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

最大和潜在的最具破坏性的火山爆发类型被称为超级火山爆发。 这样的事件是人类经验之外的，但可以肯定的是，它们将在未来发生。 尽管公众对这些罕见但具有潜在破坏性的事件有所了解，但对其最终起源，直接原因和环境影响的基础研究不足。 在北美，过去1600万年来最多产的超级火山爆发源是蛇河平原-黄石公园热点痕迹，从西南爱达荷州和北方内华达州延伸到黄石公园本身。 该地区最强烈的一幕发生在~12和9 Ma之间，流纹岩喷发量为10，000 - 20，000 km 3（作为参考，1980年圣海伦火山喷发的岩浆不到1 km 3）。 在这次耀斑爆发期间爆发的岩浆是高温流纹岩，这是一种不寻常的岩浆类型，过去一直被忽视，直到现在才被彻底研究其起源和大爆发期间的行为。 也许这些岩浆及其喷发方式最重要的方面是任何一次事件所涉及的岩浆的绝对体积，这在很大程度上决定了环境影响的大小。 火山爆发的这一点和其他方面只能通过实地详细绘制火山单元图来重建，这是一个困难的项目，需要有经验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，他将负责将不同的岩石露头联系在一起，以建立单位相关性和体积，并使用这些数据来建立蛇河平原中部流纹岩喷发的体积和频率。 这项工作还将涉及矿物和化学分析，以确定单个单元的指纹，以及确定绝对年龄的放射性测年。 所有这些信息将用于约束流纹质岩浆的成因和存储历史，结合新的和现有的岩石学数据。 这些结果将有助于我们了解火山活动主要时期的大陆地壳（最终由地幔异常高的热通量驱动），并为评估下一次火山活动可能造成的环境破坏程度提供依据。

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.