Our results demonstrate that long-term recycling of dense oceanic crust naturally leads to the formation of thermochemical piles with seismic characteristics similar to the LLSVPs. To meaningfully compare our geodynamic models to tomographic structures, we convert them into models of seismic wavespeed and explicitly account for the limited resolving power of tomography. The model suite covers the predicted density range for oceanic crust over lower mantle conditions. We use existing global geodynamic models in which dense oceanic crust forms at divergent plate boundaries and subducts at convergent ones. We examine here the hypothesis that they are piles of oceanic crust that have steadily accumulated and warmed over billions of years. Mantle tomography reveals the existence of two large low-shear-velocity provinces (LLSVPs) at the base of the mantle.
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