EAR-PF: Unleashing the petrogenetic potential of sanidine using a combined compositional, experimental, and 3D textural approach

Shamloo, Hannah I, Tempe AZ

Investigators

Abstract

Dr. Hannah Shamloo has been granted an NSF EAR Postdoctoral Fellowship to carry out research and educational plans at Oregon State University alongside mentor, Professor Adam Kent. This investigation will examine the processes that produce some of the largest volcanic eruptions known, through the study of minerals present in erupted magmas. The tool developed will help to accurately and quantitively resolve the many processes recorded in zoned minerals that lead to large eruptions. The information for relating magmatic/volcanic processes obtained from individual Barium (Ba) zoning in minerals is critical to the real-time volcano monitoring efforts of future eruptions. This study will consist of three components, (1) quantifying chemical characteristics of natural zoned sanidine from supervolcanoes, (2) perform novel 3D textural characterization of Ba zoning in sanidine, and (3) conduct a series of experiments under relevant conditions to shallow and evolved magmatic systems to constrain the behavior of Ba and other trace elements in sanidine. Additionally, the education plan will entail research opportunities for undergraduates related to this project, teaching opportunities with a focus on minorities in STEM, and outreach via social media. This investigation will better resolve large-scale processes recorded in zoned minerals including pluton formation, initiation of volcanic eruptions, and formation of continental crust. Although the zoning of Ba in sanidine and other alkali-feldspar has been widely documented since at least the 1970’s, its use as a quantitative tool is severely limited by a lack of fundamental data, and as a result, hypotheses based on Ba zoning are often difficult to test. This study will couple in-situ major- and trace-element characterization of natural zoned sanidine from a variety of supervolcanoes using laser ablation ICP-MS and electron microprobe, with 3D textural characterization of Ba zoning using high-resolution X-ray microtomography. Additionally, a series of experiments will be performed under the relevant conditions to shallow and evolved magmatic systems using cold-seal pressure vessels and non-end-loaded piston cylinders to quantify the partitioning behavior of Ba in sanidine and silicic melt. This investigation will also develop a novel technique to study chemical zoning in crystals in 3D rather than the traditional 2D approach often used in petrology that can lead to additional uncertainty. Broader impacts include research opportunities for undergraduate students that will focus on recruiting members of unrepresented minorities in STEM majors. This project received co-funding from the Petrology and Geochemistry program in the division of Earth Sciences. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.