Geophysics

Building a better mantle with BEAMS

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Science  26 May 2017:
Vol. 356, Issue 6340, pp. 817-818
DOI: 10.1126/science.356.6340.817-e

Solid-state convection has operated in the mantle since Earth's formation 4.56 billion years ago. This is difficult to reconcile with evidence for ancient and isolated regions of the mantle, though. Ballmer et al. propose bridgmanite-enriched ancient mantle structures (BEAMS) as a solution to this riddle. BEAMS have a low Mg/Si ratio, and their presence would cause a relative increase in the mantle mineral bridgmanite, along with a 20-fold viscosity increase. BEAMS may square many odd features in the lower mantle with the geochemical signatures of ancient, isolated, and persistent mantle regions.

Nat. Geosci. 10.1038/NGEO2898 (2017).

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