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 21

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, 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.
Relación entre la complejidad estructural frágil y la distribución espacial de la sismicidad en tres regímenes tectónicos diferentes (Sur de Centro América)
(Geotemas, 2000) Muñoz Martín, Alfonso; Arcila, M.; Pérez López, Raúl; Rodríguez Pascua, Miguel Angel; Vicente Muñoz, Gerardo de
Fracturation process is the main geological mechanism for earthquakes generation as well as their magnitude and spatial distribution. In this work we analyze the correlation among a geometric, cinematic and dynamic fault-slip analysis with the magnitude frequency distribution (Ms) and the epicentral setting into three different tectonic areas. In order to compare all these parameters these areas have the same surface (2°x2°) and a similar number of epicentres. The brittle structural complexity has been defined by means an index which depends on the number of active structures as well as the different type of active faults under the present-day stress tensor. The obtained results seem indicate that a bigger index of brittle structural complexity has a good relationship with an increasing of the "b" value and with a bigger complexity in the spatial distribution of earthquakes defined by the fractal dimension (capacity dimension, Dcap).
Local stress fields and intraplate deformation of Iberia: variations in spatial and temporal interplay of regional stress sources
(Tectonophysics, 1999) Andeweg, Bernd; Vicente Muñoz, Gerardo de; Cloetingh, Sierd; Giner, Jorge; Muñoz Martín, Alfonso
Tertiary to present deformation in the interior of the Iberian Peninsula reflects spatial and temporal variations of the activity of the plate boundaries. Local deformation patterns observed in many of the numerous intraplate Tertiary basins and their borders, such as the Madrid Basin and the Sierra de Altomira, are at first sight incompatible with the regional stress field under which they were formed. We demonstrate, however, that they can be explained as the effect of several stress fields that acted on the Iberian Peninsula from earliest Tertiary onward. Data on local deformation can constrain both magnitudes and directions of forces acting on the plate boundaries of Iberia, enabling us to estimate the relative importance of the different plate driving and deforming mechanisms providing further constraints on the tectonic evolution of Iberia.
Subsidence analysis, maturity modelling and hydrocarbon generation of the Alpine sedimentaty sequence in the MW ofthe Iberian Ranges (Central Spain)
(Cuadernos de geología ibérica, 1996) Ramos, Alfredo; Sopeña, Alfonso; Sánchez-Moya, Yolanda; Muñoz Martín, Alfonso
A partir de los datos geológicos disponibles, se ha realizado la modelización computerizada de la evolución térmica y de la generación de hidrocarburos de la sucesión sedimentaria pérmico-terciaria en el NW de la Cordillera Ibérica. El análisis de la subsidencia indica que existen cuatro estadios diferenciados en la evolución Mesozoica de este área durante el ciclo de sedimentación Alpino. Estas cuatro etapas corresponden al Pérmico superior, Triásico, Jurásico inferior y medio, y Jurásico superior-Cretácico medio. Las diferencias observadas en las curvas de subsidencia tectónica obtenidas, permiten diferenciar cuatro dominios de cxtensión/elevaeión. Estos dominios de extensión/elevación se definen como bloques limitados por fallas donde se han registrado similares procesos extensionales y/o de elevación en un mismo estadio tectónico. Los dominios de extensión/elevación muestran la propagación areal de los procesos tectónicos a través del tiempo. Durante los tresprimeros estadios evolutivos, se produce una extensión gradual a partir de un dominio central hacia el noreste y posteriormente hacia en suroeste. En el estadio CretAcico latendencia de propagación se invierte. El flujo de caloren la base de la sucesióny la historia térmica del área, han sido reconstruidos empleando diferentes modelos de distribución del flujo de calor. La maduración térmica de la materia orgánica ha sido evaluada tentativamente, adoptando diferentes flujos de calor. Los resultados obtenidos se corresponden con los datos hasta ahora conocidos del área.
