Earth’s mantle occupies most of its volume, connecting the deep, inaccessible core to the surface. Its convection regulates the planet’s temperature, magnetic field, chemical distribution, and habitability conditions. Changes in convective regimes therefore have profound implications for Earth’s evolution and our interpretation of the geologic record. In this talk, I will focus on the relationship between Earth’s convective regime and the long-lived geodynamo. I will show that Earth likely operated in a “sluggish-lid” tectonic mode for much of the Precambrian, characterized by partially decoupled mobile plates. This early regime, driven by higher mantle temperatures and the presence of an asthenosphere, moderated core-mantle boundary heat flow, sustaining the geodynamo. 

Speaker-suggested reading: Coupled fates of Earth’s mantle and core: Early sluggish-lid tectonics and a long-lived geodynamo, Sci. Adv. 10, eadp1991 (2024) DOI: 10.1126/sciadv.adp1991