Estimating thermal inflow to El Chichón crater lake using the energy-budget, chemical and isotope balance approaches

• Published in: Journal of volcanology and geothermal research 2008-08, Vol.175 (4), p.472-481
• Main Authors: Taran, Yuri, Rouwet, Dmitri
• Format: Article
• Language: English
• Subjects: CO 2 flux; crater lake; Crystalline rocks; Earth sciences; Earth, ocean, space; El Chichón; Exact sciences and technology; Freshwater; Igneous and metamorphic rocks petrology, volcanic processes, magmas; mass-energy budget
• ISSN: 0377-0273; 1872-6097
• DOI: 10.1016/j.jvolgeores.2008.02.019

El Chichón crater lake appeared immediately after the 1982 catastrophic eruption in a newly formed, 1-km wide, explosive crater. During the first 2 years after the eruption the lake transformed from hot and ultra-acidic caused by dissolution of magmatic gases, to a warm and less acidic lake due to a rapid “magmatic-to-hydrothermal transition” — input of hydrothermal fluids and oxidation of H 2S to sulfate. Chemical composition of the lake water and other thermal fluids discharging in the crater, stable isotope composition ( δD and δ 18O) of lake water, gas condensates and thermal waters collected in 1995–2006 were used for the mass-balance calculations (Cl, SO 4 and isotopic composition) of the thermal flux from the crater floor. The calculated fluxes of thermal fluid by different mass-balance approaches become of the same order of magnitude as those derived from the energy-budget model if values of 1.9 and 2 mmol/mol are taken for the catchment coefficient and the average H 2S concentration in the hydrothermal vapors, respectively. The total heat power from the crater is estimated to be between 35 and 60 MW and the CO 2 flux is not higher than 150 t/day or ~ 200 gm − 2  day − 1 .