The plate velocity kink: on the footsteps of a geodynamic enigma

This research presents the discovery of a kink in the frequency-size distribution of plate angular velocities in different reference frames, a feature not predicted by current physical models of plate tectonics. We analyze global plate motions to investigate the origin of this scaling break and find that larger plates systematically exhibit slower angular velocities than smaller ones. Furthermore, we explore the relationship between plate velocities and the physical properties of the lithospheric basal layers, revealing that faster-moving plates correlate with more homogeneous lid rheology and structure, as inferred from reduced P-wave velocity variability. A significant negative correlation between angular velocity and latitude is observed with a persistent westward residual drift suggesting the long-term influence of large-scale forcings determining asymmetric mantle flows with respect to the outer layers of the planet. Based on these findings, we propose two possible reasons to explain the observed plate velocity scaling break. 1) A different dominant driving mechanism for large and small plates essentially resulting in a two-tier plate tectonics with a threshold in the range 3−5×106 km2 ; 2) a substantial bias in the currently assumed absolute reference frames with respect to the true one to be recovered through an appropriate rotation.