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Dynamic topography produced by lower crustal flow against rheological strength heterogeneities bordering the Tibetan Plateau

Clark, Marin K. and Bush, John W. M. and Royden, Leigh H. (2005) Dynamic topography produced by lower crustal flow against rheological strength heterogeneities bordering the Tibetan Plateau. Geophysical Journal International, 162 (2). pp. 575-590. ISSN 0956-540X. https://resolver.caltech.edu/CaltechAUTHORS:20190118-075549596

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Abstract

Dynamic stresses developed in the deep crust as a consequence of flow of weak lower crust may explain anomalously high topography and extensional structures localized along orogenic plateau margins. With lubrication equations commonly used to describe viscous flow in a thin-gap geometry, we model dynamic stresses associated with the obstruction of lower crustal channel flow due to rheological heterogeneity. Dynamic stresses depend on the mean velocity (Ū), viscosity (µ) and channel thickness (h), uniquely through the term µŪ/h^2. These stresses are then applied to the base of an elastic upper crust and the deflection of the elastic layer is computed to yield the predicted dynamic topography. We compare model calculations with observed topography of the eastern Tibetan Plateau margin where we interpret channel flow of the deep crust to be inhibited by the rigid Sichuan Basin. Model results suggest that as much 1500 m of dynamic topography across a region of several tens to a hundred kilometres wide may be produced for lower crustal material with a viscosity of 2 × 10^(18) Pa s flowing in a 15 km thick channel around a rigid cylindrical block at an average rate of 80 mm yr^(−1).


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1111/j.1365-246X.2005.02580.xDOIArticle
Additional Information:© 2005 RAS. Accepted 2004 December 23. Received 2004 November 30; in original form 2003 September 29. Published: 01 August 2005. The work in this paper was supported by a NSF graduate fellowship to MC, and NSF grants EAR-9814303, EAR-0003571 and EAR-9614970 to LR. JB gratefully acknowledges the financial support of the NSF through Career Grant CTS-0130465. We thank P. Molnar for his constructive review of this manuscript and B. C. Burchfiel, K. Whipple and M. House for their helpful comments and discussion on an earlier version. We also thank Z. Chen, X. Zhang and W. Tang of the Chengdu Institute of Geology and Mineral Resources and M. House for their assistance and expertise with geological research and field work in eastern Tibet.
Funders:
Funding AgencyGrant Number
NSF Graduate Research FellowshipUNSPECIFIED
NSFEAR-9814303
NSFEAR-0003571
NSFEAR-9614970
NSFCTS-0130465
Subject Keywords:crustal rheology, dynamic topography, lower-crustal flow, Tibet
Issue or Number:2
Record Number:CaltechAUTHORS:20190118-075549596
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190118-075549596
Official Citation:Marin K. Clark, John W. M. Bush, Leigh H. Royden; Dynamic topography produced by lower crustal flow against rheological strength heterogeneities bordering the Tibetan Plateau, Geophysical Journal International, Volume 162, Issue 2, 1 August 2005, Pages 575–590, https://doi.org/10.1111/j.1365-246X.2005.02580.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92359
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:22 Jan 2019 22:14
Last Modified:03 Oct 2019 20:43

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