HR: 0800h
AN: V51B-0568    [Abstracts]
TI: Plumes are not what they seem: Physics of big, fat, firm plumes
AU: * Korenaga, J
EM: jun.korenaga@yale.edu
AF: Dept. of Geology and Geophysics, Yale University, PO Box 208109, New Haven, CT 06520 United States
AB: In recent years, merely philosophical and often superficial arguments regarding the origin of hotspots and the existence of mantle plumes have become very popular. What is lacking in this trend is constructive discussion based on fluid mechanics constrained by geophysical observations; plumes are fluid-mechanical phenomena, and seismic imaging alone does not tell the whole story. By the same taken, convection models without proper scaling to the Earth's mantle are merely of theoretical interest. Although it is sometimes claimed that plumes with large radii (as observed in recent seismic tomography) have been reproduced in `realistic' mantle convection models, this is simply incorrect. What is referred to as realistic models actually uses either temperature-independent viscosity or very high mantle viscosity or the combination of both. Furthermore, those numerical plumes carry volume flux considerably greater than inferred from surface observables. In this presentation, I will propose a new self-contained framework for plume dynamics that can connect seismic imaging, fluid dynamics, and surface observations. This new framework can also explain various puzzling aspects of the D'' layer and hotspot magmatism.
DE: 8180 Tomography
DE: 8121 Dynamics, convection currents and mantle plumes
DE: 8162 Rheology--mantle
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting