HR: 0800h
AN: NG41B-0431    [Abstracts]
TI: Thermal evolution of the Mantle: Attractor and/or repeller?
AU: * Bunge, E M
EM: bunge@msi.umn.edu
AF: Geophysics University of Minnesota, 310 Pillsbury Drive SE Office 32, Minneapolis, MN 555455 United States
AU: Yuen, D
EM: davey@krissey.geo.umn.edu
AF: Geophysics University of Minnesota, 310 Pillsbury Drive SE Office 32, Minneapolis, MN 555455 United States
AU: Vincent, A
EM: vincent@ASTRO.UMontreal.CA
AF: Departement de Physique Universite de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, QC H3C 3J7 Canada
AU: Belanger, E
EM: belanger@ASTRO.UMontreal.CA
AF: Departement de Physique Universite de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, QC H3C 3J7 Canada
AB: The earth has had a very complex thermal history. The mantle is now vigorously convecting but will eventually cool as heat dissipates in space.The final state can be described as an attractor because it is the fate of a dissipative systems to become uniforme or increase its entropy. The opposite is true over shorter time scales (billion years).This chaotic, non-linear system will act as a repeller. Slight changes inthe initial thermal distribution will greatly alter the final thermal distribution. This same phenomena is seen in other strongly non-linear turbulent systems such as the weather. Specifically, we test the existence of two initial conditions of mantle thermal history from a beginning of a billion years ago to present. Will it be possible for two different thermal distributions to lead to similar present conditions? Conversely, the sensitivity to initial conditions is also tested. To do this we are using a simplified but realistic model of the mantle with 2-d vertical compressibility, constant three layer rheology (400km, 650km)infinite Prandtl, constant but realistic Rayleigh Ra=10^6 to 10^7, time-dependent heating with a constant rate of radiogenic decay,constant temperature bottom boundary conditions because the exact nature of chemical-thermal core-mantle boundary is still unknown.
DE: 3200 MATHEMATICAL GEOPHYSICS (New field)
DE: 3210 Modeling
DE: 3220 Nonlinear dynamics
DE: 3230 Numerical solutions
DE: 3240 Chaos
SC: Nonlinear Geophysics [NG]
MN: 2004 AGU Fall Meeting