A cascade of magmatic events during the assembly and eruption of a super-sized magma body

Allan, Aidan S. R.; Barker, Simon J.; Millet, Marc-Alban; Morgan, D. J.; Rooyakkers, Shane M.; Schipper, C. Ian; Wilson, C. J. N.

doi:10.1007/s00410-017-1367-8

Cited by 68 publications

(135 citation statements)

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“…If it is, indeed, the case that an externally-imposed stress field is required to generate large volumes of crystal-poor rhyolite, such eruptions should be concentrated in tectonically active regions. The Taupo Volcanic Zone of New Zealand fits the bill, with Allan et al ( 2013 , 2017 ) arguing strongly that regional deformation played a key role in generating large bodies of crystal-poor rhyolite. Similarly, the Long Valley volcanic field in California (which includes the Bishop Tuff) is contemporaneous with regional trans-tensional strain (Hildreth 2004 ).…”

Section: Discussionmentioning

confidence: 70%

“…Several recent contributions (e.g., Nasipuri et al 2011 ; Allan et al 2013 , 2017 ; Webber et al 2015 ; Garibaldi et al 2017 ) have suggested that the segregation of rhyolitic melts from a crystal mush can be enhanced by an external stress field. This is not a new idea: the requirement for deformation-driven melt segregation has long been recognized by those working on anatectic regions of the crust (reviewed by Rosenberg 2001 ), with a commonly observed linkage and feedbacks between regional tectonics, migmatite segregation, and granite emplacement (e.g., Brown and Solar 1998 ).…”

Section: Discussionmentioning

confidence: 99%

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Melt segregation from silicic crystal mushes: a critical appraisal of possible mechanisms and their microstructural record

Holness

2018

Contrib Mineral Petrol

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One of the outstanding problems in understanding the behavior of intermediate-to-silicic magmatic systems is the mechanism(s) by which large volumes of crystal-poor rhyolite can be extracted from crystal-rich mushy storage zones in the mid-deep crust. The mechanisms commonly invoked are hindered settling, micro-settling, and compaction. The concept of micro-settling involves extraction of grains from a crystal framework during Ostwald ripening and has been shown to be non-viable in the metallic systems for which it was originally proposed. Micro-settling is also likely to be insignificant in silicic mushes, because ripening rates are slow for quartz and plagioclase, contact areas between grains in a crystal mush are likely to be large, and abundant low-angle grain boundaries promote grain coalescence rather than ripening. Published calculations of melt segregation rates by hindered settling (Stokes settling in a crystal-rich system) neglect all but fluid dynamical interactions between particles. Because tabular silicate minerals are likely to form open, mechanically coherent, frameworks at porosities as high as ~ 75%, settling of single crystals is only likely in very melt-rich systems. Gravitationally-driven viscous compaction requires deformation of crystals by either dissolution–reprecipitation or dislocation creep. There is, as yet, no reported microstructural evidence of extensive, syn-magmatic, internally-generated, viscous deformation in fully solidified silicic plutonic rocks. If subsequent directed searches do not reveal clear evidence for internally-generated buoyancy-driven melt segregation processes, it is likely that other factors, such as rejuvenation by magma replenishment, gas filter-pressing, or externally-imposed stress during regional deformation, are required to segregate large volumes of crystal-poor rhyolitic liquids from crustal mushy zones.

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Section: Discussionmentioning

confidence: 70%

Section: Discussionmentioning

confidence: 99%

Melt segregation from silicic crystal mushes: a critical appraisal of possible mechanisms and their microstructural record

Holness

2018

Contrib Mineral Petrol

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“…At these flux rates, model‐predicted repose stability periods at Taupo Caldera are far shorter than observed, indicating either that flux rates are far lower or that constant recharge is unlikely. The latter interpretation is intuitive since it is unlikely that a magma reservoir will grow at a constant rate for the duration of its repose period, and indeed, variable flux has been proposed by several studies of Taupo Caldera (Allan et al, , ; Barker et al, ). Our model results indicate that intermittent periods of high flux on relatively short timescales, separated by longer periods of stasis, produce the repose periods observed at Taupo Caldera.…”

