التفاصيل البيبلوغرافية
| العنوان: |
Electrical Conductivity of Dense MgSiO3 Melt Under Static Compression. |
| المؤلفون: |
Okuda, Yoshiyuki, Hirose, Kei, Ohta, Kenji, Kawaguchi‐Imada, Saori, Oka, Kenta |
| المصدر: |
Geophysical Research Letters; 6/28/2024, Vol. 51 Issue 12, p1-9, 9p |
| مصطلحات موضوعية: |
ELECTRIC conductivity, GEOMAGNETISM, OCEAN convection, IONIC conductivity, ELECTRICAL conductivity measurement, INNER planets, CONVECTION (Meteorology) |
| مستخلص: |
The magnetic fields of terrestrial planets are created by core convection. Molten silicate mantles could also generate magnetic fields through their convective motion, known as a silicate dynamo. Recent computational studies have suggested that silicate melts may exhibit high electrical conductivity (EC) at temperatures above 4000 K due to strong electronic conduction, which could activate a silicate dynamo. We determined the EC of dense molten MgSiO3 up to 71 GPa and 4490 K by static compression experiments. It jumped by one order of magnitude upon melting, but 57(27) S/m at 4490 K is much lower than previous predictions, suggesting that molten MgSiO3 carries charge via ions rather than predicted electronic conduction. Nevertheless, the strong temperature dependence of the ionic conductivity found in this study suggests that super‐Earths' hotter magma ocean with larger‐scale convection could power a dynamo that drives magnetic fields, which plays key roles in sustaining planetary surface environments. Plain Language Summary: The magnetic fields of the Earth and other terrestrial planets are vital in maintaining their early atmosphere and ocean. A convective silicate melt layer may produce a magnetic field, known as a silicate dynamo if its electrical conductivity (EC) is high enough. We measured the EC of silicate melt with the composition of MgSiO3 at pressures up to 71 gigapascals and temperatures up to 4490 K. Assuming that MgSiO3 melt conductivity represents that of the magma ocean, it is unlikely that the early Earth could have produced a magnetic field through magma ocean convection; however, we have found that magma ocean on super‐Earths can generate a silicate dynamo. Our finding provides experimental evidence that super‐Earths have the potential to generate silicate dynamo since the actual magma ocean having multiple impurities should show a higher conductivity than MgSiO3 melt. This implies that magnetic fields generated by the convective motion of magma oceans may be a common occurrence in the universe, playing a crucial role in preserving their surface environments. Key Points: We measured the electrical conductivity of MgSiO3 melt up to 71 GPa and 4490 KThe main charge carrier in MgSiO3 melt is ions at least up to 4490 KMagma ocean on super‐Earths may drive silicate dynamo [ABSTRACT FROM AUTHOR] |
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