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Sheathfolds in rheomorphic ignimbrites
Bulletin of Volcanology, 2004Structural reappraisal of several classic rheomorphic ignimbrites in Colorado, Idaho, the Canary Islands and Italy has, for the first time, revealed abundant oblique folds, curvilinear folds and sheathfolds which formed during emplacement. Like their equivalents in tectonic shear-zones, the sheathfold axes lie sub-parallel to a pervasive elongation ...
Branney, MJ, Barry, TL, Godchaux, M
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The ignimbrite source problem: Significance of a co-ignimbrite lag-fall deposit
Geology, 1977A co-ignimbrite lag-fall deposit is one that forms at or near the site of eruptive column collapse and consists mainly of pyroclasts that are too large and too heavy to be carried away in the resulting pumice flows. An example from Mexico is identified as such because it shows the same compositional zoning from rhyolite to andesite as the associated ...
John V. Wright, George P. L. Walker
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Nature, 1962
F. J. FITCH1 has criticized a new hypothesis proposed by me2 on the origin of ignimbrites of Pliocene to Pleistocene Age, from the North Island of New Zealand. The new petrogenetic concept is based on the presence of two contrasting glasses and their textural relationship, which suggest liquid immiscibility.
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F. J. FITCH1 has criticized a new hypothesis proposed by me2 on the origin of ignimbrites of Pliocene to Pleistocene Age, from the North Island of New Zealand. The new petrogenetic concept is based on the presence of two contrasting glasses and their textural relationship, which suggest liquid immiscibility.
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Crystal concentration in ignimbrites
Contributions to Mineralogy and Petrology, 1972A comparison of the crystal contents of selected sieve grades from 9 ignimbrites, with the yield of crystals from crushed pumice, shows that on average a tenfold concentration of crystals has taken place in the ignimbrites. This is explained by the selective loss of pumice by an amount equal to at least the present bulk of the samples studied.
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Nature, 1983
The Cerro Galan caldera, north-west Argentina, is one of the world's largest resurgent calderas but was not recognized as such until the advent of spacecraft imagery1,2. Here we present some initial results of the first scientific expedition to the caldera that was formed during a major eruption 2.5 Myr ago during which 1,000 km3 of ignimbrite was ...
P. W. Francis +8 more
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The Cerro Galan caldera, north-west Argentina, is one of the world's largest resurgent calderas but was not recognized as such until the advent of spacecraft imagery1,2. Here we present some initial results of the first scientific expedition to the caldera that was formed during a major eruption 2.5 Myr ago during which 1,000 km3 of ignimbrite was ...
P. W. Francis +8 more
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Products of Ignimbrite Eruptions
Geology, 1973Many ignimbrite flow units show a reverse grading of large pumice clasts and a normal grading of large lithic clasts. Each ignimbrite flow unit has a basal layer finer grained than the body of the ignimbrite, with a ground surge deposit commonly underlying the ignimbrite, and a fine ash-fall deposit commonly overlying it.
R.S.J. Sparks, S. Self, G.P.L. Walker
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Bulletin of Volcanology, 1999
The Citlaltepetl Ignimbrite records one of the largest explosive events during the Holocene activity of Citlaltepetl Volcano (Pico de Orizaba). Multiple pyroclastic flow units, a fall deposit, and some lahar units were emplaced between 8500–9000 y B.P. as a result of repetitive but discrete explosive events.
Arturo Gómez-Tuena +1 more
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The Citlaltepetl Ignimbrite records one of the largest explosive events during the Holocene activity of Citlaltepetl Volcano (Pico de Orizaba). Multiple pyroclastic flow units, a fall deposit, and some lahar units were emplaced between 8500–9000 y B.P. as a result of repetitive but discrete explosive events.
Arturo Gómez-Tuena +1 more
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Journal of Volcanology and Geothermal Research, 2015
Abstract Titanomagnetites are arguably the most important Fe–Ti oxide mineral in magmatic rocks because they are widely used in paleomagnetic, magnetic anisotropy, and petrologic studies. Elemental concentrations of Ti in titanomagnetites can change rapidly with varying temperature and oxygen fugacity, with oxidation producing “oxyexsolution ...
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Abstract Titanomagnetites are arguably the most important Fe–Ti oxide mineral in magmatic rocks because they are widely used in paleomagnetic, magnetic anisotropy, and petrologic studies. Elemental concentrations of Ti in titanomagnetites can change rapidly with varying temperature and oxygen fugacity, with oxidation producing “oxyexsolution ...
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IGNIMBRITES OF THE CAMPANIAN PLAIN.
2003Mineralogy and Petrology, Special ...
DE VIVO B., SCANDONE, Roberto
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The Thorsmörk Ignimbrite: A Review
1981The Thorsmork ignimbrite of southern Iceland outcrops over 80 km2 in profiles up to 200 m thick. It is partly welded and shows secondary crystallized wedging out towards the SE. The crystallisation shows similarities to both calcalkaline and peralkaline ignimbrites.
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