Geochemistry of fluid discharges from Peteroa volcano (Argentina-Chile) in 2010-2015: Insights into compositional changes related to the fluid source region(s)

• Autores: Tassi, Franco; Aguilera, Felipe; Benavente, Óscar; Paonita, A.; Chiodini, Giovanni; Caliro, Stefano; Agusto, Mariano Roberto; Gutierrez, Francisco; Capaccioni, B.; Vaselli, Orlando; Caselli, Alberto Tomás; Saltori, Ornella
• Año de publicación: 2016
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Ciencias Exactas y Naturales; Gas Geochemistry; Peteroa Volcano; Magmatic Degassing; Andean Volcanic Chain; Geochemical Volcano Monitoring; Ciencias Exactas y Naturales
• Institución: Universidad Nacional de Río Negro

Fil: Tassi, Franco. Universita Degli Studi Di Firenze; Italia
Fil: Aguilera, Felipe. Servicio Nacional de Geología y Minería; Chile
Fil: Benavente, Óscar. Universidad de Chile; Chile
Fil: Paonita, A. Istituto Nazionale Di Geofisica E Vulcanologia; Italia
Fil: Chiodini, Giovanni. Istituto Nazionale Di Geofisica E Vulcanologia; Italia
Fil: Caliro, S. Istituto Nazionale Di Geofisica E Vulcanologia; Italia
Fil: Agusto, Mariano Roberto. Universidad de Buenos Aires. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Buenos Aires, Argentina.
Fil: Gutierrez, Francisco. Universidad de Chile; Chile. Advanced Mining Technology Center; Chile
Fil: Capaccioni, B. Department of Earth and Geological -Environmental Science; Italia
Fil: Vaselli, Orlando. Universita Degli Studi Di Firenze; Italia
Fil: Caselli, Alberto Tomás. Universidad Nacional de Rio Negro. Río Negro, Argentina.
Fil: Saltori, Ornella. Universidad de Chile; Chile
Fil: Caselli, Alberto Tomás. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
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 from the 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 basaltic magma 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 dominating magmatic 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.
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