Isotopic composition and origin of geothermal waters at Caldetes (Maresme-Barcelona)

Several thermal springs occur within the Catalan Coastal Ranges, mainly located along bounding faults of horst-graben systems. Most of the springs are located in the Valles-Penedes graben, where they correspond to local topography-driven flow systems. The Caldetes thermal water spring cannot be explained easily in these terms. From the chemical and isotopic composition of these waters, a recharge area at an elevation of at least 600 m is inferred, most likely in the Montseny massif some 20 km NW of Caldetes. We propose a deep flow system with infiltration of meteoric fluids from the Montseny massif. Fluids then pass through tertiary units of the Valles-Penedes graben and infiltrate faults and fracture zones that are connected to the bounding faults of the Barcelona halfgraben. Fluids finally ascend along these faults and are discharged as thermal waters at Caldetes. (C) 2000 Elsevier Science B.V. All rights reserved.