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In view of the study of the three sections in the eastern Yangtze Gorges, located respec-tively at Wangjiawan, Fenxiang and Huanghuachang, Yichang, the assemblage characteris-tics of the seven zones, namely the Dicellograptus szechuanensis zone, Tangyagraptus typicuszone, Paraorthograptus-Diceratograptus mirus zone, Diplograptus bohemicus zone, Hirnantia-Kinnella zone, Glyptograptus persculptus zone and Parakidograptus acuminatus zone from theWufengian to early Longmaxian stages are discussed and correlated with the equivalentzones of the other districts in the world. It is suggested that the Ordovician-Silurian bound-ary might as well be still fixed at the base of the G. persculptus zone and any one among thethree sections could be selected as international stratotype for the Ordovician and Silurianboundary.
In view of the study of the three sections in the eastern Yangtze Gorges, located respec- tively at Wangjiawan, Fenxiang and Huanghuachang, Yichang, the assemblage characteris- tics of the seven zones, namely the Dicellograptus szechuanensis zone, Tangyagraptus typicuszone, Paraorthograptus-Diceratograptus mirus zone, Diplograptus bohemicus zone, Hirnantia-Kinnella zone, Glyptograptus persculptus zone and Parakidograptus acuminatus zone from the Wufengian to early Longmaxian stages are discussed and correlated with the equivalentzones of the other districts in the world. It is suggested that the Ordovician-Silurian bound- ary might as well be still fixed at the base of the G. persculptus zone and any one among the third section could be selected as international stratotype for the Ordovician and Silurianboundary.