title: Warm storage for arc magmas.
abstract: Felsic magmatic systems represent the vast majority of volcanic activity that poses a threat to human life. The tempo and magnitude of these eruptions depends on the physical conditions under which magmas are retained within the crust. Recently the case has been made that volcanic reservoirs are rarely molten and only capable of eruption for durations as brief as 1,000 years following magma recharge. If the "cold storage" model is generally applicable, then geophysical detection of melt beneath volcanoes is likely a sign of imminent eruption. However, some arc volcanic centers have been active for tens of thousands of years and show evidence for the continual presence of melt. To address this seeming paradox, zircon geochronology and geochemistry from both the frozen lava and the cogenetic enclaves they host from the Soufrière Volcanic Center (SVC), a long-lived volcanic complex in the Lesser Antilles arc, were integrated to track the preeruptive thermal and chemical history of the magma reservoir. Our results show that the SVC reservoir was likely eruptible for periods of several tens of thousands of years or more with punctuated eruptions during these periods. These conclusions are consistent with results from other arc volcanic reservoirs and suggest that arc magmas are generally stored warm. Thus, the presence of intracrustal melt alone is insufficient as an indicator of imminent eruption, but instead represents the normal state of magma storage underneath dormant volcanoes.
authors: Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095; tmark.harrison@gmail.com mbarboni@epss.ucla.edu.
authors: Mélanie
authors: M
authors: Barboni
authors: Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095.
authors: Patrick
authors: 0000-0002-6332-5086
authors: P
authors: Boehnke
authors: Institute of Earth Sciences, Heidelberg University, 69120 Heidelberg, Germany.
authors: Axel K
authors: AK
authors: Schmitt
authors: Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095; tmark.harrison@gmail.com mbarboni@epss.ucla.edu.
authors: T Mark
authors: TM
authors: Harrison
authors: School of Environment, The University of Auckland, 1142 Auckland, New Zealand.
authors: Phil
authors: P
authors: Shane
authors: Institute of Earth Sciences, University of Lausanne, 1015 Lausanne, Switzerland.
authors: Anne-Sophie
authors: AS
authors: Bouvier
authors: Institute of Earth Sciences, University of Lausanne, 1015 Lausanne, Switzerland.
authors: Lukas
authors: L
authors: Baumgartner
keywords: arc magma; eruption; volcano; zircon