Microgeodynamics Laboratory

The Microgeodynamics Group in the Department of Earth Sciences, University of Cambridge tackles problems in rock deformation over scales ranging from the crystal lattice to lithospheric plates. We develop and employ advanced microanalytical techniques to decipher the processes of rock deformation. High-angular resolution electron backscatter diffraction (HR-EBSD) provides a key tool for quantifying the distributions of dislocations and stress heterogeneity within grains. This focus on the direct measurement of forces distinguishes microgeodynamics from earlier kinematic approaches. We combine such microstructural analyses with deformation experiments to develop a new generation of microphysical models of deformation processes. Analyses of key field sites allow us to up-scale laboratory results to establish the role of microscale processes in macroscopic geodynamics.

Equipment

FEI Quanta 650 FEG-SEM: Equipped with EBSD, EDS, and CL.
High-temperature creep rig (under construction): For deformation of single crystals and fine-grained aggregates at temperatures up to 1500°C in a controlled chemical atmosphere. Equipped with a MISTRAS acoustic-emission system.
High-temperature in-situ stage (under construction): For deformation of single crystals and fine-grained aggregates at temperatures up to 600°C inside the SEM. In-situ experiments allow measurement of mechanical data with collection of microstructural observation at intervals during the experiments.

Sample preparation: Low-speed wafering saw with goniometer, grinding, and polishing, including vibratory colloidal silica.

Current research projects

- NWO GO grant (Netherlands Space Office): “Transient deformation of the upper mantle from the crystal to the plate scales“; PI: David Wallis (Utrecht University); CO-I: Taco Broerse, Rob Govers, Martyn Drury (Utrecht University); Wouter van der Wal, Riccardo Riva (TU Delft); Lars Hansen (University of Oxford); Karen Simon (NIOZ, Royal Netherlands Institute for Sea Research).
- UKRI Future Leaders Fellowship: “Microphysics of evolving rock viscosity in the seismic and glacial cycles“; PI: David Wallis (University of Cambridge); Project partners: Lars Hansen (University of Minnesota), Philip Benson (University of Portsmouth); Ricardo Lebensohn (Los Alamos National Laboratory).