Geogaceta -- Nº 60, (2016)
Permanent URI for this collectionhttps://hdl.handle.net/10272/13541
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Item type: Item , The evolution of a gypsum vein network in compressive tectonic settings: the Montsant anticlinorium case (NE Spain)(Sociedad Geológica de España, 2016) Martínez Rodríguez, Cristina; Playà, Elisabet; Griera, Albert; Gómez Rivas, EnriqueThe Montsant anticlinorium is part of the Pàndols-Cavalls-Montsant tectonic line situated in the southwestern area of the Catalan Coastal Ranges, adjacent to the contact with the Tertiary Ebro Basin. We have interpreted this Alpine structure as a triangular type I zone with two opposite faults. The centre of the anticlinorium is formed by middle Muschelkalk facies with intensively deformed gypsum layers and an intensively deformed zone with an associated framework of satin spar gypsum veins. A field structural analysis reveals that there are two sets of veins: one associated with a pre-folding stage (before the Alpine orogeny), and another one related to the development of the Montsant anticlinorium, and therefore syn-folding (and Alpine in age)Item type: Item , Tectonic model for the latest Triassic-Early Jurassic extensional event in and around the Iberian Peninsula(Sociedad Geológica de España, 2016) Vegas, Ramón; Olaiz, Antonio José; Medialdea, TeresaAn array of 200-Ma-old (Lower Jurassic) dolerite dikes in both the eastern and western sides of the Atlantic records an episode of SE directed extension which occurred in and around the Iberian Peninsula. This extensional regime episode is responsible for the formation of the main structures in the Iberian Peninsula and neighboring areas at the beginning of the JurassicItem type: Item , Secuencias de crecimiento en la Zona de Falla del Bajo Segura (Cordillera Bética Oriental)(Sociedad Geológica de España, 2016) Medina Cascales, Iván; Martín Rojas, Iván; Alfaro García, PedroEn este trabajo presentamos el análisis de una serie de secuencias de crecimiento asociadas a los pliegues de propagación de la Zona de Falla del Bajo Segura (Cordillera Bética oriental). Los nuevos datos de campo aportados permiten estimar la edad de inicio de la deformación durante el Mioceno superior (~ 6,5 Ma) en el frente meridional de pliegues; mientras que en el frente septentrional comenzó durante el Plioceno basal (~ 5,3 Ma). De acuerdo con estos nuevos datos, proponemos una tasa de desplazamiento del frente septentrional de 0,09 mm/año, algo más baja que las propuestas con anterioridad. También se discuten las implicaciones que tienen estos datos en las hipótesis de evolución estructural de la Zona de Falla del Bajo SeguraItem type: Item , Peces fósiles en el Eoceno Superior de La Plana de Vic (Barcelona): Nuevos yacimientos y significado sedimentario(Sociedad Geológica de España, 2016) Farrés, Francesc; Carnevale, Giorgio; Colombo Piñol, Ferrán; Cabello, Patricia; Belaústegui, Zain; Domènech, Rosa; Vidal, Albert; Martinell, JordiLa Plana de Vic, situada hacia el sector NE de la Cuenca del Ebro, se caracteriza por un espeso apilamiento de materiales marinos que fueron acumulados principalmente durante el Paleógeno. Sobre una discordancia desarrollada sobre el basamento paleozoico se acumularon materiales aluviales distales de granulometría fina (Taneciense) que quedaron recubiertos por una delgada cuña marina (Ilerdiense). Encima existen materiales aluviales distales de granulometría fina que pasan gradualmente a otros de granulometría gruesa, que en su parte superior muestran intercalaciones de areniscas y carbonatos con Nummulites y Assilina (Luteciense). Posteriormente, se depositaron lutitas de offshore que soportaron la progradación de materiales arenosos costeros. En la parte central de la cuenca siguió la acumulación de lutitas (Bartoniense) que a su vez fueron afectadas por progradaciones deltaicas en los sectores meridionales y septentrionales. A techo de algunos cuerpos deltaicos se depositaron litosomas arrecifales carbonatados. Sobre una discontinuidad sedimentaria aparece una acumulación compleja de lutitas, areniscas, evaporitas y carbonatos donde se hallan los nuevos yacimientos de peces fósiles (Priaboniense). Entre los especímenes se han identificado algunos Clupeidos, Percofórmidos y Synodontidos que representan los últimos episodios de la sedimentación marina en la zona durante el EocenoItem type: Item , Nuevos datos de evolución geomorfológica y paleoambiental de la Costa Cantábrica durante el MIS 6-4: el Monumento Natural de Cobḥi eru (Asturias)(Sociedad Geológica de España, 2016) Ballesteros, Daniel; Rodríguez