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Cuenca de la Independencia (CI) is a semi-arid basin in Central Mexico, subdivided into four administrative hydrogeological regions, and comprised of two hydrogeological units: a granular aquifer of lacustrine origin overlying a fractured acidic igneous aquifer. Although many geophysical soundings were carried out within the basin, no geophysical data exceeding 500 m of depth has ever been reported; the actual conceptual models were generated only from shallower geophysical studies, geological and hydrogeochemical mapping. We performed a geophysical survey in CI to determine the geometry of the hydrogeological units through Audio-Magnetotellurics (AMT), Time Domain Electromagnetics (TDEM), and Vertical Electrical Soundings (VES). Since the acquired data set from the different applied geophysical methods are multidimensional and band-limited, some well-known empirical relations between the applied methods were used to improve the subsurface imaging, turning data into broadband-integrated and space-time scaled into the MT frequency domain. We present a methodology on how to handle this integrated information through a 2-D inversion approach. The results reveal that, even though there are two hydrogeological units, they could not be vertically distinguished, thus is not possible to refute the previous idea of direct vertical communication between the two aquifers. Moreover, a clear lateral transition in resistivity models was not found, so the administrative division of CI would only obey political-administrative purposes. • Cuenca de la Independencia aquifer is an important ground water source in Mexico. • Space- and time-scaling can increase resolution of 2-D resistivity models. • MT-methodologies can be applied to other geophysical methods under right conditions. • Resistivity distribution suggest that CI is a single hydrogeological system. • 2-D resistivity models show both aquifers vertically semi-connected. [ABSTRACT FROM AUTHOR]

• The Juchipila graben is an unconventional geothermal system located in central Mexico. • Thermal water has anomalous concentrations of F, B, Li, and As. • δ2H and δ18O indicate a common meteoric source but different evaporation processes. • Mantle helium is transported into the system through deep-rooted faults. This work presents hydrochemical results for groundwater and dissolved gas samples collected from a thermal and cold aquifer in the Juchipila Basin, in southern Sierra Madre Occidental, central Mexico. Thermal springs in the Juchipila Basin reach temperatures of 60 °C, these manifestations are not related to recent or active volcanism as are all the known geothermal fields in Mexico. The thermal waters (>32 °C) are Na-HCO 3 and Na-SO 4 type, with an anomalous concentration of F, B, Li, and As. Their chemistry likely results from water-rock interaction processes. The cold waters (<32 °C) have a Ca-HCO 3 composition typical of recent infiltration and shallow flow, but they have an anomalous concentration of NO 3. The δ2H and δ18O indicate a common meteoric source for the warm and cold water plotting along an evaporation line. The waters have higher CO 2 and He concentrations than the air-saturated water. The helium composition is mainly atmospheric and terrigenous with a mantle helium contribution of up to 14%. This suggests that faults affecting the region are deeply rooted, permitting mantle helium uprise. Geothermometry gives mean reservoir temperatures of 58–102 °C. Based on these results, we propose a model of hydrothermal circulation in the Juchipila Basin, in which rainwater infiltrates deeply through the graben edges fault system, dissolves ions and crustal helium, incorporates mantle helium, while heated by the geothermal gradient, and eventually surges and mixes with the cold, shallow aquifer along faults cutting the whole succession within the graben. [ABSTRACT FROM AUTHOR]