HR: 14:25h
AN: T13G-04 INVITED    [Abstracts]
TI: Stress evolution and dynamics of the lithosphere from 2-D and 3-D numerical models of long-term tectonic processes.
AU: * Kaus, B J
EM: boris.kaus@erdw.ethz.ch
AF: Geophysical Fluid Dynamics, Department of Earth Sciences, ETH Zurich, Schaffmattstrasse 30, Switzerland, 8093, Switzerland
AU: * Kaus, B J
EM: boris.kaus@erdw.ethz.ch
AF: Department of Earth Sciences, University of Southern California, 3651 Trousdale Parkway, Los Angeles, CA 90089-740, United States
AB: The processes that generate stress in the lithosphere are incompletely understood. Whereas it is obvious that lithospheric deformation (and topography) is ultimately caused by cooling of the Earth from the time of formation, it is less clear how lithospheric deformation is coupled to mantle flow and how this affect stresses. Part of this is due to the somewhat complicated rheology of the lithosphere, which varies from brittle (elastoplastic) to ductile (viscous). In addition, vertical layering of the lithosphere may give rise to instabilities which affect its dynamics and stress evolution in a non-trivial manner. Obtaining a better insight in these processes thus requires numerical tools that can model the mantle-lithosphere system in a self-consistent manner (i.e. in a single computational domain) including topographic effects (i.e. free surface) and viscoelastoplastic rheologies. I have recently developed 2-D and 3-D numerical tools that incorporate the above mentioned features. Here I focus on a number of case studies to illustrate how differences in rheology and boundary conditions alter the dynamics and in particular the stress evolution of the lithosphere. Instabilities such as bending or buckling of compressed lithosphere reduce the average stress („structural weakening"). Viscoelasticity results in time- dependencies, which are particularly pronounced in highly viscous parts of the lithosphere (e.g. the mantle lithosphere). Strong parts of the lithospere thus don't necessarily have large differential stresses (and earthquakes). The Christmas-tree approximation should therefore be used with care to infer stress levels in the lithosphere. Finally I will illustrate differences in stresses between "kinematically-driven" and "internally-driven" lithospheric- scale deformation models.
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8138 Lithospheric flexure
DE: 8159 Rheology: crust and lithosphere (8031)
DE: 8163 Rheology and friction of fault zones (8034)
DE: 8164 Stresses: crust and lithosphere
SC: Tectonophysics [T]
MN: 2007 Fall Meeting