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 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL6)

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)

5:15 PM - 6:30 PM

[BPT05-P09] Constraints on the surface environments and the ocean biological activities in the Archean

*Yuusuke Nakagawa1, Peng K. Hong2, Kazumi Ozaki3, Eiichi Tajika1 (1.Graduate School of Frontier Sciences,University of Tokyo, 2.The University Museum, The University of Tokyo, 3.AORI, The University of Tokyo)

Keywords:Archean, faint young Sun paradox, anaerobic organism, methane greenhouse effect, 1-D atmospheric chemistry - ocean ecosystem - biogeochemical cycle model

In the Archean, the climate of the Earth may have been warmer than that of today in spite of the lower luminosity of the Sun at that period [1]. The greenhouse effect of methane, in addition to that of carbon dioxide, is considered to have maintained the warm climate [2, 3], however, previous studies do not support the methane flux required for the warm climate [4]. In this study, we developed a coupled model of 1-D atmospheric chemistry – ocean ecosystem – biogeochemical cycle in order to investigate the biogenic methane flux in the Archean. We found that the biogenic methane flux could have been high enough to maintain warm climate if we assume ecosystem composed of multiple anoxygenic phototrophs which uses hydrogen and iron, with acetogen and methanogens, because of the H2–CH2O–CH4 and CO–CH3COOH–CH4 biogeochemical cycles driven by Fe-CH2O-CH4 biogeochemical cycle could amplify the methane production nonlinearly through the recycling processes of organic matters.
[1] Walker et al., 1982, Palaeogeography, Palaeoclimatology, Palaeoecology, 40, 1. [2] Pavlov et al., 2001, Journal of Geophysical Research: Planets, 106, 23267. [3] Haqq-Misra et al., 2008, Astrobiology, 8, 1127. [4] Kharecha et al., 2005, Geobiology, 3, 53.