Fig. 4: Relationship between plume buoyancy flux, local spreading rate, and migration rates.

Summary relationships for 13 plume–ridge interactions during their coupling (a) and de-anchoring (b). Each plume–ridge coupled system is annotated by a unique marker and colour. The background colour is a kernel density estimate based on the density of points. a Buoyancy flux and the local spreading rate along ridges are positively correlated for coupled plume–ridge systems in the numerical model of whole-mantle convection. The approximate longevity of 13 coupled plume–ridge systems is annotated on the axes. Plumes that are active over a longer timespan within the numerical model tend to have a larger buoyancy flux, and vice-versa, suggesting that strong plumes are generally established over longer timespans than weak plumes. The longevity of plumes modulates the correlation between buoyancy flux and local spreading rate. b Buoyancy flux and rates of ridge migration within a 20 Myr time window of de-anchoring are inversely correlated. The curve shows how ridges move faster away from mantle plumes with lower buoyancy flux.