Vapor transfer prior to the October 2004 eruption of Mount St. Helens, Washington

Research Article| March 01, 2007 Vapor transfer prior to the October 2004 eruption of Mount St. Helens, Washington Adam J.R. Kent; Adam J.R. Kent 1Department of Geosciences, Oregon State University, Corvallis, Oregon 97331, USA Search for other works by this author on: GSW Google Scholar Jon Blundy; Jon Blundy 2Department of Earth Sciences, University of Bristol, Bristol BS81RJ, UK Search for other works by this author on: GSW Google Scholar Katharine V. Cashman; Katharine V. Cashman 3Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403, USA Search for other works by this author on: GSW Google Scholar Kari M. Cooper; Kari M. Cooper 4Department of Geology, University of California at Davis, Davis, California 95616, USA Search for other works by this author on: GSW Google Scholar Carrie Donnelly; Carrie Donnelly 5Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195, USA Search for other works by this author on: GSW Google Scholar John S. Pallister; John S. Pallister 6U.S. Geological Survey, David A. Johnson Cascade Volcano Observatory, Vancouver, Washington 98683, USA Search for other works by this author on: GSW Google Scholar Mark Reagan; Mark Reagan 7Department of Geoscience, University of Iowa, Iowa City, Iowa 52242, USA Search for other works by this author on: GSW Google Scholar Michael C. Rowe; Michael C. Rowe 8Department of Geosciences, Oregon State University, Corvallis, Oregon 97331, USA Search for other works by this author on: GSW Google Scholar Carl R. Thornber Carl R. Thornber 9U.S. Geological Survey, David A. Johnson Cascade Volcano Observatory, Vancouver, Washington 98683, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Adam J.R. Kent 1Department of Geosciences, Oregon State University, Corvallis, Oregon 97331, USA Jon Blundy 2Department of Earth Sciences, University of Bristol, Bristol BS81RJ, UK Katharine V. Cashman 3Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403, USA Kari M. Cooper 4Department of Geology, University of California at Davis, Davis, California 95616, USA Carrie Donnelly 5Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195, USA John S. Pallister 6U.S. Geological Survey, David A. Johnson Cascade Volcano Observatory, Vancouver, Washington 98683, USA Mark Reagan 7Department of Geoscience, University of Iowa, Iowa City, Iowa 52242, USA Michael C. Rowe 8Department of Geosciences, Oregon State University, Corvallis, Oregon 97331, USA Carl R. Thornber 9U.S. Geological Survey, David A. Johnson Cascade Volcano Observatory, Vancouver, Washington 98683, USA Publisher: Geological Society of America Received: 20 Mar 2006 Revision Received: 11 Oct 2006 Accepted: 13 Oct 2006 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2007) 35 (3): 231–234. https://doi.org/10.1130/G22809A.1 Article history Received: 20 Mar 2006 Revision Received: 11 Oct 2006 Accepted: 13 Oct 2006 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Adam J.R. Kent, Jon Blundy, Katharine V. Cashman, Kari M. Cooper, Carrie Donnelly, John S. Pallister, Mark Reagan, Michael C. Rowe, Carl R. Thornber; Vapor transfer prior to the October 2004 eruption of Mount St. Helens, Washington. Geology 2007;; 35 (3): 231–234. doi: https://doi.org/10.1130/G22809A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Dome lavas from the 2004 eruption of Mount St. Helens show elevated Li contents in plagioclase phenocrysts at the onset of dome growth in October 2004. These cannot be explained by variations in plagioclase-melt partitioning, but require elevated Li contents in coexisting melt, a fact confirmed by measurements of Li contents as high as 207 µg/g in coexisting melt inclusions. Similar Li enrichment has been observed in material erupted prior to and during the climactic May 1980 eruption, and is likewise best explained via pre-eruptive transfer of an exsolved alkali-rich vapor phase derived from deeper within the magma transport system. Unlike 1980, however, high Li samples from 2004 show no evidence of excess (210Pb)/(226Ra), implying that measurable Li enrichments may occur despite significant differences in the timing and/or extent of magmatic degassing.Diffusion modeling shows that Li enrichment occurred within ∼1 yr before eruption, and that magma remained Li enriched until immediately before eruption and cooling. This short flux time and the very high Li contents in ash produced by phreatomagmatic activity prior to the onset of dome extrusion suggest that vapor transfer and accumulation were associated with initiation of the current eruption. Overall, observation of a high Li signature in both 1980 and 2004 dacites indicates that Li enrichment may be a relatively common phenomenon, and may prove useful for petrologic monitoring of Mount St. Helens and other silicic volcanoes. Lithium diffusion is also sufficiently rapid to constrain vapor transfer on similar time scales to short-lived radionuclides. 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