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
31 results
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Item Análisis de nuevos datos gravimétricos marinos en el entorno de la Isla Decepción (Islas Shetland del Sur, Antártida)(Revista de la Sociedad Geológica de España, 2001) Carbó Gorosabel, Andrés; Muñoz Martín, Alfonso; Martín Dávila, José; Catalán, Manuel; García, AliciaLa Isla Decepción es la parte emergida de un volcán muy joven y activo. Se encuentra situada en el SO del Estrecho de Bransfield, que separa la Península Antártica de las islas Shetland del Sur. En este trabajo se muestran los resultados del levantamiento gravimétrico realizado en la campaña de investigación geofísica marina DECVOL99 (Diciembre de 1999). El procesado de los 4906 datos seleccionados, obtenidos a lo largo de 48 líneas de navegación, ha permitido la realización de dos mapas de anomalías de Bouguer en el interior y en el exterior de la Isla Decepción. El tratamiento de los datos gravimétricos ha incluido, además de las correcciones habituales, la corrección topográfica terrestre y del fondo marino utilizando una malla de 1 km de lado. Los mapas de anomalías de Bouguer resultantes muestran una serie de anomalías y gradientes gravimétricos bien definidos que, al integrarlos con el resto de información existente, permiten su interpretación desde el punto de vista estructural y tectónico. De este modo las anomalías gravimétricas en el entorno de la Isla Decepción se encuentran definidas por una serie de mínimos y máximos con dos orientaciones principales NE-SO y NO-SE, que se corresponden bien con rasgos morfoestructurales y geofísicos en otros sectores del Estrecho de Bransfield. La mayor parte de los gradientes gravimétricos alargados y con carácter neto pueden ser interpretados como zonas de fractura NO-SE y NE-SO que limitan áreas de máximos y mínimos gravimétricos. Las anomalías positivas de gran longitud de onda constituyen la continuación hacia el SO de la corteza continental de la Isla Livingston, mientras que los máximos gravimétricos de alta frecuencia están asociados a bloques elevados y de alta densidad. Las zonas de mínimos valores de anomalía de Bouguer coinciden con los principales ejes de extensión y máximo relleno de materiales sedimentarios recientes. Las orientaciones y localizaciones de las bandas de alto gradiente gravimétrico permiten su correlación con zonas de fracturas definidas mediante otros datos geofísicos marinos, así como con la batimetría y los datos estructurales medidos en superficie.Item Morphostructure at the junction between the Beata ridge and the Greater Antilles island arc (offshore Hispaniola southern slope)(Tectonophysics, 2014) Granja Bruña, José Luis; Carbó Gorosabel, Andrés; Llanes Estrada, Pilar; Muñoz Martín, AlfonsoOblique convergence between the Caribbean plate's interior and the inactive Greater Antilles island arc has resultedin the collision and impingement of the thickened crust of theBeata ridge into southern Hispaniola Island. Deformation resulting from this convergence changes from a low-angle southward-verging thrust south of easternHispaniola, to collision and uplift in south-central Hispaniola, and to left-lateral transpression along theSouthern peninsula of Haiti in western Hispaniola. Using new swath bathymetry and a dense seismic reflectiongrid, we mapped the morphological, structural and sedimentological Elements of offshore southern Hispaniola.We have identified four morphotectonic provinces: the Dominican sub-basin, the Muertos margin, the Beataridge and the Haiti sub-basin. The lower slope of the Muertos margin is occupied by the active Muertos thrustbelt, which includes several active out-of-sequence thrust faults that, were they to rupture along their entirelength, could generate large-magnitude earthquakes. The interaction of the thrust beltwith the Beata ridge yieldsa huge recess and the imbricate system disappears. The upper slope of the Muertos margin shows hick slopedepositswhere the extensional tectonics and slumping processes predominate. The northern Beata ridge consistsof an asymmetrically uplifted and faulted block of oceanic crust. Our results suggest that the shallower structureand morphology of the northern Beata ridge can be mainly explained by a mechanism of extensional unloadingfrom the Upper Cretaceous onward that is still active residually along the summit of the ridge. The tectonicmodels for the northern Beata ridge involving active reverse strike–slip faults and transpression caused by theoblique convergence between the Beata ridge and the island arc are not supported by the structural interpretation.The eastern Bahoruco slope an old normal fault that acts as a passive tear fault accommodating the sharpalong-strike transition from low-angle thrusting to collision and uplifting.Item Survey explores active tectonics in Northeastern Caribbean(Eos, Transactions American Geophysical Union, 2005) Carbó Gorosabel, Andrés; Córdoba Barba, Diego; Martín Dávila, José; Ten Brink, Uri S.; Herranz Araújo, Pedro; Von Hilldebrant, Christa; Payero, Juan; Muñoz Martín, Alfonso; Pazos, Antonio; Catalán, Manuel; Granja Bruña, José Luis; Gómez Ballesteros, MaríaThere is renewed interest in studying the active and complex northeastern Caribbean plate boundary to better understand subduction zone processes and for earthquake and tsunami hazard assessments [e.g., ten Brink and Lin, 2004; ten Brink et al., 2004; Grindlay et al, 2005]. To study the active tectonics of this plate boundary, the GEOPRICO-DO (Geological, Puerto Rico-Dominican) marine geophysical cruise, carried out between 28 March and 17 April 2005 (Figure 1), studied the active tectonics of this plate boundary. Initial findings from the cruise have revealed a large underwater landslide, and active faults on the seafloor (Figures 2a and 2c). These findings indicate that the islands within this region face a high risk from tsunami hazards, and that local governments should be alerted in order to develop and coordinate possible mitigation strategies. The cruise collected multibeam bathymetry, gravity, magnetic, high-resolution seismic, deep seismic sounding, and multichannel seismic reflection data, which are currently being processed and interpreted (Table 1). In early November 2005, 10 ocean-bottom seismometers (OBS) that had been deployed northeast of Puerto Rico and the Virgin Islands (Figure 1) during the cruise were recovered. These OBS recorded data during the cruise and the local seismicity between April and October 2005.