1996 Fiscal Year Final Research Report Summary
Organic reef frameworks and their geohistory in Paleo-Pacific Ocean
| Project/Area Number |
07640617
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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 | Miyagi Universitry of Education |
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Principal Investigator |
KAWAMURA Toshio Miyagi Universitry of Education, Associate Professor, 教育学部, 助教授 (60186145)
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| Project Period (FY) |
1995 – 1996
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| Keywords | organic reefs / reef framework / Paleopacific Ocean / oceanic seamounts / reef mounds / reef-building organisms / Paleozoic / Mesozoic |
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| Research Abstract |
Carboniferous to Jurassic organic reefs of the Paleo-Pacific (Panthalassa) Ocean were investigated from the viewpoints of internal frameworks reflecting their reef morphology, biotic compositions, and community structure. Time and space distributions and features of Paleo-Pacific reefs were well understood after progressive interpretations of several causes, suggested both by non-biological factors of paleogeographic, paleoclimato-oceanographic and paleo-eustatic controls, and by biological backgrounds of mass-extinctions and evolution of reef ecosystems. The results are summarized as follows :
1)Ancient organic reefs and mounds tend to have been unevenly distributed in the Paleopacific paleogeography. These tendencies were certainly caused by the positions of moving continental blocks in low latitude region and by the dominance of warm ocean-currents and upwellings. Their recent maldistributions were resulted from a tectonic dislocating and traveling of separated oceanic plates.
2)Development of Paleo-Pacific reefs had rise and fall during Late Paleozoic to Mesozoic period. The long-term vicissitudes reflect the changes of ocean current systems and indeed several mass-extinctions and then recoveries.
3)Reefs on seamounts and isolated arc-islands tend to have smaller morphology, firmer framework, and higher bio-diversity than those on epicontinental shelves, influenced not only by their topographic and marine conditions, but also by ocean current systems and eustatic changes.
4)Comparing Paleopacific reefs with Tethyan reefs, more or less differences are present in each geologic period. The important cause of those differences was the location of moving continental blocks and changes of global ocean water circulation.
5)Several reefs of seamounts and arc-islands include unique or peculiar examples which may become a significant evidence for a reef evolution.
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[Publications] Kawamura, T., Iryu, Y., Kawamura, M., Machiyama, H., and Yoshida, K.: "Standard lithostratigraphic succession of the Paleozoic Systems in South Kitakami Terrane and the geologic significance of "Hayachine Tectonic Belt"." The 103rd Annual Meeting of Geological Society of Japan, Excursion Guidebook. 59-97 (1996)
Description
「研究成果報告書概要(欧文)」より
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