Did the Neoproterozoic Revolution Extend to the Deep Mantle?

been the recognition of two Large Low S-wave Velocity Provinces, or LLSVPs, at the base of the mantle: one beneath Africa, the other beneath the South-Central Pacific. Each has an aerial extent of thousands of km 2 and rise several hundreds of km above the core-mantle boundary. Their nature is unclear, but several lines of evidence suggest they are both hotter and denser than surrounding mantle (see review by McNamara, 2019). Importantly, most mantle plumes appear to be generated from these regions, particularly along the margins, while subduction appears to be focused on regions surrounding the LLSVPs. Mantle plumes come in a limited variety of enriched geochemical flavors derived from recycling of oceanic and continental crust into the mantle.