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

合作研究：氧逸度在阿留申岛弧钙碱分异和大陆地壳形成中的作用

• 批准号: 1347248
• 负责人: Elizabeth Cottrell
• 金额: $ 16.19万
• 依托单位: Smithsonian Institution
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1347248&HistoricalAwards=false
• 关键词: Collaborative; Research; role; oxygen; fugacity

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.

这项建议旨在研究氧气变化在俯冲相关火山（弧火山）爆发的钙碱性岩浆起源中的作用。 特别是，PI试图确定氧气如何在分化和脱气过程中变化，并看到它如何变化沿着阿留申弧走向的功能，从俯冲板片派生的材料。这项工作还将包括对岩浆形成过程中H2O和fO 2之间的关系和相互作用进行实验研究，这是一个对大陆地壳形成有影响的关键问题。PI指出，阿留申岛弧在许多地球化学特征方面具有局部和区域性变化，但缺乏岩浆穿过大陆地壳时引入的复杂性。拟议的工作包括对玻璃中的二价铁/三价铁比例（氧含量的代表）进行新的（微观XANES分析），特别是矿物中的玻璃夹杂物。还将分析水、CO2以及主要和微量元素（包括Cl和S）。PI还提出了一个实验计划，其中在恒定含水量的情况下改变fO 2。实验玻璃将使用与天然玻璃相同的技术进行分析。更广泛的影响包括史密森尼博物馆新的互动展览，其中将包括一个在线组件。展览材料将纳入本科课程。将通过REU和/或高级论文进行本科生指导，以及格拉德生和博士后的指导。