Skip to Main content Skip to Navigation
Journal articles

Mantle weakening and strain localization: Implications for the long-term strength of the continental lithosphere

Abstract : Mechanics of the continental lithosphere require the presence of a high-strength uppermost mantle that defines the "jelly sandwich" model for lithosphere strength layering. However, in deforming regions, growing numbers of geological and geophysical data predict a sub-Moho mantle strength lower than the crustal strength, or a "crème brûlée" model. To reconcile these two opposite views of lithosphere strength layering, we account for a new olivine rheology, which could promote some weakening during dynamic grain size reduction that enhances grain boundary sliding. We performed a one-dimensional numerical model of a deforming rock in order to quantify strain localization due to this weakening rheology. Strain localization occurs at temperatures lower than 800 °C and reaches a maximum at 610 °C, increasing the strain rate from 10­15 to >10­13 s­1. These results imply the existence of a sub-Moho ductile localizing mantle on a lithosphere scale, which occurs at Moho temperatures lower than 800 °C. Also, the localizing degree of this ductile mantle increases with decreasing Moho temperatures down to 550 °C. Such a ductile localizing mantle could therefore promote large strain localization during lithosphere deformation, like the brittle mantle that is commonly assumed in the "jelly sandwich" model. Furthermore, the long-term deformation (106 yr) of the ductile localizing mantle could change the lithosphere strength layering from "jelly sandwich" to "crème brûlée" in response to the grain boundary sliding­induced weakening in mantle shear zones.
Document type :
Journal articles
Complete list of metadata

Cited literature [19 references]  Display  Hide  Download
Contributor : Isabelle Dubigeon Connect in order to contact the contributor
Submitted on : Tuesday, April 21, 2009 - 1:38:20 PM
Last modification on : Tuesday, October 19, 2021 - 6:57:18 PM
Long-term archiving on: : Thursday, June 10, 2010 - 9:19:06 PM


Files produced by the author(s)




Jacques Précigout, Frédéric Gueydan. Mantle weakening and strain localization: Implications for the long-term strength of the continental lithosphere. Geology, Geological Society of America, 2009, 37 (2), pp.147-150. ⟨10.1130/G25239A.1⟩. ⟨insu-00377275⟩



Record views


Files downloads