Geogaceta -- Nº 26, (1999)
Permanent URI for this collectionhttps://hdl.handle.net/10272/9989
Browse
Recent Submissions
Item type: Item , Zonación y principales características de los abanicos aluviales terciarios del borde norte de ja cuenca del Ebro (provincia de Huesca, España)(Sociedad Geológica de España, 1999) Luzón, AránzazuThe characteristics of the materiales outcropping in the northern limb of the Barbastro Anticline allow us to refer them to two types of fans: fluvial and alluvial fans: The first ones have a big extent (tens of km), they shows a slow transition between proximal and distal zones and its source area is located in the internal zones of the Pyrenees (Ainsa and Tremp Basins, and Axial Pyrenees). The second ones have a maximun radius of 5 km, they show faster transition between proximal and distal parts arid its source area fislocated in the External Ranges of the Pyrenean ChainItem type: Item , Variaciones -intraconcha e interconcha- de la racemización del ácido aspártico en moluscos holocenos del Golfo de Cádiz (SO de España)(Sociedad Geológica de España, 1999) Torres, Trinidad de; Llamas, F. J.; Canoira, L.; García Alonso, P.; Coello Bravo, F. J.This paper deals on intrashell and intershell aspartic acid racemization ratio variation in samples recovered from a UC 2200BP dated bar of "El Rompido" (Huelva) spit bar complex. From valves of Ostrea sp., Glycymeris sp. and Panopea sp. disc shaped subsample sets from the beack to the ventral border were obtained via drilling with a hollow diamond circular cutter. Statistical analysis of the results revealed good agreement with predicted variation coefficient in Ostrea and Glycymeris, being possible that Panopea sample would be composed by two different ones because of reworkingItem type: Item , The record of the latter glacial and intergladal periods in the Guadalquivir marshlands (Mari López drilling, S.W. Spain)(Sociedad Geológica de España, 1999) Zazo, C.; Dabrio, Cristino José; González, A.; Sierro, Francisco Javier; Yil, E. I.; Goy, José L.; Luque, L.; Pantaleón Cano, J.; Soler, Vicente; Roure, J. M.; Lario, J.; Hoyos, M.; Borja Barrera, FranciscoEl estudio de un sondeo de 65 m en las marismas del Guadalquivir permite reconocer siete intervalos que reflejan cambios climáticos y eustáticos e intensa neotectónica durante tres periodos ¡nterglaciares (IS 71, 5 y i) y dos glaciares (IS 6-Riss-, IS 4, 3 y 2-WQrm). Se discute el valor de las 'vetas' como indicadores paleogeográficosItem type: Item , Subambientes sedimentarios del sector noroeste de la laguna de Gallocanta. Provincia de Zaragoza(Sociedad Geológica de España, 1999) Luzón, Aránzazu; Pérez García, Antonio; Roc, A. C.; Soria, Ana Rosa; Mayayo, María José; Sánchez Navarro, José ÁngelThe study carried out in nortwestern sector of the carbonate-saline lake of Gallocanta point out that lutite, sapropel and salt deposition dominate in this lake, although in some zones sandstone and gravel deposition is typical. The main features of these materials linked tò its àreà! distribution allow us to identify three zones in the lake: central lake, maginal lake and pàlustrine areaItem type: Item , Structure and kinematics of the Aljibe Unit, north of Cádiz Province (Flysch Trough Complex, Betics)(Sociedad Geológica de España, 1999) Luján, María; Crespo Blanc, Ana; Balanyá, Juan CarlosLa unidad de Aljibe es la más extensa de las unidades del Dominio del Surco de los Flyschs en el Norte de la provincia de Cádiz. Esta unidad, formada por rocas de edad Paleógeno a Mioceno inferior, está-estructurada según un sistema imbricado de cabalgamientos de edad post-Aquitaniense. Estos son vergentes hacia el W o WNW en el sector oriental del área estudiada y retrovergentes en el sector occidental. En este último, se observa además como los cabalgamientos están plegados por pliegues de gran radio, de dirección aproximada N-S y E-W y de probable edad Mioceno superior a Plioceno, formando así patrones de interferencia en domos y cubetasItem type: Item , Selección del fondo geoquímico para metales pesados en sedimentos actuales: aplicación en la bahía de Santander(Sociedad Geológica de España, 1999) Irabien, María Jesús; Yusta, IñakiThe establishment of a suitable geochemical baseline for soils and sediments is of essential importance in exploration: geochemistry and environmental studies related to heavy metal pollution. Notwithstanding that obtained reference values depend directly on different factors such as sample material collected, grain size and analytical procedures, several methods have been used to estimate the natural concentrations of heavy metals and arsenic in the sediments from the Santander bay, and the appropiateness of the