Miocene molluscs from the Ichibu Formation in Nishi Island, Oki Dozen Islands, Japan.
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Accession number;00A0264779
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| Title;Miocene molluscs from the Ichibu Formation in Nishi Island, Oki Dozen Islands, Japan. |
| Author;
YAMAUCHI SEIKI
(Shimane Univ., Interdisciplinary Faculty of Sci. and Engineering, JPN)
SAKANOUE HAJIME
(Shimane Univ.)
YOSHIOKA TAKEO
(Aboritekku)
MURAKAMI HISASHI
(Kosumokensetsukonsarutanto)
ISHIKURA HIROMI
(Kyowachikenkonsarutanto)
MAEHAMA AKIO
(Taiyokensetsukonsarutanto)
NOMURA RITSUO
(Shimane Univ., Fac. of Educ.)
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Journal Title;Earth Science
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Journal Code:F0193A
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ISSN:0366-6611
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VOL.54;NO.1;PAGE.33-42(2000)
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| Figure&Table&Reference;FIG.5, TBL.3, REF.35 |
| Pub. Country;Japan |
| Language;Japanese |
| Abstract;The Oki Islands, southern Japan Sea, is a key area for the study of tectonics and middle to late Miocene molluscan fossils. The Ichibu Formation in Nishi Island has been correlated with various Miocene stages in different papers. The upper part of the Ichibu Formation which was previously exposed in only a limited area. New outcrop arising from construction of the Setoyama Tunnel yielded many molluscan fossils. The assemblages of these fossils consist predominantly of Anadara tazawensis, with Kaneharaia kaneharai and Laevicardium shiobarense, and are thus correlated with the Shiobara Fauna. Consequently, the Ichibu Formation can be correlated with the Fujina and Zinzai Formations in eastern Shimane Prefecture. These formations also contain the Shiobara Fauna are estimated to be later Middle Miocene in age. The molluscan assemblages in the Ichibu Formation indicate an upper neritic zone strongly influenced by a cold current. The Ichibu Formation contains a bivalve which we tentatively identify as Mizohopecten cf. nakatombetsuensis. Based on the results of this study and drillcore of a deep well on Naka Island, the Miocene series of the Oki Dozen is divided into the Mita, Otsu, Ichibu and Ama Formations, and succeeding alkaline volcanic rocks, in ascending order. (author abst.) |
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