Bubble growth during decompression of magma: experimental and theoretical investigation

Lensky, Nadav G.; Navon, O.; Lyakhovsky, Vladimir

doi:10.1016/s0377-0273(03)00229-4

Cited by 118 publications

(102 citation statements)

References 29 publications

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“…For embayments with bubbles attached to the embayment mouth, this diffusion, while a consequence of the drop in solubility during decompression, is driven by the concentration of dissolved volatiles at the melt-bubble interface, a direct function of vapor pressure inside the bubble. The diffusivities of H 2 O, CO 2 , and S in silicate melts are sufficiently small to prevent the attainment of equilibrium concentrations within embayments that have lengths on the order of 100 microns for a wide range of decompression rates (e.g., Lensky et al, 2004;Gonnerman and Manga, 2005;Pichavant et al, 2013;Zhang et al, 2007Zhang et al, , 2010. Consequently, distinct diffusion-controlled concentration profiles may be preserved within an embayment, allowing the estimation of decompression rates via diffusion modeling (Liu et al, 2007).…”

Section: Melt Embayments and Choice Of Samplesmentioning

confidence: 99%

Magma decompression rates during explosive eruptions of Kīlauea volcano, Hawaii, recorded by melt embayments

et al. 2016

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The decompression rate of magma as it ascends during volcanic eruptions is an important but poorly constrained parameter that controls many of the processes that influence eruptive behaviour. In this study we quantify decompression rates for basaltic magmas using volatile diffusion in olivine-hosted melt tubes (embayments) for three contrasting eruptions of Kīlauea volcano, Hawai'i. Incomplete exsolution of H 2 O, CO 2 and S from the embayment melts during eruptive ascent creates diffusion profiles that can be measured using microanalytical techniques, and then modelled to infer the average decompression rate. We obtain average rates of ~0.05-0.45 MPa s -1 for eruptions ranging from Hawaiian style fountains to basaltic subplinian, with the more intense eruptions having higher rates. The ascent timescales for these magmas vary from around ~5 to ~36 minutes from depths of ~2 to ~4 km respectively. Decompression-exsolution models based on the embayment data also allow for an estimate of the mass fraction of pre-existing exsolved volatiles within the magma body. In the eruptions studied this varies from 0.1-3.2 wt%, but does not appear to be the key control on eruptive intensity. Our results do not support a direct link between the concentration of pre-eruptive volatiles and eruptive intensity; rather they suggest that for these eruptions decompression rates are proportional to independent estimates of mass discharge rate. Although the intensity of eruptions is defined by the discharge rate, based on the currently available dataset of embayment analyses it does not appear to scale linearly with average decompression rate. This study demonstrates the utility of the embayment method for providing quantitative constraints on magma ascent during explosive basaltic eruptions.

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Section: Melt Embayments and Choice Of Samplesmentioning

confidence: 99%

Magma decompression rates during explosive eruptions of Kīlauea volcano, Hawaii, recorded by melt embayments

et al. 2016

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“…Figure 2 shows the geometry of a spatially periodic array of bubbles in the gas-liquid emulsion (Pinkerton et al 2002;Proussevitch and Sahagian 1998;Lensky et al 2004;Liu and Zhang 2000) where the fluid is arranged as a two-dimensional array of hexagons surrounding bubbles spaced a distance d apart. The average bubble size Rb and spacing d are constrained by the number of bubbles per unit volume N v and their volume fraction .!…”

Section: Bouderau Et Al (200 I) Developed a Diffusion-reaction Modelmentioning

confidence: 99%

The start of ebullition in quiescent, yield-stress fluids

Sherwood¹,

Sáez

2014

Nuclear Engineering and Design

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Non-Newtonian rheology is typical for the high-level radioactive waste (HLW) slurries processed in the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Hydrogen and other flammable gases are generated in the aqueous phase by radiolytic and chemical reactions. HLW slurries have a capacity for retaining gas characterized by the shear strength holding the bubbles still. The sizes and degassing characteristics of flammable gas bubbles in the HLW slurries expected to be processed by the WTP are important considerations for designing equipment and operating procedures. Slurries become increasingly susceptible to degassing as the bubble concentration increases. This susceptibility and the process of ebullitive bubble enlargement are described here. When disturbed, the fluid undergoes localized flow around neighboring bubbles which are dragged together and coalesce, producing an enlarged bubble. For the conditions considered in this work, bubble size increase is enough to displace the weight required to overcome the fluid shear strength and yield the surroundings. The buoyant bubble ascends and accumulates others within a zone of influence, enlarging by a few orders of magnitude. This process describes how the first bubbles appear on the surface of a 7 Pa shear strength fluid a few seconds after being jarred.

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“…Regime map of bubble growth in terms of two ratios of dimensionless time scales at two dimensionless times, t = t/ dec , 0.05 and 0.5 (Modified after Lensky et al, 2004 with permission by Elsevier). V = vis / dec , D = dif / dec .…”

Section: Figmentioning

confidence: 99%

“…, C, , and D are density, water content, viscosity, and diffusivity of water in melt, respectively, which change with r and t. The is gas volume fraction. Modified after Lensky et al (2004) with permission by Elsevier. (Toramaru, 1988;Proussevitch et al, 1993b;Klug and Cashman, 1996 ) (retraction) Bagdassarov et al, 1996 with permission by Springer).…”

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confidence: 99%

What is it that natural volcanic products remember?

Shimano¹

2006

Japanese Magazine of Mineralogical and Petrological Sciences

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The concept of vesiculation and gas loss of magma during ascent in a conduit, and the results of analytical studies of natural eruptive materials are reviewed in comparison with theoretical and experimental studies. Vesiculation of magma is a complex interplay of nucleation, growth, and coalescence of bubbles. In the recent two decades, theoretical and experimental studies on nucleation and growth of bubbles brought us a lot of information about the vesiculation mechanism by applying simplified models to natural samples. However, there are few works on coalescence and gas loss, which is believed to be the most dominant effect on the diversity in eruption style. In fact, most natural pyroclasts and some experimental products seem to be suffered from bubble coalescence. Thus, we should bear in mind when applying theoretical models to natural samples that estimations for bubble nucleation rate and growth rate without considering bubble coalescence may lead to misunderstanding. However, if we analyze natural samples systematically in terms of volatile content, some physical properties and texture, as well as geological information, it would be possible to reconstruct many processes recorded in the eruptive materials.

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Bubble growth during decompression of magma: experimental and theoretical investigation

Cited by 118 publications

References 29 publications

Magma decompression rates during explosive eruptions of Kīlauea volcano, Hawaii, recorded by melt embayments

Magma decompression rates during explosive eruptions of Kīlauea volcano, Hawaii, recorded by melt embayments

The start of ebullition in quiescent, yield-stress fluids

What is it that natural volcanic products remember?

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