Person: Muñoz Martín, Alfonso
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First Name
Alfonso
Last Name
Muñoz Martín
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Geodinámica, Estratigrafía y Paleontología
Area
Geodinámica Interna
Identifiers
43 results
Search Results
Now showing 1 - 10 of 43
Item Quantifying the erosional impact of a continental-scale drainage capture in the Duero Basin, northwest Iberia(Quaternary Research, 2018) Antón López, Loreto; Muñoz Martín, Alfonso; De Vicente Muñoz, GerardoFormerly closed drainage basins provide exceptional settings for quantifying fluvial incision and landscape dissection at different time scales. Endorheic basins trap all the sediment eroded within the watershed, which allows estimates of post–basin opening erosion patterns. The Duero Basin was a former closed basin and is presently drained by the Duero River into the Atlantic Ocean. During the Cenozoic, the basin experienced a long endorheic period, marked by the formation of continental carbonates and evaporites. The retrogressive erosion of the Atlantic drainage coming from the Portuguese coast subsequently captured the internal drainage, and significant fluvial dissection occurred. Presently, the basin contains a relatively well-preserved sedimentary fill. Gridding and surface fitting in this paper provide the first attempt to reconstruct the surface of the top of the former endorheic sedimentary sequence to quantify the erosional impact of the basin opening. At least 2251±524 km3 of sediment was removed from the formerly closed basin following the start of exorheism. This volume represents a mean basin-surface lowering of 65±13 m. Erosion estimates and landscape dissection patterns are consistent with geologic evidence of progressive establishment of an outward drainage system.Item Erosión minera en la cuenca del arroyo Peñalén (Parque Natural del Alto Tajo, Guadalajara)(Comprendiendo el relieve: del pasado al futuro, 2016) Martín Moreno, Cristina; Martín Duque, José Francisco; Nicolau Ibarra, José Manuel; Muñoz Martín, AlfonsoItem Análisis de la estructura alpina de la corteza del centro de la Península Ibérica: Una sección Magneto-Telúrica a través del Sistema Central (Sierra de Gredos)(Geotemas, 2012) Pous, Jaume; Muñoz Martín, Alfonso; Olaiz Campos, Antonio José; Seillé, H.; De Vicente Muñoz, GerardoWe present a magnetotelluric profile across the Duero basin, the Central System and the Madrid basin, acquired in the framework of the TOPO-IBERIA project. The MT profile consists of 24 magnetotelluric sites over a 200 km, NS oriented profile. Five components were measured with periods ranging from 0.001 s to 500s. The dimensional analysis reveals a dominant E-W direction and 2D joint inversion of apparent resistivity, phases and tipper was carried out. The inverse resistivity model obtained has been compared with other geological and geophysical data, and it shows a resistive and homogeneous crust that extends towards the Duero basin. The main conductive anomalies are elongated and inclined bodies that are related with the main big–scale Alpine thrusts. Other superficial conductive bodies are related with the tertiary sedimentary basins. [RESUMEN]Este trabajo muestra un nuevo perfil magnetotelúrico (MT) a través del la cuenca del Duero, el Sistema central y la Cuenca de Madrid, adquirido dentro del proyecto TopoIberia. El Perfil MT consiste en 24 sondeos a lo largo de 200 km con una orientación NS. En cada sondeo se han medido cinco componentes con periodos de 0.001 a 500 s. El análisis dimensional revela una dirección dominante E-O y se ha realizado una inversión conjunta en 2D de las resistividades aparentes, fases y tipper. El modelo de resistividades obtenido ha sido comparado con otros datos geológicos y geofísicos, y muestra una estructura cortical homogénea y resistiva que se prolonga hacia la cuenca del Duero. En esta corteza aparecen cuerpos conductores inclinados y alargados en profundidad asociados a grandes cabalgamientos alpinos. Otros cuerpos conductores superficiales están claramente relacionados con las cuencas sedimentarias terciariasItem Exceptional river gorge formation from unexceptional floods(Nature Communications, 2015) Antón López, Loreto; Mather, A.E.; Stokes, M.; Muñoz Martín, AlfonsoAn understanding of rates and mechanisms of incision and knickpoint retreat in bedrock rivers is fundamental to perceptions of landscape response to external drivers, yet only sparse field data are available. Here we present eye witness accounts and quantitative surveys of rapid, amphitheatre-headed gorge formation in unweathered granite from the overtopping of a rock-cut dam spillway by small-moderate floods (B100–1,500m3 s�1). The amount of erosion demonstrates no relationship with flood magnitude or bedload availability. Instead, structural pattern of the bedrock through faults and joints appears to be the primary control on landscape change. These discontinuities facilitate rapid erosion (4270m headward retreat; B100m incision; and B160m widening over 6 years) principally through fluvial plucking and block topple. The example demonstrates the potential for extremely rapid transient bedrock erosion even when rocks are mechanically strong and flood discharges are