RheoMan: a five-year, ERC-funded (Advanced Grant), project to model the rheology of the Earth's mantle

Feb 12, 2018 Dislocations make fat plumes Results

In the last issue of Geophysical Research Letters, we examine the implications of pure climb creep on the morphology of plumes in the lower mantle


Recent tomographic imaging suggest that mantle plumes are much thicker than previously thought. Using new laboratory experiments and scaling laws, we show that thermal plumes developing in a visco-plastic fluid present much larger diameters than plumes developing in a newtonian fluid. Such a rheology requiring a yield-stress is consistent with a lower mantle predominantly deforming by pure dislocation climb. Yield stress values between 1 and 10 MPa, implying dislocation densities between 108 and 1010 m-2 would be sufficient to reproduce the plumes morphology observed in tomographic images.


A. Davaille, Ph. Carrez & P. Cordier (2018) Fat plumes may reflect the complex rheology of the lower mantle. Geophysical Research Letters, 45, 1-6. https://doi.org/10.1002/2017GL076575