Person:
Muñoz Martín, Alfonso

First Name

Alfonso

Last Name

Muñoz Martín

URI

https://hdl.handle.net/20.500.14352/75220

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Geológicas

Department

Geodinámica, Estratigrafía y Paleontología

Area

Geodinámica Interna

Identifiers

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Now showing 1 - 10 of 17

Estructura alpina del antepaís ibérico
(Geología de España, 2004) Vicente Muñoz, Gerardo de; Muñoz Martín, Alfonso; Guimerà Rosso, Joan; Vegas, Ramón; Cloetingh, Sierd; Vicente Muñoz, Gerardo de
Análisis de la geometría en profundidad de fracturas conductoras en zonas de baja permeabilidad mediante tomografía eléctrica (El Berrocal, Sistema Central Español)
(Geogaceta, 2007) Muñoz Martín, Alfonso; Olaiz Campos, Antonio José; Vicente Muñoz, Gerardo de; Antón López, Loreto; Elorza, Francisco José; Vicente, Raquel de
The groundwater flow in zones of low permeability, as granites, is mainly associated with zones of fracture. For this reason the characterization of the fractures is fundamental, both in surface as in depth, and must integrate geological information (geological mapping, structural analysis), geophysics (mainly electrical and electromagnetic methods) and geochemistry (radon and others gases) with hydrogeology. In this work we analyze the geophysical response of a strike-slip fault zone by means of three 2D resistivity models. The objective is to investigate the presence of several conductive zones and their geometry in depth. The obtained results allow to control the geometry in depth of the fractures, the gaps between the different mapped traces along the fault zone as well as the thickness of landfill. All this information will be useful for the hidromechanical simulation of the massif, and to check the geometry and gas permeability calculated from emanometry.
Inversion of moment tensor focal mechanisms for active stresses around the Microcontinent Iberia: Tectonic implications
(Tectonics, 2008) Vicente Muñoz, Gerardo de; Cloetingh, Sierd; Muñoz Martín, Alfonso; Olaiz Campos, Antonio José; Stich, Daniel; Vegas, Ramón; Galindo-Zaldívar, Jesus; Fernández Lozano, Javier
The Iberian microcontinent and its connected oceanic crust are affected by deformations related to the Eurasian-African plate boundary. Active stress inversions from populations of moment tensor focal mechanisms have been performed around and inside the Iberian peninsula, using a total of 213 moment tensor estimates. Main results are: 1) The tensorial solutions show better consistency and lower misfits compared to those obtained previously from first P arrival focal mechanisms. 2) Along the Eurasia- Africa western boundary, the type of active stresses progressively changes easternwards from triaxial extension to uniaxial compression along the Terceira Ridge, the Gloria Fault zone and the Gulf of Cadiz. 3) In the Betics-Alboran-Rif zone, uniaxial extension predominates with Shmax N155ºE trending. 4) In N Algeria, uniaxial compression reappears. 5) The Iberian foreland is currently under strike-slip to uniaxial extension tensorial conditions.
El cabalgamiento cenozoico de Boinás (Cordillera Cantábrica, España)
(Geogaceta, 2007) Vicente Muñoz, Gerardo de; González Nistal, S.; Muñoz Martín, Alfonso; Vegas, Ramón; Olaiz Campos, Antonio José; Fernández Lozano, Javier; Vicente, Raquel de
The opencast gold mine of Boinás, has allowed to outcrops the contact between the variscan basement and the Cenozoic sediments. It is observable that the contact is a post - Lower Oligocene thrust, with a N40ºE trend. From a macrostructural point of view, Boinás thrust spreads along more than 10 km with a constant orientation, a vertical gap that reaches 400 m, and a NW vergence. Northwestwards another Alpine thrust develops (Tineo, A l o n s o y Pulgar , 2004) with a parallel orientation an opposite vergence. Between both thrusts a tectonic pop-down appears (Narcea Pop-down). The dynamic analysis shows that this structure was activated by a paleostress tensor with an horizontal s1 trending N139ºE, with a stress regime close to uniaxial compression (R=0.06). This stress allows the geometrical interchanges between s2 and s3. The outcrop also allows to observe a secondary population of normal faults, that fits to an extensional stress tensor (R=0.01) with s3 trending N146ºE, that is coaxial with the main compressive stress tensor. We interpret both fault populations as generated by the tectonic thrust emplacement.
