The composition of the core by sound velocity measurements under high pressure
| Project/Area Number |
17K14418
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Petrology/Mineralogy/Economic geology
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| Research Institution | Kumamoto University |
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Principal Investigator |
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| Project Period (FY) |
2017-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2017: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
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| Keywords | 地球コア / 軽元素 / 液体鉄合金 / 高圧下音速測定 / 非弾性X線散乱 / 地球コア組成 / 音速 / 高圧高温実験 |
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| Outline of Final Research Achievements |
We have determined the P-wave velocity of liquid Fe, Fe-P, and Fe-N alloys up to 80 GPa using the laser-heated diamond anvil cell combined with the inelastic X-ray scattering method. The results show that phosphorous has negligible effect on the P-wave velocity of liquid Fe while nitrogen increases that of liquid Fe. Bases on the present pressure-velocity data, we constructed equations of state (EoS) for liquid Fe-P and Fe-N. Using the EoSs, we estimated the velocity and density of both alloys under the Earth’s core conditions, and then compared them with the seismological observations of the liquid outer core. From the comparison, the maximum contents of phosphorus and nitrogen in the core are constrained to be 17 wt% and 3.5 wt%, respectively.
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| Academic Significance and Societal Importance of the Research Achievements |
地球中心核の化学組成は、地球の材料物質、マグマオーシャンから金属核が分離した核形成時の状況、及びマントル対流・コアダイナモといった現在のダイナミクスを理解するために欠かせない。地球中心核の大部分を占める液体外核は鉄(Fe)を主成分とし、10％程度の軽元素が含まれていることが知られているが、この軽元素種類、量比についてはは未解明のままである。当核研究課題では、コア軽元素の候補であるリンと窒素に着目し、これら元素と鉄の液体合金の音速を高圧下で測定し、地球中心核の唯一の観測情報である地震波速度と比較することで、リン及び窒素の含有量に制約を与えた。
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Report
(3 results)
Research Products
(18 results)
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[Presentation] Constrains on light elements in Earth's core via sound velocity measurements of liquid Fe alloys2017
Author(s)
Nakajima, Y., Kawaguchi, S.I., Hirose, K., Komabayashi, T., Kuwayama, Y., Baron, A.Q.R.
Organizer
JpGU-AGU Joint Meeting 2017
Related Report
Int'l Joint Research
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