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

2009; Geological Society of America; Volume: 37; Issue: 2 Linguagem: Inglês

10.1130/g25239a.1

1943-2682

Jacques Précigout, Frédéric Gueydan,

Geological and Geochemical Analysis

Research Article| February 01, 2009 Mantle weakening and strain localization: Implications for the long-term strength of the continental lithosphere Jacques Précigout; Jacques Précigout 1Géosciences Rennes, Université de Rennes 1, CNRS UMR 6118, 35042 Rennes, France Search for other works by this author on: GSW Google Scholar Frédéric Gueydan Frédéric Gueydan * 1Géosciences Rennes, Université de Rennes 1, CNRS UMR 6118, 35042 Rennes, France *E-mail: frederic.gueydan@univ-rennes1.fr Search for other works by this author on: GSW Google Scholar Geology (2009) 37 (2): 147–150. https://doi.org/10.1130/G25239A.1 Article history received: 27 Jun 2008 rev-recd: 22 Sep 2008 accepted: 09 Oct 2008 first online: 12 Oct 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Jacques Précigout, Frédéric Gueydan; Mantle weakening and strain localization: Implications for the long-term strength of the continental lithosphere. Geology 2009;; 37 (2): 147–150. doi: https://doi.org/10.1130/G25239A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search 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 10−15 to >10−13 s−1. 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 sliding–induced weakening in mantle shear zones. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.