Analysis of flow Patterns and Hydrogeochemical Characteristics of Groundwater in a Volcanic Tectonic Basin

This study uses physicochemical data and the geochemistry of major and minor ions to identify and describe groundwater flow patterns and hydrogeochemical characteristics in the Lake Cuitzeo basin. Located in the central-western region of Mexico, the basin is bounded by active faulting, subsidence, and hydrothermal activity along its margins. The study describes groundwater flow patterns, water types, water-rock interaction processes, and their relationship with geological faults traversed by the groundwater. Between 2022 and 2023, water quality was analyzed at 44 deep wells and seven springs. In situ measurements of physicochemical parameters were taken, and the concentrations of major and minor ions were plotted on D’Amore, Mifflin, and Piper diagrams. Seven hydrogeological environments were identified through which groundwater flows, promoting the weathering of Ca-Na-Mg silicates. Geological faults are directly related to flow directions, predominantly southwest-northeast. The primary recharge areas are located in the southwestern sector, where basic silicate rocks are dominant, leading to elevated Mg2+ concentrations due to feldspar leaching. The predominant hydrogeochemical processes include silicate rock weathering, ion exchange, carbonation, water mixing, calcite precipitation, and gypsum dissolution. Three groundwater flow systems were identified: 82% of the flow is local, distributed throughout the basin; 16% is intermediate flow, concentrated in the central and northern areas; and 2% is deep circulation flow, found along the southern margin of the lake.