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
11 results
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Item 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 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 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 Denitrification in a hypersaline lake–aquifer system (Pétrola Basin, Central Spain): The role of recent organic matter and Cretaceous organic rich sediments(Science of the total environment, 2014) Gómez Alday, J.J.; Carrey, R.; Valiente, Nicolás; Otero, Neus; Soler, A.; Ayora, C.; Sanz Bas, David; Muñoz Martín, Alfonso; Castaño, S.; Recio, C.; Carnicero, A.; Cortijo, A.Agricultural regions in semi-arid to arid climates with associated saline wetlands are one of the most vulnerable environments to nitrate pollution. The Pétrola Basin was declared vulnerable to NO3 − pollution by the Regional Government in 1998, and the hypersaline lake was classified as a heavily modified body of water. The study assessed groundwater NO3 − through the use of multi-isotopic tracers (δ15N, δ34S, δ13C, δ18O) coupled to hydrochemistry in the aquifer connected to the eutrophic lake. Hydrogeologically, the basin shows two main flow components: regional groundwater flow from recharge areas (Zone 1) to the lake (Zone 2), and a density-driven flow from surface water to the underlying aquifer (Zone 3). In Zones 1 and 2, δ15NNO3 and δ18ONO3 suggest that NO3 − from slightly volatilized ammonium synthetic fertilizers is only partially denitrified. The natural attenuation of NO3 − can occur by heterotrophic reactions. However, autotrophic reactions cannot be ruled out. In Zone 3, the freshwater–saltwater interface (down to 12–16 m below the ground surface) is a reactive zone for NO3 − attenuation. Tritium data suggest that the absence of NO3 − in the deepest zones of the aquifer under the lake can be attributed to a regional groundwater flow with long residence time. In hypersaline lakes the geometry of the density-driven flow can play an important role in the transport of chemical species that can be related to denitrification processes.Item The morpho-tectonic setting of the Southeast margin of Iberia and the adjacent oceanic Algero-Balearic Basin(Marine and Petroleum Geology, 2013) Acosta Yepes, Juan; Fontán Bouzas, Ángela; Muñoz, A.; Muñoz Martín, Alfonso; Rivera, Jesus; Uchupi, E.Multi-beam bathymetry and high-resolution low-penetration seismic reflection profiles of the offshore extensions of the Bétic Internal Zone off Sierra de Cartagena-La Unión margin along its south side and the Mar Menor margin along its east side, the Mazarrón Escarpment forming its southern boundary and the adjacent oceanic Algero-Balearic basin have provided images of the neo-tectonic structures of the region equal to those provided by subaerial photography. For the first time we mapped with unprecedented detail the Mazarrón Escarpment and the Southeast margin of Iberia. The first-order structures of the region are due to the consequence of the collision of the African and Eurasian plates during the Alpine orogeny in late Oligocene–Middle Miocene, the westward migration of the Alborán plate in the Middle Miocene and the desiccation of the Mediterranean in the Messinian (Late Miocene) that led to the deposition of evaporites in the Algero-Balearic basin and erosion of the Mazarrón Escarpment, the Sierra de Cartagena-La Unión shelf, the Mar Menor margin and the adjacent coast. Our data images second order tectonic features (neo-tectonic features) superimposed on the larger structures. These include the deformation of the strata in the Algero-Balearic basin by the gliding of the Plio-Quaternary sediments on Messinian halite on the margins of the basin and sediment loading in its center, the Late Miocene–Quaternary deformation of the area north of the Mazarrón Escarpment resulting from the continuous oblique convergence of the African and Eurasian plates in a NNW–SSE direction, the Miocene to Pleistocene volcanic edifices and pinnacles (dikes), the pockmarks formed by the extrusion of gas/water via faults and the massive gravitational failure of the Mazarrón Escarpment triggered by this