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
44 results
Search Results
Now showing 1 - 10 of 44
Item Glacial geomorphology of the High Gredos Massif: Gredos and Pinar valleys (Iberian Central System, Spain)(Journal of Maps, 2020) Carrasco González, Rosa María; Soteres, Rodrigo L.; De Pedraza Gilsanz, Javier; Fernandez-Lozano, Javier; Turu, Valentí; López-Sáez, Jose Antonio; Karampaglidis, Theodoros; Granja Bruña, José Luis; Muñoz Martín, AlfonsoWe present a detailed geomorphological map of the landform assemblages originated by the two major paleoglaciers of the Sierra de Gredos mountain range in the Spanish Iberian Central System. Based on previous works, our map focused on the features formed by Gredos and Pinar paleoglaciers during the last glaciation and subsequent glacial events. Based on a remote sensing analysis and exhaustive field surveys, we identified with great accuracy the local distribution of glacial, periglacial, mass movement, structural, fluvial, and lacustrine features. We recognized three main glacial geomorphological formations representing: (i) the maximum glacial extension reached (peripheral deposits); (ii) the culmination of glacial conditions (principal moraines) and (iii) the local glacial withdrawal (internal deposits). Our map offers a renewed spatial framework on which to conduct higher-resolution glacial chronologies, especially of Late Glacial and Holocene glacial activity, providing key information for performing future paleoclimatic reconstructions of the northern hemisphere mid-latitudes.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 Análisis de los esfuerzos tectónicos de la crisis sísmica de 2010 en Haití(Geogaceta, 2014) López Cuesta, Víctor; Muñoz Martín, Alfonso; Granja Bruña, José LuisEl evento de Mw=7 del 12 de enero 2010 provocó una crisis sísmica en el sur de Haití, que duró 3 meses. Se ha realizado un análisis de inversión de esfuerzos de los mecanismos focales del evento principal y 50 réplicas. El evento principal fue generado por un falla de buzamiento 64ºN y dirección N084Eº con una componente principal de deslizamiento lateral-izquierda y una componente inversa. Las réplicas se han generado por fallas inversas puras ENE-OSO situadas en la zona de interacción entre estructuras compresivas orientadas NO-SE y de desgarre orientadas E-O. Estas réplicas han sido activadas por un régimen de esfuerzos compresivo uniaxial muy homogéneo orientado con σ1 horizontal según N017ºE ±10º. La ausencia de ruptura en superficie indica que el origen de las réplicas son fallas ciegas orientadas N097º-117ºE. Los datos de deformación superficial intersísmica obtenidos a partir de velocidades derivadas de GPS para la zona epicentral muestran una desviación angular de ≈30º respecto a la orientación de σ1 obtenidos del análisis de esfuerzos. Esta desviación sugiere que una parte significativa de la energía elástica acumulada a lo largo de las estructuras de tendencia E-O no fue liberada durante la crisis sísmica de 2010.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 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 The Prados del Cervunal morainic complex: Evidence of a MIS 2 glaciation in the Iberian Central System synchronous to the global LGM(Quaternary Science Reviews, 2023) Carrasco, R.M.; Turu, V.; Soteres, R. L.; Fernández-Lozano, J.; Karampaglidis, T.; Rodés, A.; Ros, X.; De Andrés De Pablo, Nuria; Granja Bruña, José Luis; Muñoz Martín, Alfonso; López-Sáez, J.A.; Braucher, R.; De Pedraza Gilsanz, Javier; Palacios Estremera, David; ASTER TeamThe area of Prados del Cervunal (PC) is an intra-morainic topographic depression located at 1800 m asl in the divide or interfluve between Garganta de Gredos and Garganta del Pinar valleys (Central Gredos; Iberian Central System, ICS). Both valleys, along with the adjacent Hoya Nevada, were occupied by glaciers during the Upper Pleistocene, leading to the development of the Prados del Cervunal moraine complexes studied in this work. Using cartographic methods and morphostratigraphic analysis, the three main glacial formations established in the Regional Chrono-Evolutionary Pattern for the ICS, Peripheral Deposits (PD), Principal Moraine (PM) and Internal Deposits (ID), have been identified and mapped in this area. The chronology of these formations has been implemented by Cosmic Ray Exposure (CRE) techniques using 10Be (new data) and 26Cl (previous data, recalculated in this work) in samples from morainic boulders. With these data, the following chrono-evolutionary sequence has been established: (stage 1) local-Maximum Ice Extent (MIE), dated in 25.0 ± 1.4 ka and corresponding to the maximum age obtained in these paleoglaciers; (stage 2) period of oscillations around the MIE, corresponding to the development of the PD Formation between ~25 ka and ~21 ka; (stage 3) period of readvance and stabilisation, dated after ~21 ka (average age obtained for the PD moraines attached to PM moraines) and previous to ~18 (minimum age obtained for a main crest of the PM formation); and (stage 4) onset of deglaciation dated around to ~18 ka (average of ages obtained for the first main crest of the ID