Geochemical and isotopic characterization of the thermal waters in the Cuenca Alta Del Rio Laja basin, Guanajuato, Mexico

The thermal waters in the Cuenca Alta del Río Laja basin supply water for agricultural use, human consumption, and spas. The study included 25 groundwater samples from wells in the central part of the basin; 14 of those samples are considered thermal water, as their temperatures are higher than 29ºC. The thermal waters are sodium-bicarbonate type with geochemical signatures similar to those of non-thermal waters, showing a regional flow system evolution. Isotopic composition (δ¹⁸O and δD) of thermal water indicates meteoric origin without a significant δ¹⁸O enrichment. Cl/B ratios may indicate two thermal aquifers. Vertical flow is mostly caused by pumping, and the permeability seems to be controlled by the regional fault system. Chalcedony and multicomponent geothermometry suggest that at depth, the temperature may reach values between 84 and 126ºC. The estimated temperature allows utilization of the thermal water direct uses that include aquaculture, food processing and fruit, vegetable and grains drying.