Située au cœur de l'arc Ibéro-Armoricain, la zone Cantabrique a une structure complexe résultant de la surimposition, sur des nappes de décollement, d'un premier ensemble de plis décrivant un arc et ...d'un second formé de plis radiaux disparaissant vers la partie concave de l'arc. La série de plis radiaux met en évidence un rétrécissement de l'arc au fur et à mesure de la progression de l'orogenèse. Le déroulement de ces derniers plis montre l'existence d'une courbure originelle des structures longitudinales. La suppression des effets du plissement radial sur les vecteurs paléomagnétiques connus laisse subsister un angle entre ces vecteurs, des deux côtés de l'arc. Cet angle doit être expliqué par l'effet du plissement longitudinal et de la mise en place des nappes.
Les chevauchements cantabriques s'amortissent latéralement, se transformant en une paire de plis dont les axes se disposent parallèle¬ ment ou bien convergent. Dans ce dernier cas, l'effet du mouvement est une rotation autour du point de convergence. Si en plus le chevauchement est incurvé, le domaine de surimposition tectonique a une forme de croissant, l'une des extrémités finissant dans une paire de plis, et l'autre dans une faille de décrochement. Chaque unité principale chevauchante consiste en plusieurs écailles, chacune d'elles subissant la même rotation. Il en résulte une incurvation progressive de la nappe au fur et à mesure de sa mise en place. Les faits relatés suggèrent que la courbure originelle de l'arc s'accentue progressivement depuis les premières étapes de la déformation jusqu'à l'acquisition de la géométrie actuelle.
The Cantabrian zone, situated at the core of the Ibero-Armorican arc, has a complex structure resulting from the superimposition, on a décollement nappe structure, of a first set of folds describing the arc and a latter radial one disappearing towards the concave part. The radial set of folds produced a tightening of the arc as orogeny progressed. When the last folds are unfolded, a curved trace of the older structures remains. Discounting the effects of radial folding on the paleomagnetic vectors available, it can be seen that an angle between vectors at both sides of the arc still remains. This angle has to be explained by the effect of longitudinal folding and nappe emplacement.
Cantabrian thrusts die out laterally into a pair of folds whose axes can be parallel or converging. When fold axes are converging, the effect of movement is a rotation around the converging point. If, in addition, a curve trace for the thrust is considered, the tectonic overlapping area has a crescent shape ending at one end in a couple of folds and at the other end in a strike-slip fault. Each main thrust unit consists of several slices, each one of them also rotating. The result is that the plate was being curved as it was being emplaced. The forementioned suggests a primary origin of the arc which should be increasing its curvature progressively from earliest deformational events to its present-day shape.
Julivert Manuel, Arboleya Maria-Luisa. Curvature increase and structural evolution of the core (Cantabrian zone) of the Ibero-Armorican arc. In: Sciences Géologiques. Bulletin, tome 37, n°1, 1984. Tectonique et métamorphisme. pp. 5-11.
Since the 1860's superb specimens of sphalerite, perhaps the finest in the world, have been found in the lead-zinc deposits of the Picos de Europa Mountains Spain, especially at mines in 1990 and ...the dismantling of the installations make the future supply of specimens uncertain.
The application of Augmented Reality (AR), a technology that complements and enriches the live view of a place with virtual elements, is a relatively new approach that has been demonstrated to be ...useful as an educational tool for the interpretation of geological and geographic features. In addition, it is a technology consistent with challenges related to enhancing the geotourism experience in geologically diverse terrains, and consistent with the sustainable use of resources in rural and natural areas. The focus of AR in this contribution is primarily for academic use. Here, we developed a pioneering AR project, at the San Isidro Pass, located in the north-west of the Iberian Peninsula, more specifically, in the central-eastern sector of the Cantabrian Mountain range (the Asturian Massif) and the northern slope of the Sierra de Sentiles. This is a high mountain area where the low incidence of Pliocene and Quaternary fluvial erosion has favored the preservation of a great geodiversity. In this case study, the approaches of geology and physical geography as subjects in official university studies have been used as a reference framework. Fieldwork was carried out to design an itinerary, or geotrail, of Points of Interest (POIs), that highlight the geological values of this montane region by visualising and interpreting nine glacial and periglacial landscapes using dynamic graphic resources (animated videos, panoramic and spherical tours and rotating and expandable 3D models combining conventional terrestrial photography and 360° photography, aerial photography, thematic cartography, etc.) composed by graphic processing software. The result is the design of AR tools which could be used by public and private entities as a product suitable for university teaching but also a work that could guide other geoeducational actions or institutional action for official heritage recognition. In isolation, these POIs function as ‘geosites’; when combined in sequence (POI 1 to POI 9), these POIs function as a ‘geotrail’ to highlight the diversity of glacial and periglacial landscapes and their sedimentary deposits; when viewed as an ensemble, POIs combine to be similar to a ‘geopark’ that emphasises glacial and periglacial landscapes and sedimentary deposits.
The Purón River valley shows a special configuration due to convergence of surficial and groundwater processes in a phreatic conduit. Typical karst processes of dissolution–precipitation have been ...replaced by fluvial activity, where mechanical water erosion morphologies are dominant. All this seems to relate to a stage of abandonment of the underground environment in favour of the surficial domain. River incision in rock canyons is accomplished in many cases by phreatic conduits evolution, its collapse and opening to the surface. During the initial stages of this process, river piracy and superficial changes in the drainage network occur by capturing in first place the groundwater system. In this context of fluvial activity, numerous sculpted forms, such as potholes, are found in the conduit which is the result of changes and evolution in the cave into a more evolved morphology, pointing to river stream power concentration along certain conduit sections.
Research in caves is rare and restricted to speleological explorations. Picos de Europa Massif shows a spectacular development of vertical caves deeper than 500 m. Torca Teyera is a 738 m-deep and 4 ...km-long vertical cave. The aim of this work is to establish a methodology to characterize the geological and geomorphological aspects of this special group of caves, as well as to identify the factors conditioning karst development. The research involves (1) the cave survey at a 1:500 scale and the construction of a 3D model, (2) the geomorphological mapping on the topographical survey, (3) the geological mapping of the cave environment at 1:5000 and (4) the comparison in stereographic projection of the obtained survey data and joint measures.
After a short introduction on the reef development during the Late Palaeozoic, the tectono-stratigraphic history of the Cantabrian Mountains (northern Spain) during the Carboniferous is discussed, ...with an emphasis on the tectonically active Pennsylvanian (i.e., Late Carboniferous). The reef-bearing Valdeteja, San Emiliano, and Cuera formations are briefly described, and their brachiopod faunas are discussed with special emphasis on adaptations to a reef environment. The brachiopod faunas are compared with similar faunas from carbonate-platform deposits with reef structures of Mississippian (i.e., Early Carboniferous) age from Northwest Europe (the British Isles in particular), with Pennsylvanian-Permian faunas from the Alps, Urals, Spitsbergen and Arctic Canada, and with Permian reef faunas from Texas (USA). The Bashkirian brachiopod faunas of the Valdeteja Formation resemble the similarly aged Hare Fiord fauna from Arctic Canada most. This makes one wonder whether the connection between the Palaeotethys and Arctic Canada was through the Urals sea and Arctic, as generally believed, or whether there was another connection from the Cantabrian Mountains to the north along eastern North America.
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