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
4 results
Search Results
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Item The Spanish-Portuguese Central System: An Example of Intense Intraplate Deformation and Strain Partitioning(Tectonics, 2018) De Vicente Muñoz, Gerardo; Cunha, P.P.; Muñoz Martín, Alfonso; Cloetingh, S.A.P.L.; Olaiz Campos, Antonio José; Vegas, RamónThe intraplate deformation of Iberia during the Cenozoic produced a series of ranges and deformation belts with a wide variety of structural trends. The Spanish-Portuguese Central System is the most prominent feature crossing over the whole of central Iberia. It is a large thick-skinned crustal pop-up with NE-SW to E-W thrusts. However, the 500-km-long left-lateral strike-slip Messejana-Plasencia fault, also NE-SW oriented, bends these thrusts to produce NE-SW local paleostresses close to the fault, which seems to be consistent with a common deformational arrangement. This is also supported by the similar sedimentary infilling characteristics found in the surrounding Cenozoic basins. The moment of the maximum intraplate deformation is registered at the same time in all these basins during the upper Priabonian-lower Chattian. As there are two possible sources for the intraplate compressive stresses, the Pyrenean (N-S shortening) orogen to the north and the Betic (NW-SE shortening) orogen to the south, neither can simply explain both simultaneous movements (NE-SW strike-slip and NE-SW thrusting). The deduced age of the main deformation indicates a Pyrenean origin. In contrast, the concept of strain partitioning between the two types of faults gives as a result an overall north trending compression. Existing data do not support crustal detachment from the Betics neither from the Pyrenees but are consistent with a crustal uplift related to lithospheric folding. The subsequent Betic-related stress field only slightly reworked previously Pyrenean-related structures, except for the Portuguese sector, where tectonic activity occurred mainly in the Upper Miocene.Item 3D crustal-scale structure of the West Iberia margin: a novel approach to integrated structural characterization of passive margins(Marine geophysical researches, 2021) Granado, Cristina; Muñoz Martín, Alfonso; Olaiz Campos, J. A.; Fernández, Oscar; Druet Vélez, MaríaHyperextended margins are very heterogeneous along the entire length of the margin, so the definition of tectonic domains made exclusively from 2D seismic sections presents serious limitations. In this work we present an approach of the 3D crustal-scale structure of the West Iberia margin (WIM) by modelling eight lithospheric sections, using seismic, wells and gravity data. The continuous nature of gravity data allowed us to propose a new map of tectonic domains within the WIM. Maps of total horizontal (THD) and vertical gradients (dZ) of Bouguer anomaly have been calculated and compared with other criteria such as the crustal structure and thinning factor. This comparative analysis has been carried out on a section proposed as a model for the Western Iberian Margin (Tugend et al. in Tectonics, 2014; Cadenas et al. in Tectonics 37:758–785, 2018), and on four 2 + 1/2D gravimetric models transversal to the margin. The results point out a significant variation in the absolute values of Bouguer anomaly, thinning factor and crustal structure along the margin and, therefore, of the position of the different domain boundaries. Clear patterns that correlating the Bouguer anomaly signal and its derivatives to the tectonic domain are evidenced. Most significantly, the necking-zone and its transition to the hyperextended domain are characterized by high values of the THD of the Bouguer anomaly. The observed patterns in Bouguer anomaly and its derivatives provide a solid constraint for mapping the boundaries between different tectonic domains along the margin, even in those areas where limited deep seismic information could lead to uncertain interpretations. The results of this work can also inform on the general kinematics of the WIM.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; Insúa Arévalo, Juan Miguel; Vicente Muñoz, Gerardo de; Martínez Díaz, José J.; 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.Item Iberia, a natural laboratory for the quantification of the large scale erosional response to the fluvial capture processes(8º Congresso Nacional de Geomorfologia - Geomorfologia 2017, Congresso Nacional de Geomorfologia (8. 2017. Porto), 2017) Antón López, Loreto; Muñoz Martín, Alfonso; De Vicente, Gerardo; Alberto Gomes, António; Teixeira, José; Soares, LauraDue to its geological location and diversity, Iberia is a key natural laboratory for the study of tectonic and geological processes. Within those it is especially suitable for the study of large-scale fluvial capture processes, and their influence on topography and landscape evolution. Nowadays, Iberia is characterized by the presence of highly elevated extensive flat surfaces (Iberian Mesetas). Those high plains correspond to planation surfaces developed mainly on Palaeozoic and Mesozoic rocks, and sedimentation surfaces of Neogene rocks. These last mostly represent the sedimentary deposits related to infill of the, formerly closed Foreland Basins. Three main rivers (Duero, Ebro and Tajo) which watersheds cover an area over 250 km2, drain almost half of the total Iberia surface. For these basins the development of the present-day drainage network was related to the opening of formerly closed fluvial systems, developed within ancient Cenozoic basins. In The Iberian Peninsula, the signature of that change in drainage conditions is still preserved in some areas, and can be studied through the analysis of longitudinal profiles shapes and the relief characterization. The analysis of present and former topography represents a powerful qualitative tool for a relative quantification of fluvial dissection and basin denudation, allowing to illustrate the spatial distribution of surface erosion, associated to the exorheic history of the basins. This work approaches the analysis of the denudation processes for the main formerly endorheic Iberian basins.