| Abstract/Notes | China is divided into five Silurian stratigraphic regions on the basis of biostratigraphy and lithostratigraphy. These regions are: Zhungar–Xingan region, Northwest China region, Xizang (Tibet) – western Yunnan region, Yangtze region, and the South China region. Twenty-four graptolite zones are now recognized in the Silurian of China. The earliest Silurian graptolite zones include the persculptus, acuminatus, and vesiculosus zones, characterized by an akidograptid–dimorphograptid sub-fauna; these are followed by the cyphus, gregarius, convolutus, and sedgwickii zones, characterized by a rastritid subfauna. The late Early Silurian zones include the turriculatus Zone with a spirograptid subfauna and the crispus, griestoniensis, and spiralis–grandis zones bearing a streptograptid subfauna. The Middle Silurian is characterized by a cyrtograptid subfauna, which is divided into 10 zones known, in ascending order, as the lapworthi, sakmaricus, insectus, centrifugus, murchisoni, riccartonensis, rigidus?, flexilis, ramosus, and lundgreni zones. The Late Silurian is divided into only three graptolite zones, characterized by a pristiograptid subfauna. They are the nilssoni, tumescens, and transgrediens zones. |
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