Composition of the earliest ocean inferred from experimental reactions between highly acidic subcritical fluid and crustal rocks

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K13583
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Geology
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: SHIBUYA Takazo 国立研究開発法人海洋研究開発機構, 深海・地殻内生物圏研究分野, 研究員 (00512906)
• Co-Investigator(Renkei-kenkyūsha): SAITOH Masafumi 国立研究開発法人海洋研究開発機構, 次世代海洋資源調査技術研究開発プロジェクトチーム, 特任研究員 (80637588)
• Research Collaborator: UEDA Hisahiro
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 地球史 / 冥王代 / 原始海洋 / 高温高圧実験

Outline of Final Research Achievements

To reproduce the formation process of the primitive ocean on Earth, a new gold-coated hydrothermal reactor and experimental techniques were developed. Using the new experimental methods, reactions between the subcritical atmosphere and the primitive crusts were simulated, which indicates that the composition of the primitive ocean in the early Earth was clearly different from the modern equivalent and that the primitive ocean was enriched in cations other than Na in contrast to the modern seawater. Furthermore, it was also revealed that the composition of the primitive ocean varies depending on the composition of the primitive crust (komatiite or basalt). In addition, it was previously suggested that the primitive ocean was inappropriate as an environment of the emergence of life because the primitive ocean was strongly acidic but our results implies that the pH value of the primitive ocean was near-neutral and appropriate for the emergence of life on Earth.

Free Research Field

地質学　地球化学　宇宙生物学