Alberto Marcos

Alberto Marcos
University of Oviedo | UNIOVI · Department of Geology

PhD

About

163
Publications
23,788
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3,128
Citations
Citations since 2016
7 Research Items
1051 Citations
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
Additional affiliations
September 1967 - December 2015
University of Oviedo
Position
  • Professor Emeritus

Publications

Publications (163)
Article
Taphrhelminthopsis was originally introduced for trace fossils with a bilobate lower surface recorded in post-Paleozoic deep-marine deposits but has more recently been reinterpreted convincingly as a preservational variant of Scolicia. However, Taphrhelminthopsis has also been used for Cambrian shallow-marine trace fossils, whose taxonomic affinity...
Chapter
Synorogenic basins formed in all lithospheric units involved in the Variscan orogeny, i.e. the Gondwanan and Laurussian continental margins and also in the oceanic realm. However, examples of the latter are only preserved in SW Iberia. On the other hand, synorogenic deposits of the Gondwanan foreland are only preserved in NW Iberia, whereas remains...
Article
Full-text available
The Alcañices region, located in the internal zones of the Variscan Orogen of the Iberian Peninsula, is composed of the autochthonous Paleozoic succession of the Central Iberian Zone (CIZ), the allocthonous Schistose Domain of the Galicia-Tras-Os-Montes Zone (GTOMZ) and the unconformable synorogenic flysch-type deposits. A new detailed geological m...
Chapter
Full-text available
El Complejo de Cabo Ortegal es un grupo de láminas alóctonas que fueron emplazadas sobre el margen occidental de Gondwana durante la Orogenia Varisca [1]. Está formado por una Unidad Tectónica Superior, el manto de Cabo Ortegal, compuesto de rocas que registran un evento metamórfico de alta presión y alta temperatura, y una Unidad Tectónica Inferio...
Article
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High-grade, highly deformed gneisses crop out continuously along the Masanteo peninsula and constitute the upper part of the lower crustal section in the Cabo Ortegal nappe (NW Spain). The rock sequence formed by migmatitic quartzo-feldspathic (qz-fsp) gneisses and mafic rocks records the early Ordovician (ca. 480-488ĝ€Ma) injection of felsic diori...
Article
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High-grade highly deformed gneisses crop out continuously along the Masanteo peninsula in the Cabo Ortegal nappe (NW Spain). The rock sequence formed by quartzo-feldspathic gneisses and mafic rocks records two partial melting events: during the Early Ordovician (ca. 480–488 Ma.), at the base of the Qz-Fsp gneisses, and immediately after eclogizatio...
Article
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Th/U values in zircon are commonly used to discriminate between metamorphic (Th/U < 0.1) and magmatic (Th/U > 0.1) origin for zircon overgrowths. We test this hypothesis in the San Ciprián massif, a late orogenic granitic intrusion in the hinterland of the Variscan orogeny. Zircon grains from this granite have cores with inherited Ediacaran ages an...
Article
Block-in-matrix formations in the Variscan foreland of Spain (Cantabrian Zone) occur in two different geological settings. The major block-in-matrix formations are mélanges, which appear as carpets beneath or ahead of submarine thrust systems. These mélanges may reach up to kilometric thickness and are mostly composed of broken formations (boudinag...
Article
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The Vivero fault is crustal-scale extensional shear zone parallel to the Variscan orogen in the Iberian massif belt with an associated dip-slip movement toward the hinterland. To constrain the timing of the extension accommodated by this structure, we performed zircon U–Pb LA-ICP-MS geochronology in several deformed plutons: some of them emplaced s...
Article
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SHRIMP U-Pb zircon analyses have shown the complexity of dating volcanic rocks due to the presence of inner cores within zircon crystals. Using the cathodoluminescence studies assisting ion microprobe analyses allow us to conclude that: the two low-grade metavolcanic samples from the Schistose Domain of the Galicia-Tras-os-Montes Zone in the northe...
Article
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The uppermost metavolcanic layer of the Cambro-Ordovician Ollo de Sapo Formation, the largest accumulation of pre-Variscan igneous rocks in the Iberian Peninsula, have been dated in its northernmost part using U–Pb SHRIMP-RG zircon age techniques at 479.0 ± 4.7 Ma. The age obtained is the youngest age found so far in the metavolcanic facies of Ollo...
Article
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The collection of research papers in this volume provides an overview of current trends in the study of deformation structures and deformation processes in rocks from the continental crust. The volume has been divided into three sections to reflect the current interest in structures and processes: shear zones and folds; the interactions between mag...
Conference Paper
Full-text available
The block-in-matrix formations in the Variscan foreland of Spain (Cantabrian Zone) occur in two different geological settings. The major block-in-matrix formations are mélanges, which appear as carpets beneath submarine thrust systems and overlying flysch units. These mélanges may reach up kilometric thickness and are mostly composed of broken form...
Article
Full-text available
Resumen: La Falla de León reúne todas las características de un cabalgamiento cortando en fuera de secuencia, el cual duplica en el mapa las unidades tectónicas previas. De ese modo, los mantos de la denominada Región de Mantos o Unidad del Ponga son las mismas unidades tectónicas que las de la Unidad de Bodón, estando ambas separadas por la Falla...
Conference Paper
Full-text available
Metamorphic reactions, deformation mechanism and chemical changes during mylonitization and ultramylonitization of granite affected by a crustal-scale shear zone are investigated using microstructural observations and quantitative analysis. The Vivero Fault (VF) is a large extensional shear zone (>140Km) in NW of Iberia that follows the main Varisc...
Article
