Cristobalite in the 2011–2012 Cordón Caulle eruption (Chile)

Schipper, C. Ian; Castro, Jonathan M.; Tuffen, Hugh; Wadsworth, Fabian B.; Chappell, Debra; Pantoja, A. E.; Simpson, Mark P.; Ru, Eric C. Le

doi:10.1007/s00445-015-0925-z

Cited by 46 publications

(87 citation statements)

References 70 publications

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“…Using an eruptive temperature of 900 • C, a melt composition from Schipper et al (2015) with a volatile content of 0.1%, and an initial crystal content of ∼30% at the vent (Schipper et al, 2015) gives a viscosity of ∼1.5 × 10 9 Pa s. This is in close agreement to the fixed parameter model suggested here (Equations 1, 2, Figure 10A). We acknowledge that the Einstein-Roscoe equation is based on the assumption that the crystal population is isotropic.…”

Section: Inferring Cordón Caulle Flow Propertiessupporting

confidence: 75%

“…However, reliable viscosity estimates could only be made from the latter stages of the eruption when recognizable surface features could be tracked and the flow was less obscured by the eruption plume. Thus, viscosity estimates are upper bounds because they are likely to be affected by the presence of a crust, and the later lava was likely cooler, more degassed and more crystalline than during the earlier stages (Schipper et al, 2015). Flow length models offer an alternative approach to constrain plausible values of flow viscosity, crust yield strength and internal yield strength.…”

Section: Inferring Cordón Caulle Flow Propertiesmentioning

confidence: 99%

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Emplacing a Cooling-Limited Rhyolite Lava Flow: Similarities with Basaltic Lava Flows

et al. 2017

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Accurate forecasts of lava flow length rely on estimates of eruption and magma properties and, potentially more challengingly, on an understanding of the relative influence of characteristics such as the apparent viscosity, the yield strength of the flow core, or the strength of the lava's surface crust. For basaltic lavas, the relatively high frequency of eruptions has resulted in numerous opportunities to test emplacement models on such low silica lava flows. However, the flow of high silica lava is much less well understood due to the paucity of contemporary events and, if observations of flow length change are used to constrain straightforward models of lava advance, remaining uncertainties can limit the insight gained. Here, for the first time, we incorporate morphological observations from during and after flow field evolution to improve model constraints and reduce uncertainties. After demonstrating the approach on a basaltic lava flow (Mt. Etna 2001), we apply it to the 2011-2012 Cordón Caulle rhyolite lava flow, where unprecedented observations and syn-emplacement satellite imagery of an advancing silica-rich lava flow have indicated an important influence from the lava flow's crust on flow emplacement. Our results show that an initial phase of viscosity-controlled advance at Cordón Caulle was followed by later crustal control, accompanied by formation of flow surface folds and large-scale crustal fractures. Where the lava was unconstrained by topography, the cooled crust ultimately halted advance of the main flow and led to the formation of breakouts from the flow front and margins, influencing the footprint of the lava, its advance rate, and the duration of flow advance. Highly similar behavior occurred in the 2001 Etna basaltic lava flow. In our comparison of these two cases, we find close similarities between the processes controlling the advance of a crystal-poor rhyolite and a basaltic lava flow, suggesting common controlling mechanisms that transcend the profound rheological and compositional differences of the lavas.

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Section: Inferring Cordón Caulle Flow Propertiessupporting

confidence: 75%

Section: Inferring Cordón Caulle Flow Propertiesmentioning

confidence: 99%

Emplacing a Cooling-Limited Rhyolite Lava Flow: Similarities with Basaltic Lava Flows

et al. 2017

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“…%). These SiO 2 -enriched bands correspond with fractured areas associated with greater crystallinity and porosity, as encountered in the 2011-2012 Cordón Caulle rhyolite lava (Schipper et al, 2015). Other major elements are also heterogeneous in banded clasts, e.g., 6.2-23.2 wt.…”

Section: Major Element Compositionsmentioning

confidence: 99%

“…Silica-enriched portions of banded clasts are interpreted as zones of local cristobalite precipitation within lava, potentially from an earlier eruptive episode. Banding in these lava clasts probably results from shear deformation (Schipper et al, 2015). The inferred depth of magma excavation in the vein (≥360 m) likely exceeded the dome height during phase 2, as it only attained 350 m on 30/09/2008, well after Vulcanian activity ceased (Global Volcanism Program, 2008;Bernstein et al, 2013).…”

