PROSPECCIÓN MAGNETOTELÚRICA DE ACUÍFEROS Y ESPESOR BASÁLTICO EN CARLOS PELLEGRINI, PROVINCIA DE SANTA FE (ARGENTINA)

Abstract

Three magnetotelluric soundings were performed in C. Pellegrini, Santa Fe Province determining a West-East profile of 5926 m of long. The aim of the study was the estimation of possible aquifers underneath a basaltic cover. The basaltic thickness in this area of the Argentina corresponding to the Chacoparanense Basin was also estimated. These lava overfloors reached a great extension (1,2 million km2) and were contemporary with the continental aperture. Results allowed the identification of four stratigraphic formations. The first one has low resistivity of 2 to 4 Ωm (except the first 100 m with about 10 Ωm; which corresponds to modern sediments). This formation is present up to 700 m depth westwards of the profile and 850 m eastwards. The second formation is a basaltic layer, (Serra Geral Fm), with 680 m thickness in the West and 390 m and East of the profile, and resistivities between 50 Ωm to 150 Ωm. The following formation corresponds to sedimentary rocks showing a resistivity of 1-7 Ωm, where different sedimentary horizons can be discriminated; its top is approximately at 1200 m depth and the base reaches the range of depth of 2400 m to 3000 m. Within this think layer, a basal cover of 30 Ωm can be distinguished with approximately 200 m thickness, following the geometry of what can be interpreted as crystalline basement. Finally a last block has resistivities higher than 100 Ωm and it may be a massive formation corresponding to Precambrian age, as part of the continental craton.