Halogen (Cl, F) release during explosive, effusive, and intrusive phases of the 2011 rhyolitic eruption at Cordón Caulle volcano (Chile)

Schipper, C. Ian; Castro, Jonathan M.; Kennedy, Ben; Christenson, Bruce; Aiuppa, Alessandro; Alloway, Brent V.; Forte, Pablo; Seropian, Gilles; Tuffen, Hugh

doi:10.30909/vol.02.01.7390

Cited by 19 publications

(16 citation statements)

References 76 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Measured glass compositions show more heterogenous and depleted Cl contents compared to the pumice population. Depleted and heterogenous Cl contents in volcanic rocks have been reported elsewhere and attributed to (i) leaching or devolatilization of Cl by escaping steam with subsequent degassing to the surface (e.g., Soufrière Hills volcano; Harford et al 2003;Horwell et al 2013;Schipper et al 2019), (ii) outgassing (Yoshimura et al 2019;Schipper et al 2019), (iii) devitrification in rhyolitic melts (Schipper et al 2019), or (iv) groundmass crystallization in a slowly cooling magma (Signorelli and Carroll 2002). The latter process can be ruled out as groundmass crystallization of microlites with low Cl content would have Fig.…”

Section: Type 1 Dome Pyroclastsmentioning

confidence: 76%

Rheological change and degassing during a trachytic Vulcanian eruption at Kilian Volcano, Chaîne des Puys, France

et al. 2020

View full text Add to dashboard Cite

Magma ascent during silicic dome-forming eruptions is characterized by significant changes in magma viscosity, permeability, and gas overpressure in the conduit. These changes depend on a set of parameters such as ascent rate, outgassing and crystallization efficiency, and magma viscosity, which in turn may influence the prevailing conditions for effusive versus explosive activity. Here, we combine chemical and textural analyses of tephra with viscosity models to provide a better understanding of the effusive-explosive transitions during Vulcanian phases of the 9.4 ka eruption of Kilian Volcano, Chaîne des Puys, France. Our results suggest that effusive activity at the onset of Vulcanian episodes at Kilian Volcano was promoted by (i) rapid ascent of initially crystal-poor and volatile-rich trachytic magma, (ii) a substantial bulk and melt viscosity increase driven by extensive volatile loss and crystallization, and (iii) efficient degassing/outgassing in a crystal-rich magma at shallow depths. Trachytic magma repeatedly replenished the upper conduit, and variations in the amount of decompression and cooling caused vertical textural stratification, leading to variable degrees of crystallization and outgassing. Outgassing promoted effusive dome growth and occurred via gas percolation through large interconnected vesicles, fractures, and tuffisite veins, fostering the formation of cristobalite in the carapace and talus regions. Build-up of overpressure was likely caused by closing of pore space (bubbles and fractures) in the dome through a combination of pore collapse, cristobalite formation, sintering in tuffisite veins, and limited pre-fragmentation coalescence in the dome or underlying hot vesicular magma. Sealing of the carapace may have caused a transition from open- to closed- system degassing and to renewed explosive activity. We generalize our findings to propose that the broad spectrum of eruptive styles for trachytic magmas may be inherited from a combination of characteristics of trachytic melts that include high water solubility and diffusivity, rapid microlite growth, and low melt viscosity compared to their more evolved subalkaline dacitic and rhyolitic equivalents. We show that trachytes may erupt with a similar style (e.g., Vulcanian) but at significantly higher ascent rates than their andesitic, dacitic, and rhyolitic counterparts. This suggests that the periodicity of effusive-explosive transitions at trachytic volcanoes may differ from that observed at the well-monitored andesitic, dacitic, and rhyolitic volcanoes, which has implications for hazard assessment associated with trachytic eruptions.

show abstract

Section: Type 1 Dome Pyroclastsmentioning

confidence: 76%

Rheological change and degassing during a trachytic Vulcanian eruption at Kilian Volcano, Chaîne des Puys, France

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Banded obsidian bombs and clast domains represent relatively deeper fracturing in the system as supported by the high Cl concentrations in certain bands of microlite-free glass [Schipper et al 2019]. The highest Cl concentrations, <2300 ppm (Figure 4), are comparable to the Cl concentrations (~1700-2100 ppm) found in melt inclusions in plagioclase and pyroxene crystals [Castro et al 2013;Jay et al 2014].…”

