Redox-dependent distribution of early macro-organisms: Evidence from the terminal Ediacaran Khatyspyt Formation in Arctic Siberia

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  • Cui, H.
    • Other Affiliation: University of Maryland, College Park
  • Grazhdankin, D.V.
    • Other Affiliation: Novosibirsk State University
  • Xiao, S.
    • Other Affiliation: Virginia Tech
  • Peek, S.
    • Other Affiliation: United States Geological Survey
  • Rogov, V.I.
    • Other Affiliation: Siberian Branch Russian Academy of Sciences
  • Bykova, N.V.
    • Other Affiliation: Virginia Tech
  • Sievers, N.E.
    • Other Affiliation: Stanford University
  • Liu, X.-M.
    • Affiliation: College of Arts and Sciences, Department of Geological Sciences
  • Kaufman, A.J.
    • Other Affiliation: University of Maryland, College Park
Abstract
  • The Ediacaran Period witnessed the first appearance of macroscopic animal life in Earth's history. However, the biogeochemical context for the stratigraphic occurrence of early metazoans is largely uncertain, in part due to the dearth of integrated paleobiological and chemostratigraphic datasets. In this study, a comprehensive geochemical analysis was conducted on the fossiliferous Khatyspyt Formation in Arctic Siberia, in order to gain insights into the Ediacaran paleoenvironments. This study was designed to specifically address the relationship between paleoredox conditions and Ediacaran fossil occurrences in the Khatyspyt Formation. Our data reveal a dramatic shift in pyrite sulfur isotope compositions (δ34Spyrite) from ca. − 20‰ to ca. 55‰, and this shift is intriguingly associated with the first occurrence of Ediacara-type macrofossils at the studied section, suggesting a possible link between seawater redox conditions and distribution of early macroscopic organisms. Based on multiple lines of sedimentological and geochemical evidence, we propose that the development of oceanic euxinia — which may be widespread in the continental margins due to enhanced oxidative weathering in the terminal Ediacaran Period — may have locally prohibited the colonization of Ediacara-type organisms and resulted in low δ34Spyrite values in the lower Khatyspyt Formation. In the middle and upper Khatyspyt Formation, progressive secular transition from euxinic to non-euxinic and more habitable conditions may have allowed for the colonization of Ediacara-type and other macro-organisms.
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  • Article
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  • In Copyright
Journal title
  • Palaeogeography, Palaeoclimatology, Palaeoecology
Journal volume
  • 461
Page start
  • 122
Page end
  • 139
Language
  • English
ISSN
  • 0031-0182
Publisher
  • Elsevier B.V.

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