Geochemistry and age of groundwater in confined aquifers from Argentina:The Chacopampeana plain

MALDONADO, LUCIANA; CABRERA, ADRIANA; BLARASIN, MONICA; DAPEÑA, CRISTINA; PANARELLO, HECTOR

Viena

Simposio; International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers CN-225; 2015

International Atomic Energy Agency (IAEA)

The confined aquifer systems (CAS) in the South of Córdoba province, which present variable extension, are multilayered and formed by thin (4-6m) sand-pebble lenses (K 1 a 30 m/d). They are all inked to Neogene fluvial palaeosystems. These layers are situated at different depths (120-400 m) and are interbedded with thick clay strata which generate 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 Climate Optimun? and during the last glaciations, respectively. CAS D (40,000 BP) presents palaeowaters that could have been recharged during the Pleistocene (Wurm glaciations)