Hydrogeological features of a massif to be used as a nuclear repository

Abstract

Este trabajo fue presentado en el V Congreso Internacional sobre "Geología Aplicada a la Ingeniería", realizado en Buenos Aires, Argentina, del 20 al 25 de Octubre de 1986. The Sierra del Medio rocky massif is situated in the central west sector of a probably closed Cainozoic sedimentary basin. Sierra del Medio behaves as an area having a positive relief which receives rainfalls and spreads it over the superficial smaller basins around it. From the geologicaI and geophysical points of view it is believed that the massif is separated from the adjacent basin water bearing formations by fractures belonging to the direct type. It is formed by Paleozoic migmatites of granitic to tonalitic composition intruded by acidic, mesosilicic and basic dikes. Ectinite xenoliths can also be found. The different hydrogeological units in the rocky massif under study were defined preliminary in geological, geophysical, mechanical and chemical detailed studies. Tentative isopiezometric curves are shown and geophysical profiles are analyzed.