Volatile Content Implications of Increasing Explosivity of the Strombolian Eruptive Style along the Fracture Opening on the NE Villarrica Flank: Minor Eruptive Centers in the Los Nevados Group 2
Potential flank eruptions at the presently active Villarrica, Southern Andes Volcanic Zone (33.3–46 °S) require the drawing of a comprehensive scenario of eruptive style dynamics, which partially depends on the degassing process. The case we consider in this study is from the Los Nevados Subgroup 2...
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MDPI AG
2021-07-01
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| Series: | Geosciences |
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| Online Access: | https://www.mdpi.com/2076-3263/11/8/309 |
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| author | Philippe Robidoux Daniela Pastén Gilles Levresse Gloria Diaz Dante Paredes |
| author_facet | Philippe Robidoux Daniela Pastén Gilles Levresse Gloria Diaz Dante Paredes |
| author_sort | Philippe Robidoux |
| collection | DOAJ |
| description | Potential flank eruptions at the presently active Villarrica, Southern Andes Volcanic Zone (33.3–46 °S) require the drawing of a comprehensive scenario of eruptive style dynamics, which partially depends on the degassing process. The case we consider in this study is from the Los Nevados Subgroup 2 (LNG2) and constitutes post-glacial minor eruptive centers (MECs) of basaltic–andesitic and basaltic composition, associated with the northeastern Villarrica flank. Petrological studies of the melt inclusions volatile content in olivine determined the pre-eruptive conditions of the shallow magma feeding system (<249 Mpa saturation pressure, 927–1201 °C). The volatile saturation model on “pressure-dependent” volatile species, measured by Fourier Transform Infrared Microspectrometry (FTIR) (H<sub>2</sub>O of 0.4–3.0 wt.% and CO<sub>2</sub> of 114–1586 ppm) and electron microprobe (EMP), revealed that fast cooling pyroclasts like vesicular scoria preserve a ~1.5 times larger amount of CO<sub>2</sub>, S, Cl, and volatile species contained in melt inclusions from primitive olivine (Fo<sub>76–86</sub>). Evidence from geological mapping and drone surveys demonstrated the eruption chronology and spatial changes in eruption style from all the local vents along a N45° corridor. The mechanism by which LNG2 is degassed plays a critical role in increasing the explosivity uphill on the Villarrica flank from volcanic vents in the NE sector (<9 km minimum saturation depth) to the SW sector (<8.1 km), where many crystalline ballistic bombs were expulsed, rather than vesicular and spatter scoria. |
| first_indexed | 2024-03-10T08:46:48Z |
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| issn | 2076-3263 |
| language | English |
| last_indexed | 2024-03-10T08:46:48Z |
| publishDate | 2021-07-01 |
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| spelling | doaj.art-617f1b75c6d34f3cb325c15a6eed9aaf2023-11-22T07:47:33ZengMDPI AGGeosciences2076-32632021-07-0111830910.3390/geosciences11080309Volatile Content Implications of Increasing Explosivity of the Strombolian Eruptive Style along the Fracture Opening on the NE Villarrica Flank: Minor Eruptive Centers in the Los Nevados Group 2Philippe Robidoux0Daniela Pastén1Gilles Levresse2Gloria Diaz3Dante Paredes4Centro de Excelencia en Geotermia de los Andes (CEGA) y Departamento de Geología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Plaza Ercilla 803, Santiago 8370450, ChileEscuela de Geología, Universidad Mayor, Av. Manuel Montt 367, Santiago 7500994, ChileCentro de Geociencias, UNAM Campus Juriquilla Blvd. Juriquilla 3001, Querétaro 76230, MexicoEscuela de Geología, Universidad Mayor, Av. Manuel Montt 367, Santiago 7500994, ChileEscuela de Geología, Universidad Mayor, Av. Manuel Montt 367, Santiago 7500994, ChilePotential flank eruptions at the presently active Villarrica, Southern Andes Volcanic Zone (33.3–46 °S) require the drawing of a comprehensive scenario of eruptive style dynamics, which partially depends on the degassing process. The case we consider in this study is from the Los Nevados Subgroup 2 (LNG2) and constitutes post-glacial minor eruptive centers (MECs) of basaltic–andesitic and basaltic composition, associated with the northeastern Villarrica flank. Petrological studies of the melt inclusions volatile content in olivine determined the pre-eruptive conditions of the shallow magma feeding system (<249 Mpa saturation pressure, 927–1201 °C). The volatile saturation model on “pressure-dependent” volatile species, measured by Fourier Transform Infrared Microspectrometry (FTIR) (H<sub>2</sub>O of 0.4–3.0 wt.% and CO<sub>2</sub> of 114–1586 ppm) and electron microprobe (EMP), revealed that fast cooling pyroclasts like vesicular scoria preserve a ~1.5 times larger amount of CO<sub>2</sub>, S, Cl, and volatile species contained in melt inclusions from primitive olivine (Fo<sub>76–86</sub>). Evidence from geological mapping and drone surveys demonstrated the eruption chronology and spatial changes in eruption style from all the local vents along a N45° corridor. The mechanism by which LNG2 is degassed plays a critical role in increasing the explosivity uphill on the Villarrica flank from volcanic vents in the NE sector (<9 km minimum saturation depth) to the SW sector (<8.1 km), where many crystalline ballistic bombs were expulsed, rather than vesicular and spatter scoria.https://www.mdpi.com/2076-3263/11/8/309eruptive stylevolatilesVillarricamelt inclusionLos Nevados group |
| spellingShingle | Philippe Robidoux Daniela Pastén Gilles Levresse Gloria Diaz Dante Paredes Volatile Content Implications of Increasing Explosivity of the Strombolian Eruptive Style along the Fracture Opening on the NE Villarrica Flank: Minor Eruptive Centers in the Los Nevados Group 2 Geosciences eruptive style volatiles Villarrica melt inclusion Los Nevados group |
| title | Volatile Content Implications of Increasing Explosivity of the Strombolian Eruptive Style along the Fracture Opening on the NE Villarrica Flank: Minor Eruptive Centers in the Los Nevados Group 2 |
| title_full | Volatile Content Implications of Increasing Explosivity of the Strombolian Eruptive Style along the Fracture Opening on the NE Villarrica Flank: Minor Eruptive Centers in the Los Nevados Group 2 |
| title_fullStr | Volatile Content Implications of Increasing Explosivity of the Strombolian Eruptive Style along the Fracture Opening on the NE Villarrica Flank: Minor Eruptive Centers in the Los Nevados Group 2 |
| title_full_unstemmed | Volatile Content Implications of Increasing Explosivity of the Strombolian Eruptive Style along the Fracture Opening on the NE Villarrica Flank: Minor Eruptive Centers in the Los Nevados Group 2 |
| title_short | Volatile Content Implications of Increasing Explosivity of the Strombolian Eruptive Style along the Fracture Opening on the NE Villarrica Flank: Minor Eruptive Centers in the Los Nevados Group 2 |
| title_sort | volatile content implications of increasing explosivity of the strombolian eruptive style along the fracture opening on the ne villarrica flank minor eruptive centers in the los nevados group 2 |
| topic | eruptive style volatiles Villarrica melt inclusion Los Nevados group |
| url | https://www.mdpi.com/2076-3263/11/8/309 |
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