Geochemistry and age of Groundwater In Confined Aquifers from Argentina Chacopampeana Plain

MALDONADO, L.; BLARASIN, M. T; DAPEÑA, C.; PANARELLO, H.O.

Viena

Simposio; International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers - CN225; 2015

International Atomic Energy Agency

Abstract: The confined aquifer systems (CAS) in the South of Córdoba province, whichpresent variable extension, are multilayered and formed by thin (4-6m) sand-pebble lenses(K=1 a 30 m/d). They are all linked to Neogene fluvial palaeosystems. These layers aresituated at different depths (120- 400 m) and are interbedded with thick clay strata whichgenerate different confinement grades.The interpretations made from stable isotopes results,hydraulic calculations and the absence of 3H in the CAS, suggest that groundwater is old and that there is an age gradient increasing with depth and from West to South-East. The obtained 14C ages for CAS A2 (4,000-1,000 BP) and CAS C (10,000 BP) indicate groundwater recharged during Holocene cold periods, between the "Little Ice Age" and the ending of "Holocene Climatic Optimum" and during the last glaciation, respectively. CAS D (40,000 BP) presents palaeowaters that could have been recharged during the Pleistocene (Würm glaciation).