Element partitioning at the inner-outer core boundary and implications for chemistry of the Earth's core

2014 Fiscal Year Final Research Report

• Project/Area Number: 25800298
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: OZAWA Haruka 独立行政法人海洋研究開発機構, 海洋地球生命史研究分野, 技術研究員 (10598832)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: 高圧高温実験 / ダイアモンドアンビルセル / 地球中心核 / 軽元素

Outline of Final Research Achievements

Melting phase relations in the Fe-FeSi system at high pressures were studied in order to put a constraint on the amount of silicon in the Earth’s core. The results demonstrate that the Si amount in the eutectic liquid is less than 2.6 wt% at 131 GPa and that the Si content in eutectic liquid decreases rapidly with increasing pressure. If silicon is the only light element in the core, the outer core should include ~12 wt.% Si. However, such outer core liquid crystallizes the CsCl-type phase that is more enriched in silicon than coexisting liquid, which contradicts with the seismic observations. These suggest that silicon cannot be the sole light element in the core.

Free Research Field

高圧地球科学