The mantle matters

The dynamics of numerous plate tectonic processes, such as rifting, continental break-up, subduction and orogenesis, are in part controlled by the mechanical behaviour of the upper mantle. Key topics investigated include solid state flow of the lithospheric upper mantle and asthenosphere, the development of shear zones, dynamic recrystallization, and the effect of trace amounts of water.

In collaboration with our colleagues in the Structural Geology Group (Martyn Drury, Reinoud Vissers), the Experimental Rock Deformation Group has long been involved in research on these topics, and in work on the electrical conductivity of upper mantle rocks and partially molten systems. This research is conducted using our 1 GPa gas deformation apparatus and our high-temperature, controlled-atmosphere conductivity system.

Our mechanical results consist of rheological flow laws that can be included in numerical models addressing the dynamics of plate tectonic processes. Our work on conductivity aims to provide a basis for interpreting large scale electrical measurements in terms of active deformation phenomena.

Ice: cool new work

Recently, we have extended our studies of flow and recrystallization to address the rheology of ice, for inclusion in geodynamic models of icy planetoids and for better constraining polar ice flow on Earth.