proposed background values is discussedItem type: Item , Revisión estratigráfica del intervalo Kimmeridgiense medio-Tithonico basal en el perfil G10 del sector de Venta Quesada (Sierra Gorda, provincia de Granada)(Sociedad Geológica de España, 1999) Olóriz, F.; Molina, José Miguel; Serna Barquero, A.The updated stratigraphic revision of Middle Kimmeridgian - lowermost Tithonian ammonitico rosso in the Gw section at the sector of Venta Quesada (Sierra Corda, Internal Subbetic, southern Spain) enables the evaluation of stratigraphic completeness through taphonomic analysis of new collected fossil assemblages, mainly ammonites. Even in a context of low sedimentation rate, ammonite biostratigraphy proved to be accurate resulting in the recognition of the Compsum, Cávourí, Beckeri and Hybonotum Zones. The subdivision of the Beckeri Zone (Upper Kimmeridgian) in the biohorizons of pressulum, knopi-pressulum, beckeri-pressulum and beckeri provides the most complete subdivision of the Beckeri Zone hitherto proposedItem type: Item , Quaternary reverse surface faulting in Mallorca Island (Baleares, Spain): Relationships with historical seismicity(Sociedad Geológica de España, 1999) Silva, P. G.; González Hernández, F. M.; Goy, José L.; Zazo, C.; Mörner, N. A.Se analiza una falla Inversa que afecta a depósitos cuaternarios de relleno de la Dolina de Portol, situada en la zona epicentral del terremoto de Palma de 1851 (VIII MSK). La falla presenta un desplazamiento inverso acumulado de 5,58m, provocando un desplazamiento máximo de la superficie del terreno de 0,88 m que da lugar a un escarpe de falla inverso y afecta a construcciones humanas. Este evento aparentemente compresivo, se explica como un fenómeno subsidiario ligado a los procesos extensionales, tipo roll-over, que dominan la evolución de la zona antiformal que separa las cuencas sedimentarías de Palma e Inca. Las deformaciones observadas aparentemente se produjeron durante el mencionado terremoto de 1851Item type: Item , Nuevos datos sobre el Bajociense de la serie tipo del Subbético Medio (Cordillera Bética)(Sociedad Geológica de España, 1999) Jiménez Moreno, Gonzalo; Moreno, J.; Romero, G.; Sandoval, J.; Trives, V.The type section (holoestratotype) of the Median Subbetic (Campillo de Arenas, Betic Cordillera) has been studied for the Latest Aalenian-Early Bajocian interval. The obtained data allow a revision of the ammonite biostratigraphy. Early Bajocian standard ammonite-zones Discites, Laeviuscuia and Sauzei have been recognised and characterisedItem type: Item , Nuevos restos fósiles de vertebrados continentales en el Cretácico Superior de Álava (Región Vasco-Cantábrica): sistemática y posición estratigráfica(Sociedad Geológica de España, 1999) Pereda Suberbiola, Xabier; Murelaga, Xabier; Baceta, Juan Ignacio; Corral, J. C.; Badiola, A.; Astibia, H.Recent field work in the Upper Cretaceous continental beds of the Basco-Cantabrian Region has yielded new vertebrate fossil remains. Both dinosaur and turtle bones have been recovered from fluviatile sediments (sub-unit B3 of Baceta et alv 1999) outcropping near Apellaniz and Korres localities (Izkiz Mountains, eastern Alava). A fragmentary humerus from Apellaniz is referred to the Sauropoda as Titanosauridae indet., and a fragmentary turtle shell plate is assigned to the Bothremydidae as cf. Polysternon sp. (Pleurodira). Moreover, two vertebral centra of Ornithopoda indet., a scute fragment of Ankylosauria indet., and turtle shell plates of cf. Polysternon and an indeterminate solemydid (Cryptodira) are known in Korres. On the basis of both geological and palaeontological grounds, a late Campanian to early Maastrichtian age is likely for the Izkiz faunaItem type: Item , Magmatismo alcalino tardicadomiense en la zona de Ossa Morena (Macizo Ibérico): Cartografía, petrografía y geoquímica preliminar del Macizo de Almendral(Sociedad Geológica de España, 1999) Sánchez Carretero, R.; Carracedo Sánchez, Manuel; Eguiluz, Luis; Alonso Olazabal, AinhoaThe Almendral massif is located in the north-western branch of the Olivenza-Monesterio antiform (Ossa Morena Zone, Iberian Massif, Spain). The pluton is composed by gabbros, sienites and alkaline granites which define an alkaline/transitional association. This magmatism marks the transition between the Cadomian orogenic regime and the Pre-Hercynian intracontinental rift for this sectorItem type: Item , Litoestratigrafía de la formación El Hoyo (zona de Ossa-Morena, Macizo Ibérico, España)(Sociedad Geológica de España, 1999) Bandrés, A.; Eguiluz, LuisThe El Hoyo Formation js located at the boundary: between the Obejo-Valsequil/o-Puebla de la Reina Domain and the Badajo/.