By mining geochemical data of basalts from databases, such as PetDB, Iwamori and Nakamura created a large data set of isotopic values from Mid-ocean Ridge Basalts, Ocean Island Basalts and Continental Basalts. Independent Component Analysis was found to be applicable in capturing the overall structure of the data, including mantle geochemical end-members. They propose top-down hemispherical dynamics involving both the mantle and the core, with focused subduction towards the supercontinents forming a fluid component-rich hemispheric domain anchored to the asthenosphere during continental dispersal in the past several hundred million years. This process may affect the temperature and growth rate of the inner core, resulting in synchronized hemispherical structures in the mantle and the core.
Iwamori and Nakamura, (2015). Isotopic heterogeneity of oceanic, arc and continental basalts and its implications for mantle dynamics. Gondwana Research Vol 27, 1131-1152. DOI: 10.1016/j.gr.2014.09.003