105 by Xiaofeng Wang1, Svend Stouge2, Bernd-D. Erdtmann3, Xiaohong Chen1, Zhihong Li1, Chuanshang Wang1, Qingluan Zeng1, Zhiqiang Zhou4, and Huiming Chen1 A proposed GSSP for the base of the Middle Ordovician Series: the Huanghuachang section, Yichang, China 1. Yichang Institute of Geology & Mineral Resources, Yichang, Hubei 443003, China. E-mail:
[email protected] 2. Geological Museum, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark. E-mail:
[email protected] 3. Institut für Angewandte Geowissenschaften, Technical University, Berlin, Germany. E-mail:
[email protected] 4. Xi'an Institute of Geology & Mineral Resources, Xi'an, Shangxi, 710054, China. The Huanghuachang section near Yichang, southern stage), the yet-to-be-named Second stage, the Darriwilian (fourth China meets the requirements of Global Stratotype Sec- stage), and the yet-to-be-named Fifth stage— and two global series— the Lower Ordovician Series and the Upper Ordovician Series—have tion and Point (GSSP) for the base of the Middle Ordovi- thus far been formally ratified by the ICS. Among the remaining cian Series and the yet-to-be-named third stage of the series or stage, one focus is on the investigation and selection of the Ordovician System (or lower stage of Middle Ordovician GSSP for the base of the Middle Ordovician Series, which also is the Series). The conodont succession at the section is com- base of the Third stage. Two biozone levels that appear to have poten- tial for reliable correlation of the base of the Middle Ordovician plete across the Lower to Middle Ordovician series Series have been suggested by the working group of the ISOS: the boundary and several excellent phylogenetic lineages of base of Tripodus laevis conodont Biozone/Isograptus v.