538 resultados para 1052
Resumo:
Radiolarian cherts in the Tethyan realm of Jurassic age were recently interpreted as resulting from high biosiliceous productivity along upwelling zones in subequatorial paleolatitudes the locations of which were confirmed by revised paleomagnetic estimates. However, the widespread occurrence of cherts in the Eocene suggests that cherts may not always be reliable proxies of latitude and upwelling zones. In a new survey of the global spatio-temporal distribution of Cenozoic cherts in Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) sediment cores, we found that cherts occur most frequently in the Paleocene and early Eocene, with a peak in occurrences at ~50 Ma that is coincident with the time of highest bottom water temperatures of the early Eocene climatic optimum (EECO) when the global ocean was presumably characterized by reduced upwelling efficiency and biosiliceous productivity. Cherts occur less commonly during the subsequent Eocene global cooling trend. Primary paleoclimatic factors rather than secondary diagenetic processes seem therefore to control chert formation. This timing of peak Eocene chert occurrence, which is supported by detailed stratigraphic correlations, contradicts currently accepted models that involve an initial loading of large amounts of dissolved silica from enhanced weathering and/or volcanism in a supposedly sluggish ocean of the EECO, followed during the subsequent middle Eocene global cooling by more vigorous oceanic circulation and consequent upwelling that made this silica reservoir available for enhanced biosilicification, with the formation of chert as a result of biosilica transformation during diagenesis. Instead, we suggest that basin-basin fractionation by deep-sea circulation could have raised the concentration of EECO dissolved silica especially in the North Atlantic, where an alternative mode of silica burial involving widespread direct precipitation and/or absorption of silica by clay minerals could have been operative in order to maintain balance between silica input and output during the upwelling-deficient conditions of the EECO. Cherts may therefore not always be proxies of biosiliceous productivity associated with latitudinally focused upwelling zones.
Resumo:
La recepción del Quijote en Brasil está relacionada con sus traducciones, dos realizadas por portugueses y cuatro traducciones brasileñas, dos en el siglo XX y dos preparadas para el cuarto centenario del primer libro, celebrado en 2005. Se brinda un sucinto panorama historiográfico de esas publicaciones y breve biografía de sus respectivos traductores. En el capitulo XX del primer libro del Quijote, Sancho le cuenta un cuento popular al caballero, con la intención de hacerlo dormir y son utilizados varios juegos de palabras para dar vida a un 'cuento de nunca acabar', el cuento de la pastora Torralba. En esta comunicación son analizadas las seis traducciones al portugués, verificando la preservación o incremento de esos juegos de palabras, la traducción de los nombres de sus personajes (onomástica), como también la existencia e información de notas de traducción. Al final, se ofrecen cuadros de las comparaciones hechas, con algunas consideraciones sobre las opciones ofrecidas al lector brasileño interesado en disfrutar de la gran obra cervantina.
Resumo:
Fil: De Marziani, Fabián Amilcar. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.
Resumo:
Fil: De Marziani, Fabián Amilcar. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.