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; Carbó 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 Nueva interpretación del relleno sedimentario de la Cuenca de San Pedro (Offshore de la República Dominicana) en base a nuevos datos sísmicos(Geotemas, 2016) Gorosabel Araus, J.M.; Granja Bruña, José Luis; Carbó Gorosabel, Andrés; Gómez de la Peña, Laura; Rodríguez Zurrunero, Álvaro; Muñoz Martín, Alfonso; Pazos, Antonio; Gómez Ballesteros, María; Druet Vélez, María; Llanes Estrada, PilarLos nuevos datos de sísmica de reflexión multicanal 2D adquiridos en la Cuenca de San Pedro (margen sudeste de la República Dominicana), junto con antiguos perfiles sísmicos reprocesados, han permitido llevar a cabo un detallado análisis y revisión de la estratigrafía sísmica. Los nuevos datos sísmicos aportan nuevas precisiones sobre la evolución de la cuenca sugiriendo un origen de al menos Eoceno Superior, en lugar de Mioceno. La nueva interpretación se basa en la correlación onshore-offshore de un nivel guía de abanicos bien desarrollado, con los eventos tectónicos constreñidos tierra y asociados a la colisión con los Bancos de las Bahamas con el arco isla el Eoceno Medio.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; Carbó Gorosabel, Andrés; Acosta, Juan; Llanes Estrada, 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 Upper crustal structure of Deception Island area (Bransfield Strait, Antarctica) from gravity and magnetic modelling(Antarctic Science, 2005) Muñoz Martín, Alfonso; Catalán Morollón, Manuel; Martín Dávila, José; Carbó Gorosabel, AndrésDeception Island is a young, active volcano located in the south-western part of Bransfield Strait, between the Antarctic Peninsula and the South Shetland archipelago. New gravity and magnetic data, from a marine geophysical cruise (DECVOL-99), were analysed. Forty-eight survey lines were processed and mapped around Deception Island to obtain Bouguer and magnetic anomaly maps. These maps show welldefined groups of gravity and magnetic anomalies, as well as their gradients. To constrain the upper crustal structure, we have performed 2+1/2D forward modelling on three profiles perpendicular to the main anomalies of the area, and taking into account previously published seismic information. From the gravity and magnetic models, two types of crust were identified. These were interpreted as continental crust (located north of Deception Island) and more basic crust (south of Deception Island). The transition between these crustal types is evident in the Bouguer anomaly map as a high gradient area trending NE–SW. Both magnetic and gravity data show a wide minimum at the eastern part of Deception Island, which suggests a very low bulk susceptibility and low density intrusive body. With historical recorded eruptions and thermal and fumarolic fields, we interpret this anomaly as a partially melted intrusive body. Its top has been estimated to be at 1.7 km depth using Euler deconvolution techniques.Item Resultados y experiencias de aplicación del método de Refracción por Microtremor (Sísmica Pasiva) para la investigación geofísica de las nuevas líneas de metro en Madrid (España)(Geogaceta, 2006) Muñoz Martín, Alfonso; Carbó Gorosabel, AndrésGeophysical exploration with seismic methods in urban zones presents several disadvantages: the presence of numerous sources of seismic noise, the scanty penetration when the seismic source is a hammer and the disability to detect buried low-velocity beds. Recently (Louie, 2001) a new method of seismic investigation has been developed, which allows vertical modeling of Raleygh waves from spectral analysis (Vphase/frequency) using the seismic signal registered with conventional seismographs and geophones. This method allows to detect low-velocity buried beds of great interest in tunneling, and to reach depths below 50 meters. In this work we discuss the conditions of application and experiences obtained during the 2005 geophysical surveys carried out in Madrid before the excavation of the new subway tunnels.Item 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; Carbó Gorosabel, Andrés; Acosta, Juan; Llanes Estrada, 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 Modelización gravimétrica de la transición entre corteza continental y oceánica en el margen oeste de Galicia(Geotemas, 2004) Druet Vélez, María; Muñoz Martín, Alfonso; Carbó Gorosabel, Andrés; Álvarez García, Juan; Llanes Estrada, PilarSince 2001 marine gravity data have been collected on the North Atlantic Ocean around Galicia Mar,-,in. The aim of this paper is the analysis of the Bouguer anomaly map of the west margin of Galicia and the modelling of the ocean-continent boundary in this area. Very high Bouguer anomaly values have been obtained for this region, specially in the oceanic trust of the Iberian Abyssal Plain. A gravity low is related to the Galicia Bank continental block, and relative positive elongate highs correspond with the Peridotite Ridge and the Galicia Interior Basin. The two gravity models presented here, based on seismic refraction and reflection profiles, have allowed the characterization of the gravity limit between oceanic and continental trust in this margin. This limit is located 15 km eastwards in the northern profile 1, from the previous proposed limit based on sedimentary criteria.