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Dynamic topography, gravity and the role of lateral viscosity variations from inversion of global mantle flow

Yang, Ting and Gurnis, Michael (2016) Dynamic topography, gravity and the role of lateral viscosity variations from inversion of global mantle flow. Geophysical Journal International, 207 (2). pp. 1186-1202. ISSN 0956-540X. doi:10.1093/gji/ggw335.

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Lateral viscosity variations (LVVs) in the mantle influence geodynamic processes and their surface expressions. With the observed long-wavelength geoid, free-air anomaly, gravity gradient in three directions and discrete, high-accuracy residual topography, we invert for depth- and temperature-dependent and tectonically regionalized mantle viscosity with a mantle flow model. The inversions suggest that long-wavelength gravitational and topographic signals are mainly controlled by the radial viscosity profile; the pre-Cambrian lithosphere viscosity is slightly (∼ one order of magnitude) higher than that of oceanic and Phanerozoic lithosphere; plate margins are substantially weaker than plate interiors; and viscosity has only a weak apparent, dependence on temperature, suggesting either a balancing between factors or a smoothing of actual higher amplitude, but short wavelength, LVVs. The predicted large-scale lithospheric stress regime (compression or extension) is consistent with the world stress map (thrust or normal faulting). Both recent compiled high-accuracy residual topography and the predicted dynamic topography yield ∼1 km amplitude long-wavelength dynamic topography, inconsistent with recent studies suggesting amplitudes of ∼100 to ∼500 m. Such studies use a constant, positive admittance (transfer function between topography and gravity), in contrast to the evidence which shows that the earth has a spatially and wavelength-dependent admittance, with large, negative admittances between ∼4000 and ∼10^4 km wavelengths.

Item Type:Article
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URLURL TypeDescription
Yang, Ting0000-0003-2301-2525
Gurnis, Michael0000-0003-1704-597X
Additional Information:© 2016 The Author. Published by Oxford University Press on behalf of The Royal Astronomical Society. Accepted 2016 September 2. Received 2016 September 1. In original form 2016 February 13. First published online: September 6, 2016. This work was supported by Statoil ASA and the National Science Foundation (under awards EAR 10-28978, EAR-1247022 and EAR-1358646). The authors thank Thorsten Becker and Carolina Lithgow-Bertelloni for their helpful comments.
Group:Seismological Laboratory
Funding AgencyGrant Number
NSFEAR 10-28978
Subject Keywords:dynamic topography; lateral variations in viscosity; gravity-topography ratio; lithospheric stress field; inversion
Issue or Number:2
Record Number:CaltechAUTHORS:20160907-095335295
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Official Citation:Ting Yang and Michael Gurnis Dynamic topography, gravity and the role of lateral viscosity variations from inversion of global mantle flow Geophys. J. Int. (November, 2016) 207 (2): 1186-1202 first published online September 6, 2016 doi:10.1093/gji/ggw335
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:70193
Deposited By: Tony Diaz
Deposited On:07 Sep 2016 17:00
Last Modified:11 Nov 2021 04:25

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