Person: Granja Bruña, José Luis
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First Name
José Luis
Last Name
Granja Bruña
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 Geodinámica del Borde Noreste de la Placa Caribe(2005) Granja Bruña, José Luis; Carbó Gorosabel, Andrés; Muñoz Martín, AlfonsoEl extremo noreste de la Placa Caribe ha sido estudiado ampliamente desde mediados del XX, lo que nos da una idea del gran interés y expectación que ha despertado. A pesar del gran volumen de trabajo, aún hoy sigue dando lugar a enfrentados debates sobre aspectos tan fundamentales como el contexto tectónico general, la evolución geodinámica y la estructura de la cortical. El gran interés que suscita esta zona se debe a peculiaridades tales como la elevada sismicidad (terremotos y tsunamis históricos), la extrema batimetría, las mayores anomalías gravimétricas La Tierra y la existencia de una extensa plataforma carbonatada basculada uniformemente y sin apenas deformación. Para dar una explicación a este contexto tectónico en el cual se produce la interacción geodinámica de multitud de procesos (rifting, subducción, basculamiento, rotación, desgarres, transpresión y transtensión) se han propuesto diversos modelos tectónicos: subducción oblicua, deformación compartimentada, subducción opuesta (bipolar), arqueamiento, rotación, interacción de microplacas, subsidencia, escape tectónico, tear faults, etc. Los objetivos principales de este trabajo de investigación son: -Presentar un amplio contexto tectónico comenzando desde la Placa Caribe en general, el borde norte de la Placa Caribe y nuestra zona de estudio en el extremo noreste de la Placa Caribe, todo ello a partir de una amplia recopilación bibliográfica y de antecedentes. -Presentar una metodología adaptada, donde sólo se tratan los aspectos necesarios para la presentación de los resultados del trabajo, sin profundizar en los fundamentos metodológicos y dando especial importancia a los métodos de adquisición, instrumentación y procesado básico. -Presentar los trabajos realizados, que van desde la planificación y desarrollo de la campaña Geoprico-do hasta un análisis y discusión de los resultados preliminares de campos potenciales, batimetría, sísmica de reflexión multicanal y sísmica de alta resolución.Item Bivergent thrust wedges surrounding oceanic island arcs: Insight from observations and sandbox models of the northeastern caribbean plate(Geological Society of America Bulletin, 2009) Ten Brink, Uri S.; Marshak, Stephen; Granja Bruña, José LuisAt several localities around the world, thrust belts have developed on both sides of oceanic island arcs (e.g., Java-Timor, Panama, Vanuatu, and the northeastern Caribbean). In these localities, the overall vergence of the backarc thrust belt is opposite to that of the forearc thrust belt. For example, in the northeastern Caribbean, a north-verging accretionary prism lies to the north of the Eastern Greater Antilles arc (Hispaniola and Puerto Rico), whereas a south-verging thrust belt called the Muertos thrust belt lies to the south. Researchers have attributed such bivergent geometry to several processes, including: reversal of subduction polarity; subduction-driven mantle flow; stress transmission across the arc; gravitational spreading of the arc; and magmatic inflation within the arc. New observations of deformational features in the Muertos thrust belt and of fault geometries produced in sandbox kinematic models, along with examination of published studies of island arcs, lead to the conclusion that the bivergence of thrusting in island arcs can develop without reversal of subduction polarity, without subarc mantle flow, and without magmatic inflation. We suggest that the Eastern Greater Antilles arc and comparable arcs are simply crustalscale bivergent (or "doubly vergent") thrust wedges formed during unidirectional subduction. Sandbox kinematic modeling suggests, in addition, that a broad retrowedge containing an imbricate fan of thrusts develops only where the arc behaves relatively rigidly. In such cases, the arc acts as a backstop that transmits compressive stress into the backarc region. Further, modeling shows that when arcs behave as rigid blocks, the strike-slip component of oblique convergence is accommodated entirely within the prowedge and the arc-the retrowedge hosts only dip-slip faulting ("frontal thrusting"). The existence of large retrowedges and the distribution of faulting in an island arc may, therefore, be evidence that the arc is relatively rigid. The rigidity of an island arc may arise from its mafi c composition and has implications for seismic-hazard analysis.Item Geodinámica del borde sur de las Antillas mayores orientales(2009) Granja Bruña, José Luis; Carbó Gorosabel, Andrés; Muñoz Martín, AlfonsoEl presente trabajo de investigación desarrolla un estudio sobre la tectónica del Borde Sur de las Antillas Mayores orientales, concretamente analiza y discute la geodinámica del Borde de los Muertos en del contexto del NE de la placa del Caribe. El estudio sigue una metodología y un desarrollo experimental en los cuales se han integrado diferentes fuentes datos y técnicas geofísicas. La integración de los resultados obtenidos por todas estas técnicas ha permitido constreñir una serie de modelos análogos y geofísicos para contrastar diferentes hipótesis geodinámicas. La principal conclusión de este trabajo de investigación es la obtención de una hipótesis alternativa para el NE del Caribe que explica el origen del Borde de los Muertos, así como su evolución cinemática y dinámica. Según esta hipótesis el desarrollo del Borde de los Muertos se puede explicar en ausencia de un proceso de subducción. Los principales elementos de esta hipótesis son: El basamento del arco isla inactivo presenta un comportamiento relativamente más rígido que los prismas deformados en ambos lados del arco. La colisión de los Bancos de las Bahamas con el arco isla genera un acoplamiento en la zona de contacto que favorece la transmisión de los esfuerzos compresivos al retroarco. La componente