1997 Fiscal Year Final Research Report Summary
Growing mechanism and succession of reef-building organisms of the Akiyoshi Organic Reef Complex
| Project/Area Number |
08640595
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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 |
Stratigraphy/Paleontology
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| Research Institution | University of the Ryukyus |
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Principal Investigator |
NAGAI Koichi University of the Ryukyus, Faculty of Science, Associate Professor, 理学部, 助教授 (30117197)
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| Co-Investigator(Kenkyū-buntansha) |
SUGIYAMA Tetsuo Fukuoka University, Faculty of Science, Professor, 理学部, 教授 (50131826)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Akiyoshi Limestone Group / Carboniferous / Organic reef complex / Fossil reef / Reef-building organisms / Paleoecology / Paleoenvironment / Limestone |
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| Research Abstract |
The investigators carried out field researches in Chojagamori area and the Minami-dai Quarry of the Akiyoshi Limestone in 1996 and 1997. About 50 sheets of polished limestone slabs and nearly 300 thin sections of reef-building fossils have been prepared and analyzed for this investigation. The results are as below :
1.The litho-and biofacies of the reef forming limestones of the Middle Carboniferous part of the Akiyoshi Limestone Group are classified into about 30 types which represent individual characteristics of the different microenvironments in the reef complex.
2.Rugose corals, encrusting algae, chaetetids and encrusting bryozoans are the most important reef-builders in the Akiyoshi Organic Reef Complex in Middle Carboniferous time. These main reef-builders are flexible in their assembleages and growth forms in the reef complex, and form 11 types of frameworks consequently.
3.The Carboniferous part of the Akiyoshi Limestone Group includes paleokarst structures, providing evidences of subaerial exposure during regressive event. Geomorphological changes of the reef complex affected by the sea-level changes are estimated as bellow :
(1)In a stage of the transgression, an atoll with slender organic rim and deep lagoon was formed.
(2)In a stage of the stable sea-level, an stoll with a broad reef flat zone was formed as prograding growth occurred in the reef front zone. If the sea-level supported a stable condition, filling-up sedimentation in lagoon was proceeded rapidly.
(3)In a stage of the regression, the reef flat was changed to an island and new reef framework was built just below the new sea-level.
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Research Products
(6 results)
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[Publications] Ueno, K., Nagai, K., Nakornsri, N and Sugiyama, T.: "A new Moscovian forminiferal fauna from Huai Luang, east of Wang Saphung, Changwat Loei, Northeast Thailand." Jour.Southeast Asian Earth Sciences.vol.14, nos.1/2. 79-89 (1996)
Description
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