Interaction between the supercontinent cycle and the evolution of intrinsically dense provinces in the deep mantle

This is an accepted manuscript of a published article.Shear wave travel times in the Earth's deep mantle reveal broad steep-sided seismologically distinct provinces lying on the core-mantle boundary. The longevity and permanence of the two large principal provinces, located below the sites of present-day Africa and the Pacific Ocean, have become a matter of great interest. Examination of the flood basalt record and kimberlite eruption dating suggests the presence of these provinces may disclose a deep mantle component with a compositionally distinct origin that plays a role in the generation of mantle plumes at preferred locations. By extension, the presence of these provinces may affect the supercontinent cycle. Implementing a mantle convection model featuring distinct continental lithosphere and a compositionally anomalous and intrinsically dense (CAID) component, we study the distribution and mobility of naturally forming, compositionally distinct provinces and their impact on model supercontinent assembly. We employ 2-D Cartesian geometry calculations of thermochemical convection with extremely low compositional diffusion to model Earth-like convective vigor on a global scale and find that an intrinsically dense mantle component generally aggregates into one or two broad provinces. The positions of the provinces are time dependent, but in many of our calculations the province locations are characterized by periods of fixity that reach several hundred million years. Eras of province and associated plume fixity are punctuated by periods of relatively rapid migration. A correlation between supercontinent position and the locations of CAID provinces is not supported by our findings. However, we find that the frequency of supercontinent assemblies increases when CAID provinces are present.Funding from the NSERC of Canada (fund: 327084-10)