Bower, Dan J. and Wicks, June K. and Gurnis, Michael and Jackson, Jennifer M. (2011) A geodynamic and mineral physics model of a solid-state ultralow-velocity zone. Earth and Planetary Science Letters, 303 (3-4). pp. 193-202. ISSN 0012-821X. http://resolver.caltech.edu/CaltechAUTHORS:20110418-113351695
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Abstract
Recent results (Wicks et al., 2010) suggest that a mixture of iron-enriched (Mg,Fe)O and ambient mantle is consistent with wavespeed reductions and density increases inferred for ultralow-velocity zones (ULVZs). We explore this hypothesis by simulating convection to deduce the stability and morphology of such chemically-distinct structures. The buoyancy number, or chemical density anomaly, largely dictates ULVZ shape, and the prescribed initial thickness (proxy for volume) of the chemically-distinct layer controls its size. We synthesize our dynamic results with a Voigt–Reuss–Hill mixing model to provide insight into the inherent seismic tradeoff between ULVZ thickness and wavespeed reduction. Seismic data are compatible with a solid-state origin for ULVZs, and a suite of these structures may scatter seismic energy to produce broadband PKP precursors.
| Item Type: | Article | |||||||||
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| Additional Information: | © 2010 Elsevier B.V. Received 8 July 2010. Received in revised form 18 November 2010. Accepted 16 December 2010. Available online 5 February 2011. CitcomS was obtained from the Computational Infrastructure for Geodynamics (CIG). Discussions with Paul Asimow and Don Helmberger throughout this research proved most helpful, and the constructive comments of Paul Tackley and an anonymous reviewer further enhanced this paper. This work was supported by the NSF through grants EAR-0810303, EAR-0711542, and CSEDI EAR-0855815. Most figures were produced using GMT (Wessel and Smith, 1998). Contribution number 10046 of the Division of Geological and Planetary Sciences, California Institute of Technology. | |||||||||
| Group: | Seismological Laboratory | |||||||||
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| Subject Keywords: | ultralow-velocity zone; core-mantle boundary; mantle convection; PKP waves; (Mg,Fe)O | |||||||||
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| Record Number: | CaltechAUTHORS:20110418-113351695 | |||||||||
| Persistent URL: | http://resolver.caltech.edu/CaltechAUTHORS:20110418-113351695 | |||||||||
| Official Citation: | Dan J. Bower, June K. Wicks, Michael Gurnis, Jennifer M. Jackson, A geodynamic and mineral physics model of a solid-state ultralow-velocity zone, Earth and Planetary Science Letters, Volume 303, Issues 3-4, 1 March 2011, Pages 193-202, ISSN 0012-821X, DOI: 10.1016/j.epsl.2010.12.035. (http://www.sciencedirect.com/science/article/B6V61-523TD27-1/2/402a7c43720c6675ad5f5674db6cc9ab) | |||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
| ID Code: | 23362 | |||||||||
| Collection: | CaltechAUTHORS | |||||||||
| Deposited By: | Ruth Sustaita | |||||||||
| Deposited On: | 20 Apr 2011 16:24 | |||||||||
| Last Modified: | 23 Aug 2016 10:00 |
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