Organization of the tectonic plates in the last 200 Myr

• First study of the statistical properties of plate sizes during the past 200 Myr.
• Distinct statistical distributions of small and large plates.
• Discovery of homogeneous and heterogeneous Earth's tessellation in tectonic plates.
• Relationship between Earth's surface tessellation and global geodynamic evolution.

The present tessellation of the Earth's surface into tectonic plates displays a remarkably regular plate size distribution, described by either one (Sornette and Pisarenko, 2003) or two (Bird, 2003) statistically distinct groups, characterised by large and small plate size. A unique distribution implies a hierarchical structure from the largest to the smallest plate. Alternatively, two distributions indicate distinct evolutionary laws for large and small plates, the first tied to mantle flow, the second determined by a hierarchical fragmentation process. We analyse detailed reconstructions of plate boundaries during the last 200 Myr and find that (i) large and small plates display distinct statistical distributions, (ii) the small plates display little organisational change since 60 Ma and (iii) the large plates oscillate between heterogeneous (200–170 Myr and 65–50 Ma) and homogeneous (120–100 Ma) plate tessellations on a timescale of about 100 Myr. Heterogeneous states are reached more rapidly, while the plate configuration decays into homogeneous states following a slower asymptotic curve, suggesting that heterogeneous configurations are excited states while homogeneous tessellations are equilibrium states. We explain this evolution by proposing a model that alternates between bottom- and top-driven Earth dynamics, physically described by fluid-dynamic analogies, the Rayleigh–Benard and Bénard–Marangoni convection, respectively. We discuss the implications for true polar wander (TPW), global kinematic reorganisations (50 and 100 Ma) and the Earth's magnetic field inversion frequency.