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Title: Under pressure: Gaining insight into magmatic plumbing systems using open-source codes and Raman Spectroscopy
Abstract: Volcanoes are the surface expression of complex magmatic plumbing systems, often spanning 10s of km in the earths crust and mantle. Determining the geometry and inner workings of these plumbing systems is vital for societal reasons, both to be able to interpret periods of heightened unrest, and to understand the formation of economical deposits of metals such as Cu, Ni, and PGEs. At many of the worlds volcanoes where geophysical monitoring networks are spare (if present at all), we must decipher the plumbing system using only the erupted  rocks and their crystal cargo. I will start by discussing one of the most popular and widely accessible techniques – Mineral barometry, where the chemistry of erupted crystals is related to storage conditions using empirical/thermodynamical/machine learning models. Through the development of open-source codes allowing error propagation and model intercomparison, I demonstrate that many of these techniques yield errors spanning the entire crust. I will then discuss a more promising technique with far smaller errors – Raman spectroscopic analysis of fluid inclusions, small pockets of CO2-rich fluid trapped in growing crystals. This technique is far more accurate than mineral barometry and incredibly fast- we have been able to perform measurements in collaboration with Hawaii Volcano Observatory on recent Kilauea eruptions, reporting storage depths within ~7 hrs of receiving samples. This ushers in a period of ‘near real time petrology’, where we can learn about the structure and evolution of plumbing systems during volcanic eruptions, rather than working forensically in the aftermath of the disaster.
Affiliation: Assistant Professor in Earth and Planetary Sciences at UC Berkeley