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Constraints on Mantle Viscosity From Slab Dynamics

Liu, Hao and Gurnis, Michael and Leng, Wei (2021) Constraints on Mantle Viscosity From Slab Dynamics. Journal of Geophysical Research. Solid Earth, 126 (8). Art. No. e2021JB022329. ISSN 2169-9313. doi:10.1029/2021jb022329. https://resolver.caltech.edu/CaltechAUTHORS:20210817-171131162

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Abstract

The radial viscosity of the mantle is generally thought to increase by ∼10–100 times from the upper to lower mantle with a putative, abrupt increase at 660 km depth. Recently, a low viscosity channel (LVC) between 660 and 1,000 km has been suggested. We conduct a series of time-dependent flow models with viscosity either increasing or decreasing at 660 km depth while tracking slab structure, state-of-stress, and geoid. We find that a LVC will lower the amplitude of long wavelength (>5,000 km) geoid highs over slabs, with amplitudes <10 m in height, while increasing the slab dip angle and downdip tension in the upper 300 km of slabs. A viscosity increase at 660 km gives rise to strong downdip compression throughout a slab and this pattern will largely go away with the introduction of the LVC. In addition, the endothermic phase change at 660 km depth can substantially affect the stress distribution within slabs but has a minor influence on the geoid. Models that fit the observed long wavelength geoid and observed focal mechanism in the western Pacific favor models without the presence of the LVC between 660 km and 1,000 km depths.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2021jb022329DOIArticle
https://geodynamics.org/cig/Related ItemMantle convection code Citcom
ORCID:
AuthorORCID
Liu, Hao0000-0002-3200-5215
Gurnis, Michael0000-0003-1704-597X
Leng, Wei0000-0002-7979-4100
Additional Information:© 2021 American Geophysical Union. Issue Online: 21 August 2021; Version of Record online: 21 August 2021; Accepted manuscript online: 26 July 2021; Manuscript accepted: 11 July 2021; Manuscript revised: 22 June 2021; Manuscript received: 29 April 2021. Hao Liu's visit to Caltech was supported by the Strategic Priority Research Program of Chinese Academy of Sciences, Grant No. XDB 41000000 and the China Scholarship Council. Additional support provided by the National Science Foundation through awards EAR-1645775 and EAR-2009935, and National Natural Science Foundation of China (41774105 and 41820104004). Some of the computations carried out on the NSF XSEDE systems, made possible by TG-EAR160027. The authors acknowledge the advice from Wei Mao, Ting Yang, and Jiayan Tan. Data Availability Statement: The mantle convection code Citcom is available at the website https://geodynamics.org/cig/, while model data files will be available at https://data.caltech.edu/.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Chinese Academy of SciencesXDB 41000000
China Scholarship CouncilUNSPECIFIED
NSFEAR-1645775
NSFEAR-2009935
National Natural Science Foundation of China41774105
National Natural Science Foundation of China41820104004
NSFEAR-160027
Subject Keywords:mantle viscosity; slab dynamics; stress state; geoid
Issue or Number:8
DOI:10.1029/2021jb022329
Record Number:CaltechAUTHORS:20210817-171131162
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210817-171131162
Official Citation:Liu, H., Gurnis, M., & Leng, W. (2021). Constraints on mantle viscosity from slab dynamics. Journal of Geophysical Research: Solid Earth, 126, e2021JB022329. https://doi.org/10.1029/2021JB022329
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110295
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:18 Aug 2021 21:49
Last Modified:31 Aug 2021 19:43

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