Mantle plume heat flux and surface motion periodicities and their implications for the growth of continental crust

Abstract

About 40% of Earth's surface is covered by continental crust. It has been found that the global detrital zircon age distribution is dominated by multiple periodicities from <100 Myr to ∼800 Myr, suggesting that continental crust may have been produced periodically. However, what causes the periodic growth of continental crust remains unclear. Continental crust is produced mainly by arc magmatism at subduction zones and plume-induced magmatism. With 3D global mantle convection models, we investigate the long-term evolution of heat flux of mantle plumes and surface flow velocity, which can be respectively related to plume-induced magmatism and arc magmatism. About 10-30 plumes are present in our models, with significant spatial and temporal variations of heat flux for individual plumes. Both the temporal variations of the total plume heat flux and the root-mean-square (rms) of the surface velocity in our models have periodicities that decrease with the vigor of mantle convection. When extrapolated to conditions with Earth-like vigor of convection, the total plume heat flux and the rms of the surface velocity vary with periodic cycles of ∼90-200 Myr and ∼300 Myr, respectively. Therefore, the ∼90-200 Myr and the ∼300 Myr periodic cycles in the growth of continental crust as suggested by the global detrital zircon age distribution may be respectively caused by plume-induced magmatism and arc magmatism.