Perspectives for Application of 81Kr dating in the study of the Deep Thermal Aquifers of the Province of Buenos Aires, Argentina

DANIEL EMILIO MARTINEZ; ZHENG-TIAN LU; WEI JIANG; TAKUYA MATSUMOTO; ORLANDO MAURICIO QUIROZ LONDOÑO

Henfei

Workshop; Perspectives for Application of 81Kr dating in the study of the Deep Thermal Aquifers of the Province of Buenos Aires, Argentina; 2018

University of Science and Technology oF china (USTc)

Geologically the province of Buenos Aires is defined by two low altitude mountain ranges, which divide three very deep basins called (from North to South) Salado, Claromecó and Colorado. Its hydrogeology is characterized by the existence of three main sections defined respecting to a Pliocene marine formation known as Paraná Fm., formed mainly by green clays and called "Paraniana Section". Above this, the Epiparaniana Section, is formed by a fluvial sand deposit of Pleistocene age (Puelche Fm. ) and a loess aeolian Upper Pleistocene-Holocene sequence (Pampeano Fm.) , and contains the most important aquifers supporting the productive activities. Below the Paraniana Section, the Hipoparaniana section is formed sediments of Lower Tertiary Age, with aquifer properties. These deep aquifers have thermal waters (35ºC to 57ºC), of good quality in a part of the Colorado Basin, but most the wells obtain salty and very salty waters, which are used mostly for thermal resorts. The knowledge of these deep thermal aquifers is very scarce because of the few available wells. Nevertheless, its importance as potential drinking water and touristic resource makes necessary to improve the knowledge of the system. Previous 14C dating in the Colorado Basin, and specially the He concentrations determined in a Coordinated Research Project (CRP) of the International Atomic Energy Agency (IAEA), over 10 -6 cm3STP/g, makes these formations appropriated to be dated using 81Kr method. A bilateral project supported by the National Science Foundation of China (NSFC) and the National Council of Scientific and Technological Research (CONICET) of Argentina will be developed by the Universities of Science and Technology of China and CONICET-National University of Mar del Plata, Argentina in order to obtain the ages of these very old groundwater and to improve the understanding of the deep aquifers circulation and residence time.