| 项目编号: | 1524824
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| 项目名称: | Volatile Clues to the Initial Controls on Large Explosive Volcanic Eruptions |
| 作者: | Paul Wallace
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| 承担单位: | University of Oregon Eugene
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| 批准年: | 2014
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| 开始日期: | 2015-07-01
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| 结束日期: | 2018-06-30
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| 资助金额: | USD310000
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| 资助来源: | US-NSF
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| 项目类别: | Standard Grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Geosciences - Earth Sciences
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| 英文关键词: | eruption
; project
; supereruption
; large explosive eruption
; enormous explosive eruption
; eruption triggering
; ascent rate
; impending eruption
; magma body
; such eruption
; large explosive volcanic eruption
; large explosive rhyolitic eruption
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| 英文摘要: | The goal of this project is to better understand how large explosive volcanic eruptions start and the timescales (days or weeks or more) of precursory activity that might serve as a warning sign of an impending eruption. Enormous explosive eruptions (known as supereruptions) have occurred in the recent geologic past that are many times larger than any eruptions that have taken place in historic times. Some of the best and youngest examples, at Yellowstone, in eastern California, and in New Zealand will be studied in this project. A primary goal is to determine if external factors, like an earthquake and movement along a fault, can cause such eruptions to start, or whether instead, they start when a magma body in the earth?s crust becomes overpressured and bursts, like a ruptured balloon. The project will involve chemical analysis of ash and pumice deposits that were created during the opening stages of the eruptions because these preserve a record of information about how and why the eruptions started and how long it took for magma to move to the Earth's surface.
This project will test some fundamental ideas about how large explosive rhyolitic eruptions start and when caldera collapse occurs. Despite many important advances in modeling of these processes, there is a surprising lack of geochemical data on the very earliest deposits from large explosive eruptions that could inform the debate about eruption triggering. A quantitative record of magma decompression and ascent rates shortly before and during the opening stages of these eruptions will be obtained by measuring concentrations and gradients of volatiles (H2O, CO2, Cl, S, F) in melt inclusions and reentrants (unsealed inclusions) in quartz and the OH contents of plagioclase. Because magma ascent rates reflect the extent of overpressure in the underlying magma body, constraining ascent rates for the earliest materials from an eruption using diffusive loss of volatiles can provide insight into whether internal (magma overpressure) or external (little or no overpressure) triggers were involved. Based on preliminary results for the Huckleberry Ridge fall deposit (Yellowstone), such data appear to provide a unique record of the processes and timescales of vent development just prior to and during the opening phases of an eruption, with implications for when and why caldera collapse develops and how magma bodies were configured in the upper crust. The results of this investigation will provide quantitative information about how rapidly supereruptions begin and will contribute data to models of geophysical signals that could precede them. This project involves collaborations with other scientists in the U.S. and New Zealand for some of the specialized chemical analyses that will be done and for computer modeling using the results. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/94323
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| Appears in Collections: | 影响、适应和脆弱性
气候减缓与适应
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| Recommended Citation: | |
Paul Wallace. Volatile Clues to the Initial Controls on Large Explosive Volcanic Eruptions. 2014-01-01.
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