TY - JOUR
T1 - Hydrous magnesium-rich magma genesis at the top of the lower mantle
AU - Nakajima, Ayano
AU - Sakamaki, Tatsuya
AU - Kawazoe, Takaaki
AU - Suzuki, Akio
N1 - Funding Information:
This work was supported by JSPS KAKENHI Grant Numbers JP17H04860, JP17K18797 to T.S., JP15H05828 to A.S., the study abroad program COLABS, and the JSPS Japanese–German Graduate Externship. We gratefully acknowledge the technical staff supporting the multi-anvil laboratories at Bayerisches Geoinstitut, and also thank Yoshinori Ito, Takafumi Kamata, Fumiya Maeda, Shin Ozawa and William F. McDonough at Tohoku University. We would like to thank Enago (www.enago.jp) for the English language review.
Publisher Copyright:
© 2019, The Author(s).
PY - 2019/12/1
Y1 - 2019/12/1
N2 - 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.
AB - 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.
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U2 - 10.1038/s41598-019-43949-2
DO - 10.1038/s41598-019-43949-2
M3 - Article
C2 - 31092856
AN - SCOPUS:85065791630
VL - 9
JO - Scientific Reports
JF - Scientific Reports
SN - 2045-2322
IS - 1
M1 - 7420
ER -