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Influence of continental roots and asthenosphere on plate‐mantle coupling
Author(s) -
Conrad Clinton P.,
LithgowBertelloni Carolina
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl025621
Subject(s) - asthenosphere , lithosphere , geology , mantle (geology) , geophysics , mantle convection , mantle wedge , lithospheric flexure , plate tectonics , seismology , tectonics
The shear tractions that mantle flow exerts on the base of Earth's lithosphere contribute to plate‐driving forces and lithospheric stresses. We investigate the sensitivity of these tractions to sub‐lithospheric viscosity variations by comparing shear tractions computed from a mantle flow model featuring laterally‐varying lithosphere and asthenosphere viscosity with those from a model with layered viscosity. Lateral viscosity variations generally do not change the direction of shear tractions, but deeply penetrating continental roots increase traction magnitudes by a factor of 2–5 compared to 100 km thick lithosphere. A low‐viscosity asthenosphere decreases traction magnitudes by a smaller amount, and is important only if >100 km thick. Increased plate‐mantle coupling beneath thick continental lithosphere may increase plate‐driving forces, surface deformation, and mantle‐derived lithospheric stresses in these regions. By contrast, a low‐viscosity asthenosphere does not decouple the lithosphere from mantle flow, highlighting the geological importance of mantle tractions on the lithosphere.