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
17 results
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Now showing 1 - 10 of 17
Item Magnetic anomalies of the NW Iberian continental margin and the adjacent abyssal plains(Journal of maps, 2020) Druet Vélez, María; Catalán, Manuel; Martín Dávila, José; Martos, J.M.; Muñoz Martín, Alfonso; Granja Bruña, José LuisThe NW Iberian margin is a hyperextended continental margin, formed during the opening of the North Atlantic Ocean, where a subsequent partial tectonic inversion has undergone during the Alpine Orogeny. This succession of tectonic episodes determines the magnetic signature of the margin. The Spanish Exclusive Economic Zone Project has carried out seven one-month cruises between 2001 and 2009. To extend and densify the spatial coverage, we have used data from the World Digital Magnetic Anomaly Map. Here, we describe the methodology used for the acquisition and data processing of the magnetic field data. The use of diverse instrumentation, a non-complete external field’s cancelation, and the use of different magnetic core field models, contributed to the total error budget. To reduce it, we have used a leveling algorithm which minimizes all these contributions. Finally, a statistical analysis was applied using crossover residuals, showing a resolution better than 28 nT.Item Echo-character distribution in the Cantabrian Margin and the Biscay Abyssal Plain(Journal of maps, 2021) Maestro, Adolfo; Gallastegui, Alba; Moreta, Mercedes; Llave, Estefanía; Bohoyo, Fernando; Druet Vélez, María; Navas, Javier; Mink, Sandra; Fernández Sáenz, Fernando; Catalán, Manuel; Gómez Ballesteros, María; Muñoz Martín, Alfonso; Granja Bruña, José LuisIn 2003, 2006–2009, 2014 and 2015, seven oceanographic cruises were carried out onboard the Spanish R/V Hespérides in the Cantabrian Margin and the adjacent abyssal plains, covering anarea of 219,124 km2. Based on the combined analysis and interpretation of the bathymetric and reflectivity data obtained with multibeam echosounders (SIMRADEM12, EM120 and EM1002), and ultra-high-resolution reflection seismic records acquired with the SIMRAD TOPASPS18 parametric sounder, the mapping of the acoustic facies or echo-character at a scale of 1:1,200,000 has been carried out. Thirty types of echoes have been differentiated and gather into four main groups: Distinct, Irregular, Hyperbolic and Undulated. The echo-character depends on the acoustic response of the shallow sediment and these a bed morphology. Therefore, its analysis and characterization are basic for understanding recent and present-day sedimentary processes.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 Bouguer anomalies of the NW Iberian continental margin and the adjacent abyssal plains(Journal of Maps, 2019) Druet Vélez, María; Muñoz Martín, Alfonso; Granja Bruña, José Luis; Carbo Gorosabel, Andrés; Llanes Estrada, María Pilar; Catalán, Manuel; Maestro, Adolfo; Bohoyo, Fernando; Martín Dávila, JoséThe NW Iberian continental margin has a complex structure, resulting from the succession of several rifting episodes close to a ridge triple junction, and a superimposed partial tectonic inversion stage. The wide-ranging physiography matches the diverse tectonic deformation domains related to its evolution. Each deformation domain has a distinctive gravity signal, so the detailed Bouguer anomaly map presented here is a good first approach to the regional study of the whole margin. Moreover, as the presented chart is a complete Bouguer anomaly map (including terrain corrections), its analysis and interpretation can be done in terms of density, geometry and depth variations below the seafloor. This map is mainly based on the dataset obtained during seven one-month surveys carried out in the frame of the Spanish Economic Exclusive Zone project, and also includes two 2 + 3/4D density models illustrating the deep structure of the margin.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 Along-strike segmentation in the northern Caribbean plate boundary zone (Hispaniola sector): Tectonic implications(Tectonophysics, 2020) Rodríguez Zurrunero, Álvaro; Granja Bruña, José Luis; Muñoz Martín, Alfonso; Leroy, Sylvie; Ten Brink, Uri S.; Gorosabel-Araus, J.M.; Gómez de la Peña, Laura; Druet Vélez, María; Carbo Gorosabel, AndrésThe North American (NOAM) plate converges with the Caribbean (CARIB) plate at a rate of 20.0 ± 0.4 mm/yr. towards 254 ± 1º. Plate convergence is highly oblique (20-10º), resulting in a complex crustal boundary with along-strike segmentation, strain partitioning and microplate tectonics. We study the oblique convergence of the NOAM and CARIB plates between southeastern Cuba to northern Puerto Rico using new swath multibeam bathymetry data and 2D multi-channel seismic profiles. The combined interpretation of marine geophysical data with the seismicity and geodetic data from public databases allow us to perform a regional scale analysis of the shallower structure, the seismotectonics and the slab geometry along the plate boundary. Due to differential rollback between the NOAM oceanic crust north of Puerto Rico and the relative thicker Bahamas Carbonate Province crust north of Hispaniola a slab tear is created at 68.5ºW. The northern margin of Puerto Rico records the oblique high-dip subduction and rollback of the NOAM plate below the island arc. Those processes have