3D gravity modeling of the Corrientes province (NE Argentina) and its importance to the Guarani Aquifer System

Abstract

This paper presents a geological model of Corrientes province (Argentina) based on Bouguer gravity anomaly data, obtained in 2073 measurement points. To build the model, the IGMAS+ interactive program was used. Two areas of approximately 135,000 km2 were modeled in this study. The selection of these areas was based on the sectors where the largest number of gravity anomaly measurements was made and other type of data was available to perform the parameterization (i.e, lithology profiles in boreholes, seismic profiles and audiomagnetotelluric AMT soundings). The initial geological configuration proposed was composed by four layers: basement, sediments (Paleozoic–Lower Cretaceous), basalts (Serra Geral Group, Lower Cretaceous) and postbasaltic sediments. The result shows a basement compartmentalized in structural blocks separated by large faults. The connection of Asunción and Río Grande Arches is confirmed along a structural high that crosses Corrientes province from SE to NW. The basaltic layer shows lateral changes in its thickness, due to faulting, almost disappearing on the NW of Corrientes. This structural configuration has a special hydrogeological importance because it produces the rise of the Guaraní Aquifer System sedimentary series near the surface and the intense fracture network makes this area prone to local recharge and regional discharge.