plate convergence. The data also show in detail features formed on the Mazarrón Escarpment during the Messinian, Pliocene and Pleistocene regressions and those on the shelf formed during the Pleistocene glacially induced regressions/transgression and sediment drifts generated by modern currents.Item Margen Continental Gallego; Zona Económica Exclusiva Española (ZEEE): mapas temáticos de anomalías gravimétricas de aire libre y Bouguer (2012)(2012) Martín Dávila, José; Catalán, Manuel; Larran, M.; Somoza, Luis; León, R.; Gonzalez, F.J.; Carbo Gorosabel, Andrés; Muñoz Martín, Alfonso; Granja, J.L.; Llanes Estrada, María Pilar; Gómez Ballesteros, María; Druet Vélez, María; Acosta, JuanItem Morphostructure at the junction between the Beata ridge and the Greater Antilles island arc (offshore Hispaniola southern slope)(Tectonophysics, 2014) Granja Bruña, José Luis; Carbo Gorosabel, Andrés; Llanes Estrada, María Pilar; Muñoz Martín, AlfonsoOblique convergence between the Caribbean plate's interior and the inactive Greater Antilles island arc has resultedin the collision and impingement of the thickened crust of theBeata ridge into southern Hispaniola Island. Deformation resulting from this convergence changes from a low-angle southward-verging thrust south of easternHispaniola, to collision and uplift in south-central Hispaniola, and to left-lateral transpression along theSouthern peninsula of Haiti in western Hispaniola. Using new swath bathymetry and a dense seismic reflectiongrid, we mapped the morphological, structural and sedimentological Elements of offshore southern Hispaniola.We have identified four morphotectonic provinces: the Dominican sub-basin, the Muertos margin, the Beataridge and the Haiti sub-basin. The lower slope of the Muertos margin is occupied by the active Muertos thrustbelt, which includes several active out-of-sequence thrust faults that, were they to rupture along their entirelength, could generate large-magnitude earthquakes. The interaction of the thrust beltwith the Beata ridge yieldsa huge recess and the imbricate system disappears. The upper slope of the Muertos margin shows hick slopedepositswhere the extensional tectonics and slumping processes predominate. The northern Beata ridge consistsof an asymmetrically uplifted and faulted block of oceanic crust. Our results suggest that the shallower structureand morphology of the northern Beata ridge can be mainly explained by a mechanism of extensional unloadingfrom the Upper Cretaceous onward that is still active residually along the summit of the ridge. The tectonicmodels for the northern Beata ridge involving active reverse strike–slip faults and transpression caused by theoblique convergence between the Beata ridge and the island arc are not supported by the structural interpretation.The eastern Bahoruco slope an old normal fault that acts as a passive tear fault accommodating the sharpalong-strike transition from low-angle thrusting to collision and uplifting.Item Mapa de esfuerzos activos en línea de la Península Ibérica a partir de Mecanismos Focales calculados desde el Tensor de Momento Sísmico(Geotemas, 2012) Muñoz Martín, Alfonso; De Vicente Muñoz, Gerardo; Olaiz Campos, Antonio José; Antón López, Loreto; Vegas Martínez, Ramón; Granja Bruña, José LuisThis work shows a new on-line stress map for Iberian Peninsula obtained from the inversion of earthquakes focal mechanisms calculated with the centroid moment tensor. An amount of 299 focal mechanisms have been selected with several quality criteria from different catalogues (CMT Harvard, ETH, Med-Net, I.G.N. and I.A.G.) from 1973 to January 2012. Values for the maximum horizontal stress and the shape factor of the ellipsoid (horizontal/vertical stress) have been calculated following De Vicente et al. (2008).. The local results have been interpolated to a 10’ regular grid in which the relation between tectonic horizontal stress and vertical load has been taken into account. The final map shows a good correlation with the primary tectonic forces generated in the plate boundaries and the local perturbations related with main crustal heterogeneities. Both the maps and data are free for