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DAPEÑA Cristina
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Título:
Environmental Stable Isotope of the "Sistema de las Encadenadas de Chascomús", Buenos Aires, Argentina
Autor/es:
DAPEÑA, CRISTINA; MIRETZKY, PATRICIA; PANARELLO, HECTOR; FERNANDEZ CIRELLI, ALICIA
Lugar:
Pucón, Chile
Reunión:
Simposio; III South American Symposium on Isotope Geology; 2001
Institución organizadora:
Sociedad Geologica Chilena y Comité SSAGI Chile
Resumen:
The Sistema de las Encadenadas de Chascomús (Salado River drainage basin) lies in the geomorphologic unit called Pampa Deprimida in the Buenos Aires province, Argentina. The Pampeano Plio-Pleistocene sediments contain the aquifer unit. This paper studies the relation between groundwater and surficial water by hydrochemistry and environmental stable isotopes (2H, 18O). The hydrochemistry results suggest that during summer, when the precipitation-evaporation balance is negative, the evaporation process governs the surface water hydrochemistry, while appreciable differences between summer and winter groundwater values are not observed. The groundwater isotopic composition is relatively constant: -5.5? and 30? for d18O and δ2H, respectively, indicating their meteoric origin. Nevertheless, small fluctuations are probably due to evaporation of local precipitation prior to infiltration. Recharge waters reflect the mean precipitation with reasonable fidelity. The stream and lake waters fit on an evaporation line (d18O=-5.5?, d2H=-30?), indicating the groundwater contribution.  The isotopic results suggest that during summer, the evaporation process governs the surface water hydrochemistry. The origin of groundwater is meteoric and the shallow groundwater constitutes the base flow of surficial water.