HR: 15:10h
AN: T22D-07    [PDF]
TI: Chemical Heterogeneities and Layering in the Lowermost Mantle
AU: * Badro, J
EM: james.badro@lmcp.jussieu.fr
AF: Laboratoire de Min\'eralogie-Cristallographie\\ Universit\'e Paris VI -- Institut de Physique du Globe, Case 115, 4 place Jussieu, Paris, 75004 France
AU: Fiquet, G
EM: guillaume.fiquet@lmcp.jussieu.fr
AF: Laboratoire de Min\'eralogie-Cristallographie\\ Universit\'e Paris VI -- Institut de Physique du Globe, Case 115, 4 place Jussieu, Paris, 75004 France
AU: Guyot, F
EM: francois.guyot@lmcp.jussieu.fr
AF: Laboratoire de Min\'eralogie-Cristallographie\\ Universit\'e Paris VI -- Institut de Physique du Globe, Case 115, 4 place Jussieu, Paris, 75004 France
AB: An increasing number of geophysical observations, mainly seismological, indicate Earth's lower-mantle is chemically heterogeneous [1]. Recent mineral physics studies of the two main constituents of the lower mantle (magnesium silicate perovskite and magnesiow\"ustite) reveal fundamental changes in the chemical affinity of iron at 70 GPa [2], resulting in the depletion of iron in the silicate to the benefit of the oxide. Here, we will correlate the mineralogical and geophysical data, and provide a mineral-physics basis for a chemically heterogeneous and layered lower mantle. We will discuss the geophysical, geochemical, and geodynamical implications of such observations for global-Earth modelling, such as the dynamics of plumes, the chemistry at the core-mantle boundary, and heat conductivity at the basis of the lowermost mantle. [1] R. van der Hilst and S. K\'arason, Science 283, 1885 (1999) [2] J. Badro et al., Science 300, 789 (2003)
DE: 3672 Planetary mineralogy and petrology (5410)
DE: 3924 High-pressure behavior
DE: 3954 X ray, neutron, and electron spectroscopy and diffraction
DE: 5109 Magnetic and electrical properties
SC: Tectonophysics [T]
MN: 2003 Fall Meeting