Collaborative Research: The role of oxygen fugacity in calc-alkaline differentiation and the creation of continental crust at the Aleutian arc

这一建议旨在研究氧变化在俯冲相关火山（弧火山）喷发的钙碱性岩浆起源中的作用。特别是，pi试图确定在分化和脱气过程中氧气是如何变化的，并观察它是如何沿着阿留申弧走向变化的，作为俯冲板块物质的函数。这项工作还将包括对岩浆形成过程中H2O和fO2之间关系和相互作用的实验研究，这是一个对大陆地壳形成具有重要意义的关键问题。pi注意到阿留申弧在许多地球化学特征上具有局部和区域变化，但缺乏岩浆穿过大陆地壳时引入的复杂性。提出的工作包括新颖的（微XANES）分析玻璃中的铁/铁比（氧含量的代表），特别是矿物中的玻璃内含物。还将分析水、二氧化碳以及主要和微量元素（包括Cl和S）。pi还提出了一个实验方案，其中fO2在恒定含水量下变化。实验玻璃将使用与天然玻璃相同的技术进行分析。更广泛的影响包括在史密森尼博物馆举办一个新的互动展览，其中包括一个在线部分。展品中的材料将被纳入本科课程。将通过REU进行本科生指导和/或毕业论文指导，以及研究生和博士后指导。

This proposal seeks to examine the role of oxygen variations in the origin of the calc-alkaline magmas that erupt at subduction-related volcanoes (arc volcanoes). In particular, the PIs seek to determine how oxygen varies during differentiation and degassing, and see how it varies along strike of the Aleutian arc as a function of material derived from the subducted slab. The work will also include an experimental study of the relationship and interplay between H2O and fO2 during magma formation, a critical question with implications for the formation of continental crust. The PIs note that the Aleutian arc features local and regional variations in numerous geochemical features, but lacks the complexities introduced when magmas move through continental crust. The proposed work includes novel (micro XANES analysis of the ferrous/ferric ratio in glasses (a proxy for oxygen content), especially glass inclusions in mineral. Water, CO2 and major and trace elements (including Cl and S) will also be analyzed. The PIs also propose an experimental program in which fO2 is varied at constant water content. The experimental glasses will be analyzed using the same techniques as described for the natural glasses. Broader impacts include a new interactive exhibit at the Smithsonian that will include an on-line component. Material from the exhibits will be incorporated into undergraduate curricula. There will be undergraduate mentoring through REU and/or senior thesis, as well as mentoring of grad students and a post-doc.