Contributions to the Bajos Submeridionales stratigraphy, Santa Fe, Argentina

Abstract

The Bajos Submeridionales (BBSS) watershed, located on NW of Santa Fe province, SE of Santiago del Estero province, and SW of Chaco province, Argentina, occupies the distal part of the Salado-Juramento fluvial mega-fan, Gran Chaco. Groundwater is the main source for livestock production and the dispersed rural population. According to background information, the stratigraphic column was described in detail from a single 30 m deep research drilling in the central part of the BBSS. In order to contribute to the shallow stratigraphic, sedimentological and hydrogeological knowledge, an exploratory drilling of 62 m depth was carried out in the west-center of the BBSS basin (28°1'21.60"S, 61°12'11.60"W ). Considering background information and by stratigraphic correlation with existing drillings, the column is represented by the sands deposited by the Paraná River system (Ituzaingó Fm) that conform a semi-confined aquifer. Overlying, the silty clays that conform an aquitard, and a silty-clayey grayish to olive brown that contains the phreatic aquifer, characteristic of marshy environments (Fortín Tres Pozos Fm), on which are found silty clays corresponding to Sedimentos Palustres Superficiales. The results achieved contribute to the shallow stratigraphic and hydrogeological knowledge of the region. Likewise, the mineralogical analyzes of sands and clays, in addition to contributing to the identification of the formations that conform the stratigraphic profile, constitute an important contribution to the identification of processes that modify the chemical composition of the waters under investigation.