Premixing of magma and water in MFCI experiments

Zimanowski, Bernd; Büttner, Ralf; Lorenz, Volker

doi:10.1007/s004450050157

Cited by 106 publications

(63 citation statements)

References 12 publications

(17 reference statements)

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“…Phreatomagmatic explosions are discrete localized events that produce outward propagating shock waves that fragment intruding magma as well as surrounding rock and other debris (Zimanowski et al 1997;Büttner and Zimanowski 1998;Büttner et al 2005). When these explosions occur in a debris-filled vent, the relative depth of the explosion, most easily discussed as scaled depth, influences whether material is transported out of the vent or confined to the subsurface .…”

Section: Variations In Relative Explosion Position and Energymentioning

confidence: 99%

Evidence for the relative depths and energies of phreatomagmatic explosions recorded in tephra rings

Graettinger

Valentine

2017

Bull Volcanol

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Experimental work and field observations have inspired the revision of conceptual models of how maar-diatreme eruptions progress and the effects of variable energy, depth, and lateral position of explosions during an eruption sequence. This study reevaluates natural tephra ring deposits to test these new models against the depositional record. Two incised tephra rings in the Hopi Buttes Volcanic Field are revisited, and published tephra ring stratigraphic studies are compared to identify trends within tephra rings. Five major facies were recognized and interpreted as the result of different transportation and depositional processes and found to be common at these volcanoes. Tephra rings often contain evidence of repeated discrete phreatomagmatic explosions in the form of couplets of two facies: (1) massive lapilli tuffs and tuff breccias and (2) overlying thinly stratified to crossstratified tuffs and lapilli tuffs. The occurrence of repeating layers of either facies and the occurrence of couplets are used to interpret major trends in the relative depth of phreatomagmatic explosions that contribute to these eruptions. For deposits related to near-optimal scaled depth explosions, estimates of the mass of ejected material and initial ejection velocity can be used to approximate the explosion energy. The 19 stratigraphic sections compared indicate that near-optimal scaled depth explosions are common and that the explosion locations can migrate both upward and downward during an eruption, suggesting a complex interplay between water availability and magma flux. Reverse to normal coarse-tail graded tuff breccias inferred to be the product of closely timed phreatomagmatic explosions, and deposits of magmatic gas-driven explosions, were observed interspersed with discrete explosion deposits. This study not only provides a framework for more detailed interpretations of eruption sequences from tephra rings but also highlights the gap in our understanding of syn-eruptive hydrology and variations in magma flux that enables phreatomagmatic explosions.

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Section: Variations In Relative Explosion Position and Energymentioning

confidence: 99%

Evidence for the relative depths and energies of phreatomagmatic explosions recorded in tephra rings

Graettinger

Valentine

2017

Bull Volcanol

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“…Interaction of magma with wet sediment or sediment-laden water is very common (McBirney, 1963;Klein, 1985;Einsele, 1986;White, 1996), especially in subaqueous volcanic environments. Peperite is important because it provides ¢eld evidence for mechanisms of magma^water/ sediment interaction, including the mixing mechanisms that precede explosive eruptions analogous to fuel^coolant interaction (FCI) (Zimanowski et al, 1997). The study of peperite is particularly relevant to understanding within-vent processes prior to and accompanying Surtseyan or Taalian explosions (Kokelaar, 1983(Kokelaar, , 1986.…”

