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Crustal deformation induced by mantle dynamics: insights from models of gravitational lithosphere removal

Wang, Huilin and Currie, Claire A. (2017) Crustal deformation induced by mantle dynamics: insights from models of gravitational lithosphere removal. Geophysical Journal International, 210 (2). pp. 1070-1091. ISSN 0956-540X. https://resolver.caltech.edu/CaltechAUTHORS:20170921-101232312

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Abstract

Mantle-based stresses have been proposed to explain the occurrence of deformation in the interior regions of continental plates, far from the effects of plate boundary processes. We examine how the gravitational removal of a dense mantle lithosphere root may induce deformation of the overlying crust. Simplified numerical models and a theoretical analysis are used to investigate the physical mechanisms for deformation and assess the surface expression of removal. Three behaviours are identified: (1) where the entire crust is strong, stresses from the downwelling mantle are efficiently transferred through the crust. There is little crustal deformation and removal is accompanied by surface subsidence and a negative free-air gravity anomaly. Surface uplift and increased free-air gravity occur after the dense root detaches. (2) If the mid-crust is weak, the dense root creates a lateral pressure gradient in the crust that drives Poiseuille flow in the weak layer. This induces crustal thickening, surface uplift and a minor free-air gravity anomaly above the root. (3) If the lower crust is weak, deformation occurs through pressure-driven Poiseuille flow and Couette flow due to basal shear. This can overthicken the crust, producing a topographic high and a negative free-air gravity anomaly above the root. In the latter two cases, surface uplift occurs prior to the removal of the mantle stress. The modeling results predict that syn-removal uplift will occur if the crustal viscosity is less than ∼10^(21) Pa s, corresponding to temperatures greater than ∼400–500 °C for a dry and felsic or wet and mafic composition, and ∼900 °C for a dry and mafic composition. If crustal temperatures are lower than this, lithosphere removal is marked by the formation of a basin. These results can explain the variety of surface expressions observed above areas of downwelling mantle. In addition, observations of the surface deflection may provide a way to constrain the vertical rheological structure of the crust.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1093/gji/ggx209DOIArticle
https://academic.oup.com/gji/article-lookup/doi/10.1093/gji/ggx209PublisherArticle
ORCID:
AuthorORCID
Wang, Huilin0000-0003-3061-0806
Additional Information:© 2017 The Authors. Published by Oxford University Press on behalf of The Royal Astronomical Society. Received: 13 December 2016; Revision Received: 10 May 2017; Accepted: 11 May 2017; Published: 12 May 2017. We thank Laetitia Le Pourhiet, Muriel Gerbault, Saskia Goes, two anonymous reviewers and editor Gaël Choblet for invaluable advice and comments. The numerical models in this study use the SOPALE numerical modeling code, developed under the direction of Dr Christopher Beaumont (Dalhousie University, Halifax NS). Research was supported by computational resources from Compute Canada (WestGrid) and a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada (NSERC).
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Compute CanadaUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Subject Keywords:Dynamics of lithosphere and mantle; Intra-plate processes; Rheology: crust and lithosphere; Tectonics and landscape evolution
Issue or Number:2
Record Number:CaltechAUTHORS:20170921-101232312
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170921-101232312
Official Citation:Huilin Wang, Claire A. Currie; Crustal deformation induced by mantle dynamics: insights from models of gravitational lithosphere removal, Geophysical Journal International, Volume 210, Issue 2, 1 August 2017, Pages 1070–1091, https://doi.org/10.1093/gji/ggx209
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:81671
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:21 Sep 2017 17:33
Last Modified:03 Oct 2019 18:45

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