Rodríguez, Laura; González Lemos, Saúl; Giralt, Santiago; Álvarez Lao, Diego J.; Adrados, Luna; Jiménez Sánchez, MontserratSe proporcionan nuevos datos sobre la geomorfología y evolución paleoambiental de la Costa Cantábrica durante el MIS 6–4 a partir del modelo espeleogenético de la Cueva de Cobḥi eru, incluyendo: (1) la identificación de 2 fases de relleno de la cueva relacionadas con condiciones más frías y etapas de nivel del mar bajo a 60–70 y 130–150 ka, (2) el inicio de un descenso del nivel del Mar Cantábrico en la transición entre el MIS 5-4, (3) la presencia de un ambiente abierto con poca vegetación en torno a 65 ka (MIS 4), (4) el descubrimiento del Elona quimperiana más antiguo, indicando el desarrollo de bosque caducifolio húmedo hace más de 350 ka, y (5) la relación entre la erosión de los abanicos torrenciales que cubrían el karst y la entrada de fauna fría a las cuevas de la costa de AsturiasItem type: Item , Las crecidas del Ebro de febrero/marzo de 2015. ¿Qué hemos aprendido y qué falta por aprender?(Sociedad Geológica de España, 2016) Pueyo Anchuela, Óscar; Revuelto, Carlos; Casas Sainz, Antonio; Ramajo Cordero, Javier; Pocoví Juan, AndrésDurante los meses de febrero/marzo de 2015 una crecida afectó a varios sectores del sector central del cauce del Ebro. La evaluación científica de los datos es evidente: las llanuras de inundación se inundan, la periodicidad de las crecidas como la de 2015 es alta y crecidas similares generan ahora ascensos de la lámina de agua mayores en los cascos urbanos que hace unos años. Sin embargo, la percepción ciudadana, al menos en cuanto al clima que se desarrolló durante las crecidas en el entorno de la ribera del Ebro fue muy distinta, ya que la responsabilidad se achacó a la ausencia de planes de limpieza integral, encauzamiento del cauce o escasa altura de motas. Estos aspectos entran en contradicción con los conocimientos técnicos y científicos de las consecuencias que la modificación del cauce puede desencadenar. En este sentido, el oportunismo mediático y la falta de reacción de la comunidad científica, produce que algo habitual, recurrente y comprensible en una llanura de inundación sea percibido por la población como un fenómeno imprevisible. En este trabajo queremos evaluar algunos aspectos terminológicos y de conocimiento sobre la previsión de dichos eventos que seguirán afectando en su misma dinámica natural a la zona analizadaItem type: Item , La fracturación de la rampa carbonática del tránsito Jurásico Inferior a Medio y volcanismo asociado en el sector de La Salada (Sistema Ibérico, Teruel)(Sociedad Geológica de España, 2016) Santisteban, Carlos deLos depósitos del tránsito Jurásico Inferior a Medio del sector sureste del Sistema Ibérico contienen, entre carbonatos marinos, materiales volcánicos de afinidad basáltica. Una explicación a su presencia es un evento de colapso de la plataforma, en un intervalo de tiempo (¿Toarciense Superior–Bajociense?), por actividad tectónica extensional contemporánea con una transgresión marina. En el macizo de La Salada este colapso está evidenciado, además de por la presencia de intercalaciones de piroclastos volcánicos, por la fracturación y basculamiento de bloques rígidos de carbonatos. Aunque el contexto ambiental es de rampa distal, la tectónica llegó a levantar algunos de los bloques por encima del nivel del mar, produciendo su erosión parcial y discordancias angulares. Entre algunos de estos bloques se formaron pequeñas fosas tectónicas rellenas de piroclastos. La posición y geometría de estas fosas sugiere que el colapso local de la plataforma pudo estar condicionado por la reactivación del desgarre tardo-varisco de Requena–MoraItem type: Item , Influence of sedimentary density variations in décollement-related fold-and-thrust belts: insights from centrifuge analogue modelling(Sociedad Geológica de España, 2016) Santolaria, Pablo; Soto Marín, Ruth; Harris, Lyal B.We present an innovative centrifuge analogue modelling approach to evaluate the influence of density contrast on structure location and vergence affecting thin-skinned compressional settings. Our natural prototype involves a detached foreland basin characterized by a basal ductile evaporitic décollement overlain by a brittle-like cover comprising a set of rock density variations. The experimental programme included gravity spreading and shortening characterized by density contrast up to 0.5 gr/cm3. Density contrast boundaries were designed perpendicular to the shortening except for one case, where it was parallel. Under no horizontal stress conditions, i.e. the tectonically quiescence context, just the