Estimating the eruptive volume of a large pyroclastic body: the Otowi Member of the Bandelier Tuff, Valles caldera, New Mexico

Cook, G. W.; Wolff, J. A.; Self, Stephen

doi:10.1007/s00445-016-1000-0

Cited by 40 publications

(28 citation statements)

References 35 publications

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“…This outcome highlights the potential importance of including PDC deposits in VEI determination, which is not always the case [ Brown et al ., ], in order to faithfully describe the size of moderate eruptions, notably at andesitic stratovolcanoes. A recent work on ignimbrites reports mass partitioning ratios of 1:1:1 between PDCs, co‐PDC and tephra fall deposits, thus emphasizing the crucial contribution of PDC deposits in mass budget of large‐scale explosive eruptions too [ Cook et al ., ].…”

Section: Discussionmentioning

confidence: 99%

Mass budget partitioning during explosive eruptions: insights from the 2006 paroxysm of Tungurahua volcano, Ecuador

Bernard

Eychenne

Pennec

et al. 2016

Geochem Geophys Geosyst

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International audienceHow and how much the mass of juvenile magma is split between vent-derived tephra, PDC deposits and lavas (i.e., mass partition) is related to eruption dynamics and style. Estimating such mass partitioning budgets may reveal important for hazard evaluation purposes. We calculated the volume of each product emplaced during the August 2006 paroxysmal eruption of Tungurahua volcano (Ecuador) and converted it into masses using high-resolution grainsize, componentry and density data. This data set is one of the first complete descriptions of mass partitioning associated with a VEI 3 andesitic event. The scoria fall deposit, near-vent agglutinate and lava flow include 28, 16 and 12 wt. % of the erupted juvenile mass, respectively. Much (44 wt. %) of the juvenile material fed Pyroclastic Density Currents (i.e., dense flows, dilute surges and co-PDC plumes), highlighting that tephra fall deposits do not depict adequately the size and fragmentation processes of moderate PDC-forming event. The main parameters controlling the mass partitioning are the type of magmatic fragmentation, conditions of magma ascent, and crater area topography. Comparisons of our data set with other PDC-forming eruptions of different style and magma composition suggest that moderate andesitic eruptions are more prone to produce PDCs, in proportions, than any other eruption type. This finding may be explained by the relatively low magmatic fragmentation efficiency of moderate andesitic eruptions. These mass partitioning data reveal important trends that may be critical for hazard assessment, notably at frequently active andesitic edifices

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Section: Discussionmentioning

confidence: 99%

Mass budget partitioning during explosive eruptions: insights from the 2006 paroxysm of Tungurahua volcano, Ecuador

Bernard

Eychenne

Pennec

et al. 2016

Geochem Geophys Geosyst

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“…Situated at the western margin of the Rio Grande rift, the Valles Caldera was formed as a result of two major high silica, rhyolitic ignimbrite large caldera-forming eruptions dated approximately 1.61 to 1.47 Ma and 1.22 to 1.12 Ma (Cole et al, 2005;Wolff & Gardner, 1995). These two major eruptions formed the Bandelier Tuff (comprised of the Otowi [lower] and Tshirege [upper] members), which is the pervasive geologic formation exposed at the surface in much of the VCNP and surrounding area (Bailey et al, 1969;Brunstad, 2013;Cole et al, 2005;Cook et al, 2016;Smith & Bailey, 1966;Wolff & Gardner, 1995;Wolff & Ramos, 2014).…”

Section: Geologic History and Settingmentioning

confidence: 99%

Resolving Deep Critical Zone Architecture in Complex Volcanic Terrain

et al. 2020

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Critical zone (CZ) structure, including the spatial distribution of minerals, elements, and fluid-filled pores, evolves on geologic time scales resulting from both top-down climatic forcing and bottom-up geologic controls. Climate and lithology may be imprinted in subsurface structure as depth-dependent trends in geophysical, geochemical, mineralogical, and biological datasets. As the weathering profile is as much (or more) a product of past environmental conditions, development of predictive models requires understanding the relative roles of climatic forcing and the geologic template on which CZ processes evolve. Doing so in complex volcanic terrains with high initial bedrock porosity and distinct depositional and hydrothermal alteration histories is particularly challenging. To resolve CZ structure in a rhyolitic catchment in the Valles Caldera National Preserve (NM, USA), this study combined geophysics, drilling, and laboratory analyses to produce depth-resolved porosity, geochemistry, and mineralogy datasets to >40 m in depth. Quantitative X-ray diffraction analysis showed that local mineral transformations control complex chemical enrichment/depletion (τ) patterns. Using linear discriminant analysis, key variables enabled separation of complex-layered geology into discrete zones. Contemporary, matrix-dominated weathering processes and modern hydrologic fluxes occur dominantly within the top 15 m of the weathering profile. This zone is convoluted by incomplete primary mineral weathering and overprinted by post-eruption weathering and metasomatism. Matrix weathering transitions to fracture surface weathering driven by deep percolation of slower moving, longer residence time meteoric waters at depth. By altering initial conditions and weathering trajectory, geologic legacy is a critical factor in how this subsurface landscape evolved and functions.

