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Tania Karen Espinoza-Ju%u00e1rez et al. | 2083Section 2a and 2b (Figure 10) extend from northwest to southwest, encompassing the SPFM, LCR and La Cruz wells, which are situated within mineralized zones of a superficial nature. However, these zones are in areas of intermediate density that do not align with contact zones between potential intrusive granitic bodies and the carbonate sequence, suggesting an association with the volcano-sedimentary deposits of the Las Espinas Formation. Regionally, there is a marked distribution of low density oriented towards the northeast, suggesting a sedimentary and carbonate environment, but to the southwest, the density increases, indicating the dominance of a volcanic environment.6. Discussion6.1. HydrogeochemistryThe hydrogeochemical results show high arsenic concentrations in several of the water extraction wells (Table 2); according to previous results, these high values could be related to geological faults, that significantly contribute to the transport of arsenic to deep wells (Armienta et al., 2001), as evidenced by the distribution of lineaments and faults detected in this study, which used geophysical methods and the local geology (Figure 1, Figure 2 and Figure 6), and are located in the same areas as the wells with the highest As values.The physicochemical parameters taken at the sampling points, situated in fractured Cretaceus limestones, indicate that this phenomenon has been associated with exothermic oxidation reactions of sulfides, such as arsenopyrite (Armienta et al., 2001). Besides, the physicochemical parameters in Manantial Jal indicate that the increase in total dissolved solids is not driven by a thermal source, but is instead primarily associated with the proximity of mine waste, which contributes dissolved constituents to the aquifer system (Sracek et al., 2010).The Piper and D'Amore diagrams highlight differences in the ionic composition of the water samples, which are linked to distinct geological formations and hydrogeochemical processes (e.g. dissolution or mineral alteration) (D%u2019Amore et al., 1983). Most wells exhibit a dominance of HCO3- over SO42- (Facie A), in addition, it is observed that in several wells the Na+ content is representative of an environment where clayey material dominates. Detzani, P5, HA and LCR wells, and Manantial Jal show a relatively higher SO42- content (Facie B); in the case of Na+ and Cl- ratio, sodium is dominant and they have a slight similarity in concentration, which suggests dissolution of halite or alteration of Na plagioclase (Facie C); with respect to the Mg2+ and Ca2+ratio, most of the wells show a possible participation of calcite, dolomite and silicate alteration (Facie D); with respect to the source of Ca2+, Mg2+ and HCO3-, half of the wells show carbonate dissolution processes and the other half show sulfate interaction (Facie E), it should be noted that sulfates could also come from the oxidation of sulfides; and finally, in most of the wells there is a K contribution due to the alteration of Ca silicates and only one well shows alteration of K-Na silicates (Facie F).This is supported by the HCO3/SiO2 vs Mg/(Mg+Ca) diagrams (Hounslow, 2018), which align with findings from other studies conducted in proximity to the research area (Gonz%u00e1lez-Partida et al., 2003), specifically on reef limestones exhibiting hydrothermal alteration (Corona-Esquivel & Sanchez-Loyo, 2022). It is significant that, despite the widespread presence of carbonate rocks, which typically promote HCO3- enrichment through dissolution processes, the observed variability in major ion chemistry suggests the influence of additional lithological controls or geochemical processes. In particular, the anomalous behavior of sodium indicates a contribution from the alteration of sodium-bearing silicate minerals, such as sodium plagioclase, which are abundant in felsic volcanic and intrusive rocks. This interpretation is supported by previous mineralogical and geochemical analyses conducted on the minerals of the mine tailings in the study area (Moreno Tovar et al., 2012), which report homogeneous concentrations of Na2O and P2O5 with average values of 0.61% and 0.12% respectively. These elemental signatures are characteristic of felsic intrusive lithologies and indicate a persistent source of sodium (Moreno Tovar et al., 2012).The Piper diagram illustrates a chemical composition that varies from calcium bicarbonate to calcium sulfate (mainly Manantial Jal). The La Cruz well plots separately from the main group, reflecting a distinct hydrogeochemical characteristics, associated with mixing processes rather than a single dominant water-rock interaction pathway (Figure 3). This well, is situated in a region characterized by minimal effect from the mineralization, identified by the geophysical method (Figure 8, Isosurface 2), and on a volcanic-sedimentary substrate. These conditions suggest that the observed chemical composition at La Cruz is controlled by the convergence of waters with different geochemical characteristics and by limited interaction with mineralized carbonate or sulfide-bearing formations. Consequently, the hydrogeochemistry of the La Cruz well reflects a geologically constrained system with reduced mineralization influence compared to the central carbonate-dominated zones.The hydrogeochemical results indicate that the shallow groundwater that reaches the Manantial Jal explains the high concentration of arsenic and sulfates due to its proximity to a mining tailings, thus classifying it as a point source of contamination. (Sracek et al., 2010).