三重県阿波盆地の第三紀層
スポンサーリンク
概要
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The Tertiary formations distributed in the Awa Basin can be subdivided as follows from the younger to the older. Awa group {Okumakino formation, Hiramatsu formation, Ikegata formation, Makino formation, Nenobi formation. Pre-Tertiary basement of gneiss and granite The Awa group comprises conglomerate, sandstone, siltstone, tuff and other tuffaceous rocks ; and shows one sedimentary cycle. The geological structure of the about 400 meters thick Awa group is homoclinal with general southward low dip. Sedimentary structures such as pull-apart and broken layer were observed, especially the former type in the Makino formation and both in the Okumakino formation situated in the uppermost part of the group. The molluscan fauna collected from the group is noteworthy in having such characteristic early Miocene species as, Acila yanagawaensis NOMURA and ZINBO, Patinopecten kimurai (Yokoyama), Lucinoma otukai Hatai and Nisiyama, Dosinia chikuzenensis Nagao, Nassarius nakamurai Kuroba, Euspira meisensis (Makiyama) , and Turritella oyasio Ida, etc. Another feature of the molluscan fauna is the rather abundant number of undescribed species and the large size of certain forms. The fossils are of neritic origin and indicate a warm thermal condition. Judging from the fossils above mentioned, the Miocene age of it is without doubt and it may be considered that the age is early Miocene in a two-fold divisions of the series. Judging from both the molluscan fauna and lithologic characters the Awa group can be correlated with the Isshi group distributed on the east side of the Suzuka mountain range.
- 東北大学の論文
- 1960-05-05