61 research outputs found

    Morphostructure at the junction between the Beata ridge and the Greater Antilles island arc (offshore Hispaniola southern slope)

    Get PDF
    Oblique convergence between the Caribbean plate's interior and the inactive Greater Antilles island arc has resultedin the collision and impingement of the thickened crust of theBeata ridge into southern Hispaniola Island. Deformation resulting from this convergence changes from a low-angle southward-verging thrust south of easternHispaniola, to collision and uplift in south-central Hispaniola, and to left-lateral transpression along theSouthern peninsula of Haiti in western Hispaniola. Using new swath bathymetry and a dense seismic reflectiongrid, we mapped the morphological, structural and sedimentological Elements of offshore southern Hispaniola.We have identified four morphotectonic provinces: the Dominican sub-basin, the Muertos margin, the Beataridge and the Haiti sub-basin. The lower slope of the Muertos margin is occupied by the active Muertos thrustbelt, which includes several active out-of-sequence thrust faults that, were they to rupture along their entirelength, could generate large-magnitude earthquakes. The interaction of the thrust beltwith the Beata ridge yieldsa huge recess and the imbricate system disappears. The upper slope of the Muertos margin shows hick slopedepositswhere the extensional tectonics and slumping processes predominate. The northern Beata ridge consistsof an asymmetrically uplifted and faulted block of oceanic crust. Our results suggest that the shallower structureand morphology of the northern Beata ridge can be mainly explained by a mechanism of extensional unloadingfrom the Upper Cretaceous onward that is still active residually along the summit of the ridge. The tectonicmodels for the northern Beata ridge involving active reverse strike–slip faults and transpression caused by theoblique convergence between the Beata ridge and the island arc are not supported by the structural interpretation.The eastern Bahoruco slope an old normal fault that acts as a passive tear fault accommodating the sharpalong-strike transition from low-angle thrusting to collision and uplifting.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEGeological Survey Coastal and Marine Geology ProgramDirección General de Minería of the Dominican Republicpu

    Crustal structure and continent‐ocean boundary along the Galicia continental margin (NW Iberia): insights from combined gravity and seismic interpretation

    Get PDF
    The magma‐poor rifted continental margin of Galicia has an extremely complex structure. Its formation involved several rifting episodes that occurred ultimately during the early Cretaceous near a ridge triple junction, which produced a change in the orientation of the main structures in its transition to the north Iberia margin. In addition, there is a superimposed partial tectonic inversion along its northwest and northern border which developed from the Late Cretaceous to at least Oligocene times. The present study integrates a large volume of new geophysical information (mainly marine gravity data and 2D seismic reflection profiles) to provide insights on the formation of this rift system and on the development of its later inversion. The combined interpretation and modeling of this data enable the presentation of a new crustal and structural domains map for the whole Galicia margin. This includes the rift domains related to the extreme thinning of the crust and the lithospheric mantle (stretched, necking, and hyperextension and mantle exhumation (HME) domains), as well as a domain of intense compressional deformation. New constraints arise on the origin, the deep structure, and the characterization of the along‐ and across‐strike variation of the continent‐ocean transition of the margin, where a progressive change from hyperextension to partial inversion is observed. The development of both rifting and later partial tectonic inversion is influenced by the existence of former first‐order tectonic features. Most of the tectonic inversion is focused on the HME domain, which in some areas of the northwestern margin is completely overprinted by compressional deformation

    Caracterización de la comunicación pedagógica en la interacción docente – alumno en los grupos de estudiantes de I, II y VI semestre de la Licenciatura en Pedagogía Infantil de la Facultad de Educación de la Pontificia Universidad Javeriana

    Get PDF
    En el proceso educativo interactúan dos actores, el docente y el alumno. La interacción está mediada por la comunicación pedagógica, en donde se comparten conocimientos, ideas y experiencias de vida, a través del lenguaje y otros recursos que intervienen en la relación dialógica y que favorecen el proceso de formación integral del futuro profesional. El objetivo de esta investigación, es caracterizar la comunicación pedagógica en la interacción docente ? alumno, en los grupos de estudiantes de la Licenciatura en Pedagogía Infantil, de la Universidad Javeriana. La investigación tiene un enfoque cualitativo de tipo descriptivo e interpretativo. Se realizó una videograbación de las clases, una entrevista a tres docentes y tres grupos focales y se siguió la técnica de análisis de datos. Se encontró que la comunicación pedagógica se caracteriza por las funciones afectiva, reguladora y socializadora| siendo el diálogo mediado por el lenguaje verbal y no verbal, una de las formas de la comunicación. También se caracteriza por los factores intrínsecos y extrínsecos que favorecen la interacción docente - alumno, en un escenario donde se cruzan diferentes culturas, formas de ser y de actuar que propician la práctica educativa, con la participación del docente como mediador, modelo y amigo del conocimiento.Magíster en EducaciónMaestrí

