Research

In our research, we strive to understand Earth’s fundamental system of plate tectonics. To do this, we conduct targeted case studies of metamorphic and igneous terranes (using petrology, mineralogy, structural geology, geochemistry, and geochronology) to reconstruct their geological histories.

The evolution of plate tectonics

Plate tectonics is a global system of physical and chemical processes that control the evolution of the entire Earth (the solid Earth as well as the oceans, atmosphere, and life). Because of its global significance, understanding when plate tectonics began, and how it has evolved through time, are two of the most fundamental questions in Earth science. In our work, we address these questions through examination of the metamorphic rock record, which provides a direct record of Earth’s past tectonic processes.

High-T metamorphism & crustal melting

Granulites are metamorphic rocks that form at very high temperatures in the crust. Due to the large volumes of granitic melt that can be generated during granulite metamorphism, knowing how granulites form is fundamental to our understanding of how continental crust evolves: (1) How the crust differentiates into a more felsic upper crust and a more residual/mafic lower crust; (2) How the lithosphere is weakened during orogenesis and is permanently strengthened after orogenesis. The central geodynamic question in studying granulites (especially ultrahigh-temperature granulites; >900°C) is the “heat problem”; what are the sources of heat necessary to elevate (and sustain) the temperature of the crust significantly beyond its equilibrium (or quasi-equilibrium) conductive geothermal gradient?

Subduction metamorphism & dynamics

Subduction is the driving force of modern plate tectonics. Petrological, chronological, and structural data from high-P metamorphic rocks (blueschist and eclogites) give critical insight into the physical and chemical processes that operate in subduction zones, which we cannot observe directly. These processes control the formation and evolution of continental crust in magmatic arcs, the structural evolution of accretionary orogenic belts, and the cycling of elements between Earth’s surface and interior. What happens to rocks as they are subducted and how are they brought back to Earth’s surface?

Petrochronology

U–Pb geochronology—and the growing field of petrochronology: linking geochronology to rock-forming process through petrology and geochemistry—is one of the most fundamental types of data used to interpret the rock record. While broader questions of our research are concerned with plate tectonics and the evolution of Earth’s continents, another aspect of our research is developing new analytical approaches and perspectives on U–Pb dating for more rigorous interpretation of the rock record.

A few recorded talks:

  • UM 2020 Fall Preview research overview (link).
  • GSA 2021: Paired metamorphism and the evolution of plate tectonics (link).
  • Thermochronology conference 2021: Diffusion in titanite (link).
  • Goldschmidt 2021: Hydrothermal alteration of titanite (link).
  • University of Maryland 2019: Metamorphism and the evolution of plate tectonics (link).
3.5 billion-year old Morton Gneiss, Minnesota, USA
sillimanite inclusions in cordierite from Madagascar
Eclogite from Baja California, Mexico
monazite inclusion with radiation-damage halo in cordierite from Madagascar