to the arc. These estimates are compared with coeval deformational structures developed in two areas of the orogen, one in the autochthonous hinterland underlying the Galicia-Trás-os-Montes Zone in the southern branch of the arc, and the other in the Cantabrian Zone foreland in the core of the arc. From this analysis it follows that the late Variscan deformation together with the subsequent Alpine contraction is not sufficient to explain the formation of the Ibero-Armorican Arc as a secondary structure by means of vertical axis rotations. Our analysis suggests this arc is mainly a primary, or non-rotational curve, slightly modified by ca. 10 % of superposed contraction during late Carboniferous and/or Alpine times. Moreover, we propose that the assumptions underlying the interpreted geometry of the arc be re-evaluated, and we discuss the role of late-Variscan regional strike-slip faults in the Iberian and in the Armorican massifs that probably acted consecutively before and during the contraction of the arc.

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Lower Paleozoic extensional tectonics in the limit between the West Asturian-Leonese and Central Iberian Zones of the Variscan Fold-Belt in NW Spain

Cited by 59 publications

References 14 publications

Comparative geochemical study on Furongian–earliest Ordovician (Toledanian) and Ordovician (Sardic) felsic magmatic events in south-western Europe: underplating of hot mafic magmas linked to the opening of the Rheic Ocean

Comparative geochemical study on Furongian–earliest Ordovician (Toledanian) and Ordovician (Sardic) felsic magmatic events in south-western Europe: underplating of hot mafic magmas linked to the opening of the Rheic Ocean

Updated stratigraphic framework and biota of the Ediacaran and Terreneuvian in the Alcudia-Toledo Mountains of the Central Iberian Zone, Spain

A first estimation of the contraction related to vertical axis rotation: the case of the Ibero-Armorican Arc formation

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