centrifuge force (up to almost 900g), the cover depicts a syncline-anticline structure were the inflexion point was localized along the density contrast boundary. Moreover, wavelength and amplitude increased following the density contrast rise. In compression, density contrast boundaries perpendicular to the shortening direction controlled the vergence of the developed structuresItem type: Item , Impacto humano en la ría de Suances (Cantabria): indicadores geoquímicos y microfaunísticos en los sedimentos actuales(Sociedad Geológica de España, 2016) Serrano, Humberto; Cearreta, Alejandro; Irabien, María Jesús; Gómez Arozamena, JoséMetal and benthic foraminiferal contents from surface sediments of the Suances estuary have been analyzed in order to characterize the geochemical and microfaunal responses to the present environmental conditions in this coastal area. High levels of Zn, Pb, and Cd together with reduced numbers of foraminifera present in this estuary suggest very negative and persistent environmental conditions through time as a consequence of mining, industrial and urban effluents disposal in this ecosystem during the last 160 years. Multiproxy geological analysis represents a powerful tool for the historical monitoring of both the past and future environmental transformation processesItem type: Item , Geoquímica orgánica del registro de la ría Villaviciosa desde 1400 AD (Norte de España)(Sociedad Geológica de España, 2016) Ortiz, José Eugenio; Sánchez Palencia, Yolanda; Gallego, José Luis R.; Torres, Trinidad de; Borrego, Ángeles G.We have reconstructed the palaeoenvironmental conditions in the Villaviciosa estuary during the last 600 yrs, from the biomarker content (alkanes and alkanoic acids) of the sediment. The amino acid racemization method in ostracodes allowed determining that the sedimentation in the Selorio bay started in 1400 AD. Organic matter was well preserved, although certain microbial activity was interpreted. Three periods were established from the alkane content: 1.- Between 1400 and 1580 AD terrestrial input was dominant; 2.- Between 1580 and 1720 AD there was a major influence of aquatic macrophytes, coinciding with the Little Ice Age, 3.- Between 1720 and 2015 AD there were alternating periods during which land plants or aquatic macrophytes predominated, probably linked to anthropogenic activitiesItem type: Item , Geometry of the contact of the peridotites of Sierra Alpujata with the Sierra Blanca succession (Alpujarride Complex,Betic Internal Zone)(Sociedad Geológica de España, 2016) Sanz de Galdeano, Carlos; López Garrido, Ángel CarlosThe peridotites of Sierra Alpujata thrust to the north a formation of granitoid gneisses and the succession of Sierra Blanca. This structure led to the individualization of the unit of this name, and thus it is considered to crop out in a tectonic window. Nevertheless, on the western border of Sierra Alpujata the gneisses, in continuity with the formations of Sierra Blanca, are situated over the peridotites. This means that the Sierra Blanca does not crop out in a tectonic window, and that the peridotites, on the whole, are in fact situated in a lower position. This situation has important consequences for the age of their first exhumation and for the geological evolution and structure of the regionItem type: Item , Gasterópodos continentales del Pleistoceno superior-Holoceno basal de Urtiaga (Deba, Gipuzkoa)(Sociedad Geológica de España, 2016) Suárez Bilbao, Aitziber; Larraz, Mariano; Mujika Alustiza, José Antonio; Suárez Hernando, Oier; Murelaga, XabierThe Urtiaga cave is an archaeological site with a record from the Solutrean to the Azilian periods. At the site, there are numerous remains of molluscs accumulated, both marines and continentals. The presence of marine gastropods is associated to human consume. In this work the association of continental gastropods is presented, which is constituted by the species Xerosecta arigonis, Oxychilus sp., Discus rotundatus, Clausilia bidentata, Obscurella obscurum, Granaria braunii, Chondrina avenacea and Pomatias elegans. Given its small size, the hypothesis that these gastropods were accumulated as foodstuff is discarded. All species represented in the site are indicatives of humid and wooded zones. This fact would explain that the richest and most diverse levels coincide with the humid and warm moment of the AzilianItem type: Item , Experimental modelling of deformation around rigid particles in pure shear. The impact of layer anisotropy(Sociedad Geológica de España, 2016) Pascual, Ramón; Druguet, Elena; Carreras, JordiThis work focuses on how the rotation of