Publication Date:
2024-05-09
Description:
This study presents the first geochemical data of fluid discharges collected from February 2010 to March 2015
from the Planchón–Peteroa–Azufre Volcanic Complex (PPAVC), located in the Transitional Southern Volcanic
Zone (TSVZ) at the border between Argentina and Chile. During the study period, from January 2010 to July
2011, Peteroa volcano experienced phreatic to phreatomagmatic eruption possibly related to the devastating Maule earthquake occurred on February 27, 2010. The compositional dataset includes low temperature (from 43.2 to 102 °C) gas discharges from (i) the summit of Peteroa volcano and (ii) the SE flank of Azufre volcano,
both marked by a significant magmatic fluid contribution, as well as bubbling gases located at the foothill of
the Peteroa volcanic edifice, which showed a chemical signature typical of hydrothermal fluids. In 2012, strong
compositional changes affected the Peteroa gases fromthe summit area: the acidic gas species, especially SO2, increased, suggesting an input of fluids from magma degassing. Nevertheless, the R/Ra and δ13C–CO2 values decreased, which would imply an enhanced contribution from a meteoric-hydrothermal source. In 2014–2015,
the chemical and isotopic compositions of the 2010–2011 gases were partially restored. The anomalous
decoupling between the chemical and the isotopic parameters was tentatively interpreted as produced by
degassing activity from a small batch of dacitic magma that in 2012 masked the compositional signature of the
magmatic fluids released from a basalticmagma that dominated the gas chemistry in 2010–2011. This explanation
reliably justifies the observed geochemical data, although the mechanisms leading to the change in time of
the dominatingmagmatic fluid source are not clear. At this regard, a geophysical survey able to provide information
on the location of the two magma batches could be useful to clarify the possible relationships between the
compositional changes that affected the Peteroa fluid discharges and the 2010–2011 eruptive activity.
Description:
Published
Description:
41-53
Description:
2V. Dinamiche di unrest e scenari pre-eruttivi
Description:
JCR Journal
Description:
restricted
Keywords:
volcanic gas geochemistry
;
degassing model
;
isotope geochemistry
;
04. Solid Earth::04.08. Volcanology::04.08.01. Gases
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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