Geochemistry of waters in the Canalobre Cave and aquifer of Cabeco d'Or (South-East Spain)

The Canalobre Cave, situated in the Sierra del Cabeco d'Or in the southeast of Spain is a shallow-hole of approximately 100 m depth of cylindrical mor phology. Rainfall events of a certain magnitude cause precipitation in the interior of the cave. Taking advantage of these events, a series of samples was taken with the aim of characterizing the hydrochemistry of the rapid i nfiltration waters within this zone of the unsaturated zone, and defining t he processes which modify their chemical composition, At the same time, an attempt was made to understand their relationship with the waters of the sa turated zone of the Cabeco d'Or aquifer. Use of principal components analys is (PCA) and a study of hydrodynamic equilibria established a primary contr ibution from the edapho-climatic component, which enriches the infiltration waters with salts and CO2 and so favors dissolution of the rock during the downward passage of the water. In the saturated zone, where there is a rem arkable thermal anomaly, dissolution of evaporite salts at depth, together with the possible contribution of CO2 of endogenous origin (associated with gasification-degasification phenomena that cause dissolution-precipitation processes), is the likely explanation for the considerable increase in the mineralized status of the waters, and for the correlation between its cont ent of various ions.