Models of crustal flow in the India-Asia collision zone

Copley, Alex and McKenzie, D. P. (2007) Models of crustal flow in the India-Asia collision zone. Geophysical Journal International, 169 (2). pp. 683-698. ISSN 0956-540X DOI 10.1111/j.1365-246X.2007.03343.x

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Abstract

Surface velocities in parts of the India-Asia collision zone are compared to velocities calculated from equations describing fluid flow driven by topographically produced pressure gradients. A good agreement is found if the viscosity of the crust is ∼1020 Pa s in southern Tibet and ∼1022 Pa s in the area between the Eastern Syntaxis and the Szechwan Basin. The lower boundary condition of the flow changes between these two areas, with a stress-free lower boundary in the area between the Szechwan basin and the Eastern Syntaxis, and a horizontally rigid but vertically deformable boundary where strong Indian lithospheric material underlies southern Tibet. Deformation maps for olivine, diopside and anorthite show our findings to be consistent with laboratory measurements of the rheology of minerals. Gravitationally driven flow is also suggested to be taking place in the Indo-Burman Ranges, with a viscosity of ∼1019-1020 Pa s. Flow in both southern Tibet and the Indo-Burman Ranges provides an explanation for the formation of the geometry of the Eastern Himalayan Syntaxis. The majority of the normal faulting earthquakes in the Tibetan Plateau occur in the area of southern Tibet which we model as gravitationally spreading over the Indian shield.

Item Type: Article
Uncontrolled Keywords: 2007 AREP, 2007 P, IA54, COMET
Subjects: 02 - Geodynamics, Geophysics and Tectonics
03 - Mineral Sciences
Divisions: 02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title: Geophysical Journal International
Volume: 169
Page Range: pp. 683-698
Identification Number: 10.1111/j.1365-246X.2007.03343.x
Depositing User: Sarah Humbert
Date Deposited: 16 Feb 2009 13:02
Last Modified: 23 Jul 2013 10:06
URI: http://eprints.esc.cam.ac.uk/id/eprint/221

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