The History and Dynamics of Global Plate Motions, Geophys. Mon. Ser., pp. 377-398, ed. Richards, M. A., R. G. Gordon, and R. D. van der Hilst, AGU, Washington, DC., 2000.

Effects of mantle flow on hotspot motion

Bernhard Steinberger and Richard J. O'Connell


Abstract

The motion of hotspots in large--scale mantle flow is discussed. The concept of mantle plumes and the experiments and observations on which it is based are reviewed. Results that support hotspot motion (from experiments, plate reconstructions and paleolatitude data) are contrasted with observations on which the concept of hotspot fixity is based (mainly geometry and age progression of hotspot tracks). A numerical model of hotspot motion in large-scale mantle flow is introduced. It is shown how hotspot motion may approximately represent flow at mid--mantle depth, particularly plate return flow. Such a model can explain some aspects of the observed hotspot distribution, yields predictions on the origin and shape of plume conduits and gives constraints on mantle viscosity structure. Some results for the motion of individual hotspots are shown, including coherent motion toward the southeast for Hawaii and Louisville, westward motion for Easter, and southward motion for Kerguelen. For Hawaii and Louisville, the calculated motion fits well the observed geometry and age progression of hotspot tracks. Furthermore, calculations can explain observed relative motions of Pacific and African hotspots back to 43 Ma without invoking any additional plate boundary in the Pacific-Antarctic region. Paleomagnetic and modelling results of polar motion are reviewed and combined with models of hotspot motion; resulting predictions of paleolatitudes are compared with observations for the Pacific plate. Calculated hotspot motion in combination with polar motion can explain any latitudinal shift of Pacific hotspots back to about 70-80 Ma.