-Córdoba Shear Belt. This serie is composed by quartz-schists and mica-schists, finé grained quartzites, coarse grained arkoses with conglomerates and medium grained arkoses. This Formation defines a transcurrent duplex with ÑE mergences of the cartografie sketch. This Formation age is still unknown, in this paper, Lower-Middle Cambrian age is proposed for correlation with other areas of Ossa-Morena Zone and Massif IberianItem type: Item , Las doleritas neoproterozoicas de las ventanas de Agadir Melloul y del Adrar Izazen (Anti-Atlas Central, Marruecos). Restos de una distension pre-panafricana(Sociedad Geológica de España, 1999) Hafid, A.; Saquaque, A.; Navidad, M.; Saidi, A.; Sagon, J. P.; El Boukhari, A.Two swarms of diabasic dykes wich différents directions NE-SW and NW-SE cut the socle of Agadir Melloul and the Adrar Izazen neoprotero/.oic windows. This rocks show a hidrothermal transformation simultanely wich Pahafricàn deformation but the primary mineralógicaI composition preserved are formed by: plagioclase, augite, ilmenite and micropegmatite textures wich hornblende and biotite ocasionally. Their chemical composition are tholeitic and transitional basalts in the two directions respectively mentioned. This magmatism have an anorogenic continental character and it is related wich the extensif pre-panafrican phase that involved to northern edge of western african cratonItem type: Item , La roca de Getafe: trayectoria de caída, efectos del impacto y marcadores morfotexturales de vuelo(Sociedad Geológica de España, 1999) Martínez Frías, J.On 21st June, 1994, at approximately 12 noon local time, a rock, weighing 1.417 kg and measuring 18 x 8.5 x 8 cm, struck a car, which was travelling south on the Madrid-Andalucia róed (Cetafe city, south .Madrid). This area is open country made up of marls, gypsum beds and claystones, without bridges or other high places from which the rock could have been thrown. The incident was spectacular. The rock impacted the car at about 30° from the horizontal arid hit thè steering wheel arid the driver's right hand with;such force that the steel wheel was deformed:- This work constitutes the first contribution on the study of the Cetafe rock (CR), displaying a detailed analyses of the trajectory of fall, effects of impact and morphotextural evidence of flight: The CR is a semi-oriénted specimen (apex angle _75°), with an external scoriaceous texture which resembles either ari industriai slag or the highly vesicular «scoriaceous-type» micrometeorites (AM10 and M4) which were recovered in Antarctica. It does not appear to have fusion crust, although textural and colour differences exist between its external and internal parte. At least two different systems of friction striae as well as two types (milky and dark) of droplet-globules (100 m-500 m) were found scattered on its frontal, smooth surface. Some of these show presence of impact microcraters. Although the circumstances surrounding the fall are very well documented and despite clear evidence of flight were found, the CR does not exactly match ariy ofthe previously classified meteorites nor any known rocks (terrestrial or extraterrestrial)Item type: Item , La glaciación del límite Ordovícico-Silúrico en el Altiplano de Perú: evidencias e implicaciones tectónicas(Sociedad Geológica de España, 1999) Díaz Martínez, Enrique; Acosta, H.; Rodríguez, R.; Carlotto, V.; Cárdenas, J.The Lower Paleozoic strati graphic sequence cropping out immediately to the north of Ayaviri (Peruvian Altiplano) belongs to the Eastern Cordillera tectonostratigraphic domain, and includes the Sandia, San Gabán and Ananea formations. Clacially-striated and faceted clasts found within the diamictites of the San Gabán Formation provide the first evidence for the late Ashgill-Llandovery glaciation in the Peruvian Altiplano, an area where this unit was previously considered not to be deposited. The marked difference between the Lower Paleozoic sequences of the Altiplano and Eastern Cordillera tectonostratigraphic domains suggests important tectonic shortening along the boundary fault zoneItem type: Item , La fracturación en el Cabo Shirreff, Isía Livingston, Antártida Occidental(Sociedad Geológica de España, 1999) González Casado, J. M.; Giner Robles, J. L.; López Martínez, JerónimoThe Cape Shirreff, located in the northern part of Livingston Island, South Shetland Islands, represents one of the points of this island arc adjacent to the related trench. Here outcrop a volcanic succession with, probably, an Upper-Cretaceous age. A fault tectonic analysis was performed here in order to decipher the deformation processes that take place in an island arc close to a subduction zone. The measured faults show dip-slip and normal-oblique