This study was conducted to identify the origin, hydrogeochemical processes and evolution ofgroundwater in a tectonic valley. This study was carried out with the aim of quantifying the proportions of groundwater flows contributing to the water chemistry abstracted in a zone of convergence favored by the presence of active faults. The study area is located in the Trans-Mexican Volcanic Belt. End members meth-odology was applied to identify the mixing of hydrothermal with fresh groundwater, where changes in the aquifer geology result in distinct groundwater chemical signatures. Tary mixing was quantified using con-servative elements. Moreover, other evolutionary processes, such as ion exchange and silicate weathering oc-cur due to changes in the geology of the area. In tary mixing, each of the end members is associated with the lithology through which it circulates. The local flow contributes 70％ of the water to the system, the inter-mediate flow contributes 14％, and the regional flow contributes 16％. Three types of water are produced:Na-HCO3, due to the interaction of water with volcanic rocks of rhyolitic composition, Na-Mg-HCO3, due to the interaction of water with volcanic rocks of basaltic-andesite composition, and Ca-HCO3, due to the inter-action of water with sedimentary calcareous rocks.