Mantle plumes are buoyant upwellings that bring hot material from Earth's deep-mantle to the surface, forming volcanic hotspots, such as Hawaii. Although extensively studied, the geochemical variations recorded in hotspot lavas have, so far, proved difficult to understand, particularly how they relate to their heterogeneous deep-mantle source. In this project, state-of-the-art geodynamical models will be used to determine: (i) how deep-mantle heterogeneities are transported into a plume; and (ii) how such heterogeneities are mixed during plume ascent. This will allow us to link, for the first time, geochemical variations at volcanic hotspots to the deep-mantle's thermo-chemical structure, under an Earth-like, fluid dynamical framework. This work is funded by an ARC Future Fellowship.