Finite-element modelling of Tertiary paleostress fields in the eastern part of the Tajo Basin (central Spain)
(Tectonophysics, 1998) Muñoz Martín, Alfonso; Cloetingh, Sierd; Vicente Muñoz, Gerardo de; Andeweg, Bernd
Three subsequent Tertiary paleostress fields that are deduced from fault-slip data for the eastern part of the Tajo Basin are analyzed by finite-element studies. The modelling results show that maximum horizontal stresses (SHmax) are mainly controlled by the geometry of the model limits and the boundary conditions applied. The models are used to test two hypotheses on the origin of the Altomira Range. A local stress field responsible for its formation (‘Altomira') can be modelled successfully by superposition in time and place of two major paleostress fields (‘Iberian' and ‘Guadarrama'). Stress trajectories have been modelled with respect to a homogeneous cover and heterogeneous basement to investigate the role of rheological contrasts between different basement blocks on the orientation of the stress field. Results of this kind of modelling suggest a mechanical decoupling between the cover and the basement, especially for the ‘Altomira' paleostress field.
Análisis tensorial de la deformación superpuesta en el límite oriental de la cuenca de Madrid
(Cadernos do Laboratorio Xeolóxico de Laxe, 1994) Muñoz Martín, Alfonso; Vicente Muñoz, Gerardo de; González Casado, José Manuel
An analysis of Neogene brittle deformation using fault population analysis methods has been carried out between the SW border of the Iberian Range and Altomira Range. Two main paleostress fields have been established: 1) N70E - N120E compression (Altomira paleostress field) ofLate Oligocene - Early Miocene age that induced the formation of the SW border of Iberian Range and Altomira - Pareja thrust belts with reverse and strike-slip faults. 2) N140-N160E compression (Guadarrama paleostress field) of Middle Aragonian - early Pleistocene age that reactivated previous faults with strikeslip movement along the Iberian Range. A superposition of two regional stress fields (Iberian and Guadarrama) is proposed to explain E-W compression that formed Altomira Range. Stress tensorial additions have been realized to check this hypothesis.
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, J.F.
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.
Origen y relación entre las deformaciones y esfuerzos alpinos en la zona centro-oriental de la Península Ibérica
(Revista de la Sociedad Geológica de España, 1998) Muñoz Martín, Alfonso; Vicente Muñoz, Gerardo de
En este trabajo se realiza una correlación entre los principales datos estructurales, cinemáticos, paleogeográficos, y de resultados de modelos de elementos finitos obtenidos en el borde oriental de la Cuenca del Tajo, con numerosos trabajos previos realizados por otros autores. La integración de estas fuentes de información ha permitido establecer una evolución conjunta para el sector centro-oriental de la placa Ibérica en dos episodios principales: a) El primero está relacionado con una fuerte actividad en el margen N de la placa Ibérica, desde los 5 1 Ma hasta los 38 Ma (Eoceno inferior - Oligoceno inferior), en la que se produciría la estructuración Pirenaica principal. Durante este periodo se desarrollarían, relacionados con el antepaís pirenaico, los siguientes cinturones de deformación bajo un campo de esfuerzos general NNE-SSO a NE-SO: la Rama Aragonesa de la Cordillera Ibérica y el sector meridional de la Sierra de Altomira y, en menor medida, la Rama Castellana de la Cordillera Ibérica y el Sistema Central. Durante el Oligoceno superior- Mioceno inferior (entre los 38 Ma y los 24 Ma) se desarrolló una etapa intermedia con actividad tectónica simultánea en los márgenes N y S de la placa Ibérica. Asociada a esta etapa se desarrolló un campo de paleoesfuerzos local compresivo E-O en la zona de antepaís común de los Pirineos y las Béticas, responsable de la estructuración principal de los sectores central y septentrional de la Sierra de Altomira. La Sierra de Altomira se interpreta como un escape o extrusión de la cobertera hacia el O, favorecido por la presencia de niveles incompetentes del Triásico superior. En este periodo comienzó también el desarrollo de la actividad extensiva en el borde oriental de la península en relación a la apertura del Golfo de Valencia. b) Finalmente, durante el Mioceno medio - actualidad, se desarrolla una mayor actividad en el margen S de la placa Ibérica (estructuración de las Cordilleras Béticas), si bien permanece una cierta actividad en el margen N, como lo demuestra la presencia de sismicidad moderada a lo largo del margen Cantábrico-Pirenaico. Durante este periodo se desarrollaron una serie de deformaciones intraplaca en el antepaís Bético bajo un campo de esfuerzos regional NO-SE: El Sistema Central y la Rama Castellana de la Cordillera Ibérica. Este proceso aparece complicado por dos procesos tectónicos que generaron extensión: 