Person:
Muñoz Martín, Alfonso

First Name

Alfonso

Last Name

Muñoz Martín

URI

https://hdl.handle.net/20.500.14352/75220

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Geológicas

Department

Geodinámica, Estratigrafía y Paleontología

Area

Geodinámica Interna

Identifiers

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Now showing 1 - 10 of 35

Evolución geodinámica del borde oriental de la cuenca del Tajo desde el Oligoceno hasta la actualidad
(2003) Muñoz Martín, Alfonso; Vicente Muñoz, Gerardo de
La integración y aplicación combinada de técnicas y metodologías clásicas e innovadoras de análisis estructural y tectónico en el borde oriental de la cuenca del tajo, ha permitido establecer su evolución geodinámica en tres etapas principales desde el oligoceno hasta la actualidad, cada una de las cuales esta caracterizada por un campo de paleoesfuerzos de tipo compresivo. Esta evolución ha sido establecida mediante una comparación cuantitativa de los datos de acortamiento calculados en las estructuras, el análisis cinemático y dinámico de las mismas, y la elaboración de los modelos numéricos para comprobar la viabilidad de las hipótesis/propuestas finalmente, se ha realizado una integración de todos estos datos en un modelo evolutivo, incluyendo la revisión de los modelos previos y la evolución cinemática del mediterráneo occidental desde el oligoceno hasta la actualidad.
Salt Diapirs, Salt Brine Seeps, Pockmarks and Surficial Sediment Creep and Slides in the Canary Channel of NW Africa
(Marine geophysical researches, 2003) Acosta Rivera, Juan José; Uchupi, E.; Muñoz Martín, Alfonso; Herranz Araújo, Pedro; Palomo, Carlos; Ballesteros Cózar, María
Circular to elliptical mounds in the Canary Channel with reliefs of 75 to 375 m and diameters of 4 to 8 km partially surrounded by moats with reliefs of 25 to 75 m, were formed by piercement of the seafloor by Mesozoic evaporites. Several long gullies, <1 km wide, with abrupt terminations and pockmarks associated with these mounds were probably eroded by dense brine and hydrocarbon seeps. The salt brines that eroded the gullies were formed where salt diapirs intersect the seafloor, or in the subsurface by circulating ground water heated by igneous activity along the Canary Ridge. If the brines originated in the subsurface they reached the seafloor along faults. Displacement of the surficial sediments by sliding and creep is probably the result of the expulsion of hydrocarbons and/or vertical motion of the Mesozoic evaporites. Microtopographic features along or near the east flank of the Canary Ridge are the creation of uplift of the ridge, hydrothermal activity, mass wasting processes and turbidity currents.
Modelos estructurales de elementos finitos sobre la nucleación de las deformaciones compresivas en la Sierra de Altomira (España Central)
(Revista de la Sociedad Geológica de España, 1999) Muñoz Martín, Alfonso; De Vicente Muñoz, Gerardo
En este trabajo se realizan una serie de modelos estructurales de elementos finitos sobre la geometría en profundidad del cinturón de pliegues y cabalgamientos alpinos de la Sierra de Altomira. El objetivo de estos modelos es comprobar numéricamente la hipótesis de que una geometría en escalón del basamento, asociado a una falla normal, es capaz de nuclear y concentrar las deformaciones de la cobertera situada por encima. La geometría utilizada ha sido un segmento simplificado de un corte geológico equilibrado basado en datos estructurales y geofísicos (gravimetría y perfiles sísmicos de reflexión). Los modelos incluyen tres tipos de materiales: un basamento elástico y resistente indeformado, una cobertera elástica y menos resistente que se desplaza de E a O, y un nivel de despegue poco resistente y al cual se le han supuesto dos tipos de comportamiento mecánico diferentes: a) elástico y b) elástico-plástico. Los dos modelos indican que la presencia del escalón nuclea las deformaciones en la cobertera, concentrando los desplazamientos verticales y los máximos valores de esfuerzo de cizalla. El modelo con nivel de despegue elástico predice una máxima deformación inicial en la cobertera al E de la falla en el basamento. Por el contrario, en el modelo con nivel de despegue elástico-plástico las deformaciones se concentran justo encima del escalón en el basamento, tal y como sugieren los datos geofísicos. Estos resultados amplían y completan el modelo previo (Van Wees, 1994) que asociaba la formación de la Sierra de Altomira con la desaparición de las facies Keuper (Triásico Superior). Lo más probable es que la presencia de la falla en el basamento no sólo controle el espesor de los materiales triásicos y jurásicos, sino también las facies, por lo que ambos factores pueden haber actuado conjuntamente en la nucleación de las deformaciones que dieron lugar a la formación de la Sierra de Altomira.
