Earth Science Frontiers ›› 2022, Vol. 29 ›› Issue (3): 329-339.DOI: 10.13745/j.esf.sf.2021.12.1

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Cyclostratigraphy of the Devonian/Carboniferous boundary sections in South China

LI Shan1,2(), WU Huaichun1,2,*(), FANG Qiang1,2, XU Junjie1,2, SHI Meinan1,2   

  1. 1. School of Ocean Sciences, China University of Geosciences (Beijing), Beijing 100083, China
    2. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China
  • Received:2021-08-01 Revised:2021-11-20 Online:2022-05-25 Published:2022-04-28
  • Contact: WU Huaichun

Abstract:

The Devonian/Carboniferous transition is one of the most important intervals in Earth’s history characterized by the greenhouse-icehouse transition and mass extinction. To understand this event, an accurate and high-resolution geochronological framework is needed. In this paper, high-resolution magnetic susceptibility is used as the paleoclimate proxy to study the cyclostratigraphy of the deep-water sequences across the Devonian/Carboniferous boundary (DCB) in the Muhua II and Daposhang sections, Changshun County, Guizhou Province, and the Duli section, Nandan County, Guangxi Zhuang Autonomous Region. The sedimentary cycles with thicknesses of 1.09-2.39 m, 0.29-0.73 m, and 0.18-0.51 m were interpreted as short eccentricity, obliquity, and precession cycles, respectively. After astronomical calibration of short eccentricity to 100 ka, the obliquity and precession periods of late Devonian were estimated to be 27.2-32.2 ka and 15-20.9 ka, respectively. The conodont zones and Hangenberg Crisis near the DCB were constrained by the newly constructed astronomical time scale in combination with the published U-Pb radioactive isotope age. The new DCB age, constrained by high-precision cyclostratigraphic correlation among different sections, was estimated to be 359.58±1.9 Ma.

Key words: orbital cycles, Floating astronomical time scale, Devonian/Carboniferous boundary, Hangenberg Crisis

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