抄録
Formation processes of pelagic clays were reviewed in this report, particularly in relation to geochemical characteristics of pelagic deep-sea cherts. Geochemically, both pelagic clays and pelagic deep-sea cherts are characterized by constant Fe/Mg ratios. Two types of pelagic clays/cherts may be recognized according to the Fe/Mg values:(1) the Fe/Mg value for the pelagic clays formed on the mid-oceanic ridge areas, and (2) the Fe/Mg value for the pelagic clays formed off the mid-oceanic ridges and in the abyssal floor. The Fe/Mg values in the pelagic deep-sea cherts are important to reconstruct the paleogeographic condition of ancient ocean floors. Pelagic clays in the modern ocean floor are assumed to be consolidated as pelagic red cherts.