resulted in a forearc transpressive tectonics (without strain partitioning), controlled by the Septentrional-Oriente Fault Zone (SOFZ) and the Bunce Fault Zone (BFZ). Meanwhile, in the northern margin of Hispaniola, the collision of the Bahamas Carbonate Province results in high plate coupling with strain partitioning: SOFZ and Northern Hispaniola Deformed Belt (NHDB). In the northern Haitian margin, compression is still relevant since seismicity are mostly associated with the deformation front, whereas strike slip earthquakes are hardly anecdotal. Although in Hispaniola intermediate-depth seismicity should disappear, diffuse intermediate-depth hypocenter remains evidencing the presence of remnant NOAM subducted slab below central and western Hispaniola. Results of this study improve our understanding of the active tectonics in the NE Caribbean that it is the base for future assessment studies on seismic and tsunamigenic hazard.Item Cartografía del ecocarácter del Margen Continental de Galicia y de las llanuras abisales adyacentes(Geotemas, 2021) Maestro, Adolfo; Jane, G.; Fernández Saéz, F.; Llave, E.; Bohoyo, Fernando; Navas, Javier; Mink, Sandra; Druet Vélez, María; Gómez Ballesteros, María; Martín Dávila, José; Catalán, Manuel; Carbo Gorosabel, Andrés; Muñoz Martín, Alfonso; Granja Bruña, José LuisLa cartografía y análisis de las facies acústicas que se determinan a partir de la interpretación y correlación de los perfiles sísmicos de muy alta resolución, es una herramienta muy útil para la caracterización de los procesos sedimentarios recientes y su distribución en ambientes marinos profundos. Este trabajo presenta el primer mapa de ecocarácter del Margen Continental de Galicia y las llanuras abisales adyacentes. El mapa se realizó sobre la base del análisis e interpretación de los datos de batimetría y reflectividad de las ecosondas multihaz SIMRAD EM12, EM120 y EM1002, y los perfiles sísmicos de muy alta resolución de la ecosonda paramétrica SIMRAD TOPAS PS18. Sobre la base de la morfología del fondo marino, la reflectividad y los caracteres del eco acústico, se identificaron 26 tipos de ecos en la secuencia sedimentaria más superficial. Estos tipos de eco se han clasificado en cuatro grupos principales: bien definidos, irregulares, hiperbólicos y ondulados. Esta información ha sido adquirida en el marco del ‘Programa de Investigación Científica de la Zona Económica Exclusiva Española’, coordinado por el Ministerio de Defensa, durante las campañas oceanográficas que se han realizado a bordo del BIO Hespérides del 2001 a 2003 y del 2006 a 2009.Item Radiografía de un margen continental utilizando campos potenciales y espesor de sedimentos: el Margen Atlántico Ibérico(Boletín geológico y minero, 2015) Catalán, M.; Martos, J.M.; Martín-Davila, J.; Muñoz Martín, Alfonso; Carbo Gorosabel, Andrés; Druet Vélez, MaríaEl presente estudio realiza una revisión del estado del conocimiento en el Margen Atlántico Ibérico atendiendo a las tres provincias en las que clásicamente se sub-divide éste: margen gallego, planicie abisal suribérica, y planicie abisal del Tagus, utilizando como fuente de información datos de campos potenciales e información derivada de espesor de sedimentos. Se estudian las características de su basamento, estableciendo límites para la extensión de la corteza continental, y la amplitud del dominio denominado transición océano-continente cuyo fin marca el inicio de la corteza oceánica. La corteza continental en el margen gallego ocupa aproximadamente 210 km, la mayor de las tres provincias, mientras que su zona de transición océano- continente varía ligeramente entre los 65 km en su zona sur y los 56 km más al norte, difiriendo de lo propuesto por otros autores que consideran ronda los 30 km. La situación en la planicie abisal sur-ibérica es aproximadamente la contraria. El dominio continental se extiende menos que en el gallego, aproximadamente unos 60 km, mientras que la zona de transición océano-continente lo hace unos 185 km. El estudio de la planicie abisal del Tagus muestra una evolución morfológica más rápida que las otras dos, registrando a partir del análisis de la variación del factor de adelgazamiento ß una zona de transición océano-continente de aproximadamente 100 km. Los resultados obtenidos apoyarían una naturaleza intermedia a la corteza en prácticamente todo el dominio del Tagus, en contra de lo establecido por otros autores.Item Submarine morpho-structure and active processes along the North American-Caribbean boundary plate (Dominican Republic sector)(Marine Geology, 2019) Rodríguez Zurrunero, Álvaro; Granja Bruña, José Luis; Carbo Gorosabel, Andrés; Muñoz Martín, Alfonso; Gorosabel, José Miguel; Gómez de la Peña, Laura; Gómez Ballesteros, Mª Purificación; Pazos, Antonio; Catalán Morollón, Manuel; Espinosa, S.; Druet Vélez, María; Llanes Estrada, María Pilar; Ten Brink, UriThe northern margin of Hispaniola records the oblique collision/underthrusting of the Bahamas Carbonate Province with the island-arc. Due to the collision, northern Hispaniola has suffered several natural disasters caused by major earthquakes and tsunamis, such as the historic earthquake of 1842, the tsunami caused by earthquake-driven slumping in 1918 in the Mona Passage, the seismic crisis of 1943-1953 with five events of M>7.0 or the seismic crisis of 2003 with a main shock of M6.3 and a large aftershock of M5.3. Using new swath