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Out of sequence breaching thrusts may give rise to duplication of a former thrust stack in map view in the same manner that stratigraphic units are repeated by initial thrusts. In this way, large breaching thrusts may put an inicial paleogeographic pattern out of order, producing apparent paleogeographic inversions at regional scale. The León Fault...
Article
The subduction phase in the development of the Variscan Orogen in SW Europe was followed by an extended period of ‘intracontinental’ tectonics. The progressive temperature rise in the hinterland during plate convergence was accompanied by widespread partial melting in the lower crust and the nucleation of kilometric buckle folds and crustal-scale s...
Conference Paper
Full-text available
Subduction in the development of the Variscan Orogen was followed in its southwestern European segment by an extended period of `intra-continental' tectonics. This was characterised in the hinterland by the development of crustal-scale strike-slip shear zones, upright kilometric pericline folds, widespread migmatization and extensive granitoid intr...
Article
The Porma Mélange is a unit up to 1 km thick underlying the Forcada Nappe, in the Variscan foreland of the Iberian Peninsula. Most of the Porma Mélange consists of a highly deformed, boudinaged sequence, with extension values over 300 percent. The boudins or me´lange blocks are the result of bed-parallel extension in two perpendicular directions gi...
Article
The Concepenido eclogites are part of an ordered rock sequence in the upper tectonic unit of the Cabo Ortegal Complex (NW Spain). They form a continuous and about 200 m thick layer separating other mafic rocks from quartzo-feldspathic gneisses. The whole sequence has been deformed and metamorphosed at high pressure and high temperature during the d...
Article
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The northern termination of the Schistose Domain of the Galicia-Trás-os-Montes Zone is a tectonic slice named the Rio Baio Thrust Sheet, which is sandwiched between the Cabo Ortegal Complex and the Ollo de Sapo Domain of the Central-Iberian Zone. The Rio Baio Thrust Sheet is formed by two volcanosedimentary series, the Loiba and the Queiroga Series...
Article
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The northern termination of the Schistose Domain of the Galicia-Trás-os-Montes Zone is a tectonic slice named the Rio Baio Thrust Sheet, which is sandwiched between the Cabo Ortegal Complex and the Ollo de Sapo Domain of the Central-Iberian Zone. The Rio Baio Thrust Sheet is formed by two volcanosedimentary series, the Loiba and the Queiroga Series...
Article
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According to palynological analyses of low-grade metasediments samples from the "Schistose Domain:of the Galicia-Trás-os-Montes Zone in the Cabo Ortegal area (NW Spain) these can be dated back to the Middle-Upper Ordovician age. This "Domain:had been traditionally considered as a parautochthonous tectonic unit, i. e., as the stratigraphic continuat...
Article
Full-text available
The upper tectonic unit of the Cabo Ortegal Complex (northwest Spain) comprises an ordered rock sequence of ultramafic and mafic rocks and quartzofeldspathic gneisses. The entire assembly forms part of a transitional mafic crust. In an early Paleozoic subduction episode, most of this crust was metamorphosed at eclogite facies and high-pressure gran...
Article
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Resumen: La revisión cartográfica de la geología del basamento varisco en el área comprendida entre el Complejo de Órdenes y el Sinclinal de Verín (Galicia oriental) ha permitido precisar la geometría de las láminas tectónicas situadas por debajo de los complejos alóctonos del noroeste peninsular (Lámina Para-autóctona) y de su autóctono (Zona Cent...
Article
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The Cabo Ortegal Complex is a composite allochthonous terrane that was thrust onto the western edge of Gondwana during the Variscan orogeny. It is formed of two main tectonic units: the Upper Tectonic unit, comprising rocks affected by highpressure (P)–high-temperature (T) metamorphism, and the Lower Tectonic unit, which represents the resulting su...
Article
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Upper crustal rocks of the Malpica-Tui unit were buried to high-pressure (P) and low- to intermediate-temperature (T) conditions during the Variscan orogeny in northwestern Iberia and subsequently exhumed in the same tectonic cycle. The structural record of the exhumation is presented in this chapter as a sequence of structures ordered according to...
Article
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Resumen: La realización de una cartografía geológica de calidad en el área de Viana do Bolo–A Gudiña ha permitido establecer la sucesión estratigráfica del Paleozoico inferior y la estructura del Antiforme del Ollo de Sapo en este sector. La sucesión estratigráfica está representada por va-rias unidades correlacionables con las formaciones descrita...
Article
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The Variscan Belt in western Europe shows an arcuate geometry that is usually named Ibero-Armorican Arc. The nucleus of this arc, known as the Asturian Arc, comprises the Cantabrian Zone which is a foreland fold and thrust belt. The Trubia River area is located in the inflexion zone of the Asturian Arc, which is a strategic structural position for...
Article
The high pressure mafic granulites of the Bacariza Formation outcrop in the two uppermost structural units of the Cabo Ortegal Complex (La Capelada unit and Cedeira unit) were separated by a Variscan thrust. In both cases, they appear as heterogeneous metabasites in normal contact between ultramafic rocks and other more homogeneous and less differe...
Article
The Malpica–Lamego Line (MLL) is a deformation zone in the Variscan belt of NW Iberia (NW Spain and N Portugal) that runs parallel to the chain for at least 275 km, bearing I-type granodiorite plutons along most of its length. The MLL affects previous structures by which high pressure and ophiolitic rocks were exhumed and emplaced on the Iberian pl...
Article
Full-text available
En el entorno del Complejo de Cabo Ortegal se reconocen cuatro láminas alóctonas, emplazadas hacia el Este. Las tres superiores forman la unidad inferior del Complejo y están constituidas por rocas máficas con afinidad ofiolítica (lámina de Purrido), por una melange ofiolítica que incluye rocas ultramáficas (lámina de Moeche) y por ortogneises cuar...