1999 Fiscal Year Final Research Report Summary
Causation of barrier reefs of the Sekisei Lagoon and fringing reefs of the southern Okinawa Island in the southern Ryukyu Islands on island shelf on the basis of drilling and shallow reflection investigation
| Project/Area Number |
09308003
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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 |
自然地理学
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| Research Institution | University of the Ryukyus |
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Principal Investigator |
KAWANA Toshio University of the Ryukyus, College of Education, Professor, 教育学部, 教授 (60044955)
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| Co-Investigator(Kenkyū-buntansha) |
KAN Hironobu Okayama University, Faculty of Education, Associate Professor, 教育学部, 助教授 (20294390)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Ryukyu Islands / Holocene / Coral reef / Sea-level change / The 1771 Meiwa Tsunami / Typhoon / Coralline boulder |
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| Research Abstract |
Holocene coral reef in Gushichan coast in the southern Okinawa Island commenced to grow upward on the flat surface about 15〜20 m deep about 7600 yrs BP. The first phase of coral reef in Gushichan formed about 6000 yrs BP due to uplifted area. The second one was developed offshore about 4000 yrs BP, then after about 2500 yrs BP the third one was formed offshore. Holocene coral reef in the Sekisei Lagoon started to grow upward on the flat surface about 20〜25 m deep. In the southern Ishigaki Island, the first phase of coral reef was formed about 7000〜6000 yrs BP due to uplift movement. About 5500〜5000 yrs BP, a fringing reef developed in Taketomi Island and patch reef was formed in the inner part of the Sekisei Lagoon. Then about 3600 yrs BP, barrier reef was formed in the outer part of the Sekisei Lagoon. Three phases of Holocene coral reef have been formed in these areas due to uplift movement and sea-level change.
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