HR: 10:20h
AN: T42A-01    [Abstracts]
TI: HIGH HEAT FLUX AND LOW EXCESS TEMPERATURE IN MANTLE PLUMES INFERRED FROM NON-ADIABATICITY IN INTERNALLY HEATED MANTLE CIRCULATION MODELS
AU: * Bunge, H
EM: bunge@lmu.de
AF: Hans-Peter Bunge, Institute of Geophysics, Department of Earth and Environmental Sciences, Munich University, Munich, D-80333 Germany
AB: Heat transfer across the core mantle boundary (CMB) is fundamentally important to the Earth's internal energy budget, but the amount of heat entering the mantle from the core is poorly known. Classic arguments based on the dynamic topography over mantle hotspots suggest a rather modest core contribution to the mantle energy budget, on the order of 5-10%. Recent geodynamic studies, however, favor significantly higher values to overcome problems of insufficient internal mantle heat generation, and to satisfy constraints on power requirements of the geodynamo and the thermal history of the core. Here we use a high resolution mantle dynamics model to show that the non-adiabatic mantle geotherm which arises from internal mantle heating has a dramatic effect in lowering the excess temperature of hot upwelling plumes by systematically decreasing plume temperatures relative to ambient mantle away from the CMB. This non-adiabatic effect of internally heated mantle flow may explain the unusually low plume excess temperatures inferred from the petrology of hotspot lavas, and implies current estimates of the core heat flux based on hotspot topography should be raised perhaps by a factor of three.
DE: 8121 Dynamics, convection currents and mantle plumes
DE: 8130 Heat generation and transport
DE: 7207 Core and mantle
DE: 1507 Core processes (8115)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting