Abstract
This paper presents chemical and isotopic data for thermal waters, gases and S deposits from Volcan Puracé (summit elevation ∼4600 m) in SW Colombia. Hot gas discharges from fumaroles in and around the summit crater, and thermal waters discharge from three areas on its flanks. The waters from all areas have δD values of-75±1, indicating a single recharge area at high elevation on the volcano. Aircorrected values of3He/4He in thermal waters range from 3.8 to 6.7 RA, and approach those for crater fumarole gas (6.1-7.1 RA), indicating widespread addition of magmatic volatiles. An economic S deposit (El Vinagre) is being mined in the Rio Vinagre fault zone at 3600 m elevation. Sulfur isotopic data are consistent with a magmatic origin for S species in thermal waters and gases, and for the S ore deposit. Isotopic equilibration between S species may have occurred at 220±40°C, which overlaps possible equilibration temperatures (170±40°C) determined by a variety of other geothermometers for neutral thermal waters. Apparent CH4-CO2 equilibration temperatures for gases from thermal springs (400±50°C) and crater fumaroles (520±60°C) reflect higher temperatures deeper in the system. Hot magmatic gas ascending through the Rio Vinagre fault zone is though to have precipitated S and generated thermal waters by interaction with descending meteoric waters.
Original language | English (US) |
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Pages (from-to) | 289-296 |
Number of pages | 8 |
Journal | Bulletin of Volcanology |
Volume | 55 |
Issue number | 4 |
DOIs | |
State | Published - May 1993 |
Keywords
- Colombia
- He isotopes
- S isotopes
- Volcan Puracé
- hydrothermal system
- volcanic gases
ASJC Scopus subject areas
- Geochemistry and Petrology