EAR-PF: A New Technique for Determining Eruption Timescales Applied to Large Igneous Provinces and Climatic Events over Earth History

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This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Dr. Joseph Biasi has been awarded an NSF EAR Postdoctoral Fellowship to investigate the connections between volcanic eruptions and the history of life on this planet. During eruptions, large amounts of carbon dioxide, sulfur, and volcanic ash can be released into the atmosphere, affecting the earth’s climate. In some cases, eruptions release huge amounts of gases into the atmosphere in just a few days, causing a sudden change in local or global climate with the potential to cause the extinction of species. However, if that same amount of gas is released over a few decades, then the climate effects of the eruption will be much smaller. Scientists can directly observe currently active volcanoes and record how long they take to erupt; however, no records for durations of prehistoric volcanic eruptions exist. The current project expands on Dr. Biasi’s prior work to develop a method to determine the duration of past eruptions using heat from the volcano. The plumbing systems of volcanoes (magma chamber, volcanic neck, etc.) are hosted in older rocks, and the magma that passes through this plumbing system heats up the host rock. Long-lived eruptions heat up more host rock than short-lived eruptions because there is more time to transfer heat from the magma to the host rock. Dr. Biasi will apply this principle to multiple volcanic eruptions, ranging in age from thousands of years to hundreds of millions of years old. This research will help us understand how impactful volcanic eruptions were in the past, and how to prepare for future eruptions. While conducting this research at Dartmouth College and the University of Oregon, Dr. Biasi will mentor junior researchers and teach classes. He will also develop geoscience lesson plans, labs, and activities that middle- and high-school educators can use in their classrooms. The proposed research will employ a new technique, called magnetic geothermometry (MGT). This technique can constrain the amount of time that magma flowed through a conduit or fed an intrusion. In the case of shallow intrusives (such as feeder dikes) the timescales determined by MGT are roughly equivalent to the timescales of eruption. MGT combines the baked contact test (a classic paleomagnetic technique) with thermal modeling and can be applied to young (1 Ma) and old (2 Ga) magmatic systems. The MGT technique will be applied to sills and dikes of the Franklin LIP and the Columbia River flood basalts, both of which are associated with global climatic events. LIPs were chosen because there are few constraints on the timescales of individual LIP eruptions, and because of their impact on Earth History. Finally, the MGT technique will be applied to the Goat Rocks volcanic complex (an eroded Cascade arc composite volcano). Results from Goat Rocks will serve as a ‘control group’ and provide a crucial point of comparison for the LIP results. By combining the MGT results with previously published estimates of volatile content and volatile solubility, I can roughly determine the flux of volatiles (CO2, H2S, SO2) during individual LIP eruptions. These volatiles directly affect the Earth’s climate and organisms via global warming (CO2) or cooling (SO2). These results will provide the missing link between long-term climatic changes and short-term changes inferred to follow large eruptions.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.