Journal
EARTH AND PLANETARY SCIENCE LETTERS
Volume 414, Issue -, Pages 68-76Publisher
ELSEVIER
DOI: 10.1016/j.epsl.2015.01.013
Keywords
geodynamo; polarity reversals; core convection; core-mantle boundary; D '' layer; superplumes
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Funding
- National Science Foundation [EAR-1135382]
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Seismic images of the lower mantle reveal two large-scale, low shear wave velocity provinces beneath Africa and the Pacific that are variously interpreted as superplumes, plume clusters or piles of dense mantle material associated with the D layer. Here we show that time variations in the height of these structures produce variations in heat flux across the core-mantle boundary that can control the rate at which geomagnetic polarity reversals occur. Superplume growth increases the mean coremantle boundary heat flux and its lateral heterogeneity, thereby stimulating polarity reversals, whereas superplume collapse decreases the mean core-mantle boundary heat flux and its lateral heterogeneity, inhibiting polarity reversals. Our results suggest that the long, stable polarity geomagnetic superchrons such as occurred in the Cretaceous, Permian, and earlier in the geologic record were initiated and terminated by the collapse and growth of lower mantle superplumes, respectively. (C) 2015 Elsevier B.V. All rights reserved.
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