Results 161 to 170 of about 4,124 (186)

The model of an eruptive column produced by phreatomagmatic explosions

Journal of Volcanology and Seismology, 2017
This paper presents the results from the simulation of a phreatomagmatic eruption, in which the formation of the eruptive column is controlled by interaction between magma and water or ice. The process leads to intensive fragmentation of the magma and to mixing of ash and steam with ambient air.
V. M. Khazins, V. V. Shuvalov
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Phreatomagmatic maar-diatreme volcanoes and their incremental growth: a model

Geological Society, London, Special Publications, 2016
Abstract We report here a growth model for phreatomagmatic maar-diatreme volcanoes with respect to the number of eruptions documented in the tephra beds of maar tephra rings and the upper bedded diatreme facies. We show that the number of tephra beds in large diatremes is larger than that in maar tephra rings. Base surges that lack sufficient
Volker Lorenz, Peter Suhr, Stefan Suhr
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Maar-diatreme phreatomagmatism at Hopi Buttes, Navajo Nation (Arizona), USA

Bulletin of Volcanology, 1991
Remnants of an extensive maar-diatreme volcanic field are magnificently exposed at various depths of erosion in the Hopi Buttes volcanic field of northeastern Arizona. Field and petrographic studies of both the maar and diatreme elements of a selection of volcanoes within the field show that: (1) lower sections of the maar rim sequences are typically ...
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A Phreatomagmatic Kimberlite: The A418 Kimberlite Pipe, Northwest Territories, Canada

2013
The A418 kimberlite pipe, Northwest Territories, Canada, has a typical downward tapering morphology, has been explored to a depth of ~600 m where the pipe has a diameter of ~50 m, and is infilled by volcaniclastic deposits. The pipe-filling volcanic succession has a minimum volume of ~6 × 106 m3 and comprises structurally diverse deposits including ...
Lucy Anne Porritt, James Kelly Russell, Hayley McLean, Gus Fomradas, David Eichenberg   +4 more
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Morphologic features of juvenile pyroclasts from magmatic and phreatomagmatic deposits of Vesuvius

Journal of Volcanology and Geothermal Research, 1992
Abstract Three eruptive sequences of historical and recent activity of Vesuvius were carefully studied using scanning electron microscopy analysis techniques. The aim of this study was to characterize and distinguish deposits from magmatic and phreatomagmatic eruption phases.
CIONI R., SBRANA A, VECCI R.
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Phreatomagmatic breccia at the Pb-Zn-Ag Trepča deposit, Kosovo

2010
The Trepča Pb–Zn–Ag deposit is located in the Kopaonik block of Western Vardar Zone, Kosovo. The mineralization is represented by skarn and hydrothermal parageneses. Skarn paragenesis comprises prograde (hedenbergite) and retrograde mineral assemblages (ilvaite, magnetite, pyrrhotite, arsenopyrite, pyrite, quartz and carbonates).
Palinkaš, Ladislav, Strmić Palinkaš, Sabina   +1 more
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Formation of phreatomagmatic maar-diatreme volcanoes and its relevance to kimberlite diatremes

Physics and Chemistry of the Earth, 1975
Abstract Studies of maars and diatremes suggest a specific process in their formation. Magma rises along a fissure and contacts ground- or surface derived water. The resulting phreatomagmatic eruptions give rise to base surge and air-fall deposits consisting of juvenile and wall-rock material.
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Molecular water motional behaviour in volcanic glasses from magmatic and phreatomagmatic explosions

2004
A magma is permeable to the diffusion of volatile species which are in solution in the melt phase. Among volatile components in magmas, water is the most abundant. Decompression, cooling and mineral crystallization cause water exsolution out of the melt, and in supersaturation conditions the pore spaces filled by water molecules may become the sites ...
Slejko F., Petrini R., D'ANTONIO, MASSIMO, Forte C.   +3 more
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Le phréatomagmatisme du plateau de Gergovie / The phreatomagmatism of Gergovie’s plateau

Revue des sciences naturelles d'Auvergne, 2016
Le but de ce travail était initialement de produire une carte géologique du plateau de Gergovie, (zone de la carte Veyre-Monton N° 717, non encore éditée). En sus de la carte présentée ici, ce travail comporte un rapport de terrain illustré et commenté, ainsi qu’un repérage des affleurements et quatre coupes géologiques de synthèse.
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A new model for the fracture energy budget of phreatomagmatic explosions

Journal of Volcanology and Geothermal Research, 2004
The fragmentation of magma and of the hosting country rocks is a major process in explosive eruptions. It is important to quantify the mechanical energy needed for fragmentation in order to assess the physical processes of this volcanic phenomenon. This paper presents a method to calculate the fragmentation energy of country rock using granulometry ...
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