title: Experimental constraints on light elements in the Earth's outer core.
abstract: Earth's outer core is liquid and dominantly composed of iron and nickel (~5-10 wt%). Its density, however, is ~8% lower than that of liquid iron, and requires the presence of a significant amount of light element(s). A good way to specify the light element(s) is a direct comparison of density and sound velocity measurements between seismological data and those of possible candidate compositions at the core conditions. We report the sound velocity measurements of a model core composition in the Fe-Ni-Si system at the outer core conditions by shock-wave experiments. Combining with the previous studies, we found that the best estimate for the outer core's light elements is ~6 wt% Si, ~2 wt% S, and possible ~1-2.5 wt% O. This composition satisfies the requirements imposed by seismology, geochemistry, and some models of the early core formation. This finding may help us to further constrain the thermal structure of the Earth and the models of Earth's core formation.
authors.affiliation: Department of Earth and Planetary Systems Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan.
authors.forename: Youjun
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Earth and Planetary Systems Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan.
authors.forename: Toshimori
authors.initials: T
authors.lastname: Sekine
authors.affiliation: National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, PO Box 919-111, Mianyang 621900, China.
authors.forename: Hongliang
authors.initials: H
authors.lastname: He
authors.affiliation: National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, PO Box 919-111, Mianyang 621900, China.
authors.forename: Yin
authors.initials: Y
authors.lastname: Yu
authors.affiliation: College of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, China.
authors.forename: Fusheng
authors.initials: F
authors.lastname: Liu
authors.affiliation: College of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, China.
authors.forename: Mingjian
authors.initials: M
authors.lastname: Zhang