lateral de la subducción oblicua se acomoda mediante una deformación compartimentada en el antearco y en las partes internas del arco isla, y no se transmite al retroarco. Los resultados del presente trabajo integrados con los modelos evolutivos y la edad de la deformación en el NE del Caribe sugieren que el origen del Borde de los Muertos tiene lugar en el Eoceno Medio, en relación con el comienzo de la colisión de los Bancos de las Bahamas con el Arco Isla, y se prolonga hasta la actualidad.Item Análisis de Mapas de Anomalías Gravimétricas en el Borde NE de la Placa Caribe(2006) Granja Bruña, José Luis; Carbo Gorosabel, Andrés; Muñoz Martín, AlfonsoAlong the Eastern Greater Antilles (Hispaniola and Puerto Rico area) takes place the interaction between the Caribbean and North-American plates. This interaction produced inside a broad band of deformation with a complex and active tectonics. Here, many tectonic models have been proposed: strain partitioning, microplates tectonics, oblique subduction, opposing subducted slabs, crust arching, and tear fault in the downgoing plate. Except the seismological data that provide a general idea about the disposition of the lithospherics plates in depth, the most of models has been proposed from geodetic data (GPS), geological surface data (onland and onsea) and refection seismic data, so the models are constrained only in the superficial crust. In this survey, an analysis of anomaly gravity maps is presented. Those maps have been realized from the gravity data acquired during the PRICO (1997) and GEOPRICO-DO (2005) marine geophysical surveys, on-land data and satellite gravity data. In the maps analysis we emphasize the extreme values of Bouguer gravity anomaly (-400 mGals) located in the oceanic crust of the North American plate and the maximum free air gravity anomaly of the Earth (-350 mGals) located in the Puerto Rico Trench. This analysis, integrated with geomagnetic, seismologic and deep seismic sounding data is the way to approach the study of deep crust and to can elaborate lithosphere models constrained in depth.Item Cinturón Deformado de Los Muertos (Noreste de la Placa Caribe): Análisis Morfotectónico y Procesos Activos.(2006) Granja Bruña, José Luis; Carbo Gorosabel, Andrés; Muñoz Martín, Alfonso; Gómez Ballesteros, MaríaThe Muertos Deformed Belt (MDB) is a tectonic feature located within the Northeastern Caribbean Plate Boundary Zone. This deformed belt is occupying a broad band of active compression regime with an east-west trend along the south of Hispaniola and Puerto Rico islands. In our survey area, the deformed belt is limited to the south by the Muertos Trough (>5500 m depth), where the Venezuelan Basin oceanic crust is being underthrusted beneath western Puerto Rico and eastern Hispaniola areas. Here, we present the morphotectonic interpretation from the multibeam systematic survey in Muertos Deformed Belt area (from GEOPRICO-DO marine geophysical survey (2005)) and the relationship with seismicity and kinematic data (GPS). Active deformation features have been widely found in the area from bathymetry model and Chirp sub-bottom seismic profiles (TOPAS). These features include: folded and faulted recent sediments (Holocene), submarine landslides scars associated with faults (tsunamogenic potential) and submarine canyons deflected by fault traces. All these features are well preserved and show a little erosion. Future works will integrate potential field data and deep seismic data, which will allow us to elaborate complete tectonic models for this active and complex plate boundary.Item Morphotectonics of the central Muertos thrust belt and Muertos Trough (northeastern Caribbean)(Marine Geology, 2009) Granja Bruña, José Luis; Ten Brink, Uri S.; Carbo Gorosabel, Andrés; Muñoz Martín, Alfonso; Gómez Ballesteros, MaríaMultibeam bathymetry data acquired during the 2005 Spanish R/V Hespérides cruise and reprocessed multichannel seismic profiles provide the basis for the analysis of the morphology and deformation in the central Muertos Trough and Muertos thrust belt. The Muertos Trough is an elongated basin developed where the Venezuelan Basin crust is thrusted under the Muertos fold-and-thrust belt. Structural variations along the Muertos Trough are suggested to be a consequence of the overburden of the asymmetrical thrust belt and by the variable nature of the Venezuelan Basin crust along the margin. The insular slope can be divided into three east–west trending slope provinces with high lateral variability which correspond to different accretion stages: 1) The lower slope is composed of an active sequence of imbricate thrust slices and closed fold axes, which form short and narrow accretionary ridges and elongated slope basins; 2) The middle slope shows a less active imbricate structure resulting in lower superficial deformation and bigger slope basins; 3) The upper slope comprises the talus region and extended terraces burying an island arc basement and an inactive imbricate structure. The talus region is characterized by a dense drainage network that transports turbidite flows from the islands and their surrounding carbonate platform areas to the slope basins and sometimes to the trough. In the survey area the accommodation of the ongoing east–west differential motion between the Hispaniola and the Puerto Rico–Virgin Islands blocks takes place by means of diffuse deformation. The asymmetrical development of the thrust belt is not related to the geological conditions in the foreland, but rather may be caused by variations in the geometry and movement of the backstop. The map-view curves of the thrust belt and the symmetry of the recesses suggest a main north–south convergence along the Muertos margin. The western end of the Investigator Fault Zone comprises a broad band of active normal faults which result in high instability of the upper insular slope.Item Survey explores active tectonics in Northeastern Caribbean(Eos, Transactions American Geophysical Union, 2005) Carbo 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.