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

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

RADIOCARBON

UNIV ARIZONA DEPT GEOSCIENCES

Lugar: Arizona; Año: 2016 vol. 58 p. 833 - 849

0033-8222

In the central-South region of Córdoba province, Argentina, people use mainly groundwater from confined aquifers systems (CAS) for different activities (agricultural, livestock farming, urban). Therefore it is necessary to conduct comprehensive studies for the planning of a more sustainable use considering groundwater renewal times can be of several thousands of years in the different aquifer systems. The objective of this research is to estimate groundwater age based on hydraulic, geochemical and isotopical methods. The CAS present variable extension, are multilayered and formed by thin (4-6m) sand-pebble lenses (K1 m/d to 30 m/d). They are all linked 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 2H,18O and 3H results, as well as hydraulic calculations in the CAS, suggest that groundwater is old and that there is an age gradient increasing with depth and from W to SE. The obtained 14C ages for CAS A2 (3,700-1,100 BP) and CAS C (10,800 BP) indicate groundwater recharged during Holocene cold periods, between the "Little Ice Age" (Isotope Stage 1, IS 1) and the ending of "Holocene Climatic Optimum" (IS 2) and during the last glaciation, respectively. CAS D (46,100-40,500 BP) presents palaeowaters that could have been recharged during the Pleistocene (IS 3).