| Project/Area Number |
14403004
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 海外学術 |
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| Research Field |
固体地球物理学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TAJIKA Eiichi The University of Tokyo, Graduate School of Science, Dept.of Earth Planet.Sci., Associate Professor, 大学院・理学系研究科, 助教授 (70251410)
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| Co-Investigator(Kenkyū-buntansha) |
TADA Ryuji The University of Tokyo, Graduate School of Science, Dept.of Earth Planet.Sci., Professor, 大学院・理学系研究科, 教授 (30143366)
ISOZAKI Yukio The University of Tokyo, Graduate School of Science, Dept.General Systems Studies, Professor, 大学院・総合文化研究科, 教授 (90144914)
HAMANO Yozo The University of Tokyo, Graduate School of Science, Dept.of Earth Planet.Sci., Professor, 大学院・理学系研究科, 教授 (90011709)
NAGAHARA Hiroko The University of Tokyo, Graduate School of Science, Dept.of Earth Planet.Sci., Professor, 大学院・理学系研究科, 教授 (80172550)
OHKOUCHI Naohiko Institute for Frontier Research on Earth Evolution, Researcher, 地球内部変動研究センター, 研究員 (00281832)
KIRSCHVINK J. L. 東京大学, 大学院・理学(系)研究科(研究院), 教授 (10345259)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥13,000,000 (Direct Cost: ¥13,000,000)
Fiscal Year 2004: ¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2003: ¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2002: ¥5,400,000 (Direct Cost: ¥5,400,000)
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| Keywords | snowball Earth / Proterozoic / glacial sediments / glaciation / 氷河堆積物 |
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| Research Abstract |
In this project, we conducted geological surveys of the Huronian Supergroup, Ontario, in Canada to investigate environmental changes during the Paleoproterozoic (mainly, ca. 2450-2200 million years ago). We also conducted geological surveys of the Transvaal Supergroup in South Africa and the Snowy Pass Supergroup in USA for comparison. We took many rock samples from out crops and boring core samples, and analyzed them to investigate variations of color, grain size, chemical composition, and isotopic composition.
We found that concentration of manganese above the uppermost diamictite of the Coleman Member in the Gowganda Formation. We also found that there is concentration of hematite which precedes the manganese anomaly. These evidences suggest that oxygen contents in the atmosphere and the surface ocean should have been high just after the Gowganda glaciation. Considering similar ages (ca. 2222 Ma), comparable amounts of manganese deposited per unit area, and sedimentary sequence (glacial diamictite -manganese and iron concentration -redbed) between the Huronian Supergroup in Canada and the Transvaal Supergroup in South Africa, we infer that these two areas may have recorded the same global events, namely, the snowball glaciation and the oxygen rise at ca. 2222 Ma.
We also investigate variations of carbon isotopic composition of carbonates and organic carbon, mass independent fractionation of sulfur isotopes of pyrites, and paleomagnetism, based on the samples taken from the Huronian Supergroup and Snowy Pass Supergroup. We also study carbon cycle and paleoclimate change during the snowball Earth events using numerical models.
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