1988 Fiscal Year Final Research Report Summary
The opening of the Sea of Japan and related Neogene events
| Project/Area Number |
61302028
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
地質学一般
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| Research Institution | Kyoto Tachibana Women's University |
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Principal Investigator |
CHIJI Manzo Kyoto Tachibana Women's Univ.,Fac.Literature,Professor, 文学部, 教授 (80110039)
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| Co-Investigator(Kenkyū-buntansha) |
林田 明 同志社大学, 工学部, 助教授 (30164974)
小笠原 憲四郎 東北大学, 理学部, 助手 (20110653)
ITOIGAWA Junji Nagoya Univ., Fac.,Science, Professor, 理学部, 教授 (90022566)
土 隆一 静岡大学, 理学部, 教授 (60021929)
HIROOKA Kimio Toyama Univ., Fac.,Science, Professor, 理学部, 教授 (30029467)
KOIZUMI Itaru Osaka Univ., Coll., Greneral Education, Assoc. Professor (20029721)
NISHIYAMA Susumu Kyoto Univ., Fac., Science, Assoc, Professor (40026802)
TAKAYANAGI Yokichi Tohoku Univ., Fac., Science, Professor (70004299)
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| Project Period (FY) |
1986 – 1988
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| Keywords | Neogene / Opening of Japan Sea / Spreading of Japan Sea / Climatic optimum / Tropical shallow sea / Paleomagnetic data / paleogeographic map / Rotational shift / Southwest Honshu |
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| Research Abstract |
Neogene sequences in various important areas in the main lsland of Japan(Honshu) are correlated by means of datum-planes of some mage-and micro-fossils. Reliable paleomagnetic data-set is compiled to investigate exact timing of shifting of the Southwest and the Northeast Honshu,based on the above-mentioned data of the Neogene correlation
The paleogeographi reconstruction of the Sea of Japan during the time of its opening is attempted in the time-slice of 17Ma, 16Ma and 15Ma. The relationship between the geographic change and the bioevent occured in each time-slice is considered.
In the time-slice of 17Ma, no oceanic crust was exsistent in this area. The Southwest Honshu was rotated back of 47'from its present position around the eular pole at 34'N and 129'E(Eular pole 1). The Northeast Honshu was rotated back of 47'around the eular pole at 44'N and 146'E(Eular pole 2).
The initial opning of the Sea of Japan was recognized in the time-slice of 16Ma. The Southwest Honshu was rotated cockwise of 1' from its position at 17Ma around the eular pole at 37.46's and 83.33'E(Eular pole 3). The Northeast honshu was rotated anti-clockwise of 29' around the eular pole 2. the tropical-subtropical shallow sea was occured in this initial Japan Sea.
The spreading of the Sea of Japan was progressing in the time-slice of 15Ma. the paleogeographic map was drawn based on the estimated paleoposition of the Southwest Honshu rotated clockwise of 25'and the Northeast honshu rotated anti-clockwise of 14'from their positions of 17Ma, around the eular pole 1 and 2, respectively.
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