Análisis de las deformaciones y esfuerzos recientes y su relación con la sismicidad en el borde oriental de la cuenca del Tajo (España Central)
(Boletín Geológico y Minero, 2003) Muñoz Martín, Alfonso; Vicente Muñoz, Gerardo de; Giner Robles, Jorge
La cuenca del Tajo es un área de actividad sísmica baja pero con evidencias geológicas de actividad neotectónica. Para establecer su evolución reciente se han analizado las deformaciones y esfuerzos recientes, a partir de 794 planos de falla con estrías repartidas en 40 estaciones de análisis. Los resultados muestran la presencia de un campo de esfuerzos extensivo principal un eje de extensión horizontal (SHMIN) NO-SE, y un campo secundario en régimen de desgarre con la misma orientación de SHMIN. Este campo secundario aparece asociado a zonas de fractura previas de orientación NE-SO, y es simultáneo con el campo extensivo. El estudio de la sismicidad incluye la construcción de cuatro nuevos mecanismos focales de terremotos, y su análisis conjunto con los datos previamente publicados. La inversión de esfuerzos aplicada a los planos nodales de los terremotos ha permitido calcular la presencia coetánea de dos tensores de esfuerzos activos en la cuenca del Tajo: Uno en régimen compresivo, próximo a desgarre, con una dirección del máximo esfuerzo horizontal (SHMAX) según NO-SE, y un tensor minoritario de tipo extensivo con SHMIN según NO-SE. Este tensor extensivo lo interpretamos como el producto de una permutación entre σ1 y σ3 en la zona externa superficial de una flexión antiformal de escala cortical descrita previamente (Giner, 1996; Andeweg et al., 1999; Cloetingh et al., 2002)
Mapa de esfuerzos de Europa a partir de Mecanismos focales calculados desde el Tensor de Momento Sísmico
(Geogaceta, 2006) Olaiz Campos, Antonio José; Vicente Muñoz, Gerardo de; Muñoz Martín, Alfonso; Vegas, Ramón
This work shows a new stress map for Europe obtained from the inversion of earthquakes focal mechanisms calculated with the centroid tensor method (Dzieownski et al., 1982). An amount of 1608 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 present-day. Values for the maximum horizontal stress and the shape factor of the ellipsoid (horizontal/vertical stress) have been calculated following the Reches (1983) and De Vicente (1988) slip model. The local results have been interpolated to a 1ºx1º 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 as suggested by Gölke and Coblentz (1996).
Cálculo de magnitudes de esfuerzos mediante elementos finitos en el macizo de El Berrocal (Sistema Central Español)
(Boletín geológico y minero, 2005) Martín Velázquez, S.; Vicente Muñoz, Gerardo de; Elorza, F.J.; Muñoz Martín, Alfonso
Se ha analizado la distribución de las magnitudes de esfuerzos actuales mediante el método de los elementos finitos a lo largo de una sección NO-SE transversal al macizo granítico de El Berrocal (Sistema Central Español), en la que se incluye la superficie topográfica, las variaciones litológicas y las cargas tectónicas compresivas. La estructura geológica profunda se ha obtenido a partir de una modelización gravimétrica. En un modelo sencillo, con una reología media cortical y una topografía plana, se han establecido previamente las condiciones de contorno y las propiedades mecánicas de los materiales necesarias para reproducir estados de esfuerzos litostáticos y tectónicos con elementos finitos. Aplicando una carga vertical gravitacional y una carga horizontal litostática, sólo se obtienen esfuerzos verticales iguales a los horizontales si el coeficiente de Poisson es de 0,49. Cuando se incluye además una carga tectónica se consigue un estado de esfuerzos tectónicos en régimen compresivo. Sin embargo, al modelizar el caso real del macizo de El Berrocal, la carga topográfica produce una desviación de los esfuerzos respecto al estado litostático y para obtener un régimen compresivo hay que aplicar como mínimo un empuje tectónico de 13 MPa.
