HR: 09:15h
AN: U41A-05    [Abstracts]
TI: Plate mantle coupling and the state of stress of the lithosphere
AU: * Lithgow-Bertelloni, C
EM: crlb@umich.edu
AF: University of Michigan, 1100 N. University Avenue, Ann Arbor, MI 48104, United States
AU: Naliboff, J
EM: johnbn@umich.edu
AF: University of Michigan, 1100 N. University Avenue, Ann Arbor, MI 48104, United States
AU: Conrad, C
EM: conrad@jhu.edu
AF: Johns Hopkins University, 3400 N. Charlest St., Baltimore, MD 21218, United States
AB: The internal deformation of plates is controlled by the state of stress of the lithosphere. The 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. The coupling between mantle stresses and the lithosphere is determined by the rheology of the plates themselves and that of the mantle underneath. We present a study of the state of stress of the lithosphere that examines the importance of lithospheric structure, including continental root, and 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 the lithospheric stresses with the finite element package ABAQUS. We examine the effects of variations in lithospheric structure, looking at different end-members of compensation (Pratt and Airy) as well as a new global model of lithospheric density and thickness, whose properties are determined via a self-consistent thermodynamic method. 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: Union [U]
MN: 2007 Joint Assembly