Page 5 - Demo

Tania Karen Espinoza-Ju%u00e1rez et al. | 2075stones but it can form in almost any type of rock during regional or contact metamorphism and from a variety of metasomatic processes involving fluids of magmatic, metamorphic, meteoric, or marine origin. They are zoned, and the general pattern is proximal garnet, distal pyroxene, and minerals such as wollastonite, vesuvianite, or massive sulfides and/or oxides near the marble front (Meinert, Dipple & Nicolescu, 2005). Evidence of skarn and varying degrees of contact metamorphism has been identified in the La Encarnaci%u00f3n-Villa Ju%u00e1rez location and the Cerro Colorado mining district (Mora, 1998).3.3. Structural geologyThe presence of faults and fractures (Figure 1) is characteristic of this region (Ramos Leal, 1996).In the Paleocene, the deformation phase corresponding to the Laramide structures began (Carrillo-Mart%u00ednez and Suter, 1982), with compressive stresses that gave rise to structures of the ductile and ductile-brittle domains, represented by folds and thrust faults (Servicio Geol%u00f3gico Mexicano, 2002). The Laramide deformation style developed along the eastern limestone margin of El Doctor, with a regional N-NW trend (Carrillo-Mart%u00ednez & Suter, 1982; Fitz-D%u00edaz et al., 2012).In the Oligocene, monzonite intrusives were emplaced, affecting the previous rocks with contact metamorphism (Servicio Geol%u00f3gico Mexicano, 2002).In the Miocene, after the end of compressive forces, the relaxation or extensional phase begins, manifested by brittle deformation and the development of post-Laramide structures, such as extensional deformations, compressive structures, and basin-and-range normal faults (Carrillo-Mart%u00ednez & Suter, 1982; Fitz-D%u00edaz et al., 2012) with NW-SE orientations and dips towards the SW, some with a lateral component that affect the entire sequence (Servicio Geol%u00f3gico Mexicano, 2002).4. Materials and Methods4.1. HydrogeochemistryIn 2022, two sampling campaigns were conducted throughout the rainy and dry seasons, aimed at assessing water quality in wells situated in Zimap%u00e1n. The sampling procedure followed the guidelines indicated by NOM-014-SSA1-1993 (Secretar%u00eda de Salud, 1994), as well as the standard methods of APHA-AWWA (2005), and Mexican norms (NOM-127-SSA1 [Secretar%u00eda de Salud, 2022] and NOM-230-SSA1 [Secretar%u00eda de Salud, 2005]). Ten sampling sites were selected for this study (Table 1), where field parameters including temperature, pH, oxidation-reduction potential and electrical conductivity were measured at each location using a HANNA-HI98194 multiparameter device (Hanna Instruments Inc., 2020). Calibration was performed prior to the measurements at each sampling point, utilizing Quick Cal calibration solution (HI9828-0) for pH and electrical conductivity, while for the oxidation-reduction potential, ORP was calibrated with Zobell solution.The chemical analysis of major ions was conducted in accordance with the APHA-AWWA methods (APHA-AWWA, 2005) at the Analytical Chemistry Laboratory of the Institute of Geophysics, UNAM, Mexico, using standard procedures. Bicarbonate was quantified using volumetric titration with HCl, Cl- was analyzed by potentiometry with selective electrodes (4500-Cl-), and SO42- was determined by turbidimetry (method 4500-SO42-). Ca2+ and Mg2+ were analyzed by volumetry (EDTA titration); while Na+ and K+ were determined by atomic emission spectrophotometry (3500-Na+ and K+), SiO2 was determined using flame atomic absorption spectrophotometry and UV-visible spectroscopy (molybdosilicic acid method). The analytical quality was assessed using ionic balance (below 10%) and the utilization of certified reference solutions (traceable to NIST).4.2. GeophysicsThe study region was selected for 3D geophysical modeling based on the hydrogeochemical results from the sample stations, using potential field data. Magnetic Anomaly and Bouguer Anomaly data sets were collected, adapted, and processed using Oasis Montaj (2024.1) (Seequent, 2024). Both datasets encompass a region of 2321%u00a0km2, including the municipality of Zimap%u00e1n and its vicinity.We utilized data obtained from the Magnetic Anomaly Map of North America (2002) sourced from the USGS geophysical database (North American Magnetic Anomaly Group et al., 2002), which exhibits an average separation of 914%u00a0m. This subsequently produces areas of 835,306%u00a0m%u00b2. The data can be accessed and downloaded from GeoMapApp (www.geomapapp.org) in various formats for later manipulation. The national compilation included in the North American database for the research area was obtained by the Mineral Resources Council of Mexico (CRM) with a cell size of one-fifth of the flight line spacing, utilizing a minimal curvature algorithm (North American Magnetic Anomaly Group et al., 2002). We utilized the ICGEM platform, employing the gravimetric satellite dataset of the EIGEN-6C4 model, which offers the best global resolution and coverage, effectively delineating deep anomalies with commendable precision (Camacho & Alvarez, 2021). This dataset has an average separation of 107%u00a0m producing areas of 11,450 m2.