HR: 1340h
AN: T33C-0560    [Abstracts]
TI: A benchmark for the modeling of subduction zones
AU: * van Keken, P
EM: keken@umich.edu
AF: University of Michigan, Department of Geological Sciences, Ann Arbor, MI 48109 United States
AU: Currie, C
EM: claire.currie@dal.ca
AF: Dalhousie University, Department of Oceanography, Halifax, NS B3H 4J1 Canada
AU: King, S
EM: sking@purdue.edu
AF: Purdue University, Department of Earth and Atmospheric Sciences, West Lafayette, IN 47907 United States
AU: Katz, R
EM: katz@ldeo.columbia.edu
AF: Columbia University, Lamont Doherty Earth Observatory, Pallisades, NY 10964 United States
AB: We have formulated a benchmark study for the thermal structure and dynamics of subduction zones . The basis for the comparison is a simple cornerflow model with a number of cases that explore the influence of the formulation of the wedge dynamics, boundary conditions and the influence of stress- and temperature-dependent rheology. We have compared three independent finite element codes and a finite volume code. In general we find reasonable agreement between the codes for the purely kinematic models (where the cornerflow is prescribed by the Batchelor analytical solution) and for isoviscous wedge flow. An important source of error is the numerical treatment of the stress singularity that is introduced by the discontinuity in the velocity boundary condition at the wedge corner-point (between the zero-velocity and no-slip boundary conditions imposed at the slab-wedge interface). This stress singularity has particularly profound implications for temperature-dependent and/or stress-dependent rheology, where spot temperatures at the surface of the slab can disagree by more than 100 Kelvin, even with very high resolution (sub km) in the corner flow region. A minor modification of the velocity boundary conditions for the wedge flow which makes the velocity boundary conditions continuous greatly mitigates the stress singularity effect and we find improved agreement for the thermal structure between the participating codes. We welcome and encourage participation of other groups and codes for a broader and more detailed comparison. Full details of the models and updates of the comparison are availabe at www.geo.lsa.umich.edu/~keken/subduction/benchmark.html.
DE: 3225 Numerical approximations and analysis (4260)
DE: 8104 Continental margins: convergent
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: Fall Meeting 2005