New experiments to better understand high-silica rhyolites

The western United States has been the site of some of the largest and most hazardous volcanic events in the world. Two of these events occurred within the last million years: supervolcano eruptions at both Yellowstone, WY and Long Valley, CA. The magma that erupted is called high-silica rhyolite. To understand how high-silica rhyolite forms and then erupts in such large amounts, scientists need to study the structure of the underground magmatic systems that feed eruptions. Some minerals change their chemical make-up under different temperatures and pressures. That makes it hard to use their chemical composition to calculate at what temperatures and pressures those magmas formed. Experiments done in this study will help scientists more accurately find the temperatures and depths of magma beneath supervolcanoes. This will help improve our understanding of how these powerful eruptions occur, while training numerous students. During this project, a series of experiments (primarily at 200 and 500 MPa; 650-850°C) will be conducted on four natural high-silica (SiO2) rhyolites of varying titanium oxide (TiO2) content. The experiments will be focused on the temperature and pressure dependence to the partitioning of titanium (Ti) between (1) biotite and high-SiO2 rhyolite liquid and (2) quartz and high-SiO2 rhyolite liquid. Preliminary results indicate that Ti partitioning between biotite and melt has the potential to be a high-resolution thermometer in high-SiO2 rhyolite melts. The goal is to establish internal consistency among all three thermometers (and/or barometers) and to enable their application to high-SiO2 rhyolites without extrapolation. The updated biotite and quartz thermobarometers will be applied to natural samples. If successful, the updated thermobarometers will greatly improve our understanding of the magmatic conditions that precede supervolcano eruptions of high-SiO2 rhyolite. 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. NSF Award ID: 2538107 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Rebecca Lange | Institution: Regents of the University of Michigan - Ann Arbor, ANN ARBOR, MI | Award Amount: $475,000 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2538107 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2538107.html