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AGU: Geophysical Research Letters

 

Keywords

  • lithospheric stresses
  • plate-mantle coupling

Index Terms

  • Tectonophysics: Dynamics of lithosphere and mantle: general
  • Tectonophysics: Stresses: crust and lithosphere
  • Tectonophysics: Stresses: deep-seated
  • Tectonophysics: Rheology: mantle

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L22307, 5 PP., 2009
doi:10.1029/2009GL040484

Modification of the lithospheric stress field by lateral variations in plate-mantle coupling

J. B. Naliboff

Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan, USA

C. P. Conrad

Department of Geology and Geophysics, SOEST, University of Hawaii, Honolulu, Hawaii, USA

C. Lithgow-Bertelloni

Department of Earth Sciences, University College London, London, United Kingdom

The presence of deeply penetrating continental roots may locally increase the magnitude of basal shear tractions by up to a factor of 4 compared to a layered viscosity structure. Here we examine how these increases in mantle-lithosphere coupling influence stress patterns in the overlying elastic lithosphere. By coupling a mantle flow model to a model for the elastic lithosphere, we show that the amplification of mantle tractions beneath cratons increases elastic stress magnitudes by at most a factor of only 1.5 in a pattern not correlated to local basal traction changes. This disconnect is explained by the transmission of elastic stresses across large distances, which makes them sensitive to regionally-averaged changes in basal tractions, but not local variations. Our results highlight the importance of regional variations in lithospheric strength, which could allow stress patterns to more closely match regional changes in basal shear.

Received 10 August 2009; accepted 12 October 2009; published 25 November 2009.

Citation: Naliboff, J. B., C. P. Conrad, and C. Lithgow-Bertelloni (2009), Modification of the lithospheric stress field by lateral variations in plate-mantle coupling, Geophys. Res. Lett., 36, L22307, doi:10.1029/2009GL040484.

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