Densities of iron and nickel in Earth’s core were previously overestimated（ Press Release）
- Release Date
- 22 Apr, 2022
- BL10XU (High Pressure Research)
22 April 2022
Japan Synchrotron Radiation Research Institute (JASRI)
University of Hyogo
[Main Points]
・ The research group succeeded in experimentally reproducing the high-pressure (330–365 GPa) conditions in Earth’s inner core and obtained reliable compression data for iron and nickel, the main components of Earth’s inner core, under these conditions for the first time in the world.
・ The densities of iron and nickel under the pressure of Earth’s inner core were estimated to be 1–3% higher in the past.
・ Further clarification of the evolutionary process and chemical composition of Earth’s inner core is expected.
A joint research group consisting of Naohisa Hirao (principal research scientist, JASRI), Yasuo Ohishi (chief scientist, JASRI), and Yuichi Akahama (specially appointed professor, University of Hyogo) succeeded in experimentally reproducing the high-pressure (330-365 GPa) conditions that exist in Earth’s inner core and obtained reliable compression data for iron and nickel, the main components of Earth’s inner core, under these conditions for the first time in the world. Thus far, the maximum pressure achieved in experiments to obtain compression data for iron and nickel has been limited to 300 GPa because of technical difficulties. Obtaining compression data at 330–365 GPa, the pressures in Earth’s inner core, has been a major challenge. According to the results obtained in this study, the densities of iron and nickel in Earth’s inner core were estimated to be 2.3% and 1.5% higher, respectively, in the past. This finding is an important achievement that is expected to trigger a reconsideration of an unsolved problem of earth science, i.e., the amounts of light elements in Earth’s core. This achievement was published in the online edition of Matter and Radiation at Extremes published by the American Institute of Physics (AIP) on 13 April 2022. The paper was selected as a scientific highlight (Scilight) from among all the papers published by AIP. Publication |
Fig.1 Internal structure of Earth
Fig.2 Densities of iron and nickel obtained in this study and density profile of the seismological Preliminary Reference Earth Model (PREM).
The previously estimated densities of iron and nickel were 1–3% higher than those obtained in this study. The densities markedly affect the regulation of the chemical composition of Earth’s inner core.
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