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Geosciences
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Magma Degassing from Magma at Depth to the Surface
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Magma Degassing from Magma at Depth to the Surface

A special issue of Geosciences (ISSN 2076-3263). This special issue belongs to the section "Geochemistry".

Deadline for manuscript submissions: closed (20 December 2022) | Viewed by 11519

Special Issue Editors

Dr. Severine Moune

E-Mail Website
Guest Editor
1. Volcanological and Seismological Observatory of Guadeloupe (OVSG), Guadeloupe - Institut de physique du globe de paris (IPGP), 75005 Paris, France
2. Laboratoire Magmas et Volcans, Université Clermont Auvergne, Clermont-Ferrand, France
Interests: fumaroles; plume; unrest; gas chemistry; melt inclusions; volatiles; sources; degassing dynamics
Dr. Geoff Kilgour

E-Mail Website
Guest Editor
GNS Science, PO Box 30368, Lower Hutt, New Zealand
Interests: igneous petrology; physical volcanology

Special Issue Information

Dear Colleagues,

This Special Issue of Geosciences aims to gather high-quality and original research articles, reviews and technical notes on degassing from magma at depth to the surface.

Volcanoes are commonly observed to emit larger amounts of gas than can be dissolved in the volume of erupted magma, especially in subduction zones. Combined with an understanding of the underlying mechanisms, quantification of this so-called excess degassing can provide valuable insights into eruptive processes. The dynamics of eruptive processes are linked to both the gas composition in magmas and the physics of degassing, but no single approach is sufficient for describing the full range of these dynamics.  Thus, it is crucial to integrate studies on the behaviour and transfer of volatile components from their starting conditions in the deep magmatic system (e.g., pre-eruptive content, volatile solubility) through ascent in the volcanic conduit and release into the atmosphere (e.g. gas composition and flux, ash-gas-aerosol interactions). Combining these data with state-of-the-art geophysical methods and numerical modelling, will improve our understanding of the dynamics of  magma degassing. Multi-disciplinary approaches with measurements of dissolved, exsolved and emitted magmatic volatiles are essential to increase our knowledge of eruptive processes.  Therefore, we would like to invite contributions from all fields of geochemistry, geophysics, and petrology that use field, analytical, numerical, analogue and experimental approaches on the dynamics of magma degassing.  

If you wish to participate, please send in a short abstract outlining the purpose of the research and the principal results obtained.  If your submission fits with the objectives of the Special Issue, you will be invited to submit a full manuscript for consideration.

Dr. Severine Moune
Dr. Geoff Kilgour
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Geosciences is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Melt inclusions
  • Gas geochemistry
  • fumarolles
  • excess degassing
  • volcanic plume
  • deep magma system

Published Papers (4 papers)

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Research

18 pages, 6078 KiB  
Article
Monitoring Hydrothermal Activity Using Major and Trace Elements in Low-Temperature Fumarolic Condensates: The Case of La Soufriere de Guadeloupe Volcano
by Manuel Inostroza, Séverine Moune, Roberto Moretti, Vincent Robert, Magali Bonifacie, Elodie Chilin-Eusebe, Arnaud Burtin and Pierre Burckel
Geosciences 2022, 12(7), 267; https://doi.org/10.3390/geosciences12070267 - 30 Jun 2022
Cited by 7 | Viewed by 2357
Abstract
At the hydrothermal stage, volcanoes are affected by internal and external processes that control their fumarolic and eruptive activity. Monitoring hydrothermal activity is challenging given the diverse nature of the processes accounting for deeper magmatic and shallow hydrothermal sources. A better understanding of [...] Read more.
At the hydrothermal stage, volcanoes are affected by internal and external processes that control their fumarolic and eruptive activity. Monitoring hydrothermal activity is challenging given the diverse nature of the processes accounting for deeper magmatic and shallow hydrothermal sources. A better understanding of these processes has commonly been achieved by combining geochemical and geophysical techniques. However, existing geochemical techniques only include the surveillance of major gas components in fumarolic emissions or major ions in cold/thermal springs. This work presents a long-term (2017–2021) surveillance of major and trace elements in fumarolic condensates from the Cratère Sud vent, a low-temperature steam-rich emission from the La Soufriere de Guadeloupe volcano. This fumarole presented a fluctuating performance, offering a unique opportunity to reveal the behavior of major and trace elements, as well as the physicochemical processes affecting magmatic and hydrothermal sources. Time-series analyses allowed for the identification of pH-related chemical fluctuations associated with (1) variable inputs of deep magmatic components at the root of the hydrothermal system, (2) pressurization episodes of the hydrothermal system with increasing fluid–rock interaction, acid gas scrubbing, and vapor scavenging of metals, and (3) the decreased hydrothermal activity, decreasing scrubbing efficiency. Variations in the volatile content (e.g., S, Sb, B, Cl, Bi, Zn, Mo, Br, Cd, Ag, Cu, and Pb), the amount of leached rock-related elements (e.g., Na, Mg, Al, Si, P, K, Ca, Ti, Cr, Mn, Fe, Rb, Sr, Y, Cs, Ba, REEs, and U), and variations in the concentration of Cl and S alone, are postulated as key parameters to monitor volcanic–hydrothermal systems in unrest, such as La Soufriere. Our results demonstrate that monitoring using condensates is a useful geochemical technique, complementing conventional methods, such as “Giggenbach” soda flasks or the so-called Multigas. Full article
(This article belongs to the Special Issue Magma Degassing from Magma at Depth to the Surface)
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17 pages, 2491 KiB  
Article
Quantifying Strombolian Activity at Etna Volcano
by Laura Pioli, Marco Palmas, Boris Behncke, Emanuela De Beni, Massimo Cantarero and Simona Scollo
Geosciences 2022, 12(4), 163; https://doi.org/10.3390/geosciences12040163 - 6 Apr 2022
Cited by 4 | Viewed by 2532
Abstract
Understanding the dynamics of mild explosive activity is a fundamental tool for hazard assessment at open conduit volcanoes. This is a particularly critical task for Etna volcano. Etna is in fact characterized by frequent, mild explosive activity, punctuated by lava flows and paroxysmal [...] Read more.
Understanding the dynamics of mild explosive activity is a fundamental tool for hazard assessment at open conduit volcanoes. This is a particularly critical task for Etna volcano. Etna is in fact characterized by frequent, mild explosive activity, punctuated by lava flows and paroxysmal events (‘lava fountains’), which, because of their greater impact, have been the main target for hazard studies, whereas more frequent Strombolian activity has been overlooked. As a result, their impact and associated hazards have been never quantified, despite the extensive monitoring and surveillance activities carried out on this volcano. In this paper, we analyze video recordings of a sequence of Strombolian explosions occurring at the summit craters of Mt. Etna, in Italy, in February 2020. Data were also integrated with a petrographic analysis of collected samples, and drone surveys were performed at the same time as the video recordings. We estimate the frequency of explosions (20–12 per min); particle exit speeds (1–50 m/s), and erupted mass (100–102 kg) of those explosions. A very regular, small-scale activity (marked by a single burst of gas breaking the magma free surface into bombs and lapilli fragments) was occasionally punctuated by larger explosions, (at least one every 5 min), with a longer duration, fed by larger magma volumes, and consisting of two to three distinct pulses followed by a stationary phase. We found that the repose times between explosions follows a log logistic distribution, which is in agreement with the behavior of open vent explosive activity. The four largest explosions of the sequence were analyzed in detail: they emitted particles with median diameters (Mdphi) ranging from −10.1 to −8.8 phi, with bimodal distributions. Full article
(This article belongs to the Special Issue Magma Degassing from Magma at Depth to the Surface)
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26 pages, 7019 KiB  
Article
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
by Philippe Robidoux, Daniela Pastén, Gilles Levresse, Gloria Diaz and Dante Paredes
Geosciences 2021, 11(8), 309; https://doi.org/10.3390/geosciences11080309 - 25 Jul 2021
Cited by 5 | Viewed by 2623
Abstract
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 [...] Read more.
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) (H2O of 0.4–3.0 wt.% and CO2 of 114–1586 ppm) and electron microprobe (EMP), revealed that fast cooling pyroclasts like vesicular scoria preserve a ~1.5 times larger amount of CO2, S, Cl, and volatile species contained in melt inclusions from primitive olivine (Fo76–86). 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. Full article
(This article belongs to the Special Issue Magma Degassing from Magma at Depth to the Surface)
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14 pages, 10792 KiB  
Article
Elevated CO2 Emissions during Magmatic-Hydrothermal Degassing at Awu Volcano, Sangihe Arc, Indonesia
by Philipson Bani, Etienne Le Glas, Kristianto, Alessandro Aiuppa, Marcello Bitetto and Devy Kamil Syahbana
Geosciences 2020, 10(11), 470; https://doi.org/10.3390/geosciences10110470 - 20 Nov 2020
Cited by 3 | Viewed by 2898
Abstract
Awu is a remote and little known active volcano of Indonesia located in the northern part of Molucca Sea. It is the northernmost active volcano of the Sangihe arc with 18 eruptions in less than 4 centuries, causing a cumulative death toll of [...] Read more.
Awu is a remote and little known active volcano of Indonesia located in the northern part of Molucca Sea. It is the northernmost active volcano of the Sangihe arc with 18 eruptions in less than 4 centuries, causing a cumulative death toll of 11,048. Two of these eruptions were classified with a Volcanic Explosivity Index (VEI) of 4. Since 2004, a lava dome has occupied the centre of Awu crater, channelling the fumarolic gas output along the crater wall. A combined Differential Optical Absorption Spectroscopy (DOAS) and Multi-component Gas Analyzer System (Multi-GAS) study highlight a relatively small SO2 flux (13 t/d) sustained by mixed magmatic–hydrothermal emissions made-up of 82 mol.% H2O, 15 mol.% CO2, 2.55 mol.% total S (ST) and 0.02 mol.% H2. The CO2 emission budget, as observed during a short observation period in 2015, corresponds to a daily contribution to the atmosphere of 2600 t/d, representing 1% of the global CO2 emission budget from volcanoes. The gas CO2/ST ratio of 3.7 to 7.9 is at the upper limit of the Indonesian gas range, which is ascribed to (i) some extent of S loss during hydrothermal processing, and perhaps (ii) a C-rich signature of the feeding magmatic gas phase. The source of this high CO2 signature and flux is yet to be fully understood; however, given the peculiar geodynamic context of the region, dominated by the arc-to-arc collision, this may result from either the prolonged heating of the slab and consequent production of carbon-rich fluids, or the recycling of crustal carbon. Full article
(This article belongs to the Special Issue Magma Degassing from Magma at Depth to the Surface)
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