El cabalgamiento de Valdesotos: consecuencias de la acomodación del acortamiento cenozoico en el zócalo del Sistema Central
(Geotemas, 2004) Olaiz Campos, Antonio José; Vicente Muñoz, Gerardo de; Vegas, Ramón; González Casado, José Manuel; Muñoz Martín, Alfonso; Álvarez, J.
We describe and study structural evidences concerning to Alpine tectonics at NE sector o f the Spanish Central System (SCS). In Valdesotos area, the Hercynian basement is uplifted over Mesozoic sediments, throughout a main SW verging thrust. Fault population analysis and geological mapping has been used to look at the relation between structures in the basement and in the cover. As a consequence of accommodation of strains in the basement, kink folds are developed, such as secondary thrust and folds in the tegument. All these meso- and macrostructures seem to answer to a shortening in agreement with the Cenozoic deformation.
Aplicación del método electromagnético de inducción ligera para el análisis de la permeabilidad en medios fracturados (granito de “El Berrocal”, Sistema Central Español)
(Geogaceta, 2009) Vicente, Raquel de; Muñoz Martín, Alfonso; Olaiz Campos, Antonio José; Antón López, Loreto; Vicente Muñoz, Gerardo de
Fracture characterization in granites has been an important subject of study during these last years, by means of geological-structural cartography, hydrogeology and geochemical analysis. All these works have been carried out to investigate the hydromechanics and permeability in low-permeability rocks. In this study we apply a surface geophysical method in order to characterize the permeability of the fault zones affecting “El Berrocal” granite (Central System, Spain). The low-induction electromagnetic method (EM) gives us the apparent resistivity values of the rocks at a maximum depth, allowing us to differentiate between soil / altered rock from fresh granites. As the apparent resistivity depends on the granite alteration and/or the water content, this parameter allows to estimate the relative permeability of different fracture zones. The obtained results show that the high-permeability fractures are those that are larger ones which were active during Alpine deformation (Eocene-present).
Oblique strain partitioning and transpression on an inverted rift: The Castilian Branch of the Iberian Chain
(Tectonophysics, 2009) Vicente Muñoz, Gerardo de; Vegas, Ramón; Muñoz Martín, Alfonso; Wees, Jan Dierik van; Casas Sáinz, Antonio; Sopeña, Alfonso; Sánchez-Moya, Yolanda; Arche, Alfredo; López Gómez, José; Olaiz Campos, Antonio José; Fernández Lozano, Javier
The Iberian Chain is a wide intraplate deformation zone formed by the tectonic inversion during the Pyrenean orogeny of a Permian –Mesozoic basin developed in the eastern part of the Iberian Massif. The N – S convergence between Iberia and Eurasia from the Late Cretaceous to the Lower Miocene times produced signi cant intraplate deformation. The NW –SE oriented Castilian Branch of the Iberian Chain can be considered as a “key zone ” where the proposed models for the Cenozoic tectonic evolution of the Iberian Chain can be tested. Structural style of basin inversion suggests mainly strike slip d–isplacements along previous NW –SE normal faults, developed mostly during the Mesozoic. To con rm this hypothesis, structural and basin evolution analysis, macrostructural Bouguer gravity anomaly analysis, detailed mapping and paleostress inversions have been used to prove the important role of strike slip deformation. In addition, we demonstrate that two main folding trends almost perpendicular (NE SW t–o E W an–d NW SE) w–ere simultaneously active in a wide transpressive zone. The two fold trends were generated by dierent mechanical behaviour, including buckling and bending under constrictive strain conditions. We propose that strain partitioning occurred with oblique compression and transpression during the Cenozoic.