CONICET | Buscador de Institutos y Recursos Humanos

The Llanura Tucumana extends along the eastern Andean margin, between 27ºS-28ºS and 64º50´W-65º40´W. It is a structural depression infilled by a thick sedimentary sequence, as shown by the preliminary geophysical studies. It is bounded to the west by the Nevados del Aconquija (5500m) and the Sierra de Guasayán (600m) at east. Both ranges are part of the Sierras Pampeanas System. The southern part of this plain is an important thermal area, which is known through surface manifestations and drilled wells. There are a great quantity of artesian wells which discharge water at temperatures that oscillate between 30ºC and 50ºC. This geothermal area has been studied by means of hydrochemistry and Isotope Hydrology. The Tertiary aquifer units are the marine Miocene Guasayán Formation and the continental Pliocene Las Cañas Formation. The last one has good quality water, although still slightly saline. Overlaying these sediments, the Holocene sequence bears aquifers with high rate of discharge and excellent qualities for most requirements. The lack of correlation between the isotopic composition, δ2H, and chloride and sulfate ions indicates that the salinization mechanism is mainly the leaching of old marine sediments. Like it was observed by others authors, it results very difficult to correlate the different aquifer levels of a well with others neighbor one. This is a consequence of the fact that aquifers are located in sandy lenses presenting variable thickness and scarce lateral development. These characteristics are proper of the Pliocene and also Quaternary units. The same conclusion is reached through this isotopic study. As established in previous papers, the system is heterogeneous and it was not possible to find out a systematic pattern that makes possible water typifying. 3H and 14C studies are imperative in order to clarify paths and movements of groundwater into the aquifer units.

enviar mensaje