| Co-Investigator(Kenkyū-buntansha) |
HAMANO Yozo Graduate school of Science, The University of Tokyo, Professor, 大学院・理学研究科, 教授 (90011709)
KAIHO Kunio Faculty of Science, Tohoku University, Associate Professor, 理学部, 助教授 (00143082)
SUZUKI Noriyuki Graduate school of Science, Hokkaido University, 大学院・理学研究科, 助教授 (00144692)
OHNO Terufumi University Museum, Kyoto University, professor, 総合博物館, 教授 (40194245)
KUMAZAWA Mineo School of Science, Nagoya Univerisity, emeritus Professor, 理学部, 名誉教授 (60022571)
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| Research Abstract |
The purpose of this research is to develop analytical methods for efficient data aquisition, to make data base of rock samples and analytical data, and to decode the Earth's environmental history dating back to 4.0 Ga through multidisciplinary approaches. The major results of this study are as follows.
(1) Several "after 5 O'clock machines" has been developed and operated for first order chemical analysis of the obtained samples. Our samples were processed in plates with 400x200x30 mm or 200x200x30 mm in dimension. X-ray analytical microscope, one of the most useful after 5 machines, aquired chemical images of the samples, which were after image processing represented as chemical profiles corresponding to the stratigraphic sequence.
(2) The database we obtained includes (1) chert and banded iron-formation from Isua, West Greenland (3.8Ga), (2) chert and BIFs from Pilbara Blocks with 3.4 Ga in age, (3) the Hamersley BIF (2.4Ga), (4) Bell and Dwyer Lake BIFs (2.8Ga) from Yellowknife Superg
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roup, Canada, (5) the Hearne stromatolites (1.9 Ga) from Canada, and (6) Rastof cap carbonate (ca. 0.7 Ga) from Namibia. In sampling in Canada and Namibia, we used an engine cutter and a handy corer for completely continuous sampling required for the rhythm and event analysis of laminations.
(3) The Cr-enriched layer has been found in banded-iron formation from Isua, Greenland. In order to discuss its origin, the Mn-Cr isotope systematics is applied. A specimen was sent to geochemists in Australia to initiate international colaborations.
(4) As a model for early terrestrial ecosystem, we have been interested in hotspring microbial mats and started joint study with microbiologists. Recently we developed a handy spectrometer, which enabled indentification of photosynthetic microbes in the field. Further, image analysis of temperature and RGB color distribution was performed for an ecological characterization of microbial mats. On the other hand, we proposed a new view of Earth history, "co-evolution of the Earth and life", which argues that the evolution of Earth and terrestrial life is tightly related each other. Special attension has been paid for the origins of photosynthesis, eukaryotes and metazoa and evolution of atmospheric oxygen level. Less
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