The acritarchs of the South Chinese Azygograptus suecicus graptolite Biozone and their bearing on the definition of the Lower–Middle Ordovician boundary

Jun LI, Rainer BROCKE & Thomas SERVAIS

en Comptes Rendus Palevol 1 (2) - Pages 75-81

Published on 31 March 2002

In southern China, well preserved acritarch assemblages have been recovered from numerous sections in the Yangtze Platform and the Jiangshan–Changshan–Yushan (JCY) area crossing the interval where the Lower–Middle Ordovician boundary should be defined, i.e., roughly at the base of the Chinese Azygograptus suecicus graptolite biozone. The acritarch taxa Aureotesta clathrata and Arbusculidium filamentosum first appear below the suecicus zone, while the genus Ampullula and the species Barakella felix have their First Appearance Datum (FAD) in the suecicus zone. These latter taxa, that are also present in Baltica and peri-Gondwana, respectively, thus probably indicate the base of the Middle Ordovician.


acritarchs, biostratigraphy, Yangtze Platform, South China, Lower–Middle Ordovician boundary

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