HR: 1340h
AN: MR23A-0194    [Abstracts]
TI: High-Resolution 3-D Numerical Studies on the Interplay between Variable Thermal Conductivity and Post-Perovskite Phase Transition
AU: * Kameyama, M
EM: kameyama@jamstec.go.jp
AF: Earth Simulator Center, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa, Yokohama, 236-0001 Japan
AU: Yuen, D A
EM: davey@krissy.geo.umn.edu
AF: Minnesota Supercomputing Institute and Department of Geology and Geophysics, University of Minnesota, 599 Walter, 117 Pleasant St. SE, Minneapolis, MN 55455 United States
AU: Kageyama, A
EM: kage@jamstec.go.jp
AF: Earth Simulator Center, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa, Yokohama, 236-0001 Japan
AB: Numerical models of high-resolution three-dimensional mantle convection have been developed in order to study the interplay between the perovskite to post-perovskite (pv-ppv) phase transition near the core-mantle boundary and variable thermal conductivity. A time-dependent convection in a three-dimensional rectangular box of 2000km height and aspect ratio 6$\times$6$\times$1 is considered. We employed an extended Boussinesq approximation, where the effects of latent heat release and viscous dissipation are included. The viscosity of mantle materials is assumed to be dependent on temperature and depth. Spatial mesh divisions of up to 1024$\times$1024$\times$256 (or even doubling in each direction) are utilized, by the help of newly developed algorithm for the Earth Simulator, in order to resolve the interplay between the bottom phase transition and the variations in thermal conductivity and viscosity, which will play an important role in the dynamics of plumes in the lower mantle, as much as possible. In addition to the endothermic phase transition at 660km depth, the pv-ppv transition is modeled as an exothermic phase change located at 200km above the bottom surface. We take into account the temperature-dependence of thermal conductivity, which mimics the effects of radiative heat transfer expected to be dominant in a hotter part of the mantle. The temperature at the core-mantle boundary is also systematically varied, in order to adapt the spatial variations in thermal conductivity and viscosity in the mantle. The effect of the interplay on the convective flow patterns will be further discussed, by comparing the cases with and without the variation of thermal conductivity.
DE: 8121 Dynamics, convection currents and mantle plumes
DE: 8124 Earth's interior--composition and state (old 8105)
DE: 3210 Modeling
SC: Mineral and Rock Physics [MR]
MN: 2004 AGU Fall Meeting