A rapid tectonic plate reorganization event driven by changes at subduction locations in a mantle convection model

The occurrence of tectonic plate reorganization events is evident throughout the geologic record and appears to be associated with the cessation of mature and/or initiation of new subduction. Subduction initiation that produced the bend in the Hawaii-Emperor seamount chain resulted in the most recent upheaval of plate motion and engendered dramatic changes in plate velocities. Here, applying a method for identifying plate boundaries in a numerical global mantle convection model, we calculate Euler vector time series of self-consistently generated plates over a period of approximately 144 Myr. During this period, global evolution is characterized by two dominant convergent boundaries and the number of major plates identified varies between 9 and 14. Using a 2 Myr sampling rate to track the histories of three enduring plates that share a common triple junction, we observe a major plate reorganization event occurring over approximately 6-8 Myr. The catalyst for the event is identified as the development of a deep thermal feature intrinsic to internally heated convection. A buildup of heat enveloping a mature mantle downwelling accumulates a buoyancy that resists ongoing plate motion and eventually forces the over-riding plates on a new trajectory.