Research

Overview

(Pssst... not a geologist? Read this instead!)

My research focuses on the structural and rheological evolution of the subduction interface, from early subduction, to steady-state subduction, to exhumation of rocks from peak depths. Most of my work has been on a high-pressure/low-temperature subduction complex exposed on Syros Island in the Cyclades (Greece), that records blueschist-eclogite facies subduction during the Eocene, and exhumation through the Miocene along the slab interface and low-angle crustal-scale detachment faults. Syros is unique in that it preserves high-pressure metamorphism and deformation of lots of different rock types (oceanic crust, sediments, carbonates, etc.) and deformation conditions, giving us a chance to compare rheological behaviors of different rock types during the subduction-exhumation cycle.

More recently, I've begun working on the metamorphic sole of the Oman ophiolite as part of the Oman Drilling Project. Metamorphic soles are packages of mylonitized MORB and sediments that are welded to the base of most of the world's ophiolites. They have a distinct inverted thermal gradient from upper-amphibolite at the top to greenschist at the bottom, and are believed to record deformation and metamorphism during early stages of subduction, before and during ophiolite emplacement ("obduction"). Ophiolites are believed to be related to forearc spreading centers above the new subduction zones where metamorphic soles form. Soles are therefore ideal snapshots of the rheological behavior of the subduction interface during nascent subduction. If you want to learn more about the rocks I'm working on from Oman, check out the Oman Drilling Project (http://www.omandrilling.ac.uk/).

Between Syros and Oman, my work on subduction zones spans a range of metamorphic conditions and dynamic configurations. My research combines metamorphic petrology, structural geology, and microstructural analyses to investigate the evolution of subduction shear zones. Microstructural observations, when linked with metamorphic petrology, are incredibly powerful and can provide insight into the strength and degree of coupling of plate boundaries over a range of pressures and temperatures. Subduction zone mechanics and interface strength are key factors controlling subduction dynamics through geologic time.

Stay tuned for updates on my postdoc researching, coming soon!


From outcrop to microscope, my research combines observations over a range of spatial scales to understand subduction tectonics. Field of view in photo on the right ~2mm.

Slow Earthquakes and Tectonic Tremor in Subduction Zones

Subduction zones create the largest and most destructive earthquakes on the planet, so I'm interested in what rocks from ancient subduction zones can tell us about deep earthquake processes happening at these margins today. I'm particularly interested in deep episodic tremor and slow slip (ETS), which is a coupled seismic-aseismic phenomenon that has been observed at many active subduction margins in the past ~20 years. ETS is poorly understood, but I like to think of it as basically the background noise of plate boundary deformation (it has been observed along crustal-scale strike-slip faults like the San Andreas, too!). An individual ETS event can last for days to months, and can release the same amount of energy as a ~M 7.0+ earthquake (!!). Because the energy is released very slowly, you can't feel it happening. ETS is likely a huge player in managing the Earth's seismic budget at subduction zones.

ETS events have been linked to an increased likelihood of large, destructive subduction earthquakes along the plate interface. If we can better understand ETS from the geologic record, we may gain a better understanding of the megathrust earthquake cycle and different time scales of plate boundary deformation.

Rocks on Syros preserve deformation and metamorphism under conditions that are similar to where we see ETS occurring in modern subduction zones today. Part of my research uses geologic observations of subduction interface mechanics to investigate potential links between rock mechanics and ETS during subduction.

Research Tools

My research combines a range of observational and analytical tools, including:

  • Field geology
  • Metamorphic and Structural Petrology
  • Electron Backscatter Diffraction (EBSD), Environmental SEM Phillips/FEI XL30 at UT Austin
  • Raman Solid Inclusion Thermobarometry (in collaboration with Dr. Kyle Ashley, former UT postdoc now at the University of Pittsburgh)
  • Titanium-in-Quartz Thermobarometry, Secondary Ion Mass Spectrometry (SIMS) at ASU
  • Rb-Sr multi-mineral geochronology
  • Numerical modeling of shear zones (in collaboration with Dr. Luc Lavier at UT Austin)


(Right) Collecting Titanium-in-Quartz data on the SIMS at ASU in Spring 2016