Stability of foams in silicate melts

Proussevitch, A. A.; Sahagian, Dork; Kutolin, V. A.

doi:10.1016/0377-0273(93)90084-5

Cited by 116 publications

(101 citation statements)

References 48 publications

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“…Coalescing bubbles did not reach equilibrium spherical form, probably due to high viscosity of the crystal-melt system. The stability of basaltic melt foam at ambient pressure in the presence of solid phase was studied by Proussevitch et al (1993b) who also found that crystals promote coalescence of bubbles.…”

Section: Discussionmentioning

confidence: 99%

Coupled degassing and crystallization: experimental study at continuous pressure drop, with application to volcanic bombs

Simakin

Armienti²,

Epel'baum

1999

Bulletin of Volcanology

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Experiments on degassing of water-saturated granite melts with a pressure drop from 100 and 450 MPa to 40 and 120 MPa, respectively, at temperatures close to feldspar liquidus (750-700 degrees C), were carried out to determine the modality of water exsolution and vesicle formation at the liquidus temperature. Pressure-drop rates as small as approximately 100 bar/day were used. Uniform space distributions of bubbles of exsolved water were obtained with starting glass containing a small fraction (approximate to 0.5 vol.%) of trapped air bubbles. Volume crystallization of feldspar was observed in degassed melts supplied with seeds. Bubble size distributions (BSD) measured in granite glasses after degassing are presented. Data on vesicle characteristics (number, radius, area, elongation) were acquired on images digitized with standard software, while the reconstruction of size distributions was performed with the Schwartz-Saltikov "unfolding" procedure. Bubble size distributions of size classes in the range 5-1000 mu m were acquired with proper magnification and satisfactory statistical reliability of determined number densities. The BSDs of the experimental samples are compared with the results of measurements of rapidly degassed products of Mt. Etna and Vulcano Island. Many particular features of the bubble nucleation and growth can be distinguished in an individual BSD. However, the general BSD of the whole data set, including natural ones, can be relatively well described with linear regression in bilogarithmic coordinates. The slope of this regression is approximately 2.8 +/- 0.1. This dependence is in striking contrast with distributions theoretically predicted with classical nucleation models based on homogeneous nucleation of vesicles. The theoretical distribution requires the occurrence of strong maxima that are not observed in our experimental and natural samples, thus arguing for heterogeneous nucleation mechanisms

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Section: Discussionmentioning

confidence: 99%

Coupled degassing and crystallization: experimental study at continuous pressure drop, with application to volcanic bombs

Simakin

Armienti²,

Epel'baum

1999

Bulletin of Volcanology

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“…Ostwald ripening is the tendency of large bubbles to grow at the expense of smaller neighbors because of the diffusive gas exchange driven by the pressure difference between the bubbles. In order to determine whether this process may influence the changes in BSD, we calculated the time scale t for Ostwald ripening to occur after (Proussevitch et al 1993b Table 2) to contract from the mean bubble size (r 1 = 77 µm) is 4.5 hour, which is much longer than the decompression duration (140 s). We also note that the time for the largest bubble (r 0 = 147 µm) to ripen from the mean bubble size (r 1 = 77 µm) is 12.5 hour.…”

Section: Coalescencementioning

confidence: 99%

Experimental constraints on degassing and permeability in volcanic conduit flow

2004

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This study assesses the effect of decompression rate on two processes that directly influence the behavior of volcanic eruptions: degassing and permeability in magmas. We studied the degassing of magma with experiments on hydrated natural rhyolitic glass at high pressure and temperature. From the data collected, we defined and characterized one degassing regime in equilibrium and two regimes in disequilibrium. Equilibrium bubble growth occurs when the decompression rate is slower than 0.1 MPa s -1 , while higher rates cause porosity to deviate rapidly from equilibrium, defining the first disequilibrium regime of degassing. If the deviation is large enough, a critical threshold of super-saturation is reached and bubble growth accelerates, defining the second disequilibrium regime. We studied permeability and bubble coalescence in magma with experiments using the same rhyolitic melt in open degassing conditions. Under these open conditions, we observed that bubbles start to coalesce at ~43 vol.% porosity, regardless of decompression rate. Coalescence profoundly affects bubble texture and size distributions, and induces the melt to become permeable. We determined coalescence to occur on a time scale (~180 s) independent of decompression rate. We parameterized and incorporated our experimental results into a 1D conduit flow model to explore the implications of our findings on eruptive behavior of rhyolitic melts with low crystal contents stored in the upper crust.Compared to previous models that assume equilibrium degassing of the melt during ascent, the introduction of disequilibrium degassing reduces the deviation from lithostatic pressure by ~ 25 %, the acceleration at high porosities (> 50 vol.%) by a factor 5, and the associated decompression rate by an order of magnitude. The integration of the time scale of coalescence to the model shows that the transition between explosive and effusive eruptive regimes is sensitive Burgisser and Gardner January 04 2 to small variations of the initial magma ascent speed, and that flow conditions near fragmentation may significantly be affected by bubble coalescence and gas escape.

