2004 Fiscal Year Final Research Report Summary
Joint International Research Project on Free Oxygen and Biomarker on the Early Earth
| Project/Area Number |
14253007
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 海外学術 |
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| Research Field |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | Kagoshima University |
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Principal Investigator |
NEDACHI Munetomo Kagoshima Univ., Fac.Science, Professor, 理学部, 教授 (10107849)
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| Co-Investigator(Kenkyū-buntansha) |
KAKEGAWA Takeshi Tohoku Univ., Sch.Science, Ass.Professor, 大学院・理学研究科, 助教授 (60250669)
NARAOKA Hiroshi Okayama Univ., Fac.Science, Professor, 理学部, 教授 (20198386)
HAYASHI Kenitiro Tsukuba Univ., Earth Science, Professor, 地球科学系, 教授 (40124614)
KATO Yasuhiro Univ.Tokyo, Sch.Eng., Ass.Professor, 大学院・工学研究科, 助教授 (40221882)
NEDACHI Yoko Kagoshima Immaculate Heart Univ., Ass.Professor, 看護栄養学部, 助教授 (80290659)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Archean / microbe / Earth's environment / paleomagnetism / Pilbara / drilling / weathering |
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| Research Abstract |
The objectives of this research are to understand the distributions of Archean microbes in space and in time, to understand in what geochemical environment the microbes inhabited, and to study the geophysical controlling factors on the co-evolution of life and environmenta. In 2004, we drilled another hole to collect the core which cuts through the Tumbiana Formation (2.76Ga). We had failed to obtain this formation in the 2003 drilling project. The American research group (Deep Time Drilling Project) collaborated us in this year's project, along with our collaboration groups of NASA Astrobiology Institute, University of Western Australia and Geological Survey of Western Australia.
After the observation under optic and electron microscope, these cores were examined for the isotopic compositions of sulfur and carbon, and were extracted the organic compounds to examine the chemical fossils of microbes. Archean atmospheric and oceanic environment were discussed from the geochemical data. We
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also focused into paleomagnetism, assumed that geomagnetic field should play an important role to bio-activity.
The obtained results have been presented at international conferences as well as domestic conferences. The number of presentation from 2002 to present have been 21 for international conferences including AbSciCon (San Francisco), IGC (Firenze) and AGU (San Francisco), and 18 for domestic conferences.
One of the chief contribution of this project might shedding light on the history of development of microbes. Out results suggest that iron-bacteria and methanogen might be the dominant microbes around 3.46Ga, and the microbes might become diversified around 2.77 Ga including methanogen, methanotroph, sulfate-reducing bacteria and cyanobacteria. It also suggests that eukaryote inhabited at that era.
The second is the discovery of the oldest geomagnetic field by the Earth's dinamo at 3.46 Ga.. The microbial diversity around 2.77 Ga ago could strongly relates to the increasing geomagnetic field. Less
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