Biostratigraphy of conodonts and foraminifers across the boundary between permian and Triassic Systems in calcareous facies.

近年来，日本二叠系和三叠系边界问题的研究主要集中在近岸的远洋至半远洋环境地层中。然而，直到20世纪60年代，我国对钙质相的研究还停留在调查阶段，与国外的研究相比还存在不足。本研究的计划和进行是为了获得关于二叠纪和三叠纪之间边界问题的更先进的知识。在宫崎县的Kamura、Takachiho等地区建立了包括P/T界线在内的钙质相完整剖面；四国Taho石灰岩；岐阜县大垣市赤坂石灰岩；东京奥玉的Gozen-yama石灰岩；枥木县麻生县的苦津石灰岩；北海道滨顿别县函馆的神见石灰岩；北海道附近的Menashidomari。在这些剖面中，我们建立了微化石（主要是小型有孔虫、毛藻纲有孔虫、牙形刺、钙质藻类等）的组织地层，并分析了碳酸盐岩微相的垂直变化。结果表明，白云化相和碳质灰岩的夹层具有P/T边界。这一地层学和沉积学证据表明，与海平面上升回归有关的世界范围的海水地球化学变化发生在边界。

Recent study of the boundary problem of the Permian and Triassic-Systems in Japan has been initiated in strata which were deposited in the off-shore pelagic to semipelagic environments. The study in calcareous facies, however, was remained the result of investigations until 1960's and insufficient compared with the research in foreign countries. The present study was planed and conducted to obtain more advanced knowledge concerning the boundary problems between permian and Triassic Systems.We tried to establish the complete sections in calcareous facies including the P/T boundary in the following areas such as Kamura, Takachiho of Miyazaki Prefecture ; Taho Limestone, Shikoku ; Akasaka Limestone, Ogaki of Gifu Prefecture ; Gozen-yama Limestone, Okutama of Tokyo ; Kuzu Limestone, Aso county of Tochigi Prefecture ; Kamiiso Limestone, Hakodate of Hamatonbetsu of Hokkaido ; and Menashidomari near Hokkaido. In these sections, we establish hiostratigraphy of microfossils (mainly smaller foraminifers, fusulinacean foraminifers, conodonts, calcareous algae, and others) and analyzed vertical change of microfacies of carbonate rocks. As a result, we confirmed the intercalation of dolomitized facies and carbonaceous limestone in strata contain the P/T boundary.This stratigraphic and sedimentological evidence shows that the world-wide geochemical change of the sea water related with eustatic regression occurred at the boundary.