Stirring things up in the Earths mantle

New insights into the convection patterns of the Earth’s mantle and its chemical makeup have been revealed by a researcher from our Department of Geology.

The new findings suggest that the mantle does not flow ubiquitously, as has been previously thought – and that it is instead divided into two very large domains that convect only within themselves, with little evidence of them mixing together.

The research, led by Dr Tiffany Barry and published in the journal Scientific Reports, Nature, suggests that one of these domains is found under the Pacific Ocean while the other exists outside of it.

Dr Barry explained: “One of the ways our planet is unique is in the amazing way it has mobile plates at the surface that move and jostle about over time. This movement of the plates results in the process we call plate tectonics, and no other planet we know shows evidence of this process. Why or how plate tectonics started on this planet is not understood, but it has been utterly essential in the production of the crust and oceans that we recognise as Earth today. What is also not well constrained is what effect plate tectonics has on the internal workings of the Earth.

“We have found that when mantle material reaches the bottom of the mantle, at the outer core, it does not spread out and go anywhere around the core, but instead returns to the same hemisphere of the globe from where it came. We have modelled this dominantly up-down motion of convection and found that it can persist for 100’s millions of years.

“On the basis of past plate motions and geochemical evidence, we speculate that this process of mantle convection could have been a dominant process since at least 550 million years ago, and potentially since the start of plate tectonics.”