本邦白亜系における海成・非海成層の対比

概要

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In various areas of Japan, non-marine sediments (s.l.) of fluviatile, lacustrine, and brackish-water environments are frequently interfingered with marine ones which contain index species of ammonites and other groups. Therefore, the geological age of the former can be determined by that of the latter in terms of the international scale. The result of the correlation on available evidence is shown in three charts (Figs. 1-3), in which ammonites, other marine biota, brackish-water fauna, fresh-water fauna and land-plants are also stratigraphically allocated. Outside the scope of the three charts, the biostratigraphically well subdivided marine sequences of Hokkaido and the Campanian-Masstrichtian sequences of Southwest Japan do contain transported remains (petrified woods, seeds, leaves, pollen and spores) of land-plants in favourable preservation, whose geological ages can also be determined in terms of international scale. On the ground of these results, the evolutionary history of the non-marine faunas and floras can be studied precisely. This would in turn be a foundation for the correlation of the continental deposits in Eastern Asia. This paper is a contribution to the IGCP Project No.58 Mid-Cretaceous Events [MCE].
1982-06-21