Sound velocity of Fe-S liquids at high pressure: Implications for the Moon's molten outer core

Zhicheng Jing, Yanbin Wang, Yoshio Kono, Tony Yu, Tatsuya Sakamaki, Changyong Park, Mark L. Rivers, Stephen R. Sutton, Guoyin Shen

研究成果: Article

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Sound velocities of Fe and Fe-S liquids were determined by combining the ultrasonic measurements and synchrotron X-ray techniques under high pressure-temperature conditions from 1 to 8 GPa and 1573 K to 1973 K. Four different liquid compositions were studied including Fe, Fe-10 wt% S, Fe-20 wt% S, and Fe-27 wt% S. Our data show that the velocity of Fe-rich liquids increases upon compression and decreases with increasing sulfur content, whereas temperature has negligible effect on the velocity of Fe-S liquids. The sound velocity data were combined with ambient-pressure densities to fit the Murnaghan equation of state (EOS). Compared to the lunar seismic model, our velocity data constrain the sulfur content at 4 ± 3wt%, indicating a significantly denser (6.5 ± 0.5g/cm3) and hotter (1870-70+100K) outer core than previously estimated. A new lunar structure model incorporating available geophysical observations points to a smaller core radius. Our model suggests a top-down solidification scenario for the evolution of the lunar core. Such "iron snow" process may have been an important mechanism for the growth of the inner core.

元の言語English
ページ(範囲)78-87
ページ数10
ジャーナルEarth and Planetary Science Letters
396
DOI
出版物ステータスPublished - 2014 6 15
外部発表Yes

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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