slip senses of movement, and they have four different trends (N120°E, N20°E, NT50°E and N80°E). These directions are subparallel with the main linear landforms (valleys and scarps) and with the coastal line geometry. Seventy-nine fault slickensides measured in the volcanic materials have been analyzed by means of fault population analysis methods to deduce the stress tensor actives during the fault movements. Five of the calculated stress tensors are extensional, with a regional NE-SO main extension direction (i.e., <y}). The analysis also shows one extensional tensor with NO-SE extension direction. The first stress tensor was probably related with the dyke injection episode, and is compatible with the stresses transmitted from the subduction zone. And the second can be related with the extension associated with the opening of the back-arc basins located towards the south (Bransfield Basin). The precise age of these tensors and the evidences of two different episodes of faulting remain undeterminedItem type: Item , Hidrogeoquímica y microbiología en Los Hervideros del Campo de Calatrava (Ciudad Real)(Sociedad Geológica de España, 1999) Yélamos, J. G.; Redondo, R.; Castro, F. de; Galván, A.; Martínez Rubio, J.; Ruano, Patricia; Senderos, A. J.; ViIIarroya, F. I.; Rebollo Ferreiro, Luis F.CÓZ-rich springs and wells in the Campo de Calatrava commonly are named Hervideros. This .ground water is originated by deep circulation along the fractures of the paleozoic rocks of the area, with residence times longer than 15years. The hydrochemical facies is miked-catipn bicarbonate and is related to the extinct yolcanism 6f the area. It is a possibility that not all the Hervideros are originated from volcapic or . > magmatic C02. Bacterial evaluation indicates high values, but probably it is representative of the-biomass presence in the proper sampling point instead of the groundwater-microbiologyItem type: Item , Foraminíferos bentónicos holocenos del talud de Guyana y Surinam (Atlántico Central): su relación con las masas de agua(Sociedad Geológica de España, 1999) Pascual, AnaThe study of two sedimentary Holocene cores from the upper slope of Cuianas (Central West Atlantic) allows for the identification of 139 species of benthic foraminifers. This microfauna is similar to those identified in recent materials from French Guiana and Venezuela. As differences with adjácent areas are the occurrence in this site of abundant individuals of Hoeglundina elegans (a cold-water, deep bathyal species, associated with the North Atlantic Deep Water) and the occasional occurrence of Planulina ariminensis (species associated with the North East Atlantic Deep Water). Dominant assemblage, which is constituted by Uvigerína peregrina, and Cassidulina carinata, besides of the occurrence of other species such as Brizalina subaenariensis, adapted to low-water oxygenation, seem to indicate upwelling during the Holocene times in this areaItem type: Item , Evolución estratigráfica de los afloramientos septentrionales de la Formacion Sariñena (provincia de Huesca, España). Síntesis paleogeográfica(Sociedad Geológica de España, 1999) Luzón, AránzazuStratigraphicaí characterization óf the tertiary materials of Sariñena Fm. outcropping in the northern limb of the Barbastro Anticline (Huesca province) allows to increase the knowledge existing about the septentrional deposits of this formation. Interpretation of the sedimentary environments developed in this sector of the Ebro Basin during the Oligocene-Miocene limit linked to the analysis of their evolution allows to stablish a previous hypothesis about the paleogeographical evolution of this sector of the tertiary basinItem type: Item , Estudio por microscopía electrónica de transmisión de saponita activada(Sociedad Geológica de España, 1999) Suárez Barrios, M.; Romero, E.; Santiago, C. de; Martín Pozas, J. M.This work studies the modifications undergone by the Creen Clays Saponite in the Tagus Basin subjected to activation treatments, and stresses the influence of the development of the electronic microscopy technique for studying these materials. Acid treatment with HCI and pillaring treatment with All3 were performed. Characterization of the samples was carried out by DRX, chemical analysis of major elements and Transmission Electronic Microscopy. Add treament causes the delamination and fragmentation of the particles, partially dissolving the octahedral layer and generating amorphous silica, coming from the tetrahedral layer. Pillaring treatment gives rise to a stable solid with inteday.er spácing at 18Á. The high number of crystalline defects present in the saponite conditions the formátion of a low number of pillars per cell