moderate. These observations are relevant to perceived models of gorge formation and knickpoint retreat.Item Análisis de la sensibilidad de las estimaciones de la profundidad del basamento en la cuenca de Madrid (España Central)(Geotemas, 2012) Olaiz Campos, Antonio José; Muñoz Martín, Alfonso; Gascone, L.; De Vicente Muñoz, Gerardo; Mantilla Pimiento, A.The Madrid basin, over 20.000 km2 , located in Central Spain. Its evolution is conditioned by basement uplifts (Central System and Toledo Mountains) during the Alpine orogeny. The Madrid basin is connected with the Loranca basin at its NE corner and with La Mancha basin to the south. Sediment thickness accumulated from Late Cretaceous to the Late Miocene, is about 3.000 m at Pradillo well, but from seismic interpretation, a depocenter associated to Central System South Thrust is inferred. For this study four different methodologies were used(“Euler Deconvolution”, “Source Parameter Imaging”, “Analytic Signal” and “Tilt Depth”), in order to obtain depth to basement estimations from aermagnetic data. These methods work for simplified source geometries, estimating depths as a good starting point for a structural interpretation. In Madrid Basin, this knowledge is important due to the geothermal and hydrological potential of the basin, as well as for CO2 storage. [RESUMEN]La cuenca de Madrid, con un área aproximada de 20.000 km2, se extiende en la zona central de la Península Ibérica. Su evolución está condicionada por el levantamiento del Sistema Central y de los Montes de Toledo durante la orogenia Alpina. La cuenca de Madrid está conectada con las cuencas de Loranca, en su límite NE, y de La Mancha por el sur. El espesor de sedimentos, con registro continuo desde el Cretácico Superior hasta el Mioceno Superior, alcanza los 3000 m en el pozo Pradillo, aunque de la interpretación sísmica se obtiene un depocentro, de mayor profundidad, adosado al cabalgamiento del Borde Sur del Sistema Central . En este trabajo se han seguido distintas metodologías para estimar la profundidad del basamento, a partir de datos aeromagnéticos. Los distintos métodos (“Deconvolucion de Euler”, “Source Parameter Imaging”, “Analytic Signal” y “Tilt Depth”) tienen en común que asumen geometrías sencillas, pero los resultados obtenidos resultan de gran interés para la interpretación estructural del basamento. En el caso de la cuenca de Madrid, este conocimiento es muy importante dado su potencial geotérmico e hidrogeológico, así como un posible uso como almacenamiento geológico.Item Análisis de los esfuerzos tectónicos de la crisis sísmica de 2010 en Haití(Geogaceta, 2014) López Cuesta, Víctor; Muñoz Martín, Alfonso; Granja Bruña, José LuisEl evento de Mw=7 del 12 de enero 2010 provocó una crisis sísmica en el sur de Haití, que duró 3 meses. Se ha realizado un análisis de inversión de esfuerzos de los mecanismos focales del evento principal y 50 réplicas. El evento principal fue generado por un falla de buzamiento 64ºN y dirección N084Eº con una componente principal de deslizamiento lateral-izquierda y una componente inversa. Las réplicas se han generado por fallas inversas puras ENE-OSO situadas en la zona de interacción entre estructuras compresivas orientadas NO-SE y de desgarre orientadas E-O. Estas réplicas han sido activadas por un régimen de esfuerzos compresivo uniaxial muy homogéneo orientado con σ1 horizontal según N017ºE ±10º. La ausencia de ruptura en superficie indica que el origen de las réplicas son fallas ciegas orientadas N097º-117ºE. Los datos de deformación superficial intersísmica obtenidos a partir de velocidades derivadas de GPS para la zona epicentral muestran una desviación angular de ≈30º respecto a la orientación de σ1 obtenidos del análisis de esfuerzos. Esta desviación sugiere que una parte significativa de la energía elástica acumulada a lo largo de las estructuras de tendencia E-O no fue liberada durante la crisis sísmica de 2010.Item Structural Achitecture of the Madrid Basin from 3D Gravity Inversion(Conference Paper. 77th EAGE Conference & Exhibition 2015, 2015) Olaiz, A.J.; Mantilla Pimiento, A.; Muñoz Martín, Alfonso; De Vicente Muñoz, GerardoThe Madrid Basin is an intraplate Cenozoic basin located in the central area of the Iberian Peninsula. Basement is characterized by a wide range of lithologies, from meta-sediments to granites. Sedimentary section is associated with a carbonatic platform in Cretaceous time and with continental environments during Tertiary. During the second half of the last century 2D seismic data was acquired and some wells were drilled by several oil & gas companies. Due to the lack of refraction seismic, the geometry of the Moho is not very well-known in the area. This study presents the results of the 3D gravity inversion performed mainly to determine the configuration of the Moho. Also, the geometry of basement has been refined after the inversion. The initial model was constrained by surface geology, 2D seismic and well data. The final 3D model shows significant density variations within the basement and the presence of an intra-basement structure in the Central Iberian System.Item Using river long profiles and geomorphic indices to evaluate the geomorphological signature of continental scale drainage