Person: Muñoz Martín, Alfonso
Loading...
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
Search Results
Now showing 1 - 3 of 3
Item Sobre el origen de la asimetría en el patrón general del relieve en el interior de la Península Ibérica: nuevos resultados obtenidos mediante modelación análoga(Geogaceta, 2010) Fernández Lozano, Javier; Sokoutis, Dimitrios; Willingshofer, Ernst; Muñoz Martín, Alfonso; De Vicente Muñoz, Gerardo; Cloetingh, SierdAnalogue modelling contributes to the interpretation of lithosphere scale folds in Iberia as a result of largescale convergence during Oligocene-Miocene times between the Iberian and European Plates. Different tectonothermal events affected the microplate since late Paleozoic and resulted in lateral strength variations of the Iberian lithosphere. An old and cold lithosphere, Variscan in age, can be found in the westernmost part of Iberia whereas a relative weak and hot Mesozoic lithosphere affected by episodes of rifting and basin inversion during Mesozoic- Tertiary times covers the area of the Iberian Chain. Our study aims at deciphering whether deformation and topography evolution in Iberia are related to lateral strength variations and/or the inherited structural grain stemming from Variscan deformation. We also have studied the strength of the lithosphere to gain insights into the effects of rheological variations related to local thrusting or primary strength variations along the Iberian lithosphere.Item Spectral analysis of the gravity and elevation along the western Africa–Eurasia plate tectonic limit: Continental versus oceanic lithospheric folding signals(Tectonophysics, 2010) Muñoz Martín, Alfonso; De Vicente Muñoz, Gerardo; Fernández Lozano, Javier; Cloetingh, Sierd; Willingshofer, Ernst; Sokoutis, Dimitrios; Beekman, FredLarge-scale folding is a key mechanism of lithospheric deformation and has been described in many parts of the Earth, both for the continental and oceanic lithospheres. Some aspects of this process such as the presence of coupling/decoupling between the crustal deformation and the mantle lithosphere, or between different lithospheres, make it necessary to accurately control the periodic characteristics of the elevation and of the gravity signal. 1D spectral analysis of gravity and topography profiles is sensitive to a series of factors: the location, length and orientation of the profiles, as well as the number of samples taken. We carry out a systematic analysis of the periodicities in the topography and gravity, both 1D and 2D, along the western border of the Africa–Eurasia plate tectonic boundary. We analyze the sensitivity of the 1D and 2D spectral analysis in order to compare the results along a plate boundary where oceanic and continental lithospheres are in contact with different tectonic, kinematic and rheological aspects. Our 1D spectral results indicate that the greater the profile length, the longer the wavelength peaks that are found. Nevertheless there are some periodic signals that appear in almost all the analyzed profiles: 100–250 km for the N–S profiles across oceanic plate boundary and 150–250 km where the plate boundary is developed over continental lithospheres. The 2D spectral analysis avoids the problems found in relation to the particular location of the profile but the resulting wavelengths are slightly higher than those obtained from the 1D spectral analysis. The wavelengths estimated for both oceanic and continental lithospheres at the Africa–Eurasia boundary (N250 km) show low values of mean mantle strength (b1013 Pa m). he presence of lithospheric folds means that the continental and oceanic lithospheres are mechanically oupled. This had previously been suggested for Iberia but not for the limit between S Iberia and the Terceira riple Junction. The orientation of the lithospheric folds is NW–SE at the contact between continental lithospheres and NNE–SSW at the contact between oceanic lithospheres. This difference is also reflected in the signal anisotropy and must be related to the rotation of the tectonic stresses in the same direction. A large periodic signal (wavelength N600 km) was also detected both in 1D and 2D spectral results. After drawing the filtered values, the resulting maps indicate that this signal is related to the transition between continental and oceanic lithospheres and to the significant changes in crustal and/or lithospheric thickness from the Mid-Atlantic Ridge to the continental margins of western Eurasia.Item Geophysical characterization of the El Cervunal kame complex (Sierra de Gredos, Iberian Central System): Insight of infill geometry and reconstruction of former glacial formations(Journal of applied geophysics, 2021) Granja Bruña, José Luis; Turu, Valenti; Carrasco González, Rosa María; Muñoz Martín, Alfonso; Ros, Xavier; Fernández Lozano, Javier; Soteres, Rodrigo L.; Karampaglidis, Theodoros; López Saez, José Antonio; De Pedraza Gilsanz, JavierGeological and geophysical studies in complex valley troughs provide a key record for the reconstruction of paleoenvironmental conditions during the Quaternary. Here we present a study of the sedimentary infill of the El Cervunal kame complex or El Cervunal trough (Sierra de Gredos, Iberian Central System) by means of a combined interpretation of near-surface geophysical techniques supported by geomorphological and borehole data. A set of 1D and 2D near-surface geophysical methods, including electrical (Vertical Electrical Sounding and 2D Electrical Resistivity Tomography), seismic (2D Seismic Tomography and 1D Refraction Microtremor) and Magnetic Resonance Sounding techniques, were used to test their applicability in providing better insight on the infill nature and geometry. Because of greater sensitivity and higher resolution and coverage achieved with resistivity methods, the electrical resistivity has proven to be the most informative physical parameter, while seismic and magnetic resonance methods were complementary. The sedimentary infill was classified into three geophysical units and five sub-units with their geological interpretation. Unit 1 consists of a postglacial sedimentary sequence and includes alluvial-plain and alluvial-fan deposits. Units 2 and 3 below the postglacial unit were interpreted as glacial sequences including kame (glacigenetic and fluvio-glacial) and morainic deposits, respectively. Subsoil information combined with the geomorphological data enabled the partial reconstruction of the map-view geometry of the morainic bodies at the El Cervunal trough. The results suggest a complex evolution of the study area where erosive-sedimentary processes dominate, but also structural factors should be considered. At least five well-differentiated stages can be established to explain the occurrence of the trough infill: pre-glacial, maximum glacial extension, trough obturation, glacial retreat and periglacial-postglacial.