Recherches à la base de la zone à Protriticites. Un rapport du projet 5 de la SCCS. Les premiers travaux réalisés sous les auspices du Projet 5 de la SCCS dans les coupes du Spitsberg, de la ...Péninsule de Yugorsky, Nord du Timan, du Timan-Pechora, du Bassin du Donetz et de la Chaîne Cantabrique ont fourni des données détaillées sur leur contenu fossilifère, surtout en ce qui concerne les fusulinidés, mais aussi sur les brachiopodes, les coraux, les ammonoïdes, les conodontes, les spores, les algues et les plantes. A présent d' autres coupes et d'autres régions carbonifères commencent à être étudiées. En même temps on essaie d'étendre les recherches vers des niveaux plus modernes, et de favoriser l'étude des groupes à plus vaste distribution géographique tels que les conodontes et les ammonoïdes.
A progress report is presented for the Working Group on the base of the Protriticites Zone. It gives the first results obtained from various sections in Spitsbergen, the Yugorsky Peninsula, Northern Timan, Timan-Pechora, the Donetz Basin and the Cantabrian Mountains. Although the fusulinids are the group studied most extensively thus far, the brachiopods, corals, ammonoids, conodonts, spores, algae and plant megafossils have also been investigated. Research on additional areas has started already. Future plans envisage extending the range to higher stratigraphic levels and placing special emphasis on groups of wide geographic dsitribution, e. g. conodonts and ammonoids.
Résumé. — On essaie de déterminer, sur deux exemples de massifs de calcaires urgoniens bien stratifiés, en position pseudo-monoclinale, sur lesquels existent de très vastes dolines coalescentes, la ...part relative du dispositif structural, de la dissolution karstique et des processus du froid au cours de la morphogénèse.
Abstract. — This paper aims to assess, in two instances of well stratified Urgonian calcareous massifs in a pseudo-monoclinal position, with very large coalescent dolines, the comparative roles of the structure, of karstic dissolution, and of the action of the cold in the course of morphogenesis.
La mine d' Aramo est un gisement épigénétique encaissé dans des roches carbonatées. La minéralisation est formée surtout par des sulfures et arséniures de Cu-Co-Ni, avec moindre concentration de ...métaux précieux. Les faibles températures obtenues par les géothermomètres à sulfures sont en accord avec les données des inclusions fluides et permettent l'établissement d'une séquence évolutive détaillée avec des températures de 85 à 170 °C et deux maxima vers 95-100 °C et 120-125 °C. A partir de ces données, on essaie d'établir un modèle génétique de systèmes hydrothermaux en relation avec la tectonique distensive tardihercynienne dans la Cordillère Cantabrique. La bonne corrélation obtenue entre les géothermomètres de la paragenèse minérale et les données des inclusions fluides confirme la validité des études d'inclusions fluides en domaine épithermal.
The Aramo mine is an epigenetic, carbonate-hosted ore deposit formed by major Cu-Co-Ni sulphides and arsenides, with minor precious metals and others. Based on low-temperature sulphide geothermometers and fluid inclusion data a detailed evolutive sequence is proposed with temperatures from 85 °C up to 170 °C and two maxima at 95-100 °C and 120-125 °C. On this basis a genetic model of hydrothermal systems related to the distensive Late-Hercynian tectonic activity in the Cantabrian Mountains is proposed. The nice agreement observed between the paragenetic geothermometers and the fluid inclusion data confirms the validity of fluid inclusion studies in the epithermal domain.
Paniagua Andrés, Loredo Jorge, Garcia Iglesias Jesus. Epithermal (Cu-Co-Ni) mineralization in the Aramo mine (Cantabrian mountains, Spain) : correlation between paragenetic and fluid inclusion data. In: Bulletin de Minéralogie, volume 111, 3-4, 1988. Inclusions fluides. IXth symposium on fluid inclusions. University of Oporto – May 1987.
Although the Holocene has been traditionally considered as a climatically more stable period than the Lateglacial, it is now clear it has been punctuated by rapid oscillations, which had a particular ...impact in the hydrological cycle at mid and low latitudes. Recent studies in the Mediterranean region have found complex fluctuations of arid and humid periods, superimposed to the long term orbitally induced variability. However, as a consequence of the scarcity of high resolution Mediterranean marine cores for this time period and the still insufficient multi proxy and well dated terrestrial studies, the correlation of these observed fluctuations with the abrupt North Atlantic Holocene cooling events remains unknown. In addition, the timing of last glacial processes in southern Europe Mountains, such as the Alps or the Pyrenees, is a matter of debate since several records pointed to a much earlier deglaciation than in northern European sites. In this context, long and continuous lake cores from northern Iberian Peninsula are being studied to (1) describe the sequence of climate changes that occurred since the Last Glacial Maximum in the northern Iberian mountains, (2) identify the timing and describe the structure of the abrupt climate oscillations recorded and (2) test hypotheses concerning the forcing mechanisms of these hydrological variations since last deglaciation. We present here the main results from El Portalet peatbog and the Estanya lake sites, located in the Pyrenean and Pre-Pyrenean ranges, respectively. The high resolution analyses and the well constrained chronology from these two records provide an exceptional archive of the climatic events occurring since the Lateglacial period. The patterns shown by the new sedimentological and palynological data from El Portalet peatbog correlate with the rapid climate changes recorded in Greenland ice cores. The coherent response of the vegetation and the lake system to abrupt climate changes, such as Heinrich Events 3 to 1, Oldest and Older Dryas Stades, Intra Allerod Cold Period and 8200 yr BP, implies an efficient translation of climate variability from the North Atlantic to mid latitudes. In addition, our results confirm that deglaciation processes occurred earlier in southern than in northern European latitudes, and point to a glacial re-advance coinciding with the global Last Glacial Maximum. The Estanya lake record shows a large increase in water availability after 9.2 ka, fluctuating lake levels and salinity during the period 9.2 to 4.2 ka and dominant lower levels and concentrated waters since 4.2 ka. Higher lake levels occurred during the last 800 years. Periods of increased run-off and sediment delivery and less saline conditions occurred at 8.5 to 8.2, 6.7 to 5.9, and 4.9 to 4.2 ka. The main hydrological phases in Lake Estanya are coherent with Western Mediterranean and North Atlantic Holocene reconstructions, but they also show similarities with northern African records. Several speleothems are now available from the Spanish Pyrenees and are being studied to further constrain the timing of abrupt events since last deglaciation. In addition, a similar study carried out with lake cores and speleothems from the Cantabrian Mountains (NW Spain) is now in progress to check the regional variability in the northern Iberian Peninsula during deglaciation and Holocene.
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.
