ABSTRACT
Alpine and Mediterranean karst aquifers are frequently associated with Upper Triassic (Keuper) deposits which generally constitute the substratum or impervious base of the system given their predominantly clayey nature. When the groundwater stored in the carbonate aquifer comes into direct contact with the Triassic formation, the result is a modification of the chemical composition of the water due to the dissolution of high solubility evaporite rocks interspersed with the Triassic clays. A hydrochemical and temporal characterisation of the effect of evaporites on the chemical composition of two carbonate aquifers located in Sierra de Grazalema Mountain Range (Southern Spain) has been undertaken. Results show differences in the intensity of the evaporite signal as well as in the mineral species responsible for the hydrochemical modification: from sulphate-related minerals (gypsum/anhydrite) to rock salt.
