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Geoscience ›› 2021, Vol. 35 ›› Issue (05): 1343-1353.DOI: 10.19657/j.geoscience.1000-8527.2021.075

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Graptolites from OrdovicianWufeng Formation and Silurian Zhoujiaxi Group in Yiyang, Hunan

HUANG Mo1,2,3(), LI Ming2, YANG Zhenjing1,3(), DENG Liting1,2,3   

  1. 1. School of Earth Sciences, Hebei Geosciences University, Shijiazhuang, Hebei 050031, China
    2. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
    3. Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, Hebei 050800, China
  • Received:2021-02-10 Revised:2021-05-24 Online:2021-10-10 Published:2021-11-04
  • Contact: YANG Zhenjing

Abstract:

In response to the request of the Ordovician Branch of the International Commission on Stratigraphy, and to refine the biostratigraphic correlation across the Late Ordovician-Early Silurian Yangtze-Jiangnan region, we systematically studied the Nanba section (Yiyang, Hunan province) in the Jiangnan slope belt, and graptolites from the Parakidograptus acuminatus biozone at the bottom of the Silurian sequence. The Wufeng Formation comprises black shale, which is integrated with the Lower Formation of the Zhoujiaxi Group, and the sedimentation is continuous without interruption. Based on data of the study area and referenced from domestic and international graptolite literature, 6 genera and 8 species of graptolites were identified, including Parakidograptus acuminatus, Normalograptus elegantulus, Nor. mirnyensis, Metabolograptus persculptus, Neodiplograptus parajanus, Neo. guantangyuanensis, Avitograptus acanthocystus, Petalithus hamus, Streptograptus cyclodontus. On the basis of the obtained graptolite specimens, the Metabolograptus persculptus biozone and the Parakidograptus acuminatus biozone was preliminarily identified. Stratigraphic age of this section was determined to be from the Late Ordovician (Hirnantian) to the Early Silurian (Rhuddanian).

Key words: graptolites, systematic taxonomy, Wufeng Formation, Zhoujiaxi Group, Ordovician-Silurian, Yiyang, Hunan

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