Section: Banded Obsidian Domainsmentioning

confidence: 81%

“…Flow textures are not discussed in this study as the rhyolite flow undergoes additional processes at the surface as it cools that are recorded texturally and chemically, e.g. devitrification, second boiling and continued outgassing [Magnall et al 2018;Schipper et al 2015;Schipper et al 2019].…”

Section: Sampling Methodsmentioning

confidence: 99%

“…Thus it is assumed material with extensive viscous textures will have originated from deeper in the conduit than samples preserving predominantly brittle textures. Chlorine is largely retained in the melt until magma ascends into the near-surface, or is extruded as a flow or a dome, where a degree of open-system degassing occurs and Cl can be readily degassed into an available vapour phase as HCl [Edmonds et al 2002;Lowenstern et al 2012;Schipper et al 2019;Villemant et al 2008]. The loss of Cl in domains, such as heavilyoxidised and ash domains, constrains them and their processes to the near-surface environment whilst it is inferred that Cl-rich samples, such as banded obsidian domains, would have quenched at higher pressures, see below.…”

Section: Degassing: From Depth To the Surfacementioning

confidence: 99%

See 1 more Smart Citation

Degassing-induced chemical heterogeneity at the 2011-2012 Cordón Caulle eruption

Paisley

Berlo²,

Whattam³

et al. 2019

Volcanica

Self Cite

View full text Add to dashboard Cite

The mechanisms of hazardous rhyolitic eruptions such as Cordón Caulle, Chile, in 2011-2012 are controlled by poorly-understood shallow conduit processes. Here we characterise texturally and chemically heterogeneous domains (e.g. ash, breccias and tuffisites) generated via fracturing, gas fluxing and melt relaxation within the conduit, and preserved in glassy, oxidised and devitrified samples. Volatile trace element depletions (e.g. Zn, Pb) in relict degassing pathways record metal scavenging by fluxing gases. Diffusion modelling of preserved trace element concentration gradients (e.g. Li, Rb, Tl) at domain interfaces indicate deep-conduit degassing events were short-lived (~minutes) whereas late-stage venting from discrete locations was prolonged (~hours), corroborating visual observations of the eruption. Later-erupted vent deposits are volatile-depleted with respect to earlier-erupted bombs, indicating progressive syn-eruptive volatile loss. We show that a combination of in situ textural and volatile trace element analyses can provide new constraints on magmatic degassing in shallow systems depleted in H 2 O and CO 2. Résumé Les éruptions dangereuses de type rhyolitiques comme l'éruption du Cordón Caulle, au Chili, en 2011-2012, sont contrôlés par des mécanismes mal compris qui sont localisés dans un conduit peu profond. Dans cette étude, nous caractérisons des domaines où la texture et la chimie sont hétérogènes (par exemple : les cendres, les brèches et les tuffisite). Ces domaines ont été généré par la fracturation, le flux de gaz et la relaxation du liquide dans le conduit et sont conservées dans des échantillons vitreux, oxydés et dévitrifiés. L'appauvrissement des éléments traces et volatiles (par exemple Zn, Pb) enregistré dans les voies de dégazage, témoigne de l'absorption du métal par le flux de gaz. La modélisation des gradients de diffusion des éléments traces conservés (par exemple, Li, Rb, Tl) aux interfaces des domaines, indiquent que des événements de dégazage en conduit profond ont été de courte durée (~minutes) alors que la ventilation tardive de zones plus localisées était de longue durée (~heures). Ces résultats sont en accord avec des observations visuelles de l'éruption. Les dépôts tardifs sont appauvris en volatiles par rapport aux bombes éjectés antérieurement. Cela indique une perte en volatile progressive durant l'éruptive. Nous montrons qu'une association d'analyses in situ des textures et des éléments traces volatiles peut fournir de nouvelles contraintes sur le dégazage magmatique dans des systèmes peu profonds et appauvris en H 2 O et CO 2 .