rigid particles is influenced by preexisting planar anisotropy of the bounding media during deformation. Three experiments were conducted at the UAB Laboratory of Deformation using the apparatus BCN-Stage. The models were made with analogue materials (plasticine as the matrix and paraffin as rigid inclusions) and were deformed by pure shear at constant bulk strain rate and temperature. All inclusions were initially identical in orientation and dimension. In the first experiment, in which the matrix consisted of homogeneous plasticine, rotation of the rigid particles agreed with that of previous theoretical an experimental models. In the other two experiments, the rigid paraffin particles were embedded in multilayers of plasticine subjected to folding. The multilayers in both experiments had opposite initial vergences with respect to the kinematic axes. In these two cases, rigid inclusions rotate antithetically with respect to the layers that are being folded, regardless of their initial orientation, indicating the strong influence of layer anisotropy and its orientation on the rotation of rigid objects. The experiments can be correlated with natural field examples at multiple scales, from single crystals in metamorphic rocks to plutonsItem type: Item , Exhumation sequence of the basement thrust units in the west-central Pyrenees. Constraints from apatite fission track analysis(Sociedad Geológica de España, 2016) Labaume, Pierre; Meresse, Florian; Jolivet, Marc; Teixell, AntonioCompilation of new and published apatite fission track data along a transect of the west-central Pyrenees shows that exhumation across the Partial Annealing Zone (~120–60°C) started during the mid Eocene in the North-Pyrenean Zone and migrated southward to reach the southern edge of the Axial Zone during the early Miocene. An early Miocene stage of exhumation is also detected in the northern part of the Axial Zone, indicating a late pop-up thrust reactivation of the Axial ZoneItem type: Item , Evolución de la carga metálica en un tramo del río Odiel afectado por drenaje ácido de minas (provincia de Huelva)(Sociedad Geológica de España, 2016) Riera, Julia; Olías Álvarez, Manuel; Ruiz Cánovas, CarlosThis work quantifies the impact of the first acid mine discharges to the Odiel River and studies the variation of the dissolved and particulate pollutant load. The acid mine discharges cause the progressive deterioration of the river water quality, resulting in processes that favor the precipitation of the non-conservative elements (Fe, Al, As or Pb), while the more soluble ones (Mn, Co or Ni) remain in solution. Cu and Zn have an intermediate behavior due to be affected by sorption/coprecipitation processes. The dissolved pollutant load at the end of the reach is around 5000 kg/day of Al, 1900 kg/day of Fe, 860 kg/day of Zn, 643 kg/day of Mn, 385 kg/day of Cu and lower amounts of other metals. The total metal load may be up to 21 times the dissolve load in the case of Fe and among 3-4 times for As and PbItem type: Item , Evolución del drenaje en cuencas erosivas durante el Neógeno-Cuaternario. Margen oriental de la Cuenca del Ebro(Sociedad Geológica de España, 2016) Castelltort Aiguabella, F. Xavier; Balasch Solanes, Josep Carles; Cirés Fortuny, Jordi; Colombo Piñol, FerránThe monocline layout of the sedimentary pile of the Ebro Basin in its Eastern margin determines the generation and emptying of the adjacent erosive basins. It controls the drainage changes in the original sedimentary basin. A model of emptying erosive basins corresponding to a drainage architecture and sediment production is proposed. The emptying of erosive basins is achieved by two vectors: A) A drainage basin area growth due to anaclinal streams eroding into the resistant layers of the monocline stratigraphic succession. These streams empty and link small depressions generated at the expense of the lateral extension on the less resistant lithologic member. B) The drainage basin outlet point base level controls the drainage network entrenchment facilitated by the gradients created by Neogene extensional faults from the Valencia Trough. A model of the growth and entrenchment of erosive basins as well as the generated landforms and sediment production is described and analyzedItem type: Item , Evaluación sobre la caracterización de distintos tipos de cimentaciones superficiales por medio de georradar(Sociedad Geológica de España, 2016) Pueyo Anchuela, Óscar; López Julián, Pedro; Pérez Benedicto, José Ángel; Bartolomé, Juan Ignacio; Pocoví Juan, AndrésAt retrofitting of buildings or at building damages analysis, the identification