Section: Vesicle Size Distributionsmentioning

confidence: 99%

Conduit Dynamics in Transitional Rhyolitic Activity Recorded by Tuffisite Vein Textures from the 2008–2009 Chaitén Eruption

et al. 2016

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The mechanisms of hazardous silicic eruptions are controlled by complex, poorly-understood conduit processes. Observations of recent Chilean rhyolite eruptions have revealed the importance of hybrid activity, involving simultaneous explosive and effusive emissions from a common vent. Such behavior hinges upon the ability of gas to decouple from magma in the shallow conduit. Tuffisite veins are increasingly suspected to be a key facilitator of outgassing, as they repeatedly provide a transient permeable escape route for volcanic gases. Intersection of foam domains by tuffisite veins appears critical to efficient outgassing. However, knowledge is currently lacking into textural heterogeneities within shallow conduits, their relationship with tuffisite vein propagation, and the implications for fragmentation and degassing processes. Similarly, the magmatic vesiculation response to upper conduit pressure perturbations, such as those related to the slip of dense magma plugs, remains largely undefined. Here we provide a detailed characterization of an exceptionally large tuffisite vein within a rhyolitic obsidian bomb ejected during transitional explosive-effusive activity at Chaitén, Chile in May 2008. Vein textures and chemistry provide a time-integrated record of the invasion of a dense upper conduit plug by deeper fragmented magma. Quantitative textural analysis reveals diverse vesiculation histories of various juvenile clast types. Using vesicle size distributions, bubble number densities, zones of diffusive water depletion, and glass H 2 O concentrations, we propose a multi-step degassing/fragmentation history, spanning deep degassing to explosive bomb ejection. Rapid decompression events of ∼3-4 MPa are associated with fragmentation of foam and dense magma at ∼200-360 m depth in the conduit, permitting vertical gas and pyroclast mobility over hundreds of meters. Permeable pathway occlusion in the dense conduit plug by pyroclast accumulation and sintering preceded ultimate bomb ejection, which then triggered a final bubble nucleation event. Our results highlight how the vesiculation response of magma to decompression events is highly sensitive to the local melt volatile concentration, which is strongly spatially Saubin et al.Chaitén Tuffisites Record Conduit Processes heterogeneous. Repeated opening of pervasive tuffisite vein networks promotes this heterogeneity, allowing juxtaposition of variably volatile-rich magma fragments that are derived from a wide range of depths in the conduit. This process enables efficient but explosive removal of gas from rhyolitic magma and creates a complex textural collage within dense rhyolitic lava, in which neighboring fused clasts may have experienced vastly different degassing histories.

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“…In addition, prolonged residence times of the tuffisite hosting lava during outgassing are supported by the presence of cristobalite needles in some tuffisites ( Figure 4H). The presence of cristobalite only in tuffisites and not in the host lavas suggests it is likely to be a product of vapor phase deposition (Horwell et al, 2013), though it can also relate to the devitrification of glass (e.g., Schipper et al, 2015).…”

Section: Geological Observations and Measurementsmentioning

confidence: 99%

Blowing Off Steam: Tuffisite Formation As a Regulator for Lava Dome Eruptions

et al. 2016

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Tuffisites are veins of variably sintered, pyroclastic particles that form in conduits and lava domes as a result of localized fragmentation events during gas-and-ash explosions. Those observed in-situ on the active 2012 lava dome of Volcán de Colima range from voids with intra-clasts showing little movement and interpreted to be failure-nuclei, to sub-parallel lenses of sintered granular aggregate interpreted as fragmentation horizons, through to infilled fractures with evidence of viscous remobilization. All tuffisites show evidence of sintering. Further examination of the complex fracture-and-channel patterns reveals viscous backfill by surrounding magma, suggesting that lava fragmentation was followed by stress relaxation and continued viscous deformation as the tuffisites formed. The natural tuffisites are more permeable than the host andesite, and have a wide range of porosity and permeability compared to a narrower window for the host rock, and gaging from their significant distribution across the dome, we posit that the tuffisite veins may act as important outgassing pathways. To investigate tuffisite formation we crushed and sieved andesite from the lava dome and sintered it at magmatic temperatures for different times. We then assessed the healing and sealing ability by measuring porosity and permeability, showing that sintering reduces both over time. During sintering the porosity-permeability reduction occurs due to the formation of viscous necks between adjacent grains, a process described by the neck-formation model of Frenkel (1945). This process leads the granular starting material to a porosity-permeability regime anticipated for effusive lavas, and which describes the natural host lava as well as the most impervious of natural tuffisites. This suggests that tuffisite formation at Volcán de Colima constructed a permeable network that enabled gas to bleed passively from the magma. We postulate that this progressively reduced the lava dome's ability to seal and build pressure that drives explosions. Indeed, the time interval between explosions during 2007-2011 gradually increased before the onset of a period of quiescence starting in June 2011. We suggest that the permeability evolution during tuffisite formation has important consequences for modeling of gas-and-ash explosions, common at dome-forming volcanoes.

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Cristobalite in the 2011–2012 Cordón Caulle eruption (Chile)

Cited by 46 publications

References 70 publications

Emplacing a Cooling-Limited Rhyolite Lava Flow: Similarities with Basaltic Lava Flows

Emplacing a Cooling-Limited Rhyolite Lava Flow: Similarities with Basaltic Lava Flows

Conduit Dynamics in Transitional Rhyolitic Activity Recorded by Tuffisite Vein Textures from the 2008–2009 Chaitén Eruption

Blowing Off Steam: Tuffisite Formation As a Regulator for Lava Dome Eruptions

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