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
3 results
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Item Características de los tensores de esfuerzos activos entre la Dorsal Centroatlántica y la Península Ibérica(Geotemas, 2000) Vicente Muñoz, Gerardo de; Martín Velázquez, Silvia; Rodríguez Pascua, Miguel Angel; Muñoz Martín, Alfonso; Arcila, M.; Andeweg, BerndThe orientation of the principal stresses and the principal stress difference ratio has been determined along the southwestern boundary of the Euroasiatic plate with Northamerican and African plates by inversion method of focal mechanisms of earthquakes. The ridge push (30~ to 65Q N) ranges from E-W to ESE-WSW, with R values that show a triaxial extensional stress. The state of stress changes to strike-slip regime in the transform fault zones, and the Shmax strike turns clockwise to NW in the dextral strike-slip faults and counterclockwise to the NE in the sinistral ones. Along the margin between the Euroasiatic-African plates, from the Azores triple junction to Algeria, Shmax keeps a constant NW-SE strike but the stress ratio values range from triaxial extensional stress state, to the West, to uniaxial compresive stress state, to the East, passing through a strike-slip regime in the middle zone. In this context and with a widely NWSE Shmax, strike-slip and extensional stresses prevail in most Iberian peninsula, whereas southwards it is dominated by uniaxial compresive stresses.Item 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, JavierThe 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.Item 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, AlfonsoSe 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.