Hydrogeological conceptual model for the Guarani Aquifer System outcrop area in Brazil: Insights from stable isotopes and rare earth elements
This study refines the hydrogeological conceptual model of the Guarani Aquifer System (GAS) outcrop area in São Paulo state in Brazil and highlights its complexity, particularly the coexistence of semi-confined and unconfined aquifers. Diabase sills act as aquitards, separating a Na⁺-HCO₃⁻ type deep groundwater fro...