有孔虫化石群からみた日本の古第三系

• Main Author: 浅野 清
• Format: Report
• Language: Japanese
• Published: 東北大學 1962
• Subjects: Planktonic foraminifera
• Online Access: http://hdl.handle.net/10097/33151; https://tohoku.repo.nii.ac.jp/?action=repository_uri&item_id=13024; https://tohoku.repo.nii.ac.jp/?action=repository_action_common_download&item_id=13024&item_no=1&attribute_id=18&file_no=1

There have been many discussions concerning the Danian, whether it is Cretaceous or Paleogene. The problems are not discussed or documented in this paper, but the modern tendency is to place the Danian at the base of the Paleogene, because of the distinct faunal break-disappearance of Cretaceous Globotruncana and appearance of Tertiary Globigerina-at the base of the Danian. Such Danian planktonic foraminiferal assemblage was first found in the Cretaceous formation of Nemuro, Hokkaido. Asano reported on the occurrence of Globigerinoides sp. (cf. G. trilocauhnoides Plummer), Globigerina pseadobaalloides Plummer, Globigerina daubjergensis Bronnimann, Globigerina corn ressa Plummer associated with many benthonic Foraminifera from the Choboshi formation at Ochiishi, Nemuro which had been considered to he Upper Cretaceous from the megafossils contained in it. (Table 1) On the other hand, Yoshida who studied the Cretaceous Formainifera from Urahoro, Tokachi-gun stated that the foraminiferal assemblage from the so-called Cretaceous formation near the provincial boundary between Tokachi and Kushiro may be correlated with that of the Paleocene of Venezuela. More recently, Iwamoto reported on the occurrence of Globorotalia pseudonsenardii Belli, a typical Paleocene planktonic Foraminifera, from the Chippomanai formation, south of Akkeshi, which was also previously referred to Upper Cretaceous. Another type of Paleocene Globorotalia was found in the limestone of the Setogawa group, Shizuoka Prefecture by Saito. These evidences suggest that Paleocene (including Danian) deposits are distributed in Japan, although they are local at present, and it is desirable that detailed stratigraphical studies of those areas should be carried out. Well-defined Eocene and Oligocene formations are well developed in many coal-fields of Hokkaido, Kyushu and Honshu, but they are rather limited in occurrence, being of nonmarine or coal-bearing facies in most places. There is another type of Paleogene formations in the Outer Zone of Southwest ...