of footing characteristics is of high interest. The application of GPR for determining the size, depth and characteristics of footing is usual, due to the non-invasive character of this technique, the possibility to be performed at urban environments and the relatively fast survey. In this work three different footing types are evaluated; a reinforced concrete slab, isolated footing and isolated footing over shaft foundation. The objective of the analysis is to evaluate the potential identification of the foundation size, and especially, as the construction characteristics are known, to check the identification availability of the lower foundation limit (or footing depth). The presence of inverse propagation velocity contacts at the footing base, the wave phase change related to higher reflective media in the profiles, the propagation of multiple reflections or the changes of propagation velocity between the foundation and the natural soil are the main challenges in the exact identification of the foundation characteristicsItem type: Item , Estudio bioestratigráfico con foraminíferos planctónicos del Santoniense-Campaniense en la sección de Deba-Zumaia (Gipuzkoa): Nueva biozonación con heterohelícidos(Sociedad Geológica de España, 2016) Gilabert, Vicente; Arz, José Antonio; Arenillas, J. I.; Hilario, AsierA biostratigraphic study with Santonian and Campanian planktic foraminifera was carried out in the turbiditic facies of the coastline between Deba and Zumaia (Gipuzkoa), which comprises the Itziar and Aguinaga formations. Due to the low abundance of planktic foraminifera, particularly in globotruncanids, the biostratigraphic study was based on species belonging to the group of heterohelicids. We have identified 7 biozones, one of which (Sigalia rugocostata Zone) has been defined in this work. The position of the Santonian/Campanian boundary has been recognized for the first time in the Basque Coast Geopark through the use of this new biozonation with heterohelicidsItem type: Item , Estudio de la fracturación alpina en el sistema zócalo-cobertera de la zona de Boadella-Darnius (Pirineo Oriental)(Sociedad Geológica de España, 2016) García López, Francisco José; Carreras, Jordi; Druguet, ElenaThis work focusses on the Alpine faulting that affected the basementcover boundary in the Boadella-Darnius area (Eastern Pyrenees). We study the response of the Palaeozoic granitic basement, characterized by an intense jointing pattern, and the conglomeratic stratified cover to the orogeny. The used methodology is based on the analysis of the orientation of minor faults and associated structural elements (slickensides and fault striations), on fault crosscutting relationships, and on the relationship between the inferred stress tensors and tilting. The results point to a strike-slip regime, with σ1 directions rotating from NNW-SSE to NNESSW, close to N-S. Alpine faulting is accommodated by reactivated fractures in the basement and by newly formed faults in the cover rocksItem type: Item , El complejo intrusivo diorítico-gabroico de Susqueda (Macizo del Montseny–Guilleries, Cataluña): unidades litológicas y características petrográficas(Sociedad Geológica de España, 2016) Esteve, Sergi; Sunyer, Joan; Culí, Laura; Cirés Fortuny, Jordi; Alías, Gemma; Enrique Gisbert, PereThe intrusive complex of Susqueda constitutes the biggest association of plutonic mafic rocks of the Catalonian Coastal Ranges. It is located in the contact between the large calc-alkaline granitoid intrusions and the Paleozoic country rocks affected by Hercynian regional metamorphism. Intrusive relationships denote contemporaneity of basic magmas and, at least, an acid magma intrusion. A significant part of the outcrop consists of a heterogeneous mixing zone between the two magmas (mingling). The intrusion is made up of two oval-shaped outcrops about 3 km long, elongated in the N–S direction and separated by a NW–SE fault. In these units, the compositions of the plutonic rocks range from quartz diorites and tonalites (in the mixing zones) up to olivine hornblendites. Even though its distribution is quite heterogeneous, a preliminary cartography was made including the different petrographic types in three main groups: 1) hornblende gabbros and olivine hornblendites; 2) biotite-hornblende diorites; and 3) heterogeneous mixing zone between hornblende-biotite quartz diorite, granodiorite, and tonalite. The predominant mineral composition consists of plagioclase and amphibole, typical of dioritic rocks. Nevertheless, in a great part of the outcrop the plagioclase widely exceeds the 50% in An, typical of gabbroic rocks