Origin of fumarolic fluids from Tupungatito Volcano (Central Chile): interplay between magmatic, hydrothermal, and shallow meteoric sources
Author
dc.contributor.author
Benavente, Oscar
Author
dc.contributor.author
Tassi, Franco
es_CL
Author
dc.contributor.author
Gutiérrez, Francisco
es_CL
Author
dc.contributor.author
Vaselli, Orlando
es_CL
Author
dc.contributor.author
Aguilera, Felipe
es_CL
Author
dc.contributor.author
Reich Morales, Martín
es_CL
Admission date
dc.date.accessioned
2014-03-06T20:03:05Z
Available date
dc.date.available
2014-03-06T20:03:05Z
Publication date
dc.date.issued
2013
Cita de ítem
dc.identifier.citation
Bull Volcanol (2013) 75:746
en_US
Identifier
dc.identifier.other
DOI 10.1007/s00445-013-0746-x
Identifier
dc.identifier.uri
https://repositorio.uchile.cl/handle/2250/126423
General note
dc.description
Artículo de publicación ISI
en_US
Abstract
dc.description.abstract
Tupungatito is a poorly known volcano located
about 100 km eastward of Santiago (Chile) in the northernmost
sector of the South Volcanic Zone. This 5,682 m high
volcano shows intense fumarolic activity. It hosts three crater
lakes within the northwestern portion of the summit area.
Chemical compositions of fumarolic gases and isotopic signatures
of noble gases (3He/4He and 40Ar/36Ar are up to 6.09
Ra and 461, respectively), and steam (δ18O and δD) suggest
that they are produced by mixing of fluids from a magmatic
source rich in acidic gas compounds (SO2, HCl, and HF),
and meteoric water. The magmatic–hydrothermal fluids are
affected by steam condensation that controls the outlet fumarolic
temperatures (<83.6 °C), the gas chemical composition,
and the steam isotopic values. The δ13C–CO2 values
(ranging from 0.30 and −8.16‰ vs. V-PDB) suggest that
CO2 mainly derives from (1) a mantle source likely affected
by significant contamination from the subducting slab, (2)
the sedimentary basement, and (3) limited contribution from
crustal sediments. Gas geothermometry based on the kinetically
rapid H2–CO equilibria indicates equilibrium temperatures
<200 °C attained in a single vapor phase at redox
conditions slightly more oxidizing than those commonly
characterizing hydrothermal reservoirs. Reactions in the
H2O–CO2–H2–CO–CH4 system and C2–C3 alkenes/alkanes
pairs, which have relatively slow kinetics, seem to equilibrate
at greater depth, where temperatures are >200 °C and
redox conditions are consistent with those inferred by the
presence of the SO2–H2S redox pair, typical of fluids that
have attained equilibrium in magmatic environment. A comprehensive
conceptual geochemical model describing the circulation
pattern of the Tupungatito hydrothermal–magmatic
fluids is proposed. It includes fluid source regions and reequilibration
processes affecting the different gas species due
to changing chemical–physical conditions as the magmatic–
hydrothermal fluids rise up toward the surface.