Excess 210 Po in 2010 Eyjafjallajökull tephra (Iceland): Evidence for pre-eruptive gas accumulation

Sigmarsson, Olgeir; Condomines, Michel; Gauthier, Pierre‐Jean

doi:10.1016/j.epsl.2015.06.054

Cited by 8 publications

(13 citation statements)

References 41 publications

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“…There is a broad agreement that the emanation coefficient of 210 Po for basaltic systems (including Mount Etna) is close to 100%, suggesting that most of polonium atoms are transferred to the magmatic vapour upon degassing [22,[27][28][29][30]. The emanation coefficient of lead in basaltic systems appears to be higher in calk-alkaline systems than in other geodynamical settings [21].…”

Section: Po Radioactive Disequilibria In Volcanic Plumesmentioning

confidence: 92%

“…Recent studies have suggested that magmas having accumulated an 222 Rn-rich gas phase may present significant 210 Pb excesses over 226 Ra [29,[33][34][35][36]. Volcanic gases are also characterised, in some cases, by 210 Pb/Pb ratios significantly higher than those measured in lavas [23].…”

Section: Rn Enrichments In Volcanic Gases: Towards a New Degassinmentioning

confidence: 99%

“…Because polonium has no stable isotope, its emanation coefficient cannot be calculated in the same way as bismuth. The value of Po must therefore be determined from analyses of freshly erupted basaltic lavas e.g., [27][28][29][30]. All these studies show that erupting lavas are almost entirely Po-depleted and concur to a value of Po close to 100%.…”

Section: Volatilities Of Lead Bismuth and Polonium (Emanation Coeffimentioning

confidence: 99%

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A New Degassing Model to Infer Magma Dynamics from Radioactive Disequilibria in Volcanic Plumes

et al. 2018

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Pb within gas bubbles en route to the surface. Theoretical short-lived radioactive disequilibria in volcanic gases predicted by this new model differ from those produced by the former models and better match the values we measured in the plume during the 2015 campaign. A Monte Carlo-like simulation based on variable parameters characterising the degassing process (magma residence time in the degassing reservoir, gas transfer time, Rn-Pb-Bi-Po volatilities, magma volatile content) suggests that short-lived disequilibria in volcanic gases may be of use to infer both magma dynamics and degassing kinetics beneath Mount Etna, and in general at basaltic volcanoes. However, this simulation emphasizes the need for accurately determined input parameters in order to produce unambiguous results, allowing sharp characterisation of degassing processes.

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Section: Po Radioactive Disequilibria In Volcanic Plumesmentioning

confidence: 92%

Section: Rn Enrichments In Volcanic Gases: Towards a New Degassinmentioning

confidence: 99%

Section: Volatilities Of Lead Bismuth and Polonium (Emanation Coeffimentioning

confidence: 99%

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A New Degassing Model to Infer Magma Dynamics from Radioactive Disequilibria in Volcanic Plumes

et al. 2018

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“…Table 3 shows the single activities (in Bq.m −3 ) and the activity ratios of 210 Po, 210 Bi and 210 Pb measured in both 2007 and 2008 with identical procedures. We also determined the activity of 210 Pb in a fresh sample of Ambrym basalt (2007 vitrous scoria from Marum) by isotope dilution and alpha spectrometry, measuring the radioactivity of 210 Po at equilibrium and using a 209 Po spike calibrated against the A-THO and HSK-8 rock standards (Sigmarsson et al, 2015). The analytical uncertainty, derived from counting statistics, is better than 2% at the 2 σ confidence level.…”

Section: Trace Elements and Radioactive Po-bi-pbmentioning

confidence: 99%

Prodigious emission rates and magma degassing budget of major, trace and radioactive volatile species from Ambrym basaltic volcano, Vanuatu island Arc

Allard

Aiuppa

Bani

et al. 2016

Journal of Volcanology and Geothermal Research

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“…where it is described in detail. Sigmarsson et al 2122. analyzed a separate fraction of this sample.…”

Section: Recent Eruptive Productsmentioning

confidence: 99%

210Pb-226Ra disequilibria in young gas-laden magmas

Reagan

Turner

Handley

et al. 2017

Sci Rep

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We present new 238U-230Th-226Ra-210Pb and supporting data for young lavas from southwest Pacific island arcs, Eyjafjallajökull, Iceland, and Terceira, Azores. The arc lavas have significant 238U and 226Ra excesses, whereas those from the ocean islands have moderate 230Th and 226Ra excesses, reflecting mantle melting in the presence of a water-rich fluid in the former and mantle melting by decompression in the latter. Differentiation to erupted compositions in both settings appears to have taken no longer than a few millennia. Variations in the (210Pb/226Ra)0 values in all settings largely result from degassing processes rather than mineral-melt partitioning. Like most other ocean island basalts, the Terceira basalt has a 210Pb deficit, which we attribute to ~8.5 years of steady 222Rn loss to a CO2-rich volatile phase while it traversed the crust. Lavas erupted from water-laden magma systems, including those investigated here, commonly have near equilibrium (210Pb/226Ra)0 values. Maintaining these equilibrium values requires minimal persistent loss or accumulation of 222Rn in a gas phase. We infer that degassing during decompression of water-saturated magmas either causes these magmas to crystallize and stall in reservoirs where they reside under conditions of near stasis, or to quickly rise towards the surface and erupt.

show abstract

Excess 210 Po in 2010 Eyjafjallajökull tephra (Iceland): Evidence for pre-eruptive gas accumulation

Cited by 8 publications

References 41 publications

A New Degassing Model to Infer Magma Dynamics from Radioactive Disequilibria in Volcanic Plumes

A New Degassing Model to Infer Magma Dynamics from Radioactive Disequilibria in Volcanic Plumes

Prodigious emission rates and magma degassing budget of major, trace and radioactive volatile species from Ambrym basaltic volcano, Vanuatu island Arc

210Pb-226Ra disequilibria in young gas-laden magmas

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