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oai:docta.ucm.es:20.500.14352/1186232025-03-18T14:44:59Zcom_20.500.14352_14col_20.500.14352_15

00925njm 22002777a 4500 dc Ramos Prado, Luis Miguel author Velasco Tapia, Fernando author Rodríguez Díaz, Augusto Antonio author Ramírez Fernández, Juan Alonso author Canet, Carles author González Guzmán, Reneé author Castillejo Carreón. José Carlos author De Ignacio San José, Cristina author Fuentes Guzmán, Edith author Linares, Carlos author 2025-01 The Concepción del Oro – Mazapil mining District, Zacatecas, is considered one of the most important in Mexico because it contains massive Fe – Cu skarns mined for almost 500 years. Their origin has been related to post-orogenic granodioritic – monzodioritic intrusion (40–45 Ma) in the Mesozoic Zuloaga (Oxfordian) and Tamaulipas Inferior (Valanginian-Albian) limestones. In the present study, an updated paragenetic model is proposed for the Sol y Luna, Aranzazú and Cata Arroyo deposits. The hydrothermal system evolution has been explained applying a methodological scheme that included: (a) petrography, (b) electron microprobe analysis, (c) scanning electron microscopy, (d) whole-rock and zircon geochemistry, (e) U-Pb in zircon and K-Ar in annite geochronology, and (f) fluid inclusion analysis. A mineral assemblage (andradite > grossular, diopside, wollastonite, vesuvianite, and quartz) and fluid inclusion analysis suggest a prograde stage with a general homogenization temperature = 373–514 °C and salinity = 10.5–61.7% NaCl eq. The Fe-Cu mineralization occurred during the retrograde stage (homogenization temperature = 201–321 °C, salinity = 4.0–10.9% NaCl eq.). It was constituted by magnetite > hematite > pyrite ≈ chalcopyrite > bornite, accompanied by minor amounts of sphalerite, tetrahedrite, hessite, Bi-sulfosalts, covelline, goethite, and Mn oxides. An annite K-Ar age indicates that the iron deposit probably started at ∼41.3 Ma. Chemical composition of iron oxides from skarn deposits shows the interaction of fluid-rock during its precipitation. Retrograde alteration petrographic and chemical composition of hydrothermal chlorites from the Concepción del Oro-Mazapil skarns show the evolution of hydrothermal fluids and represent an exploration guide that can be used as a vector towards orebodies. Chlorite and sphalerite geothermometers indicate a retrograde stage for polymetallic deposit at 208–263 °C for Sol y Luna, 208–234 °C for Aranzazú, and at 181–215 °C for Cata Arroyo. The Concepción del Oro-Mazapil ore system shutdown was marked by low temperature hydrothermal event (homogenization temperature = 120–242 °C) and low salinity (1.7–6.2% NaCl eq.), represented by As-Sb and Au-Zn jasperoids. The proposed paragenetic model provides a better understanding of the Concepción del Oro-Mazapil skarn, being valuable information for future exploration/exploitation activities. Finally, a mineralogical and geochemical comparison of Fe-Cu (Sol y Luna) and Cu-Fe (Aranzazú and Cata Arroyo) skarns has been conducted. Ramos-Prado, L. M., Velasco-Tapia, F., Rodríguez-Díaz, A. A., Ramírez-Fernández, J. A., Canet, C., González-Guzmán, R., Castillejo-Carreón, J. C., De Ignacio-San Jose, C., Fuentes-Guzmán, E., & Linares, C. (2025). Mineralogy, geochemistry, geochronology, and fluid inclusion constraints of the Concepción del Oro-Mazapil Fe—Cu skarns, central Mexico. Journal of South American Earth Sciences, 151, 105268 0895-9811 10.1016/j.jsames.2024.105268 https://hdl.handle.net/20.500.14352/118623 1873-0647 https://doi.org/10.1016/j.jsames.2024.105268 https://www.sciencedirect.com/science/article/pii/S0895981124004905 Mineralogy, geochemistry, geochronology, and fluid inclusion constraints of the Concepción del Oro-Mazapil Fe - Cu skarns, central Mexico