multibeam bathymetry data and vintage single- and multi-channel seismic profiles, we have performed a regional scale analysis and interpretation of the shallow surface and active processes along the northern margin of the Dominican Republic. We have identified three morphostructural provinces: a) the Bahamas Banks, b) the Hispaniola Trench and c) the Insular Margin, which are divided into two tectonic domains, the Collision Domain and Underthrusting Domain. The southern slope of the Bahamas Carbonate Province shows a very irregular morphology produced by active erosive processes and normal dip-slip faulting, evidence of an extensional tectonic regime and margin collapse. This collapse is of major extent in the Oblique Collision Domain where there are erosive and fault escarpments with higher dip-slip fault throws. The Hispaniola Trench, is formed by the Caicos and Hispaniola basins in the underthrusting domain, and by the Santisima Trinidad and Navidad basins in the Oblique Collision Domain. They have a flat seafloor with a sedimentary filling of variable thickness consisting of horizontal or sub-horizontal turbiditic levels. The turbiditic fill mostly proceeds from the island arc through wide channels and canyons, which transports sediment from the shelf and upper slope. The Insular Margin comprises the Insular Shelf and the Insular Slope. The active processes are generated on the Insular Slope where the Northern Hispaniola Deformed Belt is developed. This Deformed Belt shows a very irregular morphology, with a WNW-ESE trending N verging imbricate thrust-and fold system. This system is the result of the adjustment of the oblique collision/underthrusting between the North American plate and the Caribbean plate. In the Oblique Underthrusting Domain the along-strike development of the imbricate system is highly variable forming salients and recesses. This variability is due to along-strike changes in the sediment thickness of the Hispaniola Trench, as well as to the variable topography of the underthrusting Bahamas Carbonate Province. In the Oblique Collision Domain, the morphology of the Insular Slope and the development of the Deformed Belt deeply change. The imbricate system is barely inferred and lies upslope. These changes are due to the active collision of Bahamas Carbonate Province with the Insular Margin where the spurs are indented against the Insular Margin. Throughout the entire area studied, gravitational instabilities have been observed, especially on the Insular Margin and to a lesser extent on the southern slope of the Bahamas Carbonate Province. These instabilities are a direct consequence of the active underthrusting/collision process. We have mapped large individual slumps north of Puerto Plata in the Oblique Underthrusting Domain and zones of major slumps in the Oblique Collision Domain. These evidences of active processes must be considered as near-field sources in future studies on the assessment of tsunami hazards in the region.Item New Gravity Map of the Western Galicia Margin:The Spanish Exclusive Economic Zone Project(Eos, 2004) Carbo Gorosabel, Andrés; Muñoz Martín, Alfonso; Druet Vélez, María; Llanes Estrada, María Pilar; Álvarez García, JuanSince 1995, the most intensive mapping of the seafloor off the Spanish coast has been carried out in the framework of the Spanish Exclusive Economic Zone Project (ZEEE).The main objectives of this project are to obtain improved multibeam bathymetric cartography of the areas off Spanish coastlines, and to perform a geophysical survey,well-suited with a 10-knot navigation velocity (some techniques requires lower navigation velocity). The geophysical survey includes gravity, geomagnetism, and low-penetration seismic techniques in order to infer the geological structure of the seafloor. Other oceanographic variables such as current, surface salinity, and temperature profiles, can be recorded without compromising this systematic survey effort. The ZEEE Project has carried out its survey activities for one month every year.Data acquisition is achieved aboard the Spanish R/V Hesperides. Until 1997, surveying efforts concentrated on the Balearic Sea and Valencia Gulf, both in the western Mediterranean Sea. Between 1998 and 2000, the ZEEE Project investigations were conducted offshore the Canary Archipelago. Since 2001, the third phase of the program has been focused on the West Galicia Margin in the northeastern Atlantic Ocean. Survey results on the West Galicia Margin area are of interest for two key reasons. First, there is great scientific interest in the improvement of the knowledge of this non-volcanic rifting margin, since this margin offers good conditions for the study of the processes that take place in this type of geological context,because it is sediment-starved. Second, the obtained results also have major socioeconomic repercussions because they can prove significant to defining the expansion of the Spanish shelf,beyond Spain’s Economic Exclusive Zone distance of 200 nautical miles. All of the gravity data acquired to date on this area have been stored as a database, with the aim of preparing gravity anomaly maps on a scale 1:200,000.The database and gravity anomaly charts from the ZEEE Project will provide the most coherent and complete gravity perspective available for this area. This article describes the efforts and accomplishments of the project to date.