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Updated: Dec 21, 2025

Sediment Core Extrusion Method at Millimeter Resolution Using a Calibrated, Threaded-rod
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Dating the late Proterozoic stratigraphic record.

Galen P Halverson1,2, Susannah M Porter3, Timothy M Gibson1

  • 1Department of Earth and Planetary Sciences, McGill University, 3450 University St., Montréal, QC, Canada H3A 0E8.

Emerging Topics in Life Sciences
|May 16, 2020
PubMed
Summary
This summary is machine-generated.

The Tonian and Cryogenian periods (1000-635.5 million years ago) saw major evolutionary and climate shifts. This study refines dating for these crucial geological periods, aiding our understanding of early life and Earth

Keywords:
eukaryotic evolutionfossil recordgeochronologygeological time scalestratigraphy

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Area of Science:

  • Paleontology and Geochronology
  • Earth Science and Precambrian Geology

Background:

  • The Tonian and Cryogenian periods (ca. 1000-635.5 Ma) are critical for understanding early eukaryotic diversification, the origin of Metazoa, and Snowball Earth events.
  • Accurate time-calibration of this interval is essential for ordering key biological and climatic events and testing paleoenvironmental hypotheses.
  • These periods are slated for formal definition in the geological time scale, necessitating robust age constraints.

Purpose of the Study:

  • To review methods for dating the Proterozoic time scale.
  • To compile updated age constraints for significant fossil occurrences and geological events during the Tonian and Cryogenian.
  • To develop a new age model for a Tonian composite section in Svalbard.

Main Methods:

  • Review of existing radiometric dating techniques for the Proterozoic.
  • Compilation and synthesis of published age data for key Tonian and Cryogenian markers.
  • Development of a new age model using a composite section from Svalbard, incorporating fossil data and carbon isotope stratigraphy.

Main Results:

  • An up-to-date compilation of age constraints on Tonian and Cryogenian events and fossils is provided.
  • A new age model for an 819-740 Ma composite section in Svalbard offers preliminary age estimates for the Tonian succession.
  • Distinct carbon isotope anomalies within the Svalbard section are identified as potential global correlation and indirect dating tools.

Conclusions:

  • Precise time-calibration of the Tonian and Cryogenian periods is crucial for interpreting major evolutionary and climatic developments.
  • The new age model for the Svalbard section enhances understanding of Tonian paleontology and stratigraphy.
  • Globally correlatable carbon isotope anomalies offer a valuable tool for refining the geological time scale of the late Neoproterozoic.