capture, Duero basin (NW Iberia)(Geomorphology, 2013) Antón López, Loreto; De Vicente Muñoz, Gerardo; Muñoz Martín, Alfonso; Stokes, MartinWell-constrained case studies of transient landscape responses are needed to improve our understanding of erosion processes associated with drainage captures. The Duero basin is an excellent location for such a study because the landscape is currently undergoing pronounced geomorphological changes resulting from the opening of a former closed drainage. The present-day continental interior basin (N50,000 km2) drains to the Atlantic Ocean via the Duero River, but during the Cenozoic the basin experienced a long endorheic period marked by the formation of evaporites. Currently, the entire continental interior is an area of relative tectonic quiescence, characterised by a relict low-relief upland topography (Meseta). Systematic variations in lithology and a well-constrained tectonic setting throughout the basin and adjacent areas allow for the comparison of channel morphology between the Cenozoic Duero basin and its western fringe. To explore the signal of transient geomorphic response to capture and opening of the former endorheic basin, the main channel and 24 tributaries were analysed in terms of their longitudinal profiles and the application of geomorphic indices (concavity index [Ci], valley floorwidth-to-height ratio [Vf], and stream-length gradient index [SL]). The analysis reveals two zones with distinctive morphologies: (1) an upper reach domain consisting of broad flat valleys and low-gradient streams where concave longitudinal profiles dominate and (2) a middle reach domain characterised by steep, deeply incised canyons where a convex long profile dominates marking a major kinckzone. The quantitative information on channel shapes and long profile geometries allows the interpretation of these patterns in terms of driving forces for fluvial landscape development. Large-scale morphometric analysis highlights the transient response of the entire basin to a capture-related base level lowering and illustrates the importance of drainage captures as potential internal drivers of landscape modification and topographic adjustments. Furthermore, the Duero basin case study also emphasises that well-constrained bedrock geology and tectonic patterns are essential to avoid misinterpretation of geomorphic indexes.Item New Insights on Peniche Basin (West Iberian Margin) Crustal Structure Based on Gravity Data Interpretation(Conference Paper 77th EAGE Conference&Exhibition, 2015) Sanchez de la Muela, Almudena; Gascone, L.; Muñoz Martín, Alfonso; Mantilla Pimiento, A.; Arnáiz, A.A gravimetric study has been carried out over a sector of the West Iberian Margin (WIM), constrained by well and seismic data. The analytic development was made through three main stages: the processing of different gravity datasets, the production of gravity anomaly maps and 2,5D models using the processed data, and the geophysical interpretation of maps and models. The final results of the interpretation achieved, allowed the determination of crustal structure and its variation/complexity along the WIM. The main obtained results concern the pre-saline infilling and the deep structure of the margin, which vary related to the location of first-order oblique fractures.Item A multi-isotopic approach to investigate the influence of land use on nitrate removal in a highly saline lake-aquifer system(Science of The Total Environment, 2018) Valiente, Nicolás; Carrey, R.; Otero, Neus; Soler, A.; Sanz, D.; Muñoz Martín, Alfonso; Jirsa, F.; Wanek, W.; Gómez Alday, J.J.Endorheic or closed drainage basins in arid and semi-arid regions are vulnerable to pollution. Nonetheless, in the freshwater-saltwater interface of endorheic saline lakes, oxidation-reduction (redox) reactions can attenuate pollutants such as nitrate (NO3-). This study traces the ways of nitrogen (N) removal in the Pétrola lake-aquifer system (central Spain), an endorheic basin contaminated with NO3-(up to 99.2mg/L in groundwater). This basin was declared vulnerable to NO3-pollution in 1998 due to the high anthropogenic pressures (mainly agriculture and wastewaters). Hydrochemical, multi-isotopic (δ18ONO3, δ15NNO3, δ13CDIC, δ18OH2O, and δ2HH2O) and geophysical techniques (electrical resistivity tomography) were applied to identify the main redox processes at the freshwater-saltwater interface. The results showed that the geometry of this interface is influenced by land use, causing spatial variability of nitrogen biogeochemical processes over the basin. In the underlying aquifer, NO3-showed an average concentration of 38.5mg/L (n=73) and was mainly derived from agricultural inputs. Natural attenuation of NO3-was observed in dryland farming areas (up to 72%) and in irrigation areas (up to 66%). In the Pétrola Lake, mineralization and organic matter degradation in lake sediment play an important role in NO3-reduction. Our findings are a major step forward in understanding freshwater-saltwater interfaces as reactive zones for NO3-attenuation. We further emphasize the importance of including a land use perspective when studying water quality-environmental relationships in hydrogeological systems dominated by density-driven circulation.