Section: Introductionmentioning

confidence: 99%

Peperite: a review of magma–sediment mingling

Skilling

White

McPhie

2002

Journal of Volcanology and Geothermal Research

320

206

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The study of peperite is important for understanding magma^water interaction and explosive hydrovolcanic hazards. This paper reviews the processes and products of peperite genesis. Peperite is common in arc-related and other volcano-sedimentary sequences, where it can be voluminous and dispersed widely from the parent intrusions. It also occurs in phreatomagmatic vent-filling deposits and along contacts between sediment and intrusions, lavas and hot volcaniclastic deposits in many environments. Peperite can often be described on the basis of juvenile clast morphology as blocky or fluidal, but other shapes occur and mixtures of different clast shapes are also found. Magma is dominantly fragmented by quenching, hydromagmatic explosions, magma^sediment density contrasts, and mechanical stress as a consequence of inflation or movement of magma or lava. Magma fragmentation by fluid^fluid shearing and surface tension effects is probably also important in fluidal peperite. Fluidisation of host sediment, hydromagmatic explosions, forceful intrusion of magma and sediment liquefaction and shear liquification are probably the most important mechanisms by which juvenile clasts and host sediment are mingled and dispersed. Factors which could influence fragmentation and mingling processes include magma, host sediment and peperite rheologies, magma injection velocity, volatile content of magma, total volumes of magma and sediment involved, total volume of pore-water heated, presence or absence of shock waves, confining pressure and the nature of local and regional stress fields. Sediment rheology may be affected by dewatering, compaction, cementation, vesiculation, fracturing, fragmentation, fluidisation, liquefaction, shear liquification and melting during magma intrusion and peperite formation. The presence of peperite intraclasts within peperite and single juvenile clasts with both sub-planar and fluidal margins imply that peperite formation can be a multi-stage process that varies both spatially and temporally. Mingling of juvenile clast populations, formed under different thermal and mechanical conditions, complicates the interpretation of magma fragmentation and mingling mechanisms. ß

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“…Active particles are those that are directly involved in the thermal-to-mechanical energy transfer during the MFCI process, while non-active particles are fragments of the melt that are transported away from the fragmentation zone by the kinetic energy release of the MFCI [3,71]. In other words, non-active particles are rapidly expelled when the melt is still liquid allowing for free air ductile fragmentation to occur, forming smooth surfaced particles [72]. Theoretically, active particles are smaller than 130 μm in diameter and are generated by brittle fragmentation; therefore, to "capture" the MFCI event, finer grain-size fractions need to be examined [2][3][4][5].…”

Section: Volcanic Glass Shape Parametersmentioning

confidence: 99%

Volcanic glass textures, shape characteristics and compositions of phreatomagmatic rock units from the Western Hungarian monogenetic volcanic fields and their implications for magma fragmentation

Németh

2010

Open Geosciences

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Abstract:The majority of the Mio-Pleistocene monogenetic volcanoes in Western Hungary had, at least in their initial eruptive phase, phreatomagmatic eruptions that produced pyroclastic deposits rich in volcanic glass shards. Electron microprobe studies on fresh samples of volcanic glass from the pyroclastic deposits revealed a primarily tephritic composition. A shape analysis of the volcanic glass shards indicated that the fine-ash fractions of the phreatomagmatic material fragmented in a brittle fashion. In general, the glass shards are blocky in shape, low in vesicularity, and have a low-to-moderate microlite content. The glass-shape analysis was supplemented by fractal dimension calculations of the glassy pyroclasts. The fractal dimensions of the glass shards range from 1.06802 to 1.50088, with an average value of 1.237072876, based on fractal dimension tests of 157 individual glass shards. The average and mean fractal-dimension values are similar to the theoretical Kochflake (snowflake) value of 1.262, suggesting that the majority of the glass shards are bulky with complex boundaries. Light-microscopy and backscattered-electron-microscopy images confirm that the glass shards are typically bulky with fractured and complex particle outlines and low vesicularity; features that are observed in glass shards generated in either a laboratory setting or naturally through the interaction of hot melt and external water. Textural features identified in fine-and coarse-ash particles suggest that they were formed by brittle fragmentation both at the hot melt-water interface (forming active particles) as well as in the vicinity of the interaction interface. Brittle fragmentation may have occurred when hot melt rapidly penetrated abundant water-rich zones causing the melt to cool rapidly and rupture explosively.

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Premixing of magma and water in MFCI experiments

Cited by 106 publications

References 12 publications

Evidence for the relative depths and energies of phreatomagmatic explosions recorded in tephra rings

Evidence for the relative depths and energies of phreatomagmatic explosions recorded in tephra rings

Peperite: a review of magma–sediment mingling

Volcanic glass textures, shape characteristics and compositions of phreatomagmatic rock units from the Western Hungarian monogenetic volcanic fields and their implications for magma fragmentation

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