Isotope Data

The right side of this composite stratigraphy on Neoproterozoic-subtrilobite Cambrian stratigraphy shows Carbon and Strontium isotope data. When this isotope data is available, it is another means of correlating ages of strata.

The lowermost diverse Ediacaran assemblages from Canadian Mackenzie Mountains correlate with the oldest fauna in Namibia, a rich Ediacaran site that contains beds from the Neoproterozoic-Cambrian boundary.

Correlating and dating Ediacaran fossil sites has been difficult because the fossils are preserved in sandstone. To get the carbon isotope data, the rock has to be a carbonate.

Note the big change in Carbon isotope ratio coinciding with the Varanger glaciation. Tillites, the sedimentary recored of glaciation appear on all continents in the Neoproterozoic.

Figure from GSA Bulletin, October, 1994

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