show abstract

“…% (Castro et al 2014;Forte and Castro 2019). During evolution in the shallow conduit -where the Cordón Caulle 29 composite bombs are thought to have originated from water is the only significant volatile present, as CO2 would have been lost at significantly greater depths (Toramaru 1995;Proussevitch and Sahagian 1998;Castro et al 2013;Castro et al 2014;Forte and Castro 2019;Schipper et al 2019). Therefore, in the rest of the thesis, any reference to volatile content of Cordón Caulle samples is synonymous with water content.…”

Section: Figure 22 Composite Bombs Erupted From Cordón Caulle Showing the Variability In Appearance And The Dominant Textures Adapted Fromentioning

confidence: 99%

The good, the bad, and the bubbly: Textural controls on secondary vesiculation of silicic magma through thermal heating

Jones¹

View full text Add to dashboard Cite

<p>Volcanic eruptions are driven by magma buoyancy caused by volatiles exsolving to form a separate gas phase. Gas overpressurization within the melt and subsequent fragmentation determines whether an eruption will be explosive (fragmentation) or effusive (no fragmentation). Therefore, a thorough understanding of factors which affect the ability of a melt to exsolve and retain or lose these volatiles effectively is required. Bubble nucleation and subsequent growth are the processes by which volatiles exsolve from the melt into an exsolved gas phase. As continued vesiculation occurs, bubbles may begin to interact and coalesce at a point called the percolation threshold, permeable pathways through the melt will then form until the permeability threshold is reached allowing volatiles to outgas, reducing overpressure. Currently, research has focused on the effects that pressure, temperature, and composition have on volatile solubility and eventual vesiculation. However, erupted bombs consisting of assemblages of heterogenous pyroclasts that were subsequently sintered and welded into a conduit-forming plug during the Cordón Caulle 2011-2012 eruption display vesiculation trends within naturally occurring obsidian pyroclasts formed by sintering of particles or quenched melt that cannot be resolved by volatile solubility effects alone. The erupted products have consistently low volatile contents with little variability present across erupted samples (0.07-0.32 wt. % H2O). Within these pyroclasts, the heterogeneity of internal textures is visible when viewed using backscattered electron (BSE) imaging or X-ray computed tomography (XCT) as clear borders exist between regions that are of a clastogenic (sintered) origin, of a quenched melt origin, or formed by variable forms of vesiculation. The heterogeneity of internal textures present within even a obsidian pyroclastic domain led to the hypothesis that foaming discrepancies observed within individual clasts were due to pre-existing textures promoting or inhibiting secondary vesiculation in the shallow conduit. This secondary vesiculation occurs through near isobaric temperature increases in the shallow conduit, following primary vesiculation and volatile exsolution associated with isothermal decompression from storage at depth. To test this hypothesis, obsidian samples of 1cm x 1-2cm x 1-3cm were heated above their glass transition temperature (Tg), between 850-910°C, to allow obsidians to vesiculate as the melt would have in the conduit. The textures of the samples were characterised before and after heating using x-ray computed tomography. The results show that within the slightly volatile supersaturated samples variable foaming was observed for each independent texture within obsidian pyroclasts, with foaming preferentially occurring within regions that contained pre-existing, isolated bubbles. These experiments show that limited thermally driven in situ foaming of relatively dense clasts containing small isolated bubbles, can increase overpressure if the domain doesn’t expand as bubbles form without increasing permeability leading to gas overpressure within this smaller region and localised explosions in order to clear this blockage, explaining the hybrid effusive-explosive eruptions observed at Cordón Caulle.</p>

show abstract

Halogen (Cl, F) release during explosive, effusive, and intrusive phases of the 2011 rhyolitic eruption at Cordón Caulle volcano (Chile)

Cited by 19 publications

References 76 publications

Rheological change and degassing during a trachytic Vulcanian eruption at Kilian Volcano, Chaîne des Puys, France

Rheological change and degassing during a trachytic Vulcanian eruption at Kilian Volcano, Chaîne des Puys, France

Degassing-induced chemical heterogeneity at the 2011-2012 Cordón Caulle eruption

The good, the bad, and the bubbly: Textural controls on secondary vesiculation of silicic magma through thermal heating

Contact Info

Product

Resources

About