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

Several thermal springs occur within the Catalan Coastal Ranges, mainly loc ated along bounding faults of horst-graben systems. Most of the springs are located in the Valles-Penedes graben, where they correspond to local topog raphy-driven flow systems. The Caldetes thermal water spring cannot be expl ained 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 m assif. Fluids then pass through tertiary units of the Valles-Penedes graben and infiltrate faults and fracture zones that are connected to the boundin g faults of the Barcelona halfgraben. Fluids finally ascend along these fau lts and are discharged as thermal waters at Caldetes. (C) 2000 Elsevier Sci ence B.V. All rights reserved.