A geodynamic and mineral physics model of a solid-state ultralow-velocity zone
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.
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.Additional details
- Eprint ID
- 23362
- Resolver ID
- CaltechAUTHORS:20110418-113351695
- EAR-0810303
- NSF
- EAR-0711542
- NSF
- CSEDI-EAR-0855815
- NSF
- Created
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2011-04-20Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field
- Caltech groups
- Seismological Laboratory, Division of Geological and Planetary Sciences
- Other Numbering System Name
- Caltech Division of Geological and Planetary Sciences
- Other Numbering System Identifier
- 10046