Chemical Sedimentology of Pelagic Clay Minerals Contained in Pelagic Deep-Sea Cherts

通过对冲绳群岛和北海道172块硅质岩及其伴生沉积岩的地球化学分析，揭示了大洋和半大洋硅质岩的某些地球化学特征。除玻璃碎屑岩之上的一些局部基底硅质岩外，远洋硅质岩的特征是Fe和Mg之间具有高度相关性的连续线性图。此外，铁和钾之间的相关性是高的远洋硅质岩。另一方面，半远洋硅质岩的特点是铁，镁，钾之间的相关性差。侏罗纪至白垩纪远洋硅质岩，无论是在CCD以下的深海底层状红硅质岩和作为结节燧石的远洋海山以上的CCD，暴露在伊岛和北海道。在地层序列中，红硅质岩呈单一连续分布。陆地上的这些大洋硅质岩的地层学与现代深海底的大洋硅质岩的地层学有很好的对应关系，无论是在CCD之下还是在CCD之上。

Geochemical analyses on 172 cherts and associated sedimentary rocks from the Okinawa Islands and Hokkaido reveal some geochemical characteristics for pelagic and hemipelagic cherts. Excluding some local basal cherts above the hyaloclastite, pelagic cherts are characterized by a continuous linear plots with high correlation between Fe and Mg. As well, the correlation between Fe and K is high for pelagic cherts. On the other hand, the hemipelagic cherts are characterized by poor correlations among Fe, Mg, and K.Jurassic to Cretaceous pelagic cherts, both as bedded red cherts in the abyssal floor below the CCD and as nodular flints on the pelagic seamount above the CCD, are exposed in the Ie Island and Hokkaido. The pelagic bedded red cherts occur as monotonous and continuous red cherts in the stratigraphic succession. The stratigrap of these pelagic cherts on the land is well correlated with the stratigraphy of pelagic cherts, both as cherts below the CCD and as above the CCD, in modern deep-se floors.