Geoquímica isotópica del sistema hidrogeológico del Valle de Cuernavaca, estado de Morelos, México

Abstract

Aquifers formed by karstic limestones, fractured basalts and clastic sediments are part of a complex hydrogeological system in the Cuernavaca Valley. This area is located 50 km south of Mexico City. Environmental isotopes ¹⁸O, ²H, ³H, ³⁴S, ¹³C y ¹⁴C and geochemical data have been used to study the recharge mechanism, the origin of the groundwater and the relationships between the different aquifers in this area. These data show that most of the recharge takes place in Chichinautzin and Zempoala ranges situated in the highland to the north. Different recharge areas are identified based on small but consistent isotopic differences. This is supported by chemical and geologicaI information. Sulphur and oxygen isotopes data in aqueous sulphate, indicated that the sulphur source of the groundwater with high sulphate concentration is evaporites of Cretaceous age. Sulphur of volcanic origin is fresent in groundwater close to the recharge areas. Geochemical data end evaluation of residence time using ³H and ¹⁴C indicated the presence of a mixture of water of different origin in some discharge areas of the karstic aquifer.