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

Shields, GA; Strachan, RA; Porter, SM; Halverson, GP; Macdonald, FA; Plumb, KA; de Alvarenga, CJ; ... Zhu, M; + view all (2021) A template for an improved rock-based subdivision of the pre-Cryogenian timescale. Journal of the Geological Society , Article gs2020-222. 10.1144/jgs2020-222. (In press). Green open access

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Abstract

Thegeologicaltimescalebefore720Mausesroundedabsoluteagesratherthanspecificeventsrecordedinrocksto 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.

Type: Article
Title: A template for an improved rock-based subdivision of the pre-Cryogenian timescale
Open access status: An open access version is available from UCL Discovery
DOI: 10.1144/jgs2020-222
Publisher version: https://doi.org/10.1144/jgs2020-222
Language: English
Additional information: © 2021 The Author(s). This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License (http://creativecommons.org/ licenses/by/4.0/). Published by The Geological Society of London
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10129746
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