HR: 11:05h
AN: T42A-04    [Abstracts]
TI: Models of the Earth's thermal and magnetic evolution
AU: * Costin, S O
EM: simona.costin@usask.ca
AF: Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, SK S7N 5E2 Canada
AU: Butler, S L
EM: sam.butler@usask.ca
AF: Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, SK S7N 5E2 Canada
AB: The thermal and hence magnetic evolution of the Earth's core is coupled by the heat flow at the CMB to convection in the mantle. We use numerical and parameterized models of convection in the Earth's mantle in conjunction with energy and entropy conservation models for the core to study the effects of convection style in the mantle on the core's thermal and magnetic evolution. Different scenarios for mantle convection which satisfy modern-day constraints such as surface heat flow and bulk silicate Earth composition are considered. We analyze the effects that various viscosity profiles, phase change parameters and degrees of internal heating in the mantle have on the heat flow at the CMB and the magnetic field generated in the core. The results from numerical and parameterized models are compared, with the former displaying strong short-timescale variations. We find that mantle avalanches can significantly affect the generation of the magnetic field. Models with a small degree of internal heating in the core allow for a sustained geodynamo even before the time of inner-core formation. In addition, we discuss the possibility of extending our analyses to other terrestrial bodies.
DE: 8115 Core processes (1507)
DE: 8121 Dynamics, convection currents and mantle plumes
DE: 8125 Evolution of the Earth
DE: 8130 Heat generation and transport
DE: 1560 Time variations--secular and long term
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting