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On the location of plumes and lateral movement of thermochemical structures with high bulk modulus in the 3-D compressible mantle

Tan, Eh and Leng, Wei and Zhong, Shijie and Gurnis, Michael (2011) On the location of plumes and lateral movement of thermochemical structures with high bulk modulus in the 3-D compressible mantle. Geochemistry, Geophysics, Geosystems, 12 (7). Art. No. Q07005. ISSN 1525-2027. http://resolver.caltech.edu/CaltechAUTHORS:20110802-155129575

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Abstract

The two large low shear velocity provinces (LLSVPs) at the base of the lower mantle are prominent features in all shear wave tomography models. Various lines of evidence suggest that the LLSVPs are thermochemical and are stable on the order of hundreds of million years. Hot spots and large igneous province eruption sites tend to cluster around the edges of LLSVPs. With 3-D global spherical dynamic models, we investigate the location of plumes and lateral movement of chemical structures, which are composed of dense, high bulk modulus material. With reasonable values of bulk modulus and density anomalies, we find that the anomalous material forms dome-like structures with steep edges, which can survive for billions of years before being entrained. We find that more plumes occur near the edges, rather than on top, of the chemical domes. Moreover, plumes near the edges of domes have higher temperatures than those atop the domes. We find that the location of the downwelling region (subduction) controls the direction and speed of the lateral movement of domes. Domes tend to move away from subduction zones. The domes could remain relatively stationary when distant from subduction but would migrate rapidly when a new subduction zone initiates above. Generally, we find that a segment of a dome edge can be stationary for 200 million years, while other segments have rapid lateral movement. In the presence of time-dependent subduction, the computations suggest that maintaining the lateral fixity of the LLSVPs at the core-mantle boundary for longer than hundreds of million years is a challenge.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1029/2011GC003665DOIUNSPECIFIED
http://www.agu.org/pubs/crossref/2011/2011GC003665.shtmlPublisherUNSPECIFIED
Additional Information:© 2011 American Geophysical Union. Received 18 April 2011; Revised 17 May 2011; Accepted 18 May 2011; Published 12 July 2011. E.T. and M.G. have been supported by NSF EAR‐0426271. W.L. and S.Z. have been supported by NSF EAR‐1015669. The CitcomS code from the Computational Infrastructure for Geodynamics (CIG) was used for this study.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFEAR‐0426271
NSFEAR‐1015669
Subject Keywords:LLSVP; plume; thermochemical convection
Record Number:CaltechAUTHORS:20110802-155129575
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20110802-155129575
Official Citation:Tan, E., W. Leng, S. Zhong, and M. Gurnis (2011), On the location of plumes and lateral movement of thermochemical structures with high bulk modulus in the 3-D compressible mantle, Geochem. Geophys. Geosyst., 12, Q07005, doi:10.1029/2011GC003665.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:24637
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:03 Aug 2011 14:46
Last Modified:11 Jun 2015 12:59

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