HR: 10:20h
AN: U12A-01 INVITED    [Abstracts]
TI: Mapping isotope data back into structures in the mantle
AU: * Farnetani, C
EM: cinzia@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 place Jussieu, PARIS cedex 05, 75 252, France
AB: Mapping isotope data back into structure in the mantle seems to me one of the most exciting 'route ahead'. This is obviously challenging, since it requires a profound understanding of the Earth's differentiation processes and of the stirring efficiency in the convecting mantle. Although it is widely accepted that the mantle is chemically heterogeneous, the nature of such heterogeneities, the time evolution of their shape and size and their architecture inside the mantle are still quite elusive. Important progresses can be achieved in the near future by high resolution three dimensional numerical simulations of mantle stirring which need to include: first, more realistic physical properties of the compressible mantle. Second, the ability to keep track of compositionally distinct material with specific physical properties, namely density, compressibility and viscosity. Third, the ability to keep track of heterogeneous and time-varying concentrations of heat producing elements. In other words, we have to move beyond passive heterogeneities, and consider mantle stirring in the presence of active (i.e., able to affect the flow) heterogeneities. In the last years numerical simulations and laboratory experiments of thermo-chemical convection have shown an unexpected dynamics of upwelling deep mantle material and have produced large scale lower mantle structures that are quite consistent with seismological observations. The step ahead will be to include Lagrangian methods recently proposed to quantify mixing in chaotic and time- aperiodic geophysical flows into mantle convection models solving for stretching, dispersal and segregation of active heterogeneities.
DE: 1038 Mantle processes (3621)
SC: Union [U]
MN: 2007 Fall Meeting