Three distinct types of hotspots in the Earth's mantle
The origin of mantle hotspots is a controversial topic. Only seven ('primary') out of 49 hotspots meet criteria aimed at detecting a very deep origin (three in the Pacific, four in the Indo-Atlantic hemisphere). In each hemisphere these move slowly, whereas there has been up to 50 mm/a motion between the two hemispheres prior to 50 Ma ago. This correlates with latitudinal shifts in the Hawaiian and Reunion hotspots, and with a change in true polar wander. We propose that hotspots may come from distinct mantle boundary layers, and that the primary ones trace shifts in quadrupolar convection in the lower mantle.
© 2002 Elsevier Science B.V. Received 11 July 2002; received in revised form 17 October 2002; accepted 22 October 2002. For their help in discussing various aspects of this paper during its preparation, we thank Claude Allègre, Don Anderson, Alain Bonneville, Bernard Bourdon, Anny Cazenave, Harmon Craig, David Evans, Ken Farley, Gilian Foulger, Stuart Gilder, Marc Javoy, Joe Kirshvink, Stéphane Labrosse, Jean Paul Montagner, Manuel Moreira, Jean Paul Poirier, Luc-Emmanuel Ricou, Barbara Romanowicz, Norm Sleep (whom we also thank for a preprint on his research on secondary hotspots), Bernhard Steinberger, David Stevenson, and Peter Wyllie. Particular thanks are extended to Jeroen Ritsema for extensive help with the tomographic data, for producing Fig. 1, and for numerous and useful discussions and comments. Norman Sleep and an anonymous reviewer are thanked for their comments. V.C. is particularly grateful to the California Institute of Technology and to its Division of Planetary and Geological Sciences for offering a Moore Fellowship and the best possible atmosphere to work, discuss and strengthen friendships. IPGP contribution NS number 1852.