2014 Fiscal Year Final Research Report
Decoding of the evolution of the early earth in the Hadean
| Project/Area Number |
23253007
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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 |
Geology
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| Research Institution | The University of Tokyo |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
KATAYAMA Ikuo 広島大学, 大学院理学研究科, 教授 (10448235)
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| Project Period (FY) |
2011-04-01 – 2015-03-31
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| Keywords | 冥王代 / 初期太古代 / ラブラドル / サグレックブロック / 地質調査 / 付加体 / プレートテクトニクス / 大陸成長 |
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| Outline of Final Research Achievements |
We performed geological and geochemical works on the Saglek Block, northern Labrador, Canada to decode evolution of the early earth, and obtained some new discoveries as shown below. (1) We found the second oldest rock (3,950 Ma) on the earth, and named it Iqaluk gneiss. (2) The block is underlain by the Nulliak supracrustal rocks and the Iqaluk-Uivak Gneiss, which was intruded into the former; thus the formers are the oldest supracrustal rocks in the world. (3) The formers have imbricate (duplex) structure with ultramafic rocks, mafic rocks and sedimentary rocks in ascending order. (4) The structure and stratigraphy indicate that they are the oldest accretionary complexes, suggesting operation of plate tectonics. (5) Geochemistry of banded iron formation with positive La, Eu and Y anomalies indicates paleoseawater was enriched in Co, Zn and Ni. (6) We discovered organic matter with quite low δ13CPDB values, down to -29.8 ‰ in a clastic rock, providing the oldest trace of life.
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| Free Research Field |
地質学
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