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Rehydrated glass embayments record the cooling of a Yellowstone ignimbrite

Kenneth S. Befus, James O. Thompson, Chelsea M. Allison, Anna C. Ruefer and Michael Manga
Rehydrated glass embayments record the cooling of a Yellowstone ignimbrite
Geology (Boulder) (March 2024) Pre-Issue Publication


Hydration fronts penetrate 50-135 mu m into glassy rhyolite embayments hosted in quartz crystals from the Mesa Falls Tuff in the Yellowstone Plateau volcanic field. The hydration fronts occur as steep enrichments that reach 2.4+ or -0.6 wt% H (sub 2) O at the embayment opening, representing much higher values than interior concentrations of 0.9+ or -0.2 wt% H (sub 2) O. Molecular water accounts for most of the water enrichment. Water speciation indicates the hydration fronts comprise absorbed meteoric water that modified the original magmatic composition of the rhyolitic glass. We used finite difference diffusion models to demonstrate that glass rehydration was likely produced over a few decades as the ignimbrite cooled. Such temperatures and time scales are consistent with rare firsthand observations of decadal hydrothermal systems associated with cooling ignimbrites at Mount Pinatubo (Philippines) and the Valley of Ten Thousand Smokes (Alaska).

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: Pre-Issue Publication
Title: Rehydrated glass embayments record the cooling of a Yellowstone ignimbrite
Affiliation: Baylor University, Department of Geosciences, Waco, TX, United States
Published: 20240326
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 36
Accession Number: 2024-032161
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. col., sketch map
N44°00'00" - N45°00'00", W111°00'00" - W110°00'00"
Secondary Affiliation: University of California Berkeley, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2024, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 2024
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