• DOI:10.1144/jgs2020-222
• Corpus ID: 236285974

A template for an improved rock-based subdivision of the pre-Cryogenian timescale

@article{Shields2021ATF,
  title={A template for an improved rock-based subdivision of the pre-Cryogenian timescale},
  author={Graham A. Shields and Rob A. Strachan and Susannah M. Porter and Galen P. Halverson and Francis A. Macdonald and Kenneth A. Plumb and Carlos J. de Alvarenga and Dhiraj M. Banerjee and Andrey Bekker and Wouter Bleeker and Alexander T. Brasier and Partha Pratim Chakraborty and Alan Stephen Collins and Kent C. Condie and Kaushik Das and David A. D. Evans and Richard E. Ernst and Anthony E. Fallick and Hartwig E. Frimmel and Reinhardt A. Fuck and Paul Hoffman and Balz S. Kamber and Anton Kuznetsov and Ross N. Mitchell and Daniel Gustavo Poir{\'e} and Simon W. Poulton and Robert Riding and Mukund Sharma and Craig D. Storey and Eva Stueeken and Rosalie Tostevin and Elizabeth C. Turner and Shuhai Xiao and Shuanhong Zhang and Ying Zhou and Maoyan Zhu},
  journal={Journal of the Geological Society},
  year={2021},
  volume={179}
}

• G. Shields, R. Strachan, +33 authors Maoyan Zhu
• Published 11 June 2021
• Geology
• Journal of the Geological Society

The geological timescale before 720 Ma uses rounded absolute ages rather than specific events recorded in rocks to subdivide time. This has led increasingly to mismatches between subdivisions and the features for which they were named. Here we review the formal processes that led to the current timescale, outline rock-based concepts that could be used to subdivide pre-Cryogenian time and propose revisions. An appraisal of the Precambrian rock record confirms that purely chronostratigraphic subdivision would require only modest deviation from current chronometric boundaries, removal of which could be expedited by establishing event-based concepts and provisional, approximate ages for eon-, era- and period-level subdivisions. Our review leads to the following conclusions: (1) the current informal four-fold Archean subdivision should be simplified to a tripartite scheme, pending more detailed analysis, and (2) an improved rock-based Proterozoic Eon might comprise a Paleoproterozoic Era with three periods (early Paleoproterozoic or Skourian, Rhyacian, Orosirian), Mesoproterozoic Era with four periods (Statherian, Calymmian, Ectasian, Stenian) and a Neoproterozoic Era with four periods (pre-Tonian or Kleisian, Tonian, Cryogenian and Ediacaran). These proposals stem from a wide community and could be used to guide future development of the pre-Cryogenian timescale by international bodies.