Estudio de una transversa entre la cuenca de Madrid y la Cordillera Ibérica a partir de datos estructurales, sísmicos y gravimétricos
(Geogaceta, 1995) Perucha, M.A.; Muñoz Martín, Alfonso; Tejero López, Rosa; Bergamín De La Viña, Juan Francisco
An integrated gheophysical and geological study has been carried out along a transverse extending from the Madrid Basin to the Iberian Range. Geological and seismic reflection data were used as background nodel for the gravity modeling. Mesozoic cover structure is characterized by thruss, E dipping associated with a decollement located in triassic beds. Gravity modeling shows that high-angle faults bound basement blocks. The faults control triassic sediment thickness.
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) Carbo Gorosabel, Andrés; Muñoz Martín, Alfonso; Martín Dávila, José; Catalán, Manuel; García, Alicia
La 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.
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.
Caracterización geoeléctrica de los depósitos superficiales en la Antártida Occidental (Isla Livingstone, Islas Shetland del Sur, Antártida Occidental)
(Geogaceta, 2000) Muñoz Martín, Alfonso; Giner Robles, Jorge Luis; González Casado, José Manuel; López Martínez, Jerónimo; Durán Valsero, Juan José; Gumiel, Pablo; Serrano, Enrique
The geophysical study of superficial deposits (mainly gravels) in ice-free areas near the seashore in the South Shetland Islands (Antarctica) allows establishing the possible existence of permafrost and buried ice bodies. In this work we have investigated the internal structure of Quaternary sediments using the resistivity method (vertical electric sounding, V.E.S.), with the purpose of establishing the resistivity values of the different materials and their geometry. We present here the results obtained from 17 vertical electric soundings carried out in Caleta Española, (north coast of Hurd Peninsula), and in the surroundings of Caleta del Glaciar Rocoso (south coast of Hurd Peninsula), both in Livingston Island. Vertical electric soundings interpretation has allowed us to characterise different units from the resistivity values (active layer, permafrost, buried ice, Quaternary deposits and their basement), and to establish the inter-phase between sea water and continental water. Moreover, with the resistivity method we have deduced the spatial distribution of some of these beds. In this way the permafrost (with resistivity values ranging between 13000 and 35000 Ω*m), and the associated active layer, is restrained to shallow depths(< 2 m) and located in the surveyed areas faraway from the seaside (i.e. mainly in the upper raised beaches). Buried ice under coarse Quaternary deposits have resistivity values of one major order magnitude than the permafrost (> 60000 Ω *m) and has been only found in the studied rock glacier.
Gravity analysis offshore the Canary Islands from a systematic survey
(Marine Geophysical Researches, 2003) Carbo Gorosabel, Andrés; Muñoz Martín, Alfonso; Llanes Estrada, María Pilar; Álvarez García, Juan
As part of a systematic mapping program of the Hydrographic and Oceanographic Research Plan for the Spanish Exclusive Economic Zone (EEZ), gravity surveys were carried out offshore the Canary Islands. Using the gravity data collected during cruises between 1998 and 2000 aboard the RV Hesperides and satellite and land data, we construct free air and Bouguer anomaly maps and discuss the geodynamic implications. Using maps of Bouguer anomaly, free air anomaly, vertical derivative, long wavelength Bouguer anomaly and short wavelength anomaly, a detailed description of the gravity characteristics of the archipelago is presented, describing gravity anomalies from a geologic point of view. The character of the crust throughout the studied area has been defined, as well as high gradient zones that limit crustal blocks of different density. High gradient zones have been mapped for the first time and interpreted as fracture zones, taking into account geophysical and geological information. Gravity highs and lows have been studied and related to crustal, mantle and volcanic effects.
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, Juan
Since 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.
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, Carlos
As 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.