Section: Case Study: Forecasting Repose Intervals For Taupo Calderamentioning

confidence: 95%

The Role of Tectonic Stress in Triggering Large Silicic Caldera Eruptions

Cabaniss

Gregg

Grosfils

2018

Geophysical Research Letters

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We utilize 3-D temperature-dependent viscoelastic finite element models to investigate the mechanical response of the host rock supporting large caldera-size magma reservoirs (volumes >10 2 km 3 ) to local tectonic stresses. The mechanical stability of the host rock is used to determine the maximum predicted repose intervals and magma flux rates that systems may experience before successive eruption is triggered. Numerical results indicate that regional extension decreases the stability of the roof rock overlying a magma reservoir, thereby promoting early-onset caldera collapse. Alternatively, moderate amounts of compression (≤10 mm/year) on relatively short timescales (<10 4 years) increases roof rock stability. In addition to quantifying the affect of tectonic stresses on reservoir stability, our models indicate that the process of rejuvenation and mechanical failure is likely to take place over short time periods of hundreds to thousands of years. These findings support the short preeruption melt accumulation timescales indicated by U series disequilibrium studies.Plain Language Summary Catastrophic caldera-forming volcanoes, often referred to as "supervolcanoes," are one of the greatest natural hazards on Earth. Understanding how these explosive eruptions are triggered is critical for forecasting volcanic activity at the world's largest volcanoes and mitigating their hazards. Using sophisticated numerical models, the affect of plate tectonic stress is investigated to determine its role in triggering large caldera-forming eruptions. The numerical experiments indicate that calderas located in extensional tectonic settings erupt more readily than calderas located in compressional settings or in tectonically neutral settings. Additionally, calderas in extensional settings fail on shorter timescales than calderas located in compressional or tectonically neutral settings. The most important outcome of this work is that our numerical models show for the first time that the rock surrounding a large magma reservoir is only stable on timescales of centuries to thousands of years when new magma is actively being injected into the magma reservoir. This finding provides important constraints on the amount of time necessary to recharge and erupt a large, supervolcano size reservoir from the first indication of magmatic activity.

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“…However, geospeedometry suggests that the SCL magma came about by remelting/rejuvenation of a near‐solidus source within decades of eruption (Till et al, ), with its tail of old zircon ages representing recycling of antecrysts. Similarly, fast rates for “mush‐to‐eruption” have been inferred at other calderas where tails of zircon crystallization ages are observed (e.g., Allan et al, , ).…”

Section: Discussionmentioning

confidence: 62%

Coexisting Discrete Bodies of Rhyolite and Punctuated Volcanism Characterize Yellowstone's Post‐Lava Creek Tuff Caldera Evolution

Till

Stelten

Shamloo

et al. 2019

Geochem Geophys Geosyst

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Ion‐microprobe 206Pb/238U geochronology and trace element geochemistry of the unpolished rims and sectioned interiors of zircons from Yellowstone caldera's oldest post‐caldera lavas provide insight into the magmatic system during the prelude and aftermath of the caldera‐forming Lava Creek supereruption. The post‐caldera lavas compose the Upper Basin Member of the Plateau Rhyolite and fall into two groups based on zircon crystallization age: early lavas with zircon ages between ~750 and 550 ka and late lavas with zircon ages between ~350 and 250 ka. Zircons from the early‐erupted East Biscuit Basin flow yield U‐Pb dates and trace element compositions, which when considered with the Pb isotopic compositions of their coexisting feldspars and pyroxenes, point to an isotopically distinct parental melt present during crystallization of the Lava Creek magma but untapped by the supereruption. Distinct zircon crystallization ages and Pb‐isotope compositions of major minerals between the early and late Upper Basin Member groups suggest contrasting sources in the magma reservoir. As proxies for melt evolution, the zircons indicate that Yellowstone's post‐caldera rhyolites became more evolved between mid‐ to late‐Pleistocene time, during the same interval that melting of hydrothermally altered wall rock and recharge by new silicic magmas changed in their relative roles. The results from this study indicate that discrete and ephemeral bodies of silicic magma, at times within a mush dominated reservoir and including during the prelude to the Lava Creek eruption, have characterized Yellowstone's subvolcanic reservoir.

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A cascade of magmatic events during the assembly and eruption of a super-sized magma body

Abstract: This is a repository copy of A cascade of magmatic events during the assembly and eruption of a super-sized magma body.

Cited by 68 publications

References 123 publications

Melt segregation from silicic crystal mushes: a critical appraisal of possible mechanisms and their microstructural record

Melt segregation from silicic crystal mushes: a critical appraisal of possible mechanisms and their microstructural record

The Role of Tectonic Stress in Triggering Large Silicic Caldera Eruptions

Coexisting Discrete Bodies of Rhyolite and Punctuated Volcanism Characterize Yellowstone's Post‐Lava Creek Tuff Caldera Evolution

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