LARGE-SCALE MANTLE CONVECTION AND THE HISTORY OF SUBDUCTION

A LARGE-SCALE pattern of mantle convention is evident in the shape of the Earth's gravity field 1, lateral variations in seismic velocity 2,3, the distribution of hotspots 4, and long-wavelength bathymetric anomalies 5. Paradoxically, these signals of mantle convection bear little resemblance to present-day plate motions 1,4, although they seem to be related to past subduction-zone configurations 6. Here we quantify this relationship by correlating a time-integrated history of subduction, calculated in the hotspot reference frame for the past 180 Myr, with regions of the deep mantle inferred from other geophysical observations to be colder than average. Our results support suggestions 6-9 that a direct relationship exists between large-scale thermal heterogeneity in the lower mantle and subduction during the Cenozoic and Mesozoic.