Evidence for a Saline Component at Shallow Depth in the Crystalline Armorican Basement (W France)

Luc Aquilina (1) , Antoine Armandine Les Landes (1) , Virginie Ayraud-Vergnaud (1) , Thierry Labasque (1) , Clément Roques (1) , Philippe Davy (1) , Hélène Pauwels (2) , Emmanuelle Petelet-Giraud (2)

1 GR - Géosciences Rennes
2 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)

Saline fluids at shallow depth (50 - 450 m) in the Armorican basement were investigated. Fluids with salinities ranging from 80 to 900 mg/L mix with modern shallow groundwaters containing anthropogenic solutes. The most saline fluids are deeper or more isolated from mixing. These fluids reveal Br/Cl and SO4/Cl ratios that are typically marine. This work establishes the migration and the preservation of a marine end-member in a basement aquifer, and may provide keys for the understanding of such fluid circulation.

Keywords: Saline fluids; Cristalline rocks; Groundwaters; Geochemistry

Domains: Geochemistry; Global Changes; Hydrology

Luc Aquilina, Antoine Armandine Les Landes, Virginie Ayraud-Vergnaud, Thierry Labasque, Clément Roques, et al.. Evidence for a Saline Component at Shallow Depth in the Crystalline Armorican Basement (W France). Fourteenth International Symposium on Water-Rock Interaction, WRI 14, Jun 2013, Avignon, France. pp.19-22, ⟨10.1016/j.proeps.2013.03.157⟩. ⟨insu-00853165⟩