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The boundary between the Earth’s mantle and core (CMB), at about 2900 km depth, is a key region of our planet. It controls the heat that can be extracted from the core and transported up to the surface by convection movements in the mantle. As such, it also controls the cooling and dynamics of the core and its associated geodynamo process, which generates the Earth’s magnetic field. Using numerical simulations of mantle convection, a research team led by Dr. Frédéric Deschamps at the Institute of Earth Sciences, Academia Sinica, showed that beneath regions known as large shear-wave velocity provinces (LLSVPs), which are thought to be hotter than their surroundings and enriched in iron, the amount of heat that can be extracted from the core to the mantle is lower than the amount of heat provided by the core, and that, locally, heat may even flow from the mantle to the core. By contrast, heat flux beneath slabs arriving at the CMB is high, leading to strong lateral heat flux heterogeneity. This may lead to regional stratification occurs at the top of the core and explain the onset and termination of geomagnetic superchrons. The research has been published on June 17, 2026 in Nature Geoscience.
Research team includes Dr. Joshua Martin Guerrero and Wen-Pin Hsieh from IES, and Dr. Hagay Amit from University of Nantes. The research was supported by Academia Sinica, and the National Science and Technology Council.