    Bouguer anomalies of the NW Iberian continental margin and the adjacent abyssal plains

    Full text link
    The 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 marginThe marine surveys are supported by the Spanish Defense Ministry, as this is the managing body of the Spanish Exclusive Economic Zone Project (SEEZ). Additionally, the Universidad Complutense de Madrid funds travel expenses of its personnel embarking on the surveys, as does the Instituto Geológico y Minero de España in the frame of the internal project entitled ‘Plan de Investigaciones Geológicas y Geofísicas de la Zona Económica Exclusiva Española (ZEEE)

    Seroprevalence of dengue antibodies in three urban settings in Yucatan, Mexico

    Get PDF
    Dengue transmission in Mexico has become a major public health problem. Few epidemiological studies have examined the seroprevalence of dengue in Mexico, and recent estimates are needed to better understand dengue transmission dynamics.Weconducted a dengue seroprevalence survey among 1,668 individuals including all age groups in three urban settings in Yucatan, Mexico. Children (< 19 years old) were selected randomly from schools. The adults (≥ 19 years old) were selected from healthcare facilities. Participants were asked to provide a venous blood sample and to answer a brief questionnaire with demographic information. Previous exposure to dengue was determined using indirect immunoglobulin G enzyme-linked immunosorbent assay. The overall seroprevalence was 73.6%. The age-specific seroprevalence increased with age, going from 51.4% (95% confidence interval [CI] = 45.0-57.9%) in children ≤ 8 years to 72% (95% CI = 66.3-77.2%) in the 9- to 14-years old. The highest seroprevalence was 83.4% (95% CI = 77-82.2%) in adults greater than 50 years. The seroprevalence in Merida was 68.6% (95% CI = 65-72%), in Progreso 68.7% (95% CI = 64.2-72.8%), and in Ticul 85.3% (95% CI = 81.9-88.3%). Ticul had the highest seroprevalence in all age groups. Logistic regression analysis showed that age and city of residence were associated with greater risk of prior dengue exposure. The results highlight the level of past exposure to dengue virus including young children. Similar studies should be conducted elsewhere in Mexico and other endemic countries to better understand the transmission dynamics of deng

    Bouguer anomalies of the NW Iberian continental margin and the adjacent abyssal plains

    Get PDF
    The 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

    Lithospheric domain and deformation style mapping in the Galicia continental margin (northwestern Iberian margin)

    Get PDF
    El margen continental de Galicia presenta una estructura muy compleja, debido a dos efectos principales. Por un lado, se trata de un margen de rift pobre en magma, generado en las proximidades del punto triple R-R-R que dio lugar a la apertura simultánea del Océano Atlántico y el golfo de Vizcaya durante el Cretácico. Por otra parte, el régimen de esfuerzos compresivo Cenozoico generó la inversión parcial del margen continental hacia el norte y el noroeste, aportando una mayor complejidad estructural. En este trabajo hemos realizado un análisis detallado de la nueva información gravimétrica y batimétrica obtenida durante las campañas del Proyecto ZEE, así como de nuevos perfiles de sísmica de reflexión multicanal procedentes del Proyecto ERGAP. Presentamos aquí parte de los resultados de este análisis conjunto de toda la información geofísica y geológica disponible, consistentes en una cartografía continua de los diferentes dominios litosféricos y del tipo de deformación que los afectan, desde el margen oeste de la Península Ibérica hasta el margen norte.The continental margin of Galicia presents a very complex structure, due to two main effects. On the one hand, it's a magma-poor rift margin, generated in the vicinity of the triple R-R-R junction, which resulted in the simultaneous opening of the Atlantic Ocean and the Bay of Biscay during the Cretaceous. On the other hand, the Cenozoic compressive stress regime led to the partial inversion of the continental margin to the north and northwest, providing a greater structural complexity. In this work we have carried out a detailed analysis of new gravity and bathymety data acquired during the ZEE Project cruises, as well as new 2D multichannel seismic reflection profiles from the ERGAP Project. We present here some the results of this joint analysis of all the geophysical and geological information available, consisting of a continuous mapping of the different lithospheric domains and of the style of deformation which affect them, from the western margin of the Iberian Peninsula to the northern one.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

    Bouguer anomalies of the NW Iberian continental margin and the adjacent abyssal plains

    Get PDF
    The 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
    corecore