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Late Ediacaran Hyperactivity Period: Quantifying the Reversal Frequency

Authors
  • Levashova, N. M.1
  • Golovanova, I. V.2
  • Rud’ko, D. V.3
  • Danukalov, K. N.2
  • Rud’ko, S. V.1
  • Sal’manova, R. Yu.2
  • Sergeeva, N. D.2
  • 1 Geological Institute, Russian Academy of Sciences, Moscow, 119017, Russia , Moscow (Russia)
  • 2 Institute of Geology, Ufa Federal Research Centre, Russian Academy of Sciences, Ufa, 450077, Russia , Ufa (Russia)
  • 3 Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, 123242, Russia , Moscow (Russia)
Type
Published Article
Journal
Izvestiya, Physics of the Solid Earth
Publisher
Pleiades Publishing
Publication Date
Mar 01, 2021
Volume
57
Issue
2
Pages
247–256
Identifiers
DOI: 10.1134/S1069351321020026
Source
Springer Nature
Keywords
License
Yellow

Abstract

Abstract—The previous paleomagnetic studies of the Upper Vendian Zigan Formation sediments on the western slope of Southern Ural revealed uncommonly numerous magnetic polarity zones (Bazhenov et al., 2016). The dating of magmatic zircons from the tuff interlayer constrained the age of this formation to 547.6 ± 3.8 Ma. The rate of reversals estimated from most general considerations is about 20–30 per Myr which is approximately two to three times higher than the highest reversal frequency in Phanerozoic. In this work, a more accurate estimate of the rate of reversals is obtained from cyclostratigraphic study of the lower red-rock part (74 m) of the Zigan Formation in its continuous section along the Sterlitamak–Magnitogorsk road—the longest one among those previously studied by the paleomagnetic method. The correlation of the detailed cyclostratigraphic studies with the magnetostratigraphic column allowed a more reliable estimation of the reversal rate. The studied section in which we identified 20 reversals was accumulated during 1.6 Myr, i.e., the reversal frequency in this interval was 12–13 per Myr. Our quantitative assessment shows that the previous studies overestimated the geomagnetic reversal frequency by a factor of two. However, even the reversal rate estimated in this study can be regarded anomalously high, and the previous conclusions about the existence of a period with anomalously frequent reversals in terminal Ediacaran 547.6 ± 3.8 Myr ago can be considered validated.

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