Crystallization history of Obsidian Dome, Inyo Domes, California

Swanson, Samuel E.; Naney, Michael T.; Westrich, Henry R.; Eichelberger, J. C.

doi:10.1007/bf01067953

Cited by 167 publications

(108 citation statements)

References 18 publications

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“…Simplified stratigraphy of felsic spherulitic unit that is subdivided into a basal massive fades, medial lobe-hyalodastite, and hyaloclastite faciès. crystalline felsic faciès (Appendix A-25); similar to that described by Swanson et al (1989) for the central part of a subaerial rhyolitic dome. In contrast, banded zones are defined by trains of large spherulites that can be only one or two spherulites wide ( Figure 145C), with isolated spherulites situated between bands ( Figure 145D).…”

Section: Basal Massive Fadessupporting

confidence: 49%

“…The massive interior of this faciès was insulated, thus experienced only limited undercooling. Lofgren (1971) and Swanson et al (1989) noted that with small degrees of undercooling (AT = 50-150°C) spherulites formed large, coarse framework clusters. The lava will undergo compete devitrification forming a finely crystalline core of coalesced spherulites (Garner and McPhie, 1999), sometimes described as a polyhedral mosaic (cf.…”

Section: Interpretation Offelsic Spherulitic Unitmentioning

confidence: 99%

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Physical volcanology, stratigraphy, and lithogeochemistry of an archean volcanic arc :

Scott¹

2005

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Section: Basal Massive Fadessupporting

confidence: 49%

Section: Interpretation Offelsic Spherulitic Unitmentioning

confidence: 99%

Physical volcanology, stratigraphy, and lithogeochemistry of an archean volcanic arc :

Scott¹

2005

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“…They occur in obsidian domes, vitrophyric ash-flow tuffs (e.g., Smith et al 2001), largevolume rhyolite flows such as those at Yellowstone (e.g., Wright, 1915), and in shallow volcanic conduits (e.g., Stasiuk et al, 1993;Tuffen and Castro, 2009). Spherulites nucleate and grow in response to large undercoolings (>200°C) rapidly imposed on the magma by its degassing and quenching (e.g., Swanson et al, 1989). As dictated by the thermal profile of a magma body (Manley, 1992;Tuffen et al, in review), spherulitic obsidian develops in spatially restricted zones (e.g., Manley and Fink, 1987;Stevenson et al 1994), comprising a transitional facies that separates the rapidly quenched, outermost vitrophyric rhyolite from a devitrified microcrystalline core.…”

Section: Geological Backgroundmentioning

confidence: 99%

Spherulite crystallization induces Fe-redox redistribution in silicic melt

et al. 2009

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Rhyolitic obsidians from Krafla volcano, Iceland, record the interaction between mobile hydrous species liberated during crystal growth and the reduction of ferric iron in the silicate melt. We performed synchrotron µ-FTIR and µ-XANES measurements along a transect extending from a spherulite into optically distinct colorless and brown glass zones. Measurements show that the colorless glass is enriched in OH groups and depleted in ferric iron, while the brown glass shows the opposite relationship. The color shift between brown and clear glass is sharp, suggesting that the colorless glass zone was produced by a redox front that originated from the spherulite margin and moved through surrounding melt during crystallization. We conclude that the most likely reducing agent is hydrogen, produced by magnetite crystallization within the spherulite. The Krafla obsidians dramatically capture redox disequilibrium on the micoscale and highlight the importance of hydrous fluid liberation and late-stage crystallization to the redox signature of glassy lavas.

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“…[5] Two distinct lava types comprise the three most recently emplaced Inyo domes: a finely porphyritic (phenocrysts generally <2 mm) and a coarsely porphyritic rhyolite (phenocrysts generally 3 -10 mm) [Bailey et al, 1976[Bailey et al, , 1983Sampson, 1987;Sampson and Cameron, 1987;Swanson et al, 1989]. The finely porphyritic rhyolite shows both chemical and mineralogical zonation [Bailey et al, 1976], suggesting that mingling of two different magma types occurred during emplacement [Vogel et al, 1989].…”

Section: Geologic Descriptionmentioning

confidence: 99%

The unique radar properties of silicic lava domes

et al. 2004

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[1] Silicic lava domes exhibit distinct morphologic characteristics at scales of centimeters to kilometers. Multiparameter radar observations capture the unique geometric signatures of silicic domes in a set of radar scattering properties that are unlike any other natural geologic surfaces. Backscatter cross-section values are among the highest observed on terrestrial lava flows and show only a weak decrease with incidence angle. Crosspolarization backscatter (HV) shows a unique behavior, increasing with increasing wavelength. Circular polarization ratios are relatively high, in the 0.3-0.95 range, and increase with increasing wavelength. Field measurements of boulder size frequency distributions and microtopography indicate that silicic dome surfaces are among the roughest ever measured. Rms heights at a 1 m lateral scale range from 13 cm to 50 cm. Rms slopes at 1 m spacing range from 12 to 43 degrees. Modeling of the scattering behavior suggests it results from a combination of rough surface (facet) scattering and scattering from block edges that act as a random collection of dipoles. The unusual wavelength dependence of the radar parameters appears to result from a higher component of edge scattering at large wavelengths, producing, for example, higher cross-polarized backscatter at P band (68 cm). Steep-sided volcanic domes on Venus superficially resemble terrestrial silicic domes in plan view gross morphology, but few similarities remain when the radar scattering and three-dimensional shapes of the features are compared. The unique radar scattering properties suggest that such volcanic surfaces can be identified with multiparameter radar observations in future planetary radar missions and in active terrestrial volcanoes, where dome development can represent serious hazards.

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Crystallization history of Obsidian Dome, Inyo Domes, California

Cited by 167 publications

References 18 publications

Physical volcanology, stratigraphy, and lithogeochemistry of an archean volcanic arc :

Physical volcanology, stratigraphy, and lithogeochemistry of an archean volcanic arc :

Spherulite crystallization induces Fe-redox redistribution in silicic melt

The unique radar properties of silicic lava domes

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