Hydrous magnesium-rich magma genesis at the top of the lower mantle

Ayano Nakajima, Tatsuya Sakamaki, Takaaki Kawazoe, Akio Suzuki

研究成果: Article

抜粋

Several igneous activities occur on the surface of the Earth, including island arcs, mid-ocean ridges and hot spots. Based on geophysical observations, melting phenomena in the interior also occur at the asthenosphere’s top and the upper mantle’s bottom. Additionally, a seismological low-velocity anomaly was observed at the top of the lower mantle that may result from mantle melting due to dehydration decomposition of ringwoodite to bridgmanite and ferropericlase with a downward flow. However, the corresponding high-pressure experimental data are too poor to understand the melting phenomena under the lower mantle condition. Herein, we conducted hydrous peridotite melting experiments at pressures from 23.5 to 26 GPa and at temperatures from 1300 to 1600 °C for demonstrating the melt composition and the gravitational stability of magma at the top of the lower mantle. The melt had a SiO 2 -poor and MgO-rich composition, which is completely different than that of dry peridotite melting experiments. Compared with the seismological lower mantle, the experimental melt is gravitationally lighter; thus, a similar melt could be observed as seismological low-velocity zone at the lower mantle’s top. The generated magma plays as a filter of down-welling mantle and can contribute to a formation of a silicate perovskitic lower mantle.

元の言語English
記事番号7420
ジャーナルScientific reports
9
発行部数1
DOI
出版物ステータスPublished - 2019 12 1

ASJC Scopus subject areas

  • General

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