download from http://www.ucm.es/info/lta/lta.html Applied Tectonophysics Group WebSite). [RESUMEN]Este trabajo muestra el nuevo mapa en línea de esfuerzos activos para la Península Ibérica obtenido a partir de la inversión de mecanismos focales de terremotos (MF) calculados con Tensor de Momento Sísmico (TMS). Un total de 299 MF han sido seleccionados con varios criterios de calidad de diferentes catálogos (CMT Harvard, ETH, Med-Net, I.G.N. e I.A.G.), para un periodo comprendido entre 1973 y enero de 2012 y profundidades menores de 60 km. Los valores de la dirección de máximo acortamiento horizontal (Dey) y el factor de forma (carga horizontal/vertical) han sido calculados siguiendo a De Vicente et al. (2008). Los resultados obtenidos se han interpolado a una malla regular de 10’, teniendo en cuenta las orientaciones de las componentes horizontales de esfuerzo, y el factor de forma. Los mapas finales muestran una buena correlación con indicadores geológicos y cinemáticos. Las orientaciones de los esfuerzos horizontales se relacionan con las fuerzas primarias provenientes de los límites de placas, y con perturbaciones locales relacionadas con heterogeneidades de primer orden a nivel cortical. Tanto los mapas, como los datos procesados son accesibles a través de la Web del Grupo de Tectonofísica Aplicada de la UCM http://www.ucm.es/info/lta/lta.html.Item Seismicity and potencially active faults in the Northwest and Central-West Iberian Peninsula(Journal of iberian geology, 2012) Martín-González, F.; Antón López, Loreto; Insua Arévalo, Juan Miguel; Vicente Muñoz, Gerardo De; Martínez Díaz, José Jesús; Muñoz Martín, Alfonso; Heredia, N.; Olaiz Campos, Antonio JoséThe Northwest and Central-West Iberian Peninsula configure an intraplate area far from the active plate boundaries, where the Variscan basement crops out extensively (Iberian Massif). This area of the Iberian Peninsula has been traditionally considered a seismically stable region; however, it presents a moderate intraplate seismicity which indicates the presence of active structures and the occurrence of potentially damaging earthquakes. The scarcity of Mesozoic and Cenozoic deposits makes very difficult to track the record of the more recent tectonic activity and the characterization of active tectonic structures within the Iberian Massif. Nevertheless the seismic sequences of 1995-1997 in Lugo (5.1 mb; IV) and 2003 in Zamora (4.2 Mw) provided important information about the orientation of the present stress tensor, and the distribution of the hypocenters informed about the rupture geometry of the fault planes. The present work integrates geological, geomorphological, structural, and seismological data in order to define the main potentially active faults in the region. Faults trending NE–SW to N–S are potentially active as strike-slip, in some cases with a reverse component, under a NW-SE to N–S compression. [RESUMEN] El Noroeste y Centro Oeste de la Peninsula Ibérica son parte de una región intraplaca alejada de los bordes de placa sísmicamente activos, donde aflora el basamento varisco (Macizo Ibérico). Esta región de la Península Ibérica ha sido tradicionalmente considerada sísmicamente estable; sin embargo, presenta una moderada sismicidad que indica la presencia de estructuras activas y terremotos potencialmente catastróficos. La escasez y dispersión de los depósitos Mesozoicos y Cenozoicos hace difícil identificar la actividad tectónica más reciente, así como la caracterización de las fallas potencialmente activas dentro del Macizo Iberico. Sin embargo la sismicidad de 1995 y 1997 en Lugo (5.1 mb) y de 2003 en Zamora (4.2 Mw) aportó importante información para determinar la orientación del tensor actual de esfuerzos. De igual modo, la orientación de las replicas aportó información sobre los planos de rotura. El presente trabajo integra datos geológicos, geomorfológicos, estructurales y sismotectónicos para definir las principales fallas potencialmente activas en la región. Las fallas con orientaciones NE-SW hasta N-S son potencialmente activas, bajo un tensor de esfuerzos de NW-SE a N-S, como fallas de desgarre y en algunas zonas con componente inversa.