formation). During the stages of maximum ice expansion, these three glaciers formed an Ice field whose tongues were interconnected on the PC flat by an ice transfluence system (stages 1 and 2, Plateau Glacier Period). In later stages, the ice masses were partitioned, giving rise to valley glaciers and large moraines forming morainic complexes like those of PC (stages 2, 3 and 4, Valley Glaciers Period). The local MIE and onset of deglaciation stages in this area show a good fit with the ages stablished to global level for the global Last Glacial Maximum (LGM) and the onset of the Last Glacial Termination (Termination I). They also show good correlation at local (with other areas of the ICS), peninsular (with other Iberian mountains) and continental (some areas of the Alps and mountains of Central Europe) level. Finally, this evolutionary sequence and its correlations allowed us to adjust and validate some units of the Regional Chrono-Evolutionary Pattern model and propose the Gredos-Pinar-Cabeza Nevada glacial system as benchmark for the glaciation of Marine Isotope Stage (MIS) 2 in the Iberian Peninsula.Item Contrasting catastrophic eruptions predicted by different intrusion and collapse scenarios(Scientific Reports, 2018) Rincón, Marta; Márquez González, Álvaro; Herrera, Raquel; Alonso Torres, A.; Granja Bruña, José Luis; Wyk de Vries, Benjamin vanCatastrophic volcanic eruptions triggered by landslide collapses can jet upwards or blast sideways. Magma intrusion is related to both landslide-triggered eruptive scenarios (lateral or vertical), but it is not clear how such different responses are produced, nor if any precursor can be used for forecasting them. We approach this problem with physical analogue modelling enhanced with X-ray Multiple Detector Computed Tomography scanning, used to track evolution of internal intrusion, and its related faulting and surface deformation. We find that intrusions produce three different volcano deformation patterns, one of them involving asymmetric intrusion and deformation, with the early development of a listric slump fault producing pronounced slippage of one sector. This previously undescribed early deep potential slip surface provides a unified explanation for the two different eruptive scenarios (lateral vs. vertical). Lateral blast only occurs in flank collapse when the intrusion has risen into the sliding block. Otherwise, vertical rather than lateral expansion of magma is promoted by summit dilatation and flank buttressing. The distinctive surface deformation evolution detected opens the possibility to forecast the possible eruptive scenarios: laterally directed blast should only be expected when surface deformation begins to develop oblique to the first major fault.Item BRAVOSEIS: Geophysical investigation of rifting and volcanism in the Bransfield strait, Antarctica(Journal of South American Earth Sciences, 2020) Almendros, J.; Wilcock, W.; Soule, D.; Teixidó, T.; Vizcaíno, L.; Ardanaz, O.; Granja Bruña, José Luis; Martín Jiménez, D.; Yuan, X.; Heit, B.; Schmidt-Aursch, M.C.; Geissler, W.; Dziak, R.; Carrión, F.; Ontiveros, A.; Abella, R.; Carmona, E.; Agüí Fernández, J.F.; Sánchez, N.; Serrano, I.; Davoli, R.; Krauss, Z.; Kidiwela, M.; Schmahl, L.The Bransfield Basin is a back-arc basin located in Western Antarctica between the South Shetland Islands and Antarctic Peninsula. Although the subduction of the Phoenix plate under the South Shetland block has ceased, extension continues through a combination of slab rollback and transtensional motions between the Scotia and Antarctic plates. This process has created a continental rift in the basin, interleaved with volcanic islands and seamounts, which may be near the transition from rifting to seafloor spreading. In the framework of the BRAVOSEIS project (2017–2020), we deployed a dense amphibious seismic network in the Bransfield Strait comprising 15 land stations and 24 ocean-bottom seismometers, as well as a network of 6 moored hydrophones; and acquired marine geophysics data including multibeam bathymetry, sub-bottom profiler, gravity & magnetics, multi-channel seismics, and seismic refraction data. The experiment has collected a unique, high quality, and multifaceted geophysical data set in the Central Bransfield Basin, with a special focus on Orca and Humpback seamounts. Preliminary results confirm that the Bransfield region has slab-related intermediate depth seismicity, with earthquake characteristics suggesting distributed extension across the rift. Gravity and magnetic highs delineate a segmented rift with along-axis variations that are consistent with increased accumulated strain to the northeast. Orca volcano shows evidences of an active caldera and magma accumulation at shallow depths, while Humpback volcano has evolved past the caldera stage and is currently dominated by rifting structures. These differences suggest that volcanic evolution is influenced by the position along the rift. Although a lot of analysis remains, these results provide useful constraints on the structure and dynamics of the Bransfield rift and associated volcanoes.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.