Cone Morphology, Volcanic Deposits, and Eruption and Deposition Mechanisms at Red Mountain, Northern Arizona

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Author
Holm, Richard F.
Wade, William J.
Affiliation
Northern Arizona University
Issue Date
2024-02-29
Keywords
Red Mountain
volcanology
volcanic eruptions
geomorphology
northern Arizona
geochemistry
composite volcano
Volcanic ash, tuff, etc. -- Arizona -- Coconino County.
San Francisco Volcanic Field

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Citation
Holm, R.F. and Wade, W.J., 2024, Cone Morphology, Volcanic Deposits, and Eruption and Deposition Mechanisms at Red Mountain, Northern Arizona. Arizona Geological Survey Contributed Report, CR-24-A, 19 p.
Publisher
Arizona Geological Survey (Tucson, AZ)
Description
Red Mountain is a composite tuff cone in the San Francisco volcanic field in northern Arizona; its morphology is unique. A large amphitheater-like valley cuts deep into the northeast side, exposing over 900 feet of firmly cemented tuffs. A large breach penetrates the west side. The slopes of the cone are concave, reflecting bedding dips that flatten from the summit to the base. The cone height to basal width ratio is 28 % smaller than the ratios of young, fresh cinder cones. The tuffs are grouped into two lithologic types: (1) palagonitic lapilli tuffs and thin fine-ash tuffs, and (2) scoriaceous lapilli tuffs. Groups 1. and 2. are interlayered in beds centimeters to decimeters to meters thick. Outcrop textures, structures, sorting, bedding characteristics, and colors indicate that group 1 tuffs originated by hydromagmatic steam explosions, and deposition by wet base surges and fallout from ash clouds. Group 2 tuffs originated by Strombolian blasts and ballistic-fall deposition. The eruption occurred during the middle Pleistocene (0.740+/-110 Ma), concurrent with a cold period when the water table could have been high, perhaps in the cavernous Kaibab Formation. Here, Strombolian blasts could have been followed quickly by resupply of ground water for steam explosions. The amphitheater’s origin is ambiguous. Erosion is the simplest explanation.
URI
http://hdl.handle.net/10150/671107
Additional Links
https://library.azgs.arizona.edu/
Language
en
Series/Report no.
Arizona Geological Survey Contributed Report
Rights
Arizona Geological Survey. All rights reserved.
Collection Information
Documents in the AZGS Documents Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact azgs-info@email.arizona.edu.
North Bounding Coordinate
35.79881565052138, -111.77160683969382
South Bounding Coordinate
34.92815425496206, -111.68548571866557
West Bounding Coordinate
35.24768366235605, -112.50186675924878
East Bounding Coordinate
35.19274822447731, -110.9481473510868
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