Billen, Magali I. and Gurnis, Michael (2003) Comparison of dynamic flow models for the Central Aleutian and Tonga-Kermadec subduction zones. Geochemistry, Geophysics, Geosystems, 4 (4). 2001GC000295. ISSN 1525-2027. http://resolver.caltech.edu/CaltechAUTHORS:BILggg03
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Using three-dimensional (3-D) instantaneous dynamic models of the Central Aleutian subduction zone, we show that a low viscosity, low density (deltarho = 10 kg/m3) region in the wedge is needed to match observations of topography, the geoid and the stress-state in the slab and overriding plate. Previous models of the Tonga-Kermadec subduction zone also require a low viscosity, low density (deltarho = 20 kg/m3) region in the wedge. A low viscosity region in the wedge decouples the overriding plate from the downward flow in the wedge caused by the sinking slab, reducing the magnitude of negative dynamic topography on the overriding plate and changing the state of stress in the slab from down-dip tension to down-dip compression. If the low viscosity region is large, as in the Tonga-Kermadec models, then the decoupling may also cause the overriding plate to go into extension. These are the first dynamic models to simultaneously match the state of stress in the slab and overriding plate and suggest that the combination of stress state within the slab and overriding plate may provide an additional constraint on the viscosity structure within subduction zones.
|Additional Information:||Copyright 2003 by the American Geophysical Union. Received: 12 December 2001; Revised: 11 November 2002; Accepted: 20 January 2003; Published: 11 April 2003. We thank Don Anderson for helpful discussion on water within the mantle and Paul Asimow for help estimating the density anomalies within a wet subduction zone wedge. Calculations were carried out on the facilities of the Caltech Center for Advanced Computer Research (CACR). Supported by NSF grants EAR-9725629 and EAR-9814577. Contribution no. 8850, Division of Geological and Planetary Sciences, California Institute of Technology.|
|Subject Keywords:||Viscosity; water; stress; mantle-wedge; topography; geoid; 8120 Tectonophysics: Dynamics of lithosphere and mantle—general; 8162 Tectonophysics: Evolution of the Earth: Rheology—mantle; 8168 Tectonophysics: Evolution of the Earth: Stresses—general|
|Official Citation:||Billen, M. I., and M. Gurnis, Comparison of dynamic flow models for the Central Aleutian and Tonga-Kermadec subduction zones, Geochem. Geophys. Geosyst., 4(4), 1035, doi:10.1029/2001GC000295, 2003.|
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|Deposited On:||19 Dec 2005|
|Last Modified:||26 Dec 2012 08:42|
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