The Missão Velha - Rio da Batateira Aquifer System and the Mauriti Aquifer in the Cariri Valley, Araripe Basin, Ceará, Brazil, were studied through chemical, isotopic, and mineralogical analyses between 2017 and 2018. Isotopic analyses included oxygen-18, deuterium, and excess deuterium, while mineralogy was assessed using X-ray diffractometry. Weathering of minerals like quartz, feldspar, and micas released ions such as sodium, potassium, magnesium, aluminum, and calcium, influencing groundwater composition. Cation exchange was identified as the main hydrochemical process, with albite weathering contributing to groundwater mineralization. The Mauriti Aquifer showed stable composition, while the Missão Velha - Rio da Batateira Aquifer experienced more pronounced ion exchange processes. Isotopic analysis confirmed groundwater origin from direct precipitation, with recharge occurring through rainfall and no evidence of evaporation or anthropogenic contamination.