CO-OPERATIVE STUDY OF TERTIARY SILICEOUS SHALE FORMATIONS

日本北方新近纪硅质页岩建造是北太平洋地区第三纪硅质沉积的一部分。本文对本州岛东北部青森的硅质页岩建造进行了岩石地层学和微生物地层学（硅藻、放射虫、钙质超微化石、有孔虫和花粉）研究。硅质页岩地层覆盖于中中新世至上新世，其中中中新世分布最为广泛。在青森西部的Ajigasawa地区，中中新世Ohdoji组的底部存在沉积在岸边的海绿石层;黑崎川路线上的7.3 m厚的海绿石层代表3.3亿年。平均积累率约为4500万年/ m或2.2 cm/m.y.在Ajigasawa地区，从中新世中期到上新世，生物硅的平均沉积速率几乎保持不变，为7.3 ~ 9.3 g/cm^2kry，尽管硅质页岩地层的平均沉积速率从中新世中期到上新世有所增加。那里 ...更多信息 因此，硅质页岩地层的不同沉积速率不是由于硅质生物，特别是硅藻的生产力的差异，而是由于陆源物质的流入。峡文anytime.硅质页岩地层的模式显示正常或正的Ce异常，表明强烈的陆地影响。铀含量为1 - 18 ppm，在Aomosri西部大部分为10 ppm，东部小于5 ppm;这些值远低于加州蒙特雷组硅质页岩中的值。在青森的硅质页岩地层中，既没有发现磷岩层，也没有发现磷质岩。在青森南部的秋田组的上中新统黑色泥岩中发现了晚成岩作用的磷块岩结核，在半岛的诺托发现了鸟粪型磷块岩。东北本州岛岛弧和诺托半岛的中中新世硅质和石化硅质沉积物堆积在一个拉长的、上至中半深海盆地中，该盆地是沿日本西海岸沿着形成的。盆地的东侧与北上和阿武熊高原的小块陆地接壤，而其西侧则被海底隆起或陆地所限制，将盆地与新生的日本海的古大和盆地分开。盆地的宽度填充中中新世硅质页岩地层将是200 - 250公里。少

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