Japan Geoscience Union Meeting 2016

Presentation information


Symbol B (Biogeosciences) » B-PT Paleontology

[B-PT05] Decoding the history of Earth: From Hadean to Modern

Wed. May 25, 2016 3:30 PM - 5:00 PM 105 (1F)

Convener:*Tsuyoshi Komiya(Department of Earth Science & Astronomy Graduate School of Arts and Sciences The University of Tokyo), Yasuhiro Kato(Department of Systems Innovation, Graduate School of Engineering, University of Tokyo), Katsuhiko Suzuki(Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology), Chair:Shogo Aoki(Graduate School of arts and science, University of Tokyo)

3:30 PM - 3:45 PM

[BPT05-19] The rise of oxygen in the Earth surface at 3.5–3.4 Ga and 2.7–2.2 Ga

*Kunio Kaiho1, Yuki Katayama1, Tomohiro Kawase1, Wladyslaw Altermann3, Martin Van Kranendonk4, Tsuyoshi Komiya2, Ryosuke Saito1 (1.Graduate School of Science, Tohoku University, 2.University of Tokyo, 3.University of Pretoria, 4.University of New South Wales)

Keywords:Archean, oxygen, organic molecules

Great oxidation event (GOE) on Earth occurred approximately 2.3 billion years ago (Ga) based on iron redox state and sulfur isotopes. However, the age of first oxidation of the Earth’s surface is controversial. Presence of small amount of O2 in the environment at 2.5 Ga has been suggested by redox sensitive elements and sulfur isotopes and at 2.7 Ga by nitrogen isotopes. We analyzed hydrocarbon-derived geochemical parameters diagnostic for sedimentary redox conditions, i.e., the pristane/phytane ratio (Pr/Ph), from shallow marine sedimentary rocks in Labrador, Canada, Western Australia, and South Africa. Here, we show that anoxic shallow sea at >3.95 Ga was followed by intermediate conditions at 3.5–2.9 Ga, local oxic conditions at 2.7 Ga, and subsequently global oxidation at 2.6–2.2 Ga. These results indicate that the rise of oxygen in the Earth surface occurred at 3.5–3.4 Ga and 2.7–2.2 Ga.