1) Al este en relación a los procesos de rifting del Golfo de Valencia, y al oeste de la Cordillera Ibérica, y a partir del Mioceno superior, en relación a flexiones corticales NE-SO transversales a la dirección regional de σ HMAX. [ABSTRACT] A correlation amongst macro and mesostructural analysis results, kinematic and paleogeographic data, paleostresses and finite element models results has been established in the eastern border of the Tajo Basin. This comparison allows us to establish an evolutionary pattern for the central part of the Iberian plate in two main episodes: a) The first one was related to a strong tectonic activity in the northern border of the Iberian plate during the Lower Eocene to the Upper Oligocene (Pirenees uplift). In this period, the following intraplate chains were formed in the Pyrenees foreland under a regional NNE-SSO compressive stress field: the Aragonian Branch of the Iberian Range and the southern part of the Altomira Range, and to a lesser extent, the Castillian Branch of the Iberian Range and the Spanish Central System. During the Upper Oligocene and Lower Miocene a transition between the two main episodes, with tectonic activity in both borders of the Iberian plate (Pyrenees and Betics), took place. Related to this episode a E-O local compressive stress field is developed in the eastern border of the Tajo Basin (Altomira Stress field). This stress field generated a N-S fold and thrust belt west verging that affected the Mesozoic cover. Thus, the Altomira Range is interpreted as a cover extrusion westwards in a regional N-S compression supported by the presence of evaporitic Upper Triassic rocks and the presence of normal basement faults. During this period extension processes in the eastern border of the Iberian plate began associated with the opening of the Valencia Through. b) Finally, from Middle Miocene to Present the main tectonic activity has been developed in the southern border of the Iberian Plate (Betics). However, sorne tectonic activity remained in the northern border of the Iberian plate as it is shown by sorne moderate seismic activity along the Pyrenees and the Cantabrian margino In this period sorne intraplate deformations were developed in the Betic foreland under a NW-SE regional stress field: Spanish Central System and the Castillian Branch of the Iberian Range. This main sketch is complicated by two different extensional processes: 1) doming related to opening of the Valencia Trough, and 2) superficial extension along NE-SO litospheric folding formed perpendicular to the regional Valencia Through. b) Finally, from Middle Miocene to Present the main tectonic activity has been developed in the southern border of the Iberian Plate (Betics). However, sorne tectonic activity remained in the northern border of the Iberian plate as it is shown by sorne moderate seismic activity along the Pyrenees and the Cantabrian margino In this period sorne intraplate deformations were developed in the Betic foreland under a NW-SE regional stress field: Spanish Central System and the Castillian Branch of the Iberian Range. This main sketch is complicated by two different extensional processes: 1) doming related to opening of the Valencia Trough, and 2) superficial extension along NE-SO litospheric folding formed perpendicular to the regional σHMAX.
Determination of present-day stress tensor and neotectonic interval in the Spanish Central System and Madrid Basin, central Spain
(Tectonophysics, 1996) Vicente Muñoz, Gerardo de; Giner, Jorge; Muñoz Martín, Alfonso; González Casado, José Manuel; Lindo, Rubén
A brittle deformation tectonic analysis was performed in central Spain (Spanish Central System and Madrid Basin) in order to decipher and understand the deformation processes that take place in a typical intracontinental zone. 1174 fault slickensides obtained in materials with ages between Late Cretaceous and Quaternary have been analyzed by means of fault population analysis methods to reconstruct paleostress tensors. Nine earthquake focal mechanisms have been determined, with magnitudes ranging between 3 and 4.1. With regard to regional structural features and sedimentary record data, the characteristics of present-day and neotectonic stress fields have been figured out, which determine the neotectonic period for this region. Thus, we have established that the intraplate zone represented by central Spain has been subjected to a stress field from the Middle Miocene until the present-day with a largest horizontal shortening direction (SHMAX) located between N130E and N160E. Finally, three paleostress maps with the main active structures are presented for: (a) Middle Miocene to Late Miocene, the period when the Spanish Central System was mainly formed, (b) Late Miocene to Quaternary, and (c) the present-day stress field, deduced from earthquake focal mechanisms.
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; 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.