Revalorización del patrimonio geológico como recurso turístico de Capilla del Monte

Fil: Zilio, María Cristina. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Chert intervals in DSDP and ODP sites (Table 1)

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.

La querella de la lengua en Argentina (1828-1928)

La tesis pretende demostrar que la formación identitaria de la Argentina se ha erigido, en buena medida, a partir de la querella en torno a la lengua que hablamos los argentinos. Esta querella consta de dos períodos. El primero se inicia en 1828, con el ensayo de Juan Cruz Varela sobre «Literatura Nacional», y tiene sus motivos más característicos durante el siglo XIX. El segundo viene de la mano del siglo XX, con Idioma nacional de los argentinos (1900), de Lucien Abeille, y sus estelas llegan hasta el día de hoy. Abeille puede considerarse una bisagra entre la vieja forma de estudiar las lenguas -ligada a la herencia del romanticismo y a la ciencia decimonónica-, y la nueva forma, de carácter ya lingüístico, que en España se desarrollaba en los albores del siglo XX. Estos dos períodos, no obstante, tuvieron como horizonte común discutir -ya sea negándolo, ya sea defendiéndolo- el idioma nacional, el idioma patrio, la lengua argentina, modos alternativos con que se ha aludido siempre a un mismo problema: la cuestión de la lengua en Argentina