Super-eruptions, Eruptive Centers and Time-volume Behavior of a Continental Hotspot: The Central Snake River Plain

大陆热点的超级喷发、喷发中心和时间体积行为：中央蛇河平原

• 批准号: 0911457
• 负责人: John Wolff
• 金额: $ 21.06万
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-15 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0911457&HistoricalAwards=false
• 关键词: Super; eruptions; Eruptive; Centers; Time

The largest and potentially most devastating types of volcanic eruptions are known as super-eruptions. Such events are outside human experience, yet it is quite certain that they will occur in the future. Despite some public awareness of these rare but potentially devastating events, there is a shortfall of basic research into their ultimate origins, immediate causes, and environmental impacts. In North America, the most prolific source of super-eruptions for the past 16 million years has been the Snake River Plain-Yellowstone hotspot trace, stretching from SW Idaho and northern Nevada to Yellowstone itself. The most intense episode in this region occurred between ~12 and 9 Ma, with the eruption of the order of 10,000 - 20,000 km3 of rhyolite (for reference, the 1980 eruption of Mount St. Helens involved less than 1 km3 of magma). The magmas erupted during this flare-up were high-temperature rhyolites, an unusual type of magma that has been somewhat neglected in the past and only now is being thoroughly studied with respect to its origin, and behavior during large eruptions. Perhaps the most important aspect of these magmas and the way they erupt is the sheer volume of magma involved in any one event, which largely determines the magnitude of the environmental impact. This and other aspects of the eruptions can only be reconstructed through detailed mapping of volcanic units in the field, a difficult project that requires the full-time attention of an experienced researcher. Therefore, this project will fund a post-doctoral researcher who will be charged with tying together different rock outcrops to establsh unit correlations and volumes, and to use these data to establish the volume and frequency of rhyolitic eruptions from the central Snake River Plain. The work will additionally involve mineral and chemical analysis to fingerprint individual units, and radiometric dating to establish absolute ages. All this information will be used constrain genesis and storage history of the rhyolitic magmas in conjunction with new and existing petrologic data. The results will help inform our understanding of Earth's continental crust during major episodes of volcanism (ultimately driven by unusually high heat flux from the mantle), and provide a basis for assessing the degree of enviromental disruption that might be expected from the next such event.

火山喷发的最大，可能是最具破坏性的类型的类型是超级爆发。 这样的事件超出了人类的经验，但是可以肯定的是，它们将来会发生。 尽管公众对这些罕见但可能具有毁灭性事件的意识，但基础研究的最终起源，直接原因和环境影响却有短缺。 在北美，过去1600万年中最多产的超级爆发来源是Snake River Plain-Yellowstone Hotspot Trace，从SW Idaho和Nevada延伸到内华达州北部到黄石本身。 该地区最激烈的发作发生在〜12至9 mA之间，其次数为10,000-20,000 km3的rhyolite（供参考，1980年的圣海伦斯山爆发涉及不到Magma的1 km3）。 在这种爆发过程中爆发的岩浆是高温的流纹岩，这是一种不寻常的岩浆，过去在过去被忽略了，直到现在，就其起源和大型喷发期间的行为进行了彻底研究。 也许这些岩浆最重要的方面以及它们爆发的方式是任何一项事件涉及的岩浆的巨大体积，这在很大程度上决定了环境影响的幅度。 爆发的这一方面和其他方面只能通过对现场火山单元的详细映射进行重建，这是一个困难的项目，需要经验丰富的研究人员的全职关注。因此，该项目将资助一名博士后研究人员，该研究人员将被指控将不同的岩石露头绑在一起以建立单位相关性和量，并使用这些数据来确定中央蛇河平原的流纹岩的体积和频率。 这项工作还将涉及指纹单位单位的矿物质和化学分析，以及建立绝对年龄的辐射测年。 所有这些信息都将用于限制流感岩浆的起源和存储历史，并结合新的和现有的岩石学数据。 结果将有助于我们在火山症重大发作期间对地球大陆地壳的理解（最终是由地幔异常高的热通量驱动），并为评估下一个此类事件可能会预期的环境破坏程度提供了基础。