Geochemical processes influencing As distribution in waters associated with volcanic-hydrothermal systems: A case study of Coconucos volcanic chain-Puracé volcano, Colombia
Por:
Almeida Miranda E.O., Inguaggiato C., Meza Maldonado L.F., Peiffer L., Schiavo B., Levresse G.
Publicada:
1 ene 2025
Resumen:
This study mainly combines hydrogeochemical and geochemical modelling approaches to elucidate the roles of mineral equilibria, water-rock interaction and fluid mixing processes, in controlling arsenic (As) mobility in eight thermal springs of the Coconucos volcanic chain - Puracé volcano in Colombia. Three distinct water groups were identified based on physico-chemical parameters and chemical composition. Group 1, near-neutral SO4-Cl-HCO3 waters with temperatures ranging from 54.8 to 73.3 °C, showed moderate As concentrations of 3.4 and 126.2 ppb. Waters of Group 1 are the only ones partially equilibrated, with reservoir temperatures from 118 to 226 °C estimated through solute geothermometers. Geochemical equilibrium modelling performed using PHREECQ software, allowed us to propose that As concentrations could be controlled by iron (oxyhydr)oxides at the outlet temperature and by the precipitation of sulfide minerals under higher H2S conditions. Group 2, acid-SO4 waters (pH 1.7–2.3) with the lowest temperatures (23.8–44.7 °C), displays As concentrations from 2.1 to 57.5 ppb and near isochemical dissolution of local andesite rock. Low As in most Group 2 waters are likely due to the dilution caused by mixing thermal water with cold water. PHREEQC simulation reveals Fe and Cu sulfides oversaturation at elevated H2S, potentially contributing to As depletion in waters. Group 3, acid SO4-Cl waters with pH from 2.3 to 3.6 and the highest temperatures (80.4–81.6 °C), contained the highest As concentrations (380.8–987.5 ppb). Hypotheses for such enrichment are intense water-rock interaction, As-rich mineral dissolution, and minimal secondary mineral precipitation, as evidenced by PHREEQC saturation index results. © 2025 Elsevier Ltd
Filiaciones:
Almeida Miranda E.O.:
Posgrado en Ciencias de La Tierra, Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California (CICESE), Ensenada, Mexico
Inguaggiato C.:
Departamento de Geología, Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California (CICESE), Carretera Ensenada-Tijuana 3918, Zona Playitas, Baja California, Ensenada, 22860, Mexico
Meza Maldonado L.F.:
Servicio Geológico Colombiano, Observatorio Vulcanológico y Sismológico de Popayán, Popayán, Colombia
Peiffer L.:
Departamento de Geología, Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California (CICESE), Carretera Ensenada-Tijuana 3918, Zona Playitas, Baja California, Ensenada, 22860, Mexico
Unidad La Paz (ULP), Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California (CICESE), Baja California Sur, La Paz, Mexico
Schiavo B.:
Instituto de Geofísica, Universidad Nacional Autónoma de México, Mexico City, 04150, Mexico
Levresse G.:
Instituto de Geociencias, Universidad Nacional Autónoma de México, Campus Juriquilla, Qro, Querétaro, 76230, Mexico
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