Estudio de los procesos secundarios en el sistema geotermal de Caldas de Boí (Lérida)

Resumen

The Caldas de Boí geothermal system is associated with granitic rocks of the La Maladeta massif (Pyrenees of Lérida, Axial Zone). A geochemical characterization of these waters has been carried out with the aim of determining their evolution during ascent from the reservoir to the surface and the effects that secondary processes have on their geochemical signature. Ion-ion diagrams clearly show the existence of mixing processes between a thermal (Estufa) and a non-thermal (Ferro) end-member. The high correlation between the selected conservative tracer (Na) and other conservative elements like Si or F corroborates the mixing process. Besides, it is observed that some springs have a lower temperature than expected if mixing were the only operative process. This additional drop in temperature is related to conductive cooling during ascent. Variations in C 0 2 content explain the main differences between two of the springs, Termas and Estufa. Termas has been affected by CO, ingassing and equilibrated with the atmospheric, causing a decrease in pH.