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“…It has been previously demonstrated that explosive volcanic eruptions are driven by the nucleation and growth of exsolved gas bubbles in the magma (Sparks 1978;Proussevitch and Sahagian 1996;1998;2005;Sahagian 2005;Gonnermann and Manga 2007) which leads to foam disruption due to instability of interbubble films and plateau borders, causing fragmentation (McBirney and Murase 1970;Proussevitch et al 1993;Alidibirov 1994;Zhang 1999;Alidibirov and Dingwell 2000;Gonnermann and Manga 2007;Castro et al 2012). Despite the necessity to understand mechanisms of ash production during explosive volcanic eruptions, knowledge is limited due to (1) the disruption of magmatic foams during fragmentation that destroys existing bubbles, and (2) the small size of the ash particles that result from energetic eruptions.…”

Section: Introductionmentioning

confidence: 99%

The size range of bubbles that produce ash during explosive volcanic eruptions

et al. 2013

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Volcanic eruptions can produce ash particles with a range of sizes and morphologies. Here we morphologically distinguish two textural types: Simple (generally smaller) ash particles, where the observable surface displays a single measureable bubble because there is at most one vesicle imprint preserved on each facet of the particle; and complex ash particles, which display multiple vesicle imprints on their surfaces for measurement and may contain complete, unfragmented vesicles in their interiors. Digital elevation models from stereo-scanning electron microscopic images of complex ash particles from the 14 October 1974 sub-Plinian eruption of Volcán Fuego, Guatemala and the 18 May 1980 Plinian eruption of Mount St. Helens, Washington, U.S.A. reveal size distributions of bubbles that burst during magma fragmentation. Results were compared between these two well-characterized eruptions of different explosivities and magma compositions and indicate that bubble size distributions (BSDs) are bimodal, suggesting a minimum of two nucleation events during both eruptions. The larger size mode has a much lower bubble number density (BND) than the smaller size mode, yet these few larger bubbles represent the bulk of the total bubble volume. We infer that the larger bubbles reflect an earlier nucleation event (at depth within the conduit) with subsequent diffusive and decompressive bubble growth and possible coalescence during magma ascent, while the smaller bubbles reflect a relatively later nucleation event occurring closer in time to the point of fragmentation. Bubbles in the Mount St. Helens complex ash particles are generally smaller, but have a total number density roughly one order of magnitude higher, compared to the Fuego samples. Results demonstrate that because ash from explosive eruptions preserves the size of bubbles that nucleated in the magma, grew, and then burst during fragmentation, the analysis of the ash-sized component of tephra can provide insights into the spatial distribution of bubbles in the magma prior to fragmentation, enabling better parameterization of numerical eruption models and improved understanding of ash transport phenomena that result in pyroclastic volcanic hazards. Additionally, the fact that the ash-sized component of tephra preserves BSDs and BNDs consistent with those preserved in larger pyroclasts indicates that these values can be obtained in cases where only distal ash samples from particular eruptions are obtainable.

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Stability of foams in silicate melts

Cited by 116 publications

References 48 publications

Coupled degassing and crystallization: experimental study at continuous pressure drop, with application to volcanic bombs

Coupled degassing and crystallization: experimental study at continuous pressure drop, with application to volcanic bombs

Experimental constraints on degassing and permeability in volcanic conduit flow

The size range of bubbles that produce ash during explosive volcanic eruptions

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