| Project/Area Number |
60303010
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Stratigraphy/Paleontology
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| Research Institution | UNIVERSITY OF TOKYO |
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Principal Investigator |
IIJIMA AZUMA GEOLOGICAL INSTITUTE, FACULTY OF SCIENCE, UNIVERSITY OF TOKYO, 理学部, 教授 (90011501)
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| Co-Investigator(Kenkyū-buntansha) |
青柳 宏一 石油資源開発(株), 技術研究所, 次長
TADA RYUJI FACULTY OF SCIENCE, UNIVERSITY OF TOKYO, 理学部, 助手 (30143366)
OKADA HISATAKE FACULTY OF SCIENCE, YAMAGATA UNIVERSITY, 理学部, 助教授 (80111334)
MATOBA YASUMOCHI FACULTY OF MINING, AKITA UNIVERSITY, 鉱山学部, 教授 (30006663)
TAKAYANAGI YOKICHI FACULTY OF SCIENCE, TOHOKU UNIVERSITY, 理学部, 教授 (70004299)
AOYAGI KOICHI TECHNOLOGICAL INSTITUTE, JAPAN PETROLEUM EXPLORATION COMPANY
西村 年晴 兵庫教育大学, 学校教育学部, 助教授 (00011750)
相田 吉昭 秋田大学, 鉱山学部, 講師 (90167768)
丸山 俊明 東北大学, 理学部, 助手 (70165950)
佐藤 誠司 北海道大学, 理学部, 講師 (30000813)
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| Project Period (FY) |
1985 – 1987
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| Project Status |
Completed (Fiscal Year 1987)
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| Budget Amount *help |
¥5,400,000 (Direct Cost: ¥5,400,000)
Fiscal Year 1987: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1986: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1985: ¥3,200,000 (Direct Cost: ¥3,200,000)
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| Keywords | Neogene siliceous shale formations / microbiostratigraphy / diatom / Radiolaria / average accumulation rate of glauconite bed / average sedimentation rate of biogenic silica / REE pattern / 東北本州弧第三系堆積盆 / 四つ沢層 / 和田川層 / 石灰質ナンノ化石 / 青森県新第三系 / 第三紀珪質頁岩 / 下北 / 蒲野沢層 / 珪藻生層序 / シリカ続成作用 / 夏泊半島 / 鯵ケ沢 |
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| Research Abstract |
Neogene siliceous shale formations in northern Japan are a part of the Tertiary siliceous deposits of the North Pacific region. Lithostratigraphy and microbiostratigraphy (diatom, Radiolaria, calcareous nannofossils, foraminifera, and pollen) of the siliceous shale formations of Aomori, Northeast Honshu have been established. The siliceous shale formations cover from Middle Miocene to Pliocene, of which the Middle Miocene is most widespread. Glauconite bed deposited on a bank exists at the base of the Middle Miocene Ohdoji Formation in the Ajigasawa area of western Aomori; the 7.3 m-thick glauconite bed on the Kurosakigawa route represents 330 m.y. with an average accumulation rate of about 45 m.y./m or 2.2 cm/m.y. In the Ajigasawa area, the average sedimentation rate of biogenic silica had been nearly constant, 7.3 - 9.3 g/cm^2kry, from Middle Miocene to Pliocene, although the average sedimentation rates of the siliceous shale formations increase from Middle Miocene to Pliocene. There
… More
fore, the variable sedimentation rates of the siliceous shale formations are not due to the difference in the productivity of siliceous organisms, in particular diatom, but due to the inflow of terrigenous material. REE. patterns of the siliceous shale formations show normal or positive Ce anomalies, suggesting strong terrestrial influence. The uranium content is 1 - 18 ppm, largely 10 ppm in the west of Aomosri and less than 5 ppm in the east; these values are far less than those in siliceous shale of the Monterey Formation of California. Neither phosphorite beds nor phosphatic rocks have not been recognized in the siliceous shale formations of Aomori. So far as known, some phosophatic nodule of a late diagenesis origin were reported from Upper Miocene black mudstone of the Funakawa Formation of Akita on the south of Aomori and guano-type phophorite was mined in the Noto Peninsula. The Middle Miocene diatomaceous and lithified siliceous deposits of the Northeast Honshu Arc and Noto Peninsula were accumulated in an elongated, upper to middle bathyal basin which was formed along a rift zone on the west coast of Japan. The east side of the basin was bordered by the small landmasses of the Kitakami and Abukuma Plateaus, whereas its west side was limited by a submarine rise or landmass separating the basin from the Paleo-Yamato Basin of the newly-born Sea of Japan. The width of the basin filling the Middle Miocene siliceous shale formations would be 200 - 250 km. Less
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