Atmospheric oxygen and carbon dioxide in the late Archean and early Proterozoic

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K05338
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: The University of Tokyo
• Principal Investigator: Murakami Takashi 東京大学, 大学院理学系研究科(理学部), 名誉教授 (00253295)
• Co-Investigator(Kenkyū-buntansha): 鈴木 庸平 東京大学, 大学院理学系研究科(理学部), 准教授 (00359168) ; 宇都宮 聡 九州大学, 理学研究院, 准教授 (40452792)
• Research Collaborator: KANZAKI YOSHIKI カリフォルニア大学, 博士研究員
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 大気進化 / 酸素 / 二酸化炭素 / 風化 / 古土壌 / 先カンブリア時代

Outline of Final Research Achievements

The late Archean and early Proterozoic witnessed tremendous changes on the Earth’s surface environments: climate change, ocean evolution and life evolution to which atmospheric oxygen and carbon dioxide concentrations can give more accurate limitations. We made quantitative calculations based on newly constructed weathering models: an increase from 10E－6 to 10E－3 atm between 2.5 and 1.8 Ga in atmospheric oxygen, and a decrease from 10E－0.5 to 10E－1.5 atm between 2.8 and 1.8 Ga in atmospheric carbon dioxide. The carbon dioxide concentrations were high enough not to maintain the Earth above the freezing point. Our results has given a deeper understanding of the changes on the Earth’s surface environments between 2.8 and 1.8 Ga.

Free Research Field

環境鉱物学