2000 Fiscal Year Final Research Report Summary
The transportation systems of clastic materials on the Earth's surface with reference to the changes of sedimentary system ; -comparison between the modern Japanese Islands and its ancient continental situations-.
| Project/Area Number |
11640449
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | Shinshu University |
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Principal Investigator |
HOYANAGI Koichi Shinshu Univ.Fac.Science, Associate Professor, 理学部, 助教授 (30202302)
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| Co-Investigator(Kenkyū-buntansha) |
ITO Yasuto Osaka Pref.Univ., Coll.Integ.Arts & Sci., Associate Professor, 総合科学部, 助教授 (20285315)
YOSHIDA Kohki Shinshu Univ., Fac.Science, Assistant Professor, 理学部, 助手 (00303446)
KUMON Fujio Shinshu Univ., Fac.Science, Professor, 理学部, 教授 (60161717)
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| Project Period (FY) |
1999 – 2000
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| Keywords | sea-level change / sedimentary sequence / maximum flooding surface / diagenesis / porosity / organic matter / maceral / seismic profile |
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| Research Abstract |
The followings are the results of this research project :
(1) The geological developments of the Gotonada basin since the Pliocene was reconstructed as follows using the seismic profiles.
Rift-formation stage : Under the normal fault systems of NW-SE and N-S directions, rift-valley trending NW-SE direction started to open at the southeastern part of the basin about 4 Ma ago. The topography was an estuary of large river and marine transgression was also started...
Maximum flooding stage : The subsidence became maximum around 3 Ma, and maximum flooding surface was formed at this stage. The normal fault system of E-W trend was active and the E-W direction of rift-valley became prominent. Warm current input caused the high productivity of plankton.
High-stand stage : subsidence of the basin became calm, and the relative sea-level has been kept in high level since 2 Ma to present. But, the delta from the Hikine Peninsula of Kyushu repeated to advance or retreat as controlled by the eustatic sea-level changes. These sediments formed the fourth-order cycles burying the basin.
1. It is clarified that the sandstones of the Paleogene Ishikari Group have some variability in chemistry and texture due to the difference of provenance. Especially, it is important that the pores in the sandstone are mostly originated from solution in diagenetic stage.
2. Organic chemistry effectively indicate the sedimentary environment of marine sediment, on the basis of the Tertiary sediments in the Niigata oil field, a backarc basin.
3. On the basis of the analyses of the Pleistocene sediments from ODP Leg 174A, it became clear that the eustatic sea-level changes have controlled greatly the grain size and sequence style of the sediments on the continental shelves.
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