Research

Overview

My research is focused on quantitative structural geology and tectonics.  In particular, I am interested in studying deformation processes within rocks caught up in tectonic plate collisions, particularly ductile shear zones and faults in the brittle/ductile regime. My emphasis is to link structures in naturally deformed rocks with processes of deformation. I am especially interested in kinematics of ductile shear zones and rheology of naturally deformed rocks.

Folded & Sheared (Ductile and Brittle) outcrop from North Cala Bona

Approach

My approach is to link classical structural analysis fieldwork with mathematical modeling of deformation, geochemical techniques (X-ray fluorescence, microprobe, synchrotron-sourced Fourier transform infrared spectroscopy), texture and microstructural analysis of deformation mechanisms (petrographic, electron back scatter diffraction EBSD, cathodoluminescence SEM-CL), geophysical techniques (magnetic fabrics), and image analysis.

Questions being addressed in current work:
  • How do fluids and strain interrelate during fault and shear zone deformation?
  • How can we use naturally deformed rocks to extract rheologic information?
  • How does strain partition into a variety of structures during oblique tectonic plate collisions over space and time?
  • How can kinematic models constrain ancient tectonic plate collision geometries?
Examples of Ongoing Projects

1) Fluid interactions within the Willard Thrust Fault Zone, Utah

Fluids may affect deformation in faults and shear zones by altering rock strength, changing the operational deformation mechanism(s), localizing strain, and enhancing metamorphic reactions. In many cases, fluids are key agents that facilitate deformation localization, and the localized deformation zones they create may further enhance channeling of fluids, generating a positive feedback system and strongly influencing the heterogeneity of crustal deformation. While the importance of fluids in shear zones is clear, the transient nature of fluids in deformation and our ability to only look at the deep crust in ancient deformation zones brought to the surface by erosion makes directly analyzing fluids in natural shear zones unfeasible. However, fluids often leave behind their signatures by altering rock chemistry and/or enabling metamorphic reactions and/or forming distinctive microstructures. In an ongoing project, I am working with Dr. Adolph Yonkee at Weber State University to study fluid interactions along the Willard thrust fault in northern Utah (a brittle/ductile feature), including within some beautiful metamorphosed diamictites on Antelope Island. Our current emphasis is on using synchrotron Fourier transform infrared (FTIR) analysis to map water impurities within quartz grains.

2) Strain localization and kinematic partitioning within the Southern Iberian Shear Zone, Spain

In a related project, I am investigating structural, geochemical, and microstructural changes across the Southern Iberian Shear Zone (Spain). Similar to the work in Utah, we are evaluating whether geochemical changes induced by fluid interaction were primarily responsible for strain softening and deformation localization and how that may have channeled fluid. Ongoing parts of the project include a detailed study of strain localization and kinematic partitioning in the metasedimentary units on the south side of the shear zone including structural analysis, electron backscatter diffraction (EBSD) textures, magnetic fabrics, and kinematic modeling. This work is collaborative with Dr. Carlos Fernández (Universidad Complutense de Madrid, Spain), Dr. Manuel Díaz Azpiroz (Universidad Pablo de Olavide, Spain), and Dr. Javier Fernández-Lozano (Universidad de León, Spain). The most fascinating part of this work has been unraveling the kinematic partitioning of this shear zone (different parts take up various portions of the left-lateral versus thrust motion).  I plan to pursue future work in similar oblique shear zones to see whether kinematic partitioning is commonplace and what factors control it.