Edgar M. Parmentier

The 2018 Augustus Love Medal is awarded to Edgar M. Parmentier for outstanding research in the fundamental geodynamical processes of sea-floor spreading, melt extraction and crustal formation, and the application of geodynamical principles to flow in the mantle.

E. Marc Parmentier is awarded the EGU Augustus Love Medal for contributions that have been fundamental to our understanding of the dynamics of oceanic spreading centres, the processes of melt extraction and crustal formation, buoyant convection in non-linear materials, asthenospheric flows in subduction zones and the application of geodynamical principles to planetary evolution. A signature of Parmentier’s work is the mathematical elegance and deep physical insight he uses to address some of the most complex questions in geodynamics, relating multiphase grain-scale processes to large-scale tectonic processes. Using a combination of theoretical and numerical modelling techniques, constrained by geophysical observations such as gravity and seismology, Parmentier has led the effort to understand the transition from the 2D symmetry of ridges controlled by the kinematics of divergent plate motion to the more complex and variable 3D geometry characterised by ridge segmentation and melt extraction variability along axis. He showed that the competition between buoyancy-driven upwelling and divergent flow forced by the lithosphere controlled this transition.

In a series of papers on the dynamics of oceanic spreading centres with J. Phipps Morgan, he developed a theory for rift propagation in terms of fracture mechanics that remains a significant landmark in the field. His contributions to the understanding of ridge segmentation and the localisation of melt at a spreading centre have provided a basic understanding of oceanic spreading centres that is central to the fields of plate tectonics and marine geophysics. His many contributions in the area of mantle flows have also led to improved understanding of the extraction of melt, its focusing and migration in a decompacting layer, and subsequent extraction. These ideas have inspired new understanding of magmatism in other contexts, even other planets. As one of the first to recognise that comparative planetology would help us to better understand the Earth as well as the other planets, Parmentier’s analyses of data from the rocky planets and moons of the solar system have provided many new insights. In particular, his analyses of how density overturns can produce remarkable effects on the surfaces of other planets have also led to new insights into how such processes may have affected the Earth. His dynamical insights are clearly in keeping with the legacy of Augustus Love, making him a worthy recipient of this medal.