Plate motion on a sphere
With Robert Parker, McKenzie applied spherical rigid-body motion to plate tectonics. His later work with Jason Morgan examined the geometry of three-plate motions, connecting boundary behaviour to a calculable global framework.
References: [1]
Cooling lithosphere
He studied cooling after a plate forms at a ridge, explaining broad changes in ocean depth and heat flow away from ridges. This connected descriptions of plate movement with the lithosphere’s thermal evolution.
References: [1]
Mantle and melt
His research also concerns mantle convection, magma generation, melt segregation and geochemistry, using gravity and seismic information to investigate lithospheres on Earth and other rocky bodies.