The geothermal systems of the Vallès Fault (NE of Spain) (ROCS)
The ongoing energetic transition needs of critical raw materials as lithium or other metals and renewable energies, such as low to mid-enthalpy geothermal energy. Geothermal systems, mostly located near plate bounda-ries, undergo strong structural controls essentially through crustal faults, also known to drain fluids. Furthermore, dissolved metals in geothermal fluids can be exploited as a byproduct in geothermal plants. In the present project we define spatial variations in metal content and the structural control in the Vallès geothermal system and along the Vallès Fault.
The Vallès Fault is a crustal fault that juxtaposes the Miocene detrital basin infill to a syn- and late-Hercynian granitic basement. With a crustal thermal anomaly, a geothermal gradient >35°C/km, several geothermal systems of low enthalpy (<130°C at 1km depth) are closely associated to the Fault. These geothermal systems are revealed by several springs with temperatures ranging from 20 to 75°C (La Puda, Caldes de Montbui and La Garriga).
This project combines hydrogeochemical, structural and petrological approaches to characterize the architecture and the relative chronology of the fracture networks of the sites of hot springs; and the metal content of thermal waters, particularly Lithium, to reconstruct the spatial evolution of the metal content of the geo-thermal fluids.
The metal content of hot waters is low but significant to establish differences according to their structural position. Tectonic structures and surrounding lithologies seem to be decisive in water compositions.
The Vallès geothermal system and related hot springs
Keywords: Geothermal systems, Vallès Fault, metals, aqueous geochemistry
Project leader : Antonio Benedicto (de la Tâche O2.3)
Funding : ROCS – Rifting-orogeny cycles and their geologic products: multiscale investigations of mountain-basin systems and implications for geothermal resources. Projet AEDI (équivalent d’une ANR) cofinancé par l’UE. Tâche O2.3. : “Study of spatial-temporal variability of metal content in rift faults with geothermal potential”.
Staff involved at GEOPS : Damien Guinoisseau, Gael Monvoisin, Agathe Julien-Sicre (Master 2), Théo Rubio (Master 2)
Collaboration with
Universitat Central de Barcelone : A. Travé, I. Cantarero et V. Baqués)
Université Autonome de Barcelone : E. Carola
Sorbonne Université : V. Plagnes