Collaborative Research: Volcanism on the Edge - Basaltic Volcanism from Source to Surface across the Colorado Plateau/Basin & Range Transition in SW Utah

美国西南部有近40个玄武岩火山区，总共有2,000多座第四纪火山，其中包括许多最近（过去50，000年）爆发的火山。这些火山中的大多数被认为是“单成因”的（即，它们只喷发一次），而且喷发量一般较小（1立方公里）。然而，最近已经清楚的是，这种喷发可能造成重大的危险，因为它们的喷发方式多种多样，包括爆炸行为，而且未来任何喷发的位置都是未知的。在美国西南部，这种火山活动的原因和最近爆发的频率都不清楚。该项目将重点关注西南部犹他州的火山活动，该地区位于科罗拉多高原与盆地和山脉省之间的过渡地带，该地区在火山活动的原因方面特别神秘，并且在近期火山活动的性质和频率方面受到很大限制。通过综合详细的实地观察和绘图、放射性测年、物理火山学和地球化学分析，该项目将提供关于岩浆上升和储存导致喷发的来源、过程和时间尺度的关键制约因素，以及与喷发类型和危害的联系。除了向公众提供有关危害的信息外，这项工作还包括对两名博士生和几名本科生进行实地、分析和成像技术方面的指导和培训。PI还将参与与该项目相关的各种推广活动，包括面向K-12学生和教师的基于研究的教育活动，公开讲座，以及面向初中和高中学生的暑期课程。美国西南部至少有2229座第四纪火山，其中大多数是单源火山。重大问题围绕火山活动的原因和来源、年龄和喷发复发间隔以及喷发风格的范围和控制。了解美国西南部单成因火山作用的过程，以及这些过程的时间尺度，对于灾害和风险评估至关重要。此外，许多这些单成因火山岩场的镁铁质性质使它们成为理想的地幔来源的探针，他们挖掘，时空成分的变化，从而可以提供一个独特的记录在这个地区的复杂的构造历史。我们提出了一个综合的物理火山学和岩石学/地球化学研究第四纪火山活动在西南犹他州火山领域，跨越过渡盆地和山脉的科罗拉多高原，阐明构造，岩浆来源，喷发风格和危害之间的联系。主要目标包括：1）建立年龄范围和系统的年龄进展，如果存在; 2）评估喷发风格和相关危害的范围; 3）确定喷发活动与当地构造特征的潜在关系; 4）限制自然（岩石圈与软流圈），位置（深度）和空间异质性的地幔源挖掘的爆发; 5）评估地幔与地壳控制岩浆成分和喷发方式的相对重要性，以及岩浆水含量的影响; 6）限制时间尺度和岩浆储存系统在从源上升到地表的重要性。我们的综合方法将包括详细的野外测绘、40 Ar/39 Ar测年、喷发产物的结构分析以及全岩和矿物尺度的元素和同位素分析。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The American Southwest is home to nearly forty basaltic volcanic fields that collectively contain more than 2,000 Quaternary volcanoes, including many that have erupted relatively recently (past 50,000 years). Most of these volcanoes are considered to be “monogenetic” (i.e., they erupt only once), and they generally produce relatively small volume eruptions (1 km3). Nevertheless, it has recently become clear that such eruptions can pose significant hazards due to their wide variety of eruptive styles, including explosive behavior, and the fact that the location of any future eruption is unknown. In the southwest US, neither the cause of this volcanism nor the frequency of recent eruptions is well understood. This project will focus on volcanism in SW Utah, in the transition between the Colorado Plateau and the Basin and Range provinces, an area that is particularly enigmatic with regard to the causes of volcanism, and poorly constrained with regard to the nature and frequency of recent volcanic activity. By integrating detailed field observations and mapping, radiometric dating, physical volcanology, and geochemical analyses, this project will provide key constraints on the sources, processes, and timescales of magma ascent and storage leading to eruption, and the link to eruptive style and hazards. In addition to providing information about hazards to the public, this work includes mentoring and training of two PhD students and several undergraduate researchers in field, analytical and imaging techniques. PIs will also engage in a variety of outreach activities related to the project, including research-based educational activities for K-12 students and teachers, public talks, and a summer course for middle and high school students.The Southwest US contains at least 2229 Quaternary volcanoes, most of which are monogenetic. Significant questions surround the causes and sources of the volcanism, the ages and eruptive recurrence intervals, and the range of – and controls on – eruptive styles. Understanding the processes that govern monogenetic volcanism in the Southwest US, and the time scales over which these processes operate, is critical for hazard and risk assessment. In addition, the mafic nature of many of these monogenetic volcanic fields makes them ideal as probes of the mantle sources that they tap, and spatial-temporal-compositional variations can thus provide a unique record of the complex tectonic history in this area. We propose an integrated physical volcanology and petrology/geochemistry study of Quaternary volcanism in the SW Utah volcanic field, spanning the transition from the Basin and Range to the Colorado Plateau, to elucidate links between tectonics, magma sources, and eruptive styles and hazards. Primary objectives include: 1) establishing age ranges and systematic age progressions, if extant; 2) evaluating the range of eruptive styles and associated hazards; 3) determining potential relationships of eruptive activity to local tectonic features; 4) constraining the nature (lithospheric vs. asthenospheric), location (depth), and spatial heterogeneity of the mantle sources tapped in the eruptions; 5) assessing the relative importance of mantle versus crustal control on magma composition and eruptive style, and the influence of magmatic water content; and 6) constraining timescales and the importance of magma storage systems in ascent from source to surface. Our integrated approach will involve detailed field mapping, 40Ar/39Ar dating, textural analysis of eruptive products, and elemental and isotopic analyses at both the whole-rock and mineral scales.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.