HR: 15:10h
AN: T13G-07 INVITED    [Abstracts]
TI: Mantle-lithosphere coupling and the state of stress of the lithosphere
AU: * Lithgow-Bertelloni, C
EM: crlb@umich.edu
AF: Earth Sciences, University College London, Gower St., London, WC1E6BT, United Kingdom
AU: Naliboff, J
EM: johnbn@umich.edu
AF: Geological Sciences, University of Michigan, 1100 N. University, Ann Arbor, MI 48109, United States
AU: Conrad, C P
EM: conrad@jhu.edu
AF: Earth and Planetary Sciences, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, United States
AU: de Koker, N
EM: dekoker@umich.edu
AF: Geological Sciences, University of Michigan, 1100 N. University, Ann Arbor, MI 48109, United States
AB: An understanding of the tectonic stress field is geologically important because it is the agent, which preserves in the crust a memory of past dynamical processes. The ability to model the manifestations of intra-plate stresses, mountain building, rifting, etc., depends on our knowledge of dynamical processes in the Earth's interior over geologically long periods of time. Sources of stress include variations in density and thickness of the lithosphere as well as basal and edge tractions that arise from plate driving forces. Mantle-lithospheric coupling and in particular the transmission of stress from mantle to lithosphere is determined by the rheology of the plates themselves and that of the mantle below. We show past and current results on the relative importance of the difference sources of stress for understanding intraplate stresses. We examine the importance of assumptions about the composition and structure of the lithosphere, including continental roots, and mode of compensation, and present a new global model of lithospheric structure. We also focus on the effects mantle shear tractions that arise from mantle density and viscosity heterogeneity. We compute global mantle flow in the presence of strong lateral viscosity variations using the finite element code CitComS and lithospheric stresses with the finite element package ABAQUS. We find that both mantle and lithospheric heterogeneity are important in determining the state of stress in continents and oceans and the mantle signal is particularly strong in SE Asia and other areas of long- lived subduction. The primary effect of lateral variations in mantle viscosity is to strongly couple continents and deeper mantle, enhancing deformation near continental roots.
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8155 Plate motions: general (3040)
DE: 8164 Stresses: crust and lithosphere
SC: Tectonophysics [T]
MN: 2007 Fall Meeting