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“…The VCC has undergone two episodes of large-scale ignimbrite eruptions, followed by caldera collapse and resurgence, resulting in the Toledo caldera (embayment) (1.61 Ma), and the younger (1.23 Ma) Valles caldera (Spell et al, 1996b), which largely destroyed the Toledo caldera. Each of these eruptions had a volcanic explosivity index (VEI) of 7 (Newhall and Self, 1982); the Toledo caldera produced ~298 km 3 of ash comprising the Otowi (Lower) Member of the Bandelier Tuff (Cook et al, 2016), while the Valles caldera produced ~400 km 3 of ash comprising the Tshirege (Upper) Member of the Bandelier Tuff (Goff et al, 2014).…”

Section: The Valles Calderamentioning

confidence: 99%

Petrogenesis of the El Rechuelos Rhyolite, Jemez Mountains Volcanic Field, New Mexico, Usa

Konkright¹

2018

Geological Society of America Abstracts With Programs

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The El Rechuelos Rhyolite represents volcanic activity preceding the multiple caldera collapse events of the Jemez Mountains volcanic field (JMVF) in northern New Mexico. This study focuses on seven rhyolitic units clustered north of the Valles caldera. These units have been studied in order to interpret their relationships to one another and the eruptive history of the JMVF. Additionally, this study adds to the research on the relationships between effusive and explosive rhyolitic volcanism, and understanding how caldera-forming eruptions develop from silicic systems. Limited previous research includes K/Ar dates and a few inconsistent 40 Ar/ 39 Ar dates, in addition to whole rock geochemistry, petrography, and radiogenic isotope analyses. This previous work has been expanded using comprehensive 40 Ar/ 39 Ar geochronology, and more extensive whole rock geochemistry, detailed petrography, and electron microprobe analyses. Five distinct eruptive episodes are characterized by distinctive petrography and geochemistry, which when combined with their ages, suggests that these units are the products of separate, independent magma batches. The Early Rhyolite (7.10 + 0.04 Ma), is comprised of phenocrysts of plagioclase, quartz, biotite, sanidine, and accessory oxides in a devitrified groundmass. The Intermediate Rhyolite (7.05 + 0.24 Ma) consists of plagioclase, sanidine, biotite, and minor accessory oxides in a devitrified, altered groundmass. The Pumice Ring Rhyolite (5.61 + 0.48 Ma) is composed of phenocrysts of plagioclase, biotite, quartz, amphibole, and accessory oxides in a finer crystalline groundmass. The three units comprising the El Rechuelos Rhyolite (2.23 + 0.15 Ma) appear almost identical to each other petrographically; these units are sparsely porphyritic, comprised primarily of rhyolitic glass and sparse, small crystals of plagioclase, sanidine, biotite, quartz, and accessory oxides. The Young Rhyolite (1.19 + 0.01 Ma) consists of sanidine, quartz, plagioclase, sparse fayalite, and accessory oxides and zircon in an altered glassy iv groundmass. All seven of these units plot as rhyolite on the Le Bas Classification Diagram, however there are five distinct suites based on major element comparisons, such as SiO2 vs. K2O, Al2O3, and CaO. Additionally, trace element geochemical analyses, including Nb vs. Sr, Rb, and Th, indicate five separate magma batches, with only the three 2.23 + 0.15 Ma units being geochemically related to one another. Previous studies have disputed the relationships of these units to one another, and which units should be referred to as the El Rechuelos Rhyolite. This study concludes that these seven units represent five separate eruptive episodes, and that only the three 2.23 + 0.15 Ma units should retain the name of El Rechuelos Rhyolite. Additionally, this study suggests that the Young Rhyolite is a phase of Bandelier Tuff. Geochemical modeling and analysis suggests that the four pre-caldera units are likely products of varying degrees of partial melting and crustal assimilation, whil...

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Estimating the eruptive volume of a large pyroclastic body: the Otowi Member of the Bandelier Tuff, Valles caldera, New Mexico

Cited by 40 publications

References 35 publications

Mass budget partitioning during explosive eruptions: insights from the 2006 paroxysm of Tungurahua volcano, Ecuador

Mass budget partitioning during explosive eruptions: insights from the 2006 paroxysm of Tungurahua volcano, Ecuador

Resolving Deep Critical Zone Architecture in Complex Volcanic Terrain

Petrogenesis of the El Rechuelos Rhyolite, Jemez Mountains Volcanic Field, New Mexico, Usa

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