The Base of the austrodentatus Zone as a Level for Global Subdivision of the Ordovician System
Edited by Chen Xu and Stig M. Bergström
pp. 1-117, 8 plates, in English
As a contribution to on-going international efforts to establish globally recognizable major subdivisions of the Ordovician System, the base of the U. austrodentatus Zone is proposed as a suitable stage or series boundary. The Huangnitang section near Changshan in Zhejiang Province, China is proposed as a boundary stratotype with sections at Hengtang in Jiangshan and Chenjiawu in Yushan as supplementary stratotypes. Continuous graptolite and conodont successions across the U. austrodentatus interval, as well as key taxa of these index fossil groups, are described from these sections in the Jiangshan-Changshan-Yushan (JCY) area. Global correlation of recognized graptolite and conodont zones, as well as major bioevents, in the Castlemanian to Darriwilian interval are reviewed, and the lithology and depositional environments of the JCY rocks studied are discussed. Recently discovered K-bentonites in the A. suecicus Zone in the Hengtang section in Jiangshan have the potential to yield isotope dates and may be useful for local and regional correlations.
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