The Earth's rigid lithosphere varies laterally in thickness and strength. Areas of thicker, older lithosphere known as continental roots penetrate deeper into the mantle in some places under continents. Because these continental roots are in contact with deeper, more viscous mantle, the shear traction at the base of the lithosphere in those areas is increased by up to a factor of 4 compared with a model lithosphere without continental roots.
To study how those areas of increased traction affect patterns of lithospheric stress above, Naliboff et al. examined a model of mantle flow coupled to a model of the elastic lithosphere. The authors find that greater traction at the bottom of thicker areas of continental lithosphere raises elastic stress in the lithosphere above by at most a factor of 1.5.
Furthermore, greater lithospheric stress is not located simply in small areas directly above deep continental roots; instead, increased stress is spread out over a larger regional area.
The study highlights the need to incorporate variations in lithosphere thickness and strength into models of both mantle flow and lithospheric deformation.
The research is published in Geophysical Research Letters. Authors include 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; and C. Lithgow-Bertelloni: Department of Earth Sciences, University College London, London, United Kingdom
- Naliboff et al. Modification of the lithospheric stress field by lateral variations in plate-mantle coupling. Geophysical Research Letters, 2009; 36 (22): L22307 DOI: 10.1029/2009GL040484
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