Constraining Processes & Timescales of Magma Evolution

智力优势：在活跃的火山系统中运行的过程最终控制着岩浆演化到爆炸状态的时间尺度，以及由此产生的喷发的性质。因此，将岩浆演化的过程和时间尺度与喷发行为和喷发量联系起来，是理解活动火山系统过去、现在和未来行为的根本目标。提出了一种多方面的方法，通过对亚速尔群岛化学分区的硅质火山矿床的组成相进行多同位素、宏观到微观尺度的研究，来限制岩浆分异过程和时间尺度，以：[1]确定开放系统过程和封闭系统过程在大洋岛屿背景硅质岩浆发展中的相对作用；[2]记录地壳同化物的性质以及同化和补给事件的历史；[3]建立“晶体货物”的来源和岩浆停留时间的多样性以及对岩浆系统寿命的影响；[4]限制硅质、碱性岩浆系统的岩浆分异时间，重点放在液态(玻璃)年龄；以及[5]评估喷发量和喷发前岩浆停留时间之间的联系，重点放在成分和构造变异性受限的岩浆系统。提出的方法将包括利用光学显微镜、阴极发光和矿物相微探针分析在多个尺度上表征样品；全岩的主量元素和痕量元素以及锶-钕-铅同位素分析；玻璃和单一闪锌矿晶体的锶-氧同位素分析；玻璃(238U-230Th-226Ra)和单一闪锌矿(226Ra/Ba)的U系列不平衡分析；以及晶体内锶同位素显微采样和三辉橄榄岩中的Ba和Sr丰度/扩散剖面。该项目的一个独特之处包括直接确定玄武岩和粗面岩熔体之间的Ra和Ba分配系数，这对于使用230-226Ra-(Ba)系统进行岩浆分异时间尺度评估至关重要。该项目将支持两名博士生(包括一名日裔美国女性，可能还有一名非裔美国学生)，以及两到三名本科生。学生培训和教育：参与该项目的学生将在各种最先进的分析技术方面获得丰富的经验，至少有一名学生将参与实地考察，接受宝贵的火山学和野外地质学培训。预计实地工作将与火山学实地讲习班一起进行，该讲习班将为更多的学生提供从这一经历中受益的机会。这项研究的结果也将纳入课堂讲授材料以及相关的动手、探究性学习活动中。指导科学领域的女性：国际科学协会是科学领域女性的榜样和导师，目前有一个由4名女性博士生组成的研究小组。PI和她的博士生过去一直与本科生密切合作，预计这个研究小组将有助于吸引女本科生的参与。外展活动：PI和她的研究生将通过迈阿密大学林珀地质博物馆参与外展项目，包括通过K-12项目向社区提供以研究为基础的教育经验，以及由当地高中生和社区退休人员参加的系列讲座。国际合作：该项目将促进与多斯阿索雷大学的阿佐里亚地质学家正在进行的国际合作，国际和平协会与他们有着长期的合作，包括实地项目和组织了2009年亚速尔群岛彭罗斯会议。火山灾害评估：该项目的结果将有助于限制几个活跃的、爆发的火山系统的喷发历史和岩浆演化的过程和时间尺度，并最终应有助于促进对亚速尔群岛和全球火山灾害的评估

Intellectual Merit: The processes that operate in active volcanic systems ultimately control the timescales over which magmas evolve to explosive states, as well as the nature of the resulting eruptions. Thus, linking processes and timescales of magma evolution to eruptive behavior and eruptive volume is a fundamental goal for understanding the past, present and future behavior of active volcanic systems. A multi-faceted approach is proposed to constrain magma differentiation processes and timescales via a multi-isotopic, macro- to micro-scale study of constituent phases from chemically zoned, silicic volcanic deposits in the Azores, in order to: [1] determine the relative roles of open versus closed system processes in the development of silicic magmas in ocean island settings; [2] document the nature of crustal assimilants and the history of assimilation and recharge events; [3] establish the diversity of sources and magma residence times of the "crystal cargo" and the implications for the longevity of magmatic systems; [4] constrain the timescales of magma differentiation for silicic, alkaline magmatic systems with a focus on liquid (glass) ages; and [5] assess the link between eruptive volume and pre-eruptive magma residence timescales with a focus on magmatic systems of restricted compositional and tectonic variability. The proposed approach will involve sample characterization at multiple scales using optical microscopy, cathodoluminescence and microprobe analysis of mineral phases; major and trace element and Sr-Nd-Pb isotopic analyses of whole rocks; Sr-O isotopic analyses of glass and single sanidine crystals; U-series disequilibria analyses of glass (238U-230Th-226Ra) and single sanidines (226Ra/Ba); and intra-crystal Sr isotope microsampling and Ba and Sr abundance/diffusion profiling in sanidines. A unique aspect of this project includes the direct determination of Ra and Ba partition coefficients between sanidine and trachyte melt, which is critical for magmatic differentiation timescale assessments using the 230Th-226Ra-(Ba) system.Broader Impacts: Minority Student Support & Recruiting. This project will support two Ph.D. students (including a Japanese-American female and, likely, an African-American student), as well as two to three undergraduate students. Student Training & Education: Students involved in this project will gain extensive experience in a variety of state-of-the-art analytical techniques, and at least one student will participate in fieldwork, receiving valuable training in volcanology and field geology. It is anticipated that the field work will be done in conjunction with a volcanology field workshop that will provide the opportunity for additional students to benefit from this experience. Results from this research will also be incorporated into the classroom in lecture material as well as related hands-on, inquiry-based learning activities. Mentoring Women in Science: The PI serves as a role model and mentor for women in science, and currently has a research group with 4 female Ph.D. students. The PI and her Ph.D. students have worked closely with undergraduates in the past, and it is anticipated that this research group will help attract participation of female undergraduate students. Outreach Activities: The PI and her graduate students will be involved in outreach programs through Miami University's Limper Geology Museum including providing research-based educational experiences to the community through K-12 programs and a lecture series attended by local high school students and retirees in the community. International Collaboration: The project will foster ongoing international collaboration with Azorean geologists of the Universidade dos Açores, with whom the PI has long-standing collaborations including field projects and organization of a 2009 Azores Penrose Conference. Volcanic Hazard Assessment: The results of this project will help constrain eruptive history and processes and timescales of magma evolution in several active, explosive volcanic systems, and should ultimately help facilitate evaluation of volcanic hazards in the Azores and globally