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
