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
7 results
Search Results
Now showing 1 - 7 of 7
Item Alboran basin, Southern Spain. Part II: Neogene tectonic implications for the orogenic float model(Marine and Petroleum Geology, 2008) Gómez Ballesteros, María; Rivera, Jesus; Muñoz, Araceli; Muñoz Martín, Alfonso; Acosta, Juan; Carbo Gorosabel, Andrés; Uchupi, E.We infer that the Alboran Basin, the first western Mediterranean Basin found after crossing Gibraltar, is an orogenic float underlained by a de´ collement system, a multi-layered ductile shear extending from 10km to between 30 and 40km below sea level. This float was formed as consequence of the collision of the African–Eurasian plates in the Oligocene–late Miocene. Synchronous with this compression the float experienced basin wide crustal thinning and subsidence about 25 m/year ago by subcrustal processes. Since latest Miocene the float has undergone compression due to the continuous convergence of Eurasia and Africa. The faults created as a result of this compression are dominated by a conjugate system of northeast trending left-lateral and northwest right-lateral strike–slip faults. This deformation is taking place under a simple shear mechanism. Associated with the northwest and northeast lateral faults are zones of compression trending west and east of north extending from the base of the basin’s north upper slope to the Alboran Ridge. The initial morphology of the Alboran Ridge on the southern side of the Alboran Basin was due to the construction of a volcanic edifice at the northeast end of the ridge and igneous activity along northeast trending fractures southwest of the edifice. At the northeast end of the Alboran Ridge motion along a right-lateral fault cutting across the ridge led to sediment collapse and the creation of a prominent embayment on the ridge’s northwest flank. Deformation is more subdued in the western than in the eastern part of the Alboran Basin, a tectonic style due either to differences in sediment rheology or that the accommodation of the convergence of Africa and Iberia is more diffused and attenuated in the west than in the east.Item Sea floor morphology and Plio-Quaternary sedimentary cover of the Mallorca Channel, Balearic Islands, western Mediterranean(Marine Geology, 2004) Acosta, Juan; Canals, Miquel; Carbo Gorosabel, Andrés; Muñoz, Araceli; Urgeles, R.; Muñoz Martín, Alfonso; Uchupi, E.A complete multibeam coverage of the sea floor of Mallorca Channel, in the western Mediterranean, was recorded during the Spanish Exclusive Economic Zone surveys in 1995, 1996 and 1997. These data, combined with previous high-resolution seismic reflection profiles, allow an assessment of the geomorphology of the area. The channel seafloor is disrupted by a fault complex and pockmarks. Motion along the faults split the sea floor into a series of undulations separated by narrow V-shaped notches. Faulting may be a consequence of recent seaward gravitational sliding that occurred along a soft surface at the top of a late Messinian–early Pliocene unit and a late Messinian evaporite. These units have been tilted during recent subsidence of the Mallorca Channel at the same time that the insular shelf was uplifted along a fault at the shelf’s edge. The set of pockmarks in the channel sequence were probably formed by the expulsion of gas of hydrothermal origin, and expulsion may have been enhanced by the faulting. This gas seepage could be an additional factor leading to sediment instability.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 Crustal structure and continent?ocean boundary along the Galicia continental margin (NW Iberia): insights from combined gravity and seismic interpretation(Tectonics, 2018) Druet Vélez, María; Muñoz Martín, Alfonso; Granja Bruña, José Luis; Carbo Gorosabel, Andrés; Acosta, Juan; Llanes Estrada, María Pilar; Ercilla, GemmaThe magma?poor rifted continental margin of Galicia has an extremely complex structure. Its formation involved several rifting episodes that occurred ultimately during the early Cretaceous near a ridge triple junction, which produced a change in the orientation of the main structures in its transition to the north Iberia margin. In addition, there is a superimposed partial tectonic inversion along its northwest and northern border which developed from the Late Cretaceous to at least Oligocene times. The present study integrates a large volume of new geophysical information (mainly marine gravity data and 2D seismic reflection profiles) to provide insights on the formation of this rift system and on the development of its later inversion. The combined interpretation and modeling of this data enable the presentation of a new crustal and structural domains map for the whole Galicia margin. This includes the rift domains related to the extreme thinning of the crust and the lithospheric mantle (stretched, necking, and hyperextension and mantle exhumation (HME) domains), as well as a domain of intense compressional deformation. New constraints arise on the origin, the deep structure, and the characterization of the along? and across?strike variation of the continent?ocean transition of the margin, where a progressive change from hyperextension to partial inversion is observed. The development of both rifting and later partial tectonic inversion is influenced by the existence of former first?order tectonic features. Most of the tectonic inversion is focused on the HME domain, which in some areas of the northwestern margin is completely overprinted by compressional deformation.Item Cartografía de dominios litosféricos y estilo de deformación en el margen continental de Galicia (margen noroeste de la Península Ibérica)(Geotemas, 2016) Druet Vélez, María; Muñoz Martín, Alfonso; Granja Bruña, José Luis; Carbo Gorosabel, Andrés; Acosta, Juan; Llanes Estrada, María Pilar; Ercilla, GemmaEl margen continental de Galicia presenta una estructura muy compleja, debido a dos efectos principales. Por un lado, se trata de un margen de rift pobre en magma, generado en las proximidades del punto triple R-R-R que dio lugar a la apertura simultánea del Océano Atlántico y el golfo de Vizcaya durante el Cretácico. Por otra parte, el régimen de esfuerzos compresivo Cenozoico generó la inversión parcial del margen continental hacia el norte y el noroeste, aportando una mayor complejidad estructural. En este trabajo hemos realizado un análisis detallado de la nueva información gravimétrica y batimétrica obtenida durante las campañas del Proyecto ZEE, así como de nuevos perfiles de sísmica de reflexión multicanal procedentes del Proyecto ERGAP. Presentamos aquí parte de los resultados de este análisis conjunto de toda la información geofísica y geológica disponible, consistentes en una cartografía continua de los diferentes dominios litosféricos y del tipo de deformación que los afectan, desde el margen oeste de la Península Ibérica hasta el margen norte.Item Geological evolution of the volcanic island La Gomera, Canary Islands, from analysis of its geomorphology(Marine geology, 2009) Llanes Estrada, María Pilar; Herrera, R.; Gómez, M.; Muñoz Martín, Alfonso; Acosta, Juan; Uchupi, E.; Smith, D.Erosion and landslide processes played an important role in shaping the geomorphology of the Canary Islands. But for the heavily eroded La Gomera Island, those processes have been unclear. We conducted an integrated study of its offshore extension, onshore geology, and links between them in order to determine the geomorphological evolution of the island relative to the rest of the archipelago. The characteristics of the island's barrancos and its interfluves have led us to differentiate four types of morphological areas whose fluvial networks are in different stages of evolution. Those barrancos offshore are interrupted by La Gomera's shelf, and its erosion has been much greater than for the rest of the Canary Islands. Such erosion is both a function of time and varied swell action. La Gomera's insular slope is carved by a system of submarine canyons and channels that have morphology indicative of turbidity current erosion. Many of the barrancos onshore and the canyons offshore have steps or knickpoints: some are the result of varied resistance to erosion, and others are explained by other mechanisms. A ridge whose crest is covered by cone-like shape structures is interpreted as of volcanic origin, with the particularity that it lacks onshore continuation, the opposite of what has been observed elsewhere in the Canary Islands. Also in contrast with the other islands of the archipelago, La Gomera's margin does not seem to have resulted from destructive mass wasting and the only offshore sign of catastrophic events are the presence of two embayments along La Gomera's northern shelf edge and a lobe structure on the insular apron at 3000 m depth. These features may be the remains of the catastrophic failures that took place on the island 9.4-8.7 Ma ago. Alternatively, they could be due to recent catastrophic failures on the upper slope due to sediment steeping. Since the conclusion of the main volcanic activity 4.0 Ma ago, La Gomera has been intensively eroded by gradual fluvial denudation and secondary failures. La Gomera's insular margin reveals much regarding its evolution, but more comprehensive studies including seismic and coring are needed to understand its whole geological history.Item Morphological and structural analysis in the Anaga offshore massif, Canary Islands: fractures and debris avalanches relationships(Marine Geophysical Researches, 2003) Llanes Estrada, María Pilar; Muñoz, Araceli; Muñoz Martín, Alfonso; Acosta, Juan; Herranz Araújo, Pedro; Carbo Gorosabel, Andrés; Palomo, CarlosAs part of the ‘National Hydrographic and Oceanographic Research Plan for the Spanish Exclusive Economic Zone’, multibeam bathymetry and seismic reflection profiles were obtained in the Canary Islands aboard the R/V Hespérides. The submarine flanks of the Anaga offshore extension of Tenerife Island are here studied to analyze its geomorphology. In the north sector of the Anaga submarine massif, the extension of the Anaga Debris Avalanche has been mapped for the first time, and a volume of 36 km3 was calculated. The relationship between the Anaga and Orotava Debris Avalanches is also described. Faulting has been recognized as a key process for the occurrence of debris avalanches and the growth of volcanic lineaments. Moreover, faulting affects previous structures and the channelling of debris flows. Structural analysis shows the typical radial pattern of an oceanic island. In addition, a NE-SW dominant direction of faulting was obtained, consistent with the Tenerife Island structural trend seen in the Anaga Massif and Cordillera Dorsal. NW-SE and E-W are two other main trends seen in the area. Special interest is manifest in two long faults: ‘Santa Cruz Fault’ bounds the southern edge of Anaga offshore Massif with a length of 50 km and a direction that changes from NE-SW to almost E-W. The Güimar Debris Avalanche was probably channeled by this fault. The ‘Guayotá Fault’ was recognized in several seismic profiles with a N-S direction that changes towards NW-SE at its southern end. This fault affects the more recent sediments with a vertical offset of 25–30 m, along 60 km. It has been interpreted as a transpressive strike-slip fault.