Andrew Cross

Postdoctoral Research Associate

  • andrew.cross@wustl.edu
  • CV
  • I grew up on the outskirts of Sherwood Forest in England, and went to the University of Liverpool for my undergraduate degree. Unable to choose between geography and physics, I chose a major that combined them: geophysics. After a third-year course in rock mechanics introduced me to the possibility of squashing rocks and working in the mountains for a career, I moved to New Zealand for graduate school, and studied deformation processes along the Alpine Fault zone. I relocated to St. Louis in 2015 for a postdoc, and have continued to work on the microphysics of rock deformation.

Research interests: rock deformation; microstructural evolution; EBSD; structural geology

Many major geodynamic phenomena – including plate tectonics, mantle convection, mountain building, post-seismic rebound, and ice sheet flow – are controlled by microphysical (atom- or grain-scale) deformation processes in Earth materials. These small-scale processes enable the solid Earth to flow over very long timescales, like a viscous fluid.

My research explores the rheology (flow and deformation) of rocks and minerals, in order to understand the geodynamic evolution of the Earth. The key to understanding rock rheology is through the study of microstructures – grain size and shape, or the alignment of crystal lattices, for example – that evolve during deformation, and record crucial information about the conditions and mechanisms of flow in the Earth’s interior. To decipher this information, I combine field-based, numerical, and experimental approaches, to reveal how microstructures observed in exhumed rocks relate to stress, temperature, and strain-rate conditions deep within the Earth.

As a postdoc in the ESPM group, my main focus is the ongoing development of the Large Volume Torsion (LVT) solid-medium apparatus. The LVT is capable of generating much higher pressures than conventional (gas-medium) torsion apparatus, allowing us to reproduce a range of conditions representative of the middle crust to upper mantle (P < 6 GPa; T < 1500 K). Using the LVT, I am investigating the mechanisms that lead to the intermixing of different mineral phases, which is thought to be an essential ingredient in the formation and persistence of tectonic plate boundaries. I am also involved in ongoing research, based on my Ph.D. studies, regarding the quantification of stress states within the Earth’s lithosphere, particularly around the Alpine Fault zone of New Zealand.

Some snapshots of my current and recent research (click to enlarge):

 

For research updates, musings and mishaps:


 

My publications: