The subsidence of an aging seafloor starts to slow down at ~70 m.y. old with respect to that expected from simple half-space cooling, and this phenomenon has long been known as seafloor flattening. The flattening signal remains even after removal of the influence of the emplacement of hotspot islands and oceanic plateaus. The combination of small-scale convection and radiogenic heating has been suggested as a mechanism to explain seafloor flattening, and this study explores the possibility of using the magnitude of seafloor flattening to constrain the amount of radiogenic heating in the convecting mantle. By comparison of properly scaled geodynamic...