A central tenet of the Neoproterozoic snowball Earth hypothesis is that glaciations ended synchronously. Although this condition is borne out by U-Pb and Re-Os geochronology, the time scale of deglaciation is much less than the intrinsic error of the highest resolution dating techniques, and consequently calibrating the pace and synchronicity of biogeochemical recovery from Cryogenian glaciations remains a challenge. Given the importance of obtaining a globally synoptic view of paleoenvironmental conditions and biological evolution during these extraordinary transitions, robust correlations and chronologies are imperative. Here we extend the negative triple oxygen isotope (∆17O) anomaly previously documented in ca. 635 Ma postglacial cap carbonates to two new paleocontinents, Brazil and Norway. The global footprint of this geochemical signal coupled to its short duration provides a unique time datum that can be used to cross-correlate Marinoan postglacial cap carbonate sequences and track the geochemical evolution of the oceans during deglaciation.

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