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Enhanced convection and fast plumes in the lower mantle induced by the spin transition in ferropericlase

Bower, Dan J. and Gurnis, Michael and Jackson, Jennifer M. and Sturhahn, Wolfgang (2009) Enhanced convection and fast plumes in the lower mantle induced by the spin transition in ferropericlase. Geophysical Research Letters, 36 . L10306. ISSN 0094-8276. http://resolver.caltech.edu/CaltechAUTHORS:20090731-092513663

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Abstract

Using a numerical model we explore the consequences of the intrinsic density change (Δρ/ρ ≈ 2–4%) caused by the Fe^(2+) spin transition in ferropericlase on the style and vigor of mantle convection. The effective Clapeyron slope of the transition from high to low spin is strongly positive in pressure-temperature space and broadens with high temperature. This introduces a net spin-state driving density difference for both upwellings and downwellings. In 2-D cylindrical geometry spin-buoyancy dominantly enhances the positive thermal buoyancy of plumes. Although the additional buoyancy does not fundamentally alter large-scale dynamics, the Nusselt number increases by 5–10%, and vertical velocities by 10–40% in the lower mantle. Advective heat transport is more effective and temperatures in the core-mantle boundary region are reduced by up to 12%. Our findings are relevant to the stability of lowermost mantle structures.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1029/2009GL037706DOIUNSPECIFIED
http://www.agu.org/pubs/crossref/2009/2009GL037706.shtmlPublisherUNSPECIFIED
Additional Information:© 2009 American Geophysical Union. Received 10 February 2009; accepted 23 April 2009; published 28 May 2009. We obtained CitcomS version 3.0 from the Computational Infrastructure for Geodynamics (CIG), and we thank Eh Tan for technical advice. All figures in this paper were produced using GMT. We thank John Hernlund and an anonymous reviewer for their comments which improved the manuscript. JMJ acknowledges NSF (0711542) and COMPRES. Contribution number 10017 of the Division of Geological and Planetary Sciences, California Institute of Technology.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSF0711542
Consortium for Materials Properties Research in Earth Sciences (COMPRES)UNSPECIFIED
Subject Keywords:convection; spin; plumes
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Division of Geological and Planetary Sciences10017
Record Number:CaltechAUTHORS:20090731-092513663
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20090731-092513663
Official Citation:Bower, D. J., M. Gurnis, J. M. Jackson, and W. Sturhahn (2009), Enhanced convection and fast plumes in the lower mantle induced by the spin transition in ferropericlase, Geophys. Res. Lett., 36, L10306, doi:10.1029/2009GL037706.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14752
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:07 Aug 2009 17:08
Last Modified:11 Jun 2015 12:58

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