Earth Science Frontiers ›› 2020, Vol. 27 ›› Issue (6): 199-212.DOI: 10.13745/j.esf.sf.2020.6.8

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A review on Ordovician conodont biostratigraphy of the North China Plate and new research advances on its northwestern margin

JING Xiuchun1(), ZHOU Hongrui1, WANG Xunlian1, YANG Zhihua1, FANG Qiang2, WANG Zhentao3, FAN Jie4   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences (Beijing), Beijing 100083, China
    2. School of Ocean Sciences, China University of Geosciences (Beijing), Beijing 100083, China
    3. Ministry of Natural Resources Key Laboratory of Saline Lake Resources and Environments, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
    4. Exploration and Development Research Institute of Huabei Oilfield Company, PetroChina, Renqiu 062552, China
  • Received:2020-03-24 Revised:2020-05-28 Online:2020-11-02 Published:2020-11-02

Abstract:

Conodonts are particularly important biostratigraphically for the subdivision and correlation of the carbonate-dominated Ordovician strata in North China. Studies of Ordovician conodonts from northern China have lasted for nearly half a century and can be distinguished into two stages. Researches in the first stage, from the 1970s to the beginning of the 21st century, were aimed to establish a basic conodont biostratigraphic framework for the paleontological dating and stratigraphic correlation of Ordovician strata in petroleum exploration. Studies in the second stage, from 2010-present, have been focused on the improvements and/or revisions of the conodont zonation established in the first stage in order to connect with international stratigraphic research. Investigations conducted recently on Ordovician conodonts from the northwestern margin of the North China Paleoplate suggested that three stratigraphic intervals with ecological differentiation can be recognized. The first ecologically-specific stratigraphic interval, which covers the middle Darriwilian, is characterized by the presence of conodont taxa inhabiting the marginal areas of tropical carbonate platforms between the North American midcontinent and North Atlantic ecoprovinces. The second interval, with a stratigraphic range spanning from the late Darrwilian to middle Sandbian, features conodonts mainly of North Atlantic affinity and associated with some Australasian species. The third interval, ranging from the late Sandbian to middle Katian, possesses conodont taxa with a mixture of Australasia and North American midcontinent affinities. For an easy and reliable international correlation, recent biostratigraphic studies on Ordovician strata on the northwestern margin of the North China Paleoplate have concentrated on using widespread conodonts as zonal indices, and an updated conodont biozonal succession comprising 12 biozones has been established. They are, in ascending order, (Darriwilian) the Histiodella cf. holodentata Interval Zone, Histiodella kristinae Phylozone, Histiodella bellburnensis Range Zone, Dzikodus tablepointensis Interval Zone, Eoplacognathus suecicus Interval Zone, Pygodus serra Interval Zone, Pygodus anserinus (early form) Interval Subzone, (Sandbian) Pygodus anserinus (late form) Interval Subzone, Belodina compressa Interval Zone, (Katian) Belodina confluens Interval Zone, Yaoxianognathus neimengguensis Interval Zone, and Yaoxianognathus yaoxianensis Interval Zone. However, correlations of some conodont biozones with their international namesakes are still somewhat controversial, hence additional biostratigraphical work remains to be done.

Key words: Conodonts, Ordovician, biostratigraphy, subdivision and correlation, northwestern margin of the North China Paleoplate

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