Role of the geologic-geomorphic setting of the Río de la Plata estuary coastal landscape in controlling freshwater lenses shape and distribution

CAROL, ELEONORA; CELLONE FRANCISCO; TANJAL, CAROLINA; GALLIARI, MARÍA JULIETA

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2022

0895-9811

Sea level fluctuations during the Holocene led to the deposition of differentsedimentary facies in the Argentinean littoral of the Río de la Plata estuary and theadjacent sea area. This work aims to analyze the role of the geologic ? geomorphicsetting related to the Holocene evolution of the coastal landscape of the Río de la Plataestuary in terms of its control over the shape and distribution of freshwater lenses forwater supply. For this purpose, satellite image analysis, field surveys, Vertical ElectricalSoundings (VES), and sediment tests from boreholes were carried out. In addition,water samples were taken for electrical conductivity (EC) measurement, and majorions and stable isotopes of the water molecule determination. The results show that thegeological and geomorphological evolution of the Río de la Plata estuary gave rise topositive landforms composed of highly permeable sediments that favor rainwaterinfiltration, which is stored in the shape of lenses. EC measurements in groundwaterbelow these landforms recorded low values indicative of freshwater with isotopiccontent similar to that of local ? global rainfall. Furthermore, the VES study allowed thedefinition of the freshwater ? saline water interface. The outcomes of this study showthat a detailed and exhaustive analysis of the geological ? geomorphic setting resultingfrom the Holocene evolution of coastal zones constitutes, along with hydrochemistryand geophysics, appropriate tools for the exploration of freshwater lenses in coastalareas.