Hairuo Fu, Shihong Zhang, Daniel Condon, Hanbiao Xian

The rate of movement of Earth’s solid shell relative to its spin axis, or true polar wander, depends on variations in mantle convection and viscosity. We report paleomagnetic and geochronologic data from South China that constrain the rate of rapid true polar wander (>5° Myr-1) from 832–821 million years ago. Analysis of the paleomagnetic database demonstrates secular change of true polar wander related to mantle cooling and thermal structure across supercontinent cycles. True polar wander rates are relatively muted with a partially insulated mantle during supercontinent assembly and accelerate as mantle thermal mixing re-establishes with supercontinent breakup. Decreasing true polar wander rate through the Neoproterozoic was succeeded by smaller variations in the Phanerozoic. We propose that extensive Neoproterozoic plate-tectonic activities enhanced mantle cooling, giving rise to a reduction in mantle convective forcing, an increase in mantle viscosity, and a decrease in true polar wander rates into the Phanerozoic.