EAR-PF: Resolving the tempo of edifice development and rhyolite formation in a large-caldera system, Atitlan, Guatemala

EAR-PF：解决危地马拉阿蒂特兰大型破火山口系统中建筑物发育和流纹岩形成的速度

• 批准号: 0948228
• 负责人: Heather Cunningham
• 金额: $ 17万
• 依托单位: Cunningham Heather S
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-02-01 至 2012-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0948228&HistoricalAwards=false
• 关键词: EAR; PF; Resolving; tempo; edifice

Dr. Heather S Cunningham has been granted the NSF Earth Sciences Postdoctoral Fellowship to carry out a research and education plan at the University of Wisconsin - Madison. The investigation aims to detail the short- and long-term trends in caldera edifice development at Atitlán Caldera, Guatemala. Selected volcanic ash and lavas representing the large silicic eruptions, associated scoria layers and cone-growth phases will be collected during a field campaign for geochemical analysis. Major and trace element data will be integrated into petrologic models to determine how large silicic magma bodies develop and if they are related by shallow-level modification processes such as fractional crystallization, magma mixing or assimilation. Isotopic data (87Sr/86Sr and 143Nd/144Nd) will be measured to support petrologic models since these isotopic ratios are distinctive to source composition. To constrain eruptive age, 40Ar/39Ar isotopes will be analyzed on phenocrysts in distinctive eruptive units. 230Th/238U disequilibrium will be measured on volcanic ash to resolve whether large silicic bodies are rapidly differentiated from a homogeneous source, such as a deep crustal hot zone, formed by the coalescence of several magma bodies or the product of crustal assimilation. By resolving the time scales and processes that lead to large-caldera eruptions and associated cone-building phases potential volcanic risk can be inferred. However, our understanding of the processes that lead to large caldera-forming eruptions is limited by the lack of recent, well-exposed deposits. Thus, the Atitlán volcanic complex is ideally suited to test conflicting models for the generation of large-volume silicic eruptions and more importantly time scales over which caldera-systems develop. In addition to the development of geochemical models, an educational exercise will be created. A Dynamic Digital Map of Atitlán Caldera will be made available to educators that will allow students hands-on access to real world data.

Heather S Cunningham博士被授予美国国家科学基金会地球科学博士后奖学金，在威斯康星大学麦迪逊分校开展研究和教育计划。调查的目的是详细的火山口大厦发展在Atitlán火山口，危地马拉的短期和长期趋势。选定的火山灰和熔岩代表了大的硅喷发，相关的矿渣层和锥状生长阶段将在实地活动中收集地球化学分析。主要元素和微量元素数据将整合到岩石学模型中，以确定大型硅质岩浆体是如何发育的，以及它们是否与分离结晶、岩浆混合或同化等浅层改造过程有关。同位素数据（87Sr/86Sr和143Nd/144Nd）将被测量以支持岩石学模型，因为这些同位素比率与源成分不同。为了确定喷发年龄，将对不同喷发单元的斑晶进行40Ar/39Ar同位素分析。将在火山灰上测量230Th/238U不平衡，以确定大型硅质体是由几个岩浆体合并形成的深部地壳热区还是地壳同化的产物等均质源迅速分化而来的。通过解决导致大型火山口喷发的时间尺度和过程以及相关的锥形形成阶段，可以推断潜在的火山风险。然而，由于缺乏最近的、暴露良好的沉积物，我们对导致大型火山口形成的喷发过程的理解受到限制。因此，Atitlán火山复合体非常适合用于测试产生大量硅质喷发的相互矛盾的模型，更重要的是测试火山口系统发展的时间尺度。除了开发地球化学模型外，还将进行一次教育练习。一个动态数字地图Atitlán火山口将提供给教育工作者，让学生动手访问真实世界的数据。