Chemical and isotopic composition of fumarolic gases from the Peteroa volcano (Argentina-Chile)

Name: Chemical and isotopic composition of fumarolic gases from the Peteroa volcano (Argentina-Chile)
Keywords: PETEROA VOLCANO

Datos de investigación

Chemical and isotopic composition of fumarolic gases from the Peteroa volcano (Argentina-Chile)

Autores: Agusto, Mariano Roberto Icon

; Lamberti, María Clara Isabel Icon

; Llano, Joaquin Icon

Publicador: Consejo Nacional de Investigaciones Científicas y Técnicas

Fecha de depósito: 15/08/2023

Fecha de recolectado: 1/1/2016-5/5/2023

Clasificación temática:

Vulcanología

Resumen

Our dataset includes new chemical and isotopic analyses of fumarolic gas samples collected from 2015 to 2021 at Peteroa volcano. This period includes a phreato-magmatic event in 2018-2019. Peteroa is one of the most active volcanoes in the Argentine-Chilean Andean range. Peteroa volcano is part of the Planchón – Peteroa Volcanic Complex, which is located in the northern segment of the Southern Volcanic Zone of the Andes. The geochemical dataset, consisting of chemical and isotopic analyses of fluids from vents occurring in the summit craters of the volcano, was compiled as part of different investigation programs involving an Argentine-Italian research group.

Métodos

From March 2015 to April 2021 gas samples were collected from Peteroa crater fumaroles. The sampling and analytical procedures adopted for the gases constituting this new dataset (from 2015 to 2021) were similar to those used to produce the 2010 to 2015 dataset previously published by Tassi et al. (2016). The gas sampling line consisted of a 0.6 m long titanium tube (Ø = 2.5 cm) and pyrex glass dewared pipes connected to pre-weighed and pre-evacuated 60-mL glass Thorion®-tapped flasks filled with 20 mL of a 4N NaOH and 0.15M Cd(OH)2 suspension (Montegrossi et al., 2001; Vaselli et al., 2006). This technique allows to separate in situ SO2 and H2S, the latter forming insoluble CdS. whereas SO2 is dissolved in the alkaline solution with water vapor and other acidic gases (CO2, HCl, HF). The flask head-space contained the low-solubility gas species no reacting with the soda suspension (N2, O2, CO, H2, He, Ar, CH4 and light hydrocarbons). Gases after removal of condensable species (namely dry gas, used for the analysis of the13C/12C ratios in CO2 and He isotopes) and an aliquot of condensate (for the analysis of F- and Cl- and ?18O-H2O and ?D-H2O) were also collected using a water-cooled condenser connected to the soda flask sampling line.

Información Técnica

Inorganic (N2, Ar, O2, H2, He and CO) and organic (C1-C3 hydrocarbons) gases from the flask headspace were analyzed at the Fluid Geochemistry Laboratory of the University of Florence (Italy) by gas chromatography (GC: Shimadzu 15A, Shimadzu 14, and Thermo Focus). The liquid and the solid phases of the suspension were separated by centrifugation, to analyze CO2, SO2, and HCl, as CO32- (by acidimetric titration, AT; Metrohm Basic Titrino), SO42-, Cl- and F- (by ion chromatography, IC; Methrom 761), respectively. The CdS precipitate was dissolved by oxidation with H2O2 to analyze H2S as SO42- by IC. The analytical error for GC, AT and IC analyses was <5%. In the condensates, he analysis of F- for the determination of HF was carried out by IC, whereas the ?18O and ?D values in water vapor (?18O-H2O and ?D-H2O, expressed as ‰ vs. V-SMOW) were determined using a Finningan Delta Plus XL mass spectrometer at the Geokarst Engineering Laboratory (Trieste, Italy) following the method described by Epstein and Mayeda. (1953) and Coleman et al. (1982), respectively. The ?13C–CO2 values in the dry gases were determined at the Laboratory of Stable Isotopes of CNR-IGG in Pisa (Italy) by using a Finnigan Delta S mass spectrometer (MS), after extracting and purifying CO2 by using liquid N2 and N2- trichloroethylene cryogenic traps (Evans et al., 1998; Vaselli et al., 2006). Carrara and San Vincenzo marbles, as well as international NBS18 and NBS19 standards, were used to estimate the external precision. Analytical uncertainty and the reproducibility were ± 0.05‰ and ± 0.1‰, respectively. The 3He/4He (expressed as R/Ra, where R is the 3He/4He measured in the sample and Ra is the 3He/4He ratio in the air: 1.39 10?6; Mamyrin and Tolstikhin, 1984) and 4He/20Ne ratios were determined at the Laboratory of Noble gas isotopes of INGV in Palermo (Italy), by separately introducing He and Ne into a split-flight-tube mass spectrometer (GVI Helix SFT) after performing standard purification procedures (Rizzo et al., 2015). The analytical error on 3He/4He was ?1%, while on 20Ne was < 0.1%. Argon isotopes (40Ar, 38Ar, 36Ar) were measured in a Helix MC-GVI mass spectrometer, with an analytical uncertainty < 0.2% (Rizzo et al., 2019).

Palabras clave: PETEROA VOLCANO, FUMAROLIC GASES, GEOCHEMICAL COMPOSITION, ISOTOPIC COMPOSITION

Alcance geográfico

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Identificador del recurso

URI: http://hdl.handle.net/11336/208244

Colecciones

Datos de Investigación(IDEAN)
Datos de Investigación de INSTITUTO DE ESTUDIOS ANDINOS "DON PABLO GROEBER"

Citación

Agusto, Mariano Roberto; Lamberti, María Clara Isabel; Llano, Joaquin; (2023): Chemical and isotopic composition of fumarolic gases from the Peteroa volcano (Argentina-Chile). Consejo Nacional de Investigaciones Científicas y Técnicas. (dataset). http://hdl.handle.net/11336/208244

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