1999 Fiscal Year Final Research Report Summary
Origin and depositional environment of Archean particle-bearing sandstones in the Japanese Islands
| Project/Area Number |
09304048
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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 | 一般 |
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| Research Field |
Geology
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| Research Institution | Nagoya University |
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Principal Investigator |
ADACHI Mamoru Nagoya University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (10113094)
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| Co-Investigator(Kenkyū-buntansha) |
TAKEUCHI Makoto Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (80273217)
YAMAMOTO Koshi Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (70183689)
SUZUKI Kazuhiro Graduate School of Science, Professor, 大学院・理学研究科, 教授 (90111624)
KOJIMA Satoru Gifu University, School of Engineering, Professor, 工学部, 教授 (20170243)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Archean clastic particle / CHIME geochronology / ICP mass spectrometric analysis / Mino terrane / Hida terrane / Shimanto terrane / zircon / monazite |
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| Research Abstract |
Recent CHIME geochronological studies have revealed that the origin of the rocks in the Japanese Islands was as long as ca. 3000 Ma ago, namely during late Archean time (e.g. Suzuki & Adachi, 1991; Adachi and Suzuki, 1993). Since in East Asia, the distribution of the Archean rocks is restricted to part of North China, the Archean clastic particles in Mesozoic sandstones provide important key information as to the birth and tectonic evolution of the Japanese Islands. During these three years of the project, we have carried out the CHIME dating on detrial zircon, monazite, zenotime and allanite, together with ICP mass spectrometric analysis of the Mesozoic sandstones. The dating results have shown that ca. 2000 Ma detrial zircons are common in the sandstones of the Mino, Hida and Shimanto Terrenes, while Archean (older than 2500 Ma) zircons are not common and ca. 3000 Ma zircons are very rare. Although scarce, these rare zircons demonstrate an input of sediment from Archean rocks of northeastern China and Korea. Some fundamental analytical problems with the determination of rare earth elements (REE) that are contained in detrial zircon, monazite, etc. were also addressed.
The origin and tectonic evolution of the Archean particle-bearing sandstones were discussed in the light of the newly obtained chronological and geochemical data, the distribution of the Archean rocks, and the Mesozoic tectonic setting of East Asia.
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