EAR-PF: An Experimental Investigation of the Rheological Behavior and Seismic Anisotropy Signature of Deep Crustal Amphibole-Rich Rocks

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Dr. Cailey Condit has been granted an NSF EAR postdoctoral fellowship to carry out research and educational plans at the Massachusetts Institute of Technology. She will investigate the way amphibole, a common but poorly understood mineral within the earth's crust, behaves when it is deformed under high temperatures and pressures. This work will directly augment our understating of continuous deformation within ductile shear zones in the deep crust, where rocks flow rather than break, and within subduction zones, where oceanic crust is descending beneath continents. This experimental work is aimed at constraining the strength of these highly deformed, amphibole-rich zones and investigating their geophysical properties so that geophysicists can make more accurate inferences about amphibole-rich rocks from remote observations of the deep crust. By shedding new light on the strength and deformation behavior of amphibole, these data allow us to better predict how continuous deformation may influence the mechanics within zones of earthquake production. The education plan involves Dr. Condit (1) co-teaching a graduate-undergraduate seminar in rock deformation at MIT, (2) acting as a research mentor for several undergraduate researchers, (3) continuing and expanding her geologic outreach on social media, and (4) making geologic presentations at assisted living facilities to disseminate geologic knowledge across generations. Dr. Condit will utilize the state-of-the-art facilities at MIT's rock deformation laboratory to conduct a series of experiments on amphibole, deforming samples at a range of temperatures, pressures, and strain rates representative of those found in the middle to lower crust. With these experimental results, she will determine the deformation mechanisms of amphibole and its rheology under deep crustal conditions. She will then directly tie her observations of these experimentally deformed rocks to naturally deformed amphibole, and collect seismic anisotropy data from the experimentally deformed amphibole samples. This will allow for a direct comparison between deformation mechanism, rock strength, and seismic anisotropy signals produced by the deformed amphibole. These insights will allow geophysicists to better link their remotely sensed observations of seismic anisotropy with the amphibole-rich rocks that produce those signals in the deep crust. Geologists working on naturally deformed amphibole-rich rocks will also be able to use these data to constrain the strength and deformation mechanisms of their rocks.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.