Gas compositions of fumaroles and bubbling springs from the Andean Central Volcanic Zone (Chile and Argentina)

DE MOOR M.; RODRIGUEZ A. ; BARRY P.; AGUILERA, F.; AGUILERA M.; GONZALEZ C.; LAYANA S.; VALLEJOS H.; AGOSTINA CHIODI; JIMENEZ C.; BARTELS C.; BARNES J.; RAMIREZ C.; GIOVANELLI D.; LLOYD K.

Workshop; 14th Field Workshop on Volcanic Gases; 2022

We will present complete gas chemistry and C, He, H, and O isotope results from sampling campaigns conducted in Chile (2022) and Argentina (2019), together representing a transect of ~1000 km through the Andean Central Volcanic Zone (CVZ). The campaigns (51 sites) targeted a broad array of fluid emission types from across a convergent margin characterized by thickened continental crust to assess the effects of upper plate processes (crustal assimilation, volatile sequestration in hydrothermal systems, and biological processing). The samples represent fluids emitted from the backarc subandean fold and thrust belt (SFTB), caldera-hosted silicic geothermal systems of the Altiplano-Puna, actively degassing volcanoes of the main volcanic front of the CVZ, and forearc springs located on the coast. Sample types range from high temperature fumarole samples (max 408°C at Irruputuncu volcano), high and low enthalpy geothermal systems, travertine-depositing bubbling hot springs, to mineral springs with little to no gas phase. Samples were collected for complete gas analysis in Giggenbach bottles containing NaOH and NaOH+Cd(OH)2 for complete gas chemistry, evacuated glass vials for C isotopes, and Cu tubes for He isotopes. Head space gas and C isotope analyses are complete at the time of writing, and NaOH solution analyses are in progress. He/Ar varies from 0.17 to 1.95 in volcanic fumaroles down to