School of Earth and Space Exploration assistant professor Christy Till, right, and research assistant professor Maitrayee Bose, left, stand with the NanoSIMS. This advanced mass sprectrometer was a key ingredient in the discovery because it lets scientists examine the elemental and isotopic composition of microscopic samples smaller than a human hair's thickness. Photo: Deanna Dent/ASUNow.
In collaboration with UC Davis Professor Kari Cooper, EPIC PI Christy Till and SESE collaborator Maitrayee Bose pioneer a new method to quantify the magmatic thermal histories prior to eruption in a Science paper out today. The group used Li in zircon concentrations profiles to conduct diffusion chronometry on the same zircon grains used for U-Th dating, thereby determining the timing of thermal events in the magma in both absolute and relative time preceding the 0.7 ka Kaharoa eruption, New Zealand. The results are surprising. The zircons spent more than 90% of their lifetime (10,000-100,000's of years) in an uneruptible, mostly crystalline, and deep magmatic reservoir. Any thermal pulses the system saw lasted only years to centuries, much shorter than usually predicted. These thermal pulses seem to have occurred in more rapid succession prior to the eruption.