RUI: Collaborative Research: Linking Small-volume Silicic Magmas to a Yellowstone Super-eruption Using a Petrochronologic Approach

在过去的两百万年里，黄石国家公园及其附近地区发生了三次超级火山爆发。在超级喷发之间，成分相似的熔岩的较小的流出物会喷发到地表，然而，前兆岩浆产生的时间和超级喷发之间的关系是未知的。该项目旨在测试两种截然不同的假设，即黄石超级火山爆发是由周期性的前兆喷发产生的岩浆逐渐积聚的高潮，或者超级火山爆发是独立的快速岩浆产生的结果，与较小的前兆喷发无关。这一研究有助于我们对活火山破火山口下大量超级喷发岩浆的生成和驻留速度的理解，对火山喷发复发性和火山危险性的评估具有重要意义。为了评估超级喷发与较小的熔岩流出物之间的潜在联系，将使用210万至130万年前超级喷发期间喷发的小体积流纹岩熔岩的形态、化学、温度、同位素和年龄特征来确定岩浆产生和演化的时间尺度和过程。这些过程包括早期火山产物的部分熔融及其晶体再循环、岩浆结晶和分异以及与幔源玄武岩的混合和杂交作用；每个过程的相对重要性最好通过每次喷发的结晶来探索。具体来说，将从熔岩中提取矿物锆石和硅胺，并通过各种最先进的方法进行分析，以评估小体积岩浆批对超级喷发的贡献。确定间歇喷发的时间将为黄石火山活动的复发间隔提供一个框架，并与可喷发岩浆的寿命问题有关。该奖项将允许来自威斯敏斯特学院（犹他州）的三名本科生参加为期三年的实地和实验室研究，并促进这所仅限本科生的文理学院与博伊西州立大学（爱达荷州）同位素地质年代学实验室之间的知识和技术转移。合作模式将允许学生与博伊西州立大学的研究生和实验室技术人员互动，并使用威斯敏斯特学院没有的仪器进行动手研究。学生将参与数据处理、解释和在地方和国家会议上的展示；这项研究的结果将被纳入威斯敏斯特学院的本科课程，并在火山喷发地点附近的公共土地上作为解释性材料展示。

Yellowstone National Park and vicinity is home to three volcanic super-eruptions within the last two million years. Between super-eruptions, smaller effusions of compositionally similar lavas have erupted onto the surface, however the relationship between the timing of magma production for precursory and super-eruptions is unknown. This project seeks to test the contrasting hypotheses that Yellowstone super-eruptions are the culmination of gradual accumulation of magma that is periodically tapped by precursory eruptions, or alternatively, super-eruptions are the result of independent episodes of rapid magma production without connection to the smaller pre-cursor eruptions. This research bears on our understanding of how quickly large super-eruption volumes of magma may be generated and reside under active volcanic calderas, with implications for the assessment of eruption recurrence and volcanic hazards.To assess the potential connections between super-eruptions and smaller lava effusions, the morphological, chemical, thermometric, isotopic, and age characteristics for small volume rhyolitic lavas that erupted between the 2.1 and 1.3 million year old super-eruptions will be used to establish the timescales and processes by which magmas are generated and evolve. These processes include partial melting of earlier-formed volcanic products and associated crystal recycling, magma crystallization and differentiation, as well as mixing and hybridization with mantle-derived basalts; the relative importance of each process is best explored through the crystal cargos of each eruption. Specifically, the minerals zircon and sanidine will be extracted from the lavas and analyzed by various state-of-the-art methods to assess the contribution of small volume magma batches to the super-eruption. Dating the intermittent eruptions will provide a framework for the recurrence interval of Yellowstone volcanism and bear upon the question of lifespans of eruptable magmas. This award will allow three undergraduate students from Westminster College (Utah) to participate in field and lab based research over three years, and promote knowledge and technology transfer between this undergraduate-only liberal arts college and the Isotope Geochronology Laboratory at Boise State University (Idaho). The collaborative model will allow students to interact with graduate students and laboratory technicians at Boise State University, and conduct hands-on research with instrumentation not available at Westminster College. Students will participate in data processing, interpretation, and presentation at local and national conferences; results from this study will be included in undergraduate courses at Westminster College, and displayed as interpretive materials on public lands near the eruption sites.