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Melting of subducted basalt at the core-mantle boundary

By Denis Andrault, Giacomo Pesce, Mohamed Ali Bouhifd, Nathalie Bolfan-Casanova, Jean-Marc Hénot and Mohamed Mezouar

Abstract

International audienceThe geological materials in Earth's lowermost mantle control the characteristics and interpretation of seismic ultra–low velocity zones at the base of the core-mantle boundary. Partial melting of the bulk lower mantle is often advocated as the cause, but this does not explain the nonubiquitous character of these regional seismic features. We explored the melting properties of mid-oceanic ridge basalt (MORB), which can reach the lowermost mantle after subduction of oceanic crust. At a pressure representative of the core-mantle boundary (135 gigapascals), the onset of melting occurs at ~3800 kelvin, which is ~350 kelvin below the mantle solidus. The SiO2-rich liquid generated either remains trapped in the MORB material or solidifies after reacting with the surrounding MgO-rich mantle, remixing subducted MORB with the lowermost mantle

Topics: [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography
Publisher: 'American Association for the Advancement of Science (AAAS)'
Year: 2014
OAI identifier: oai:HAL:hal-01134845v1
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