HR: 16:00h
AN: T14A-01 INVITED     [Abstracts]
TI: Petrological-thermomechanical modeling: methodology and examples
AU: * Gerya, T V
EM: taras.gerya@erdw.ethz.ch
AF: Department of Earth Sciences, Swiss Federal Institute of Technology, Zurich, Sonneggstrasse 5, Zurich, CH-8092 Switzerland
AU: Connolly, J A
EM: james.connolly@erdw.ethz.ch
AF: Department of Earth Sciences, Swiss Federal Institute of Technology, Zurich, Sonneggstrasse 5, Zurich, CH-8092 Switzerland
AU: Yuen, D A
EM: davey@krissy.geo.umn.edu
AF: of Minnesota Supercomputing Institute and Department of Geology and Geophysics, University of Minnesota, Minneapolis, 117 Pleasant St. SE, Minneapolis, MN 55455-0219 United States
AB: We have developed a coupled petrological-thermomechanical modeling approach to investigate the dynamical effects of phase transformations (including melting) on various geodynamic processes. We have included density changes due to phase transitions in both the continuity and the momentum equations, and latent heat of mineral reactions and adiabatic and shear heating in the energy conservation equation. The continuity equation is solved in Lagrangian form with substantive time derivative of density computed from moving active markers. The model rheology is viscoelastoplastic and dependent on pressure, temperature, stresses and strain rate as well as chemical and mineralogical composition. Our model accounts for dependence of thermal conductivity, which has a strong radiative component in the deep mantle, on temperature, pressure and composition. The petrological model covers both crustal rocks and the entire mantle (including post-perovskite layer) and is derived by free energy minimization together with estimates for the thermodynamic properties of crustal and mantle minerals. This approach precisely quantifies the thermodynamic and mechanical influence of phase transformations, which depend on temperature, pressure and composition .We have applied a well-tested marker-in-cell method and conservative finite-differences to solve governing equations in 2-D. We employ up to 10 billion active markers to represent details of lithological field with resolution from 1000 to 2 m. Our petrological-thermomechanical approach for has been tested for various geodynamic scenarios including crustal diapirism, oceanic subduction and global mantle convection.
DE: 3612 Reactions and phase equilibria (1012, 8412)
DE: 3660 Metamorphic petrology
DE: 8020 Mechanics, theory, and modeling
DE: 8104 Continental margins: convergent
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
SC: Tectonophysics [T]
MN: Fall Meeting 2005