ASSESSING GROUNDWATER AGE IN CONFINED AQUIFERS FROM THE CENTRAL PAMPEAN PLAIN OF CORDOBA, ARGENTINA

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

RADIOCARBON

UNIV ARIZONA DEPT GEOSCIENCES

Lugar: Arizona; Año: 2016

0033-8222

In Córdoba province, Argentina, people mainly use groundwater from confined aquifers systems (CAS) for different activities. Therefore, it is necessary to carry out comprehensive studies for the planning of a more sustainable use considering that groundwater renewal times can be of several thousands of years. The objective of this research is to evaluate groundwater age in confined aquifers based on hydraulic and isotope methods. The CAS present variable extension, are multilayered and formed by thin (4-6 m) sand-pebble lenses,linked to Neogene fluvial palaeosystems. These layers are situated at different depths (120- 400 m) and interbedded with thick clay strata. The interpretations made from 2H, 18O and 3H results and hydraulic calculations, suggest that groundwater is old. Furthermore, it was observed an age gradient that increases with depth and flow direction. The 14C ages obtained for CAS labelled A2, C and D were 3.6 ka BP -1.1 ka BP, 10.8 ka BP and 46.0 ka BP - 40.5 ka BP, respectively. These results indicate that A2 and C contain groundwaterrecharged during Holocene cold periods, between the "Little Ice Age" and the ending of "Holocene Climatic Optimum" and during the last glaciation. D CAS contains palaeowaters that would have recharged during the Pleistocene.