2006 Fiscal Year Final Research Report Summary
Paleoecological and paleoenvironmental information decorded from hard substrates ichnofacies
| Project/Area Number |
17540440
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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 | Hokkaido University of Education |
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Principal Investigator |
SUZUKI Akihiko Hokkaido University of Education, Faculty of Education, Iwamizawa Campus, Associate Professor, 教育学部, 助教授 (20235930)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Hard substrate / Paleoecology / Paleoenvironment / Trace fossil / Bioerosion |
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| Research Abstract |
Rock-boring trace fossils are characterized by boring organisms such as bivalves, gastropods, brachiopods, barnacles, polychaete annelids, sponges, bryozoans, etc. In general, these trace fossils are used as indicators of ancient rocky shores, and are useful for reconstruction of pal eoenvironments.
The shallow-marine facies of Hokkaido rich in rock-boring bivalves was deposited during the Miocene. I studied rock-boring bivalves and their clavate borings at two localities in northern Hokkaido. In locality Akebono, basal part of the Sankebetsu Formation unconformably overlies the basement and is composed of fine-grained sandstone. Rock-boring bivalves such as Penitella kotakae and Platyodon nipponica are recognized, and the clavate boring of Penitella, Gastrochaenolites turbinatus, dominated in the basements. This occurrence represent autochthonous, and is presumed to wave-cut bench of ancient rocky shore. In locality Yamato, basal part of the Yamato Formation unconformably overlies the basement and is composed of basal conglomerate. Boring bivalves dominated in clasts of conglomerates, and no occurrence on the basements. Rock-boring bivalves, P sp., and their clavate borings, G. turbinatus, dominated in the clasts. This occurrence represent semi-autochthonous, and is presumed to boulder beach of ancient rocky shore.
The paleoecological characteristics of the molluscan and ichnofossil assembleges in these localities reflect changes in the sedimentary environment during a sea-level transgression. The rocky shores were formed during the transgression events in the Miocene time. Bioerosion on marine rocky surfaces demonstrates to be a very good tool to reveal geological episodes such as relative oscillations of the sea-level, erosion/sedimentation rates and intensity of physical disturbance.
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Research Products
(22 results)
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[Journal Article] Bioerosive structures of Miocene rock-boring bivalves in rocky-shore environments, northern Hokkaido, Japan.2006
Author(s)
SUZUKI, A., HIRANAKA, N., HIKIDA, Y.
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Journal Title
Abstracts, 17th International Sedimentological Congress, Fukuoka, Japan 1
Pages: 277
Description
「研究成果報告書概要(和文)」より
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[Journal Article] Miocene Pectinidae from the Onishika Formation developed in Obira Town of Northern Hokkaido
Author(s)
Akamatsu, M., Hikida, Y., Suzuki, A., Sagayama., T., Soeda, Y., Koshitaka, D., Hiranaka, N., Nojo, A., Togo, Y.
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Journal Title
Bulletin of the Historical Museum of Hokkaido No.34
Pages: 1-20
Description
「研究成果報告書概要(欧文)」より
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