My Research:
My name is Jason Ott, and I am a Ph.D. candidate in the graduate program in the Department of Earth and Space Sciences at the University of Washington. I am studying the deformation mechanisms and rheology (flow behavior) of amphibole minerals in subduction zones. My current research involves using electron microscopy to map the mineralogy and grain orientations in naturally deformed blueschist samples by electron backscatter diffraction (EBSD) and using these maps to interpret micro-scale structures from their deformation history in ancient subduction zones. We also use energy-dispersive X-ray spectroscopy (EDS) to look at chemical variation within individual mineral grains. Together, the two techniques give insight into the physical and chemical processes that are active in subduction zones. These observation-based studies of naturally deformed rocks are paired with in situ deformation experiments on glaucophane, the dominant amphibole mineral in many blueschists. We use large volume presses to deform our samples at temperatures and pressures relevant to subduction zones, and characterize their strength, then analyze the preserved microstructures in the deformed samples to make comparisons to microstructures in the naturally deformed rocks. This combined field and laboratory sample approach will help us better understand the deformation behavior of these rocks in particular and the dynamics of subduction zones as a whole.
Subduction zones are the complex regions where oceanic crust dives into the Earth to be recycled, and are a key element to understanding the plate tectonics of our home planet. Subduction zones host some of the most dangerous hazards on our planet, including megathrust earthquakes, tsunamis, and explosive volcanism-and are often in close proximity to population centers. Therefore, the work we do to better understand them is of importance beyond the scientific community.
News:
Thursday, April 3, 2025:
The second manuscript from my dissertation research: Dislocation creep of glaucophane in mafic blueschists during subduction: Weighted Burgers vector analysis from the Catalina Schist (California, USA) has been published in Geology. This work investigates the microstructural evidence of the deformation mechanisms active in glaucophane in a lawsonite blueschist that was deformed at the subduction interface downdip of the seismogenic zone (~30 km deep). Using optical petrography, electron backscattered diffraction (EBSD) data, energy dispersive X-ray spectroscopy (EDS), petrological modeling (pseudosections), and novel analyses including weighted Burgers vector and inheritance analysis, we show that dislocation creep is an important deformation mechanism in blueschists at the P-T conditions at the base of the seismogenic zone (~350°C and 1 GPa). A key implication of this work is that blueschist in the subduction slab is governed by a power-law rheology and likely plays a key role in coupling between the subducting and overriding plate and in convergence velocities.