Seismic evidence for heterogeneous mantle plumes

I will present evidence from high frequency body waves on whole-mantle plumes and their thermo-chemical nature. The first part of my talk will focus on mapping ultra-low velocity zones at the base of the mantle using shear diffracted waves, uncovering potential roots for whole-mantle plumes. The second part will focus on signatures in the upper mantle and mantle transition zone beneath hotspots using P-to-s converted phases.  A revealing observation here is the persistent presence of a so-called X-discontinuity around 300